A Video Diary: Learning About Chinese Laser Cutting Technology 03

By Russ Sadler

Introduction

This technically is a video diary of my mistakes and successes as I gradually come to terms with the mysteries of owning one of these little Chinese dragons {Russ’s videos are also considered to be some of the best How to use a laser cutter tutorial videos on the web}. It seems illogical that a diary should have an index. That is something done by historians (after my passing) who have too much time on their hands waiting for history to happen!!!

Russ Sadler - LaserUser Legend Tutorial on how to use a laser cutter
Russ Sadler – LaserUser Legend Tutorial on how to use a laser cutter

However, after being put into a psychological headlock, I have relented and with the help of Gene Uselman who has carefully created the skeleton of this index, I have added pertinent bullet points to each video to help others find elements of interest.

This bullet point index has been made a year into my learning journey when I am older and wiser. It must be remembered at all times that this is a video record of me learning about a technology that is very poorly documented and, in my naivety, I make (what I can now see as) lots of silly mistakes. Where it is appropriate, I warn of my error BUT in the spirit of leaving the work as an unedited record of discovery I leave you to watch ahead to that point where I begin to realize and correct those errors

Thanks for your interest.

Russ                      July 2016

RDWorks Learning Lab 101 ~ 150

101 The Importance of Scan Interval

101 The Importance of Scan Interval
  • Looking at dithered picture as opposed to a greyscale picture
  • How does the laser work with both types of pictures?
  • Design a special coarse resolution picture and set it to 64pixels per inch
  • Calculate the ideal line spacing (interval) for this pitch.
  • Test the pattern at several incorrect pitches to observe effects as well as the perfect pitch.
  • Now take into consideration the spot size capability of the lens you are using
  • Calculate the best dot to dot resolution you can achieve with your lens.
  • Draw a new test pattern to match the resolution of the lens
  • Recalculate a new interval to suit.
  • Stressing the importance of understanding what the smallest spot size your lens is capable of achieving.
  • Choice of material influences the effective spot size
  • How to use a laser cutter tutorial

102 Laser Beam Diameter

102 Laser Beam Diameter
  • Demonstration of how I go about checking the REAL rather than the claimed beam diameter.
  • IMPORTANT. Remove your lens before carrying out this test
  • Start off using mid power about 40 watts and burn to a maximum hole.
  • Set to full power and the burn gets even bigger, indicating that the beam size is not a constant feature, but power related.
  • It was necessary to open the lens down tube to accommodate my beam diameter.
  • Examining the power profile within the beam by burning into a piece of thick acrylic
  • Discussion of the beam power profile
  • Look at the result of the “mode burn” test

103 Gold Mirrors

103 Gold Mirrors
  • An unanswered question about mirrors remained. Real gold is supposed to be naturally 99% reflective.
  • A correspondent has kindly volunteered to coat a set of my lapped copper mirrors with 24K gold so that we can do the FINAL setoff mirror tests.
  • The results were showing about 97% efficiency which is on a par with my polished raw copper mirrors.
  • Final recommendation for mirrors is….. buy molybdenum. They are not very expensive; they are very durable and about 95% efficient.

104 Dithered Graphics Not What They Seem

104 Dithered Graphics Not What They Seem
  • Exploring Dithered graphics.
  • There is a difference between ppi and dpi
  • First you must prepare your picture Photo) n an external program. I use Photoshop
  • Convert coloured pictures to grey scale and adjust tonal range.
  • Change the image to a DITHERED bitmap where the picture is composed purely of black dots of varying density This density variation fools the eye and brain into seeing a grey scale image.
  • Set the scan INTERVAL to match the picture resolution and set scanning parameters
  • I use white card as a nice simple test medium.
  • This is a 600pixels per inch resolution and the scan interval was also set to 600 lines per inch.
  • Run test at various powers and speeds and examine results.
  • What can be causing the 3D effects because this looks like some sort of result you may get from grey scale engraving.
  • Grey scale engraving can only occur if you set the max ad min powers to different values. These results were achieved with max and min equal.
  • The dithered bitmap was run on an inkjet printer to show that the picture was indeed a series of varying density black dots.
  • Now we go into a very detailed analysis of the pictures, finding that we do NOT have a pattern of uniformly coloured dots., but many shades of brown dots and lines.
  • Now follows a long step by step analysis of what may be causing varying power dots
  • Conclusion is that it is all to do with the response time of the beam forming and decaying
  • These findings are a steppingstone into a whole new set of investigations.
  • How to use a laser cutter tutorial

105 How Shapely are Your Bitmap Dots?

105 How Shapely are Your Bitmap Dots?
  • As a consequence of the previous session, several people have commented that the beam propagation time that I was assuming to be result of a cascade of physical atomic interactions, may well be mainly due to the response capability of the HV power supply.
  • To investigate this in more detail I prepare a special set of pixel patterns at a fairly coarse 100 pixels per inch ( easy to calculate with)
  • I set the patterns at various grey levels to investigate the dithering effect when we convert to black dots
  • I am lucky enough to have two completely different machines. I ran these patterns at various speeds on both machines to look at the performance of two power supplies. The physics inside the tubes will be the same so any differences in results must be the power supply performance.
  • Examining the results under a microscope for both machines at extremes of power and speed, shows the Lightblade producing much crisper “dots”
  • It looks as though the decay time is the more significant factor

106 Going Dotty Part 1

106 Going Dotty Part 1
  • Continuing with my investigation into bitmap engraving I realize that I am just scratching the surface of a very complex subject
  • I can produce reasonable pictures onto most materials using luck and experience. However, I now realize that I do not understand exactly what is going on
  • I have created a list of all the factors that I think are important to mastering that understanding A quick preview of this list…the next few sessions?
  • In this session we will start by trying to find out the difference between theoretical and practical lens spot size.
  • My vital USB microscope and measuring graticule.
  • Using white card, and a fixed power pulse I try to establish the smallest practical spot burn for a 1.5” and a 2” focal length lens.
  • Increasing power increases the spot size
  • After tests on a static dot, I design a special pixel pattern (100ppi) so that I can run dynamic tests at various speeds and powers.
  • All results show “sausages” rather than dots
  • I plot the results graphically for each focal length to display how “sausage” width and length varies with speed and power.
  • How to use a laser cutter tutorial

107 Going Dotty Part 2

107 Going Dotty Part 2
  • Does RDWorks do something to my binary picture when it imports it
  • Yes, it adds some grey pixels and can mess with the resolution if you resize the picture.
  • I have designed some special 100ppi special binary bitmaps
  • When I import my pure patterns I find the same grey additions
  • Carry out physical tests on clear acrylic at different speeds and powers to check what effect that grey is having on dot depth/power
  • First amazing observation is that black is NOT a solid line but still a series of dpi dots
  • There are no noticeable differences between dot depths despite the grey colour of some key pixels. So, we conclude that RDWorks is NOT messing with the binary data
  • Summary of photographic results
  • Still more questions to be answered. The offset between left and right scan lines gets bigger as speed increases. Is it the line start or the line end that is being delayed?
  • Back to my pixel pattern to add a shallow cut reference frame round the pattern to act as a static reference to check what is moving as speed increases.
  • It shows that it is the START of each line that is being delayed
  • Experimenting with the USER Backlash setting caused a one-sided offset.
  • The lines can be aligned on one end but not the other….a strange problem. Yet to be investigated further.

108 Going Dotty Part 3

108 Going Dotty Part 3
  • Look at the special 1.5” fl lens I use on the Lightblade machine so that I can do comparative testing with a more responsive power supply
  • My incorrect understanding and misuse of backlash User settings
  • Using the REVERSE INTERVAL to correct scan offsets.
  • Summary of all my dotting discoveries
  • How to use a laser cutter tutorial

109 Joining the Dots Part 4

109 Joining the Dots Part 4
  • Review of REVERSE INTERVAL settings on my China Blue machine
  • Using “beer mat” card as my drawing medium
  • Turn air assist OFF for engraving
  • Changing the picture resolution in RDWorks
  • Using the RDWorks dithering system to get to a DOT picture.
  • Head position set to bottom corner to give scanning UP the page
  • Setting the parameters
  • Slow mo video to see if beam switches off between dots
  • 150 dpi picture turns out remarkably well
  • Double resolution to 300dpi but leave interval at 150 dpi
  • Under the microscope the 150dpi dots and lines look nice and even in tone and good dot definition
  • 300dpi ….not good…..too light.
  • Analysis of different parameters and results
  • The stupidity of trying to get 600dpi to work
  • Testing high resolution asymmetric engraving 600dpi (x),150dpi interval (y) and 400mm/s with 40%power
  • The pseudo grey scale effect that this produces
  • Slow mo of the pseudo gey scale beam intensity
  • Microscope view of the reason why we call it pseudo grey scale It’s TIME regulated greyscale not variable power greyscale
  • Reminder of what the pink beam means
  • Summary
  • How to use a laser cutter tutorial

110 3D Engraving. In depth revisit part 1

110 3D Engraving. In depth revisit part 1
  • The difference between bitmap and vector images
  • Is the dotting information going to be helpful for 3D engraving?
  • Rapid control of machine power is the key to 3D engraving
  • The problem of the tube’s non-linear power characteristic
  • How I have linearized the output
  • Generating a grey scale test pattern.
  • Setting parameters for scanning greyscale
  • Running the same greyscale tests on both my machines.
  • Examination of the results
  • Analysis of the results.
  • Are my peaks due to pixel power?
  • Not all the peaks match my pixel pattern. An interesting question, why not?
  • Increase to 6 times the resolution but there is an exact replication of the pattern Why?
  • Rapidly beginning to conclude there is no relationship between pixels and the peak pattern
  • The same questions and patterns exist with Lightblade patterns.
  • Are my peaks due to stepper motor ? Not sure at present.
  • Trying to guess how 3D is working via RDWorks. Is there a software algorithm that is averaging pixels?

111 3D Engraving. In depth revisit part 2

111 3D Engraving. In depth revisit part 2
  • Choosing a linear range from the tube power graph so that no correction will be required.
  • First test results seem to be showing too much power for the test speed.
  • Reduced power seems to be better. Still, lots of pixel peaks.
  • What does defocussing do? It gets rid of the serious peaks
  • Jump onto engraving a real 3D image
  • 3 passes and the results are very good.
  • Change the resolution from 300 or more down to 100dpi and changing to ash wood
  • Not a good result. Lots of burning
  • Try without air assist. Oops lots of flame
  • Can a fast cut clean it up? Not really. But it does change the background texture from lines to pimples.
  • Detail resolution does not appear to be affected by setting the beam out of focus
  • The suppressed power range seems to work well.

112 Checking those Dots with an Oscilloscope

112 Checking those Dots with an Oscilloscope
  • I plan to use my little USB Pico Scope to see what signals are going into the HV power supply to control the tube.
  • The beam ON/OFF signal is NOT switching pixel pulses on solid black engraving
  • Look at beam switching AND the PWM signal that controls the current flow through the tube
  • No pulses there either!!!!!!
  • OK ……I must admit that all my thoughts about pixel pulses were completely WRONG
  • Let’s check the 3D engraving swatch
  • Wrong again. No pixel pulses.
  • Import the checkerboard pattern into RDWorks and it shows as a mid-grey rectangle
  • The scope pictures show discrete switching for isolated pixels
  • A solid black pattern shows no sign of individual pixels .
  • A dithered picture reveals variable ON/OFF beam switching but constant power
  • 3D engraving signals show beam ON/OFF at beginning/end of scan and varying current throughout the scan caused by the grey scale level.
  • Are we looking at stepper motor pulses causing my phantom pixels?
  • That’s another whole investigation
  • How to use a laser cutter tutorial

113 What the FACULA is going on

113 What the FACULA is going on
  • The controller talks to the tube via the HV power supply via just TWO wires.
  • One to switch the beam ON/OFF and one to set/control the current level.
  • Individual isolated dots can be seen to switch the tube on and off
  • Greyscale can be seen to change the current level according to the grey scale pixel shade
  • What is FACULA?
  • Design a simple grey scale test pattern and demonstrate it working the red and blue wires.
  • Set up the machine to SPECIAL mode and 50%
  • The red signal shows 20khz PWM signal at a constant grey scale current value and the blue signal (which would normally be ON during burning) is switching on and off at 10khz with 50% on and 50% off
  • Reset FACULA to 75%
  • Now the 10khz blue signal is 25% off and 75% on
  • Reset FACULA to 99%
  • Yes, that proves that all FACULA setting is A) switching the normally constant beam on and off automatically at a rate of 10khz. B) Adjusting the % setting changes the ratio of beam on and off time
  • How does this change the beam size?
  • Explanation of how beam exposure TIME is important for determining beam size.
  • Can I replicate this effect with DOT mode?
  • No. Although DOT mode promises dots at 1khz max, I was only able to achieve 750 hz at best.

114 Can we Dither Greyscale images?

114 Can we Dither Greyscale images?
  • This question arose from a dithered file that someone sent me which had also been set for greyscale engraving. Was this someone just ticking all the boxes in ignorance or was there a secret buried here worth investigating?
  • Now that I can use the oscilloscope to view current levels and beam switching we should be able to answer the question
  • Import a colour picture to RDWorks and it automatically turn it to greyscale
  • Dither the picture and close examination displays a picture with 6 grey levels instead of the expected 2 (black and white)
  • We are only running the program as a test, we are not actually engraving a picture
  • First test is normal dithered settings with max min power set the same.
  • As expected, current was constant, and beam on/off was switching to match pixels and pixel groups.
  • Reset power to 10% and 50% and set output direct to generate greyscale engraving.
  • Do we see grey levels in our dithered image? NO!!
  • So, it is confirmed that RDWorks is telling lies when it adds greys to our displayed dithered picture.
  • Starting again with the same picture but this time we dither with GREYSCALE rather than DOTS
  • Now we can see current changes for every pixel, and we have therefore created a greyscale image for engraving
  • Examination of the trace for a speed of 50mm/sec and 120ppi clearly shows the machine is cleanly changing current for EVERY pixel.
  • What happens if we run at 200mm/sec (4 times speed) can the machine still respond?
  • Yes. We can see 1ms per pixel for small grey scale steps
  • How about 400mm/sec
  • Seems too fast, so check at300mm/sec
  • Pixels just about discernible so we should not attempt greyscale at pixel times of less than 0.75ms
  • All looks good at the electronic signal level, but I can only guess what the output power from the tube will look like after those signals have passed through the power supply and the gas physics of the tube
  • After making some assumptions I do a real-world test of a greyscale dithered picture
  • Conclusion. Rubbish ….stick to dot dithering for photo engraving
  • How to use a laser cutter tutorial

115 The Russ Formula for Photo Engraving

115 The Russ Formula for Photo Engraving
  • This formulaic approach has been designed and tested for organic materials such as wood, card, leather, and low formaldehyde content MDF.. It may work on mineral materials but that has yet to be researched.
  • Choose the shortest focal length lens that your machine will take.
  • Choose your material
  • Important to understand the principles of binary dot engraving.
  • The ratio between the dots and the background is paramount for a crisp picture
  • Organic materials have a scorching colour range whereas something like clear acrylic does not. It’s a binary material that engraves white. This is the opposite of burning and hence when working with acrylic you must make the image a negative before engraving .
  • Set your lens to the ideal focal position
  • I have designed a test pattern to help determine the smallest spot size.
  • I use step gauges to set/test the best focus point.
  • Use a magnifier to view your results
  • How to decide on the dot size by using the test pattern.
  • Converting that dot size back to a Pixels Per Inch resolution.
  • Modifying the brightness and contrast of a picture
  • Resizing and setting the resolution of the picture and dot dither.
  • Setting the interval is very important
  • CALCULATE the speed ……DONT guess it
  • Reset the head position in the config system settings
  • Explanation of what happens if you ignore the resolution rules.
  • Testing to find the best power setting
  • Cross flow of air and almost zero air assist is essential
  • Examination of a very good end result.
  • A look at another picture done on the Lightblade machine. One picture done with a 2” lens and a second with a 1.5” lens. Big difference. 1.5” lens wins

116 Super Ultimate Air Assist

116 Super Ultimate Air Assist
  • Can we remove the pulses from the air assist?
  • Making a crude accumulator to act as a pulse killer
  • Result seems successful but when compared to the undamped flow there appears little difference.
  • Look at the circuit diagram for the proposed air assist controller and all the fittings required.
  • A few sessions ago I demonstrated marking stainless steel WITHOUT molybdenum disulphide, so I make a label for my switch using the same technique.
  • Installation of switch, pneumatic pipes, and wiring.
  • Set the Vendor settings to enable the blowing solenoid
  • Everything working correctly
  • With the cycle paused. Set the restricted air flow
  • Test the manual override.
  • Oops I’ve damaged my lens by engraving the stainless label BE WARNED
  • Test of system with a piece of engraving and cutting MDF
  • How to use a laser cutter tutorial

117 Hunting those Phantom Pixels

117 Hunting those Phantom Pixels
  • How did my pattern of pixels get generated if not by pixel generated power pulses?
  • I do believe that the stepper motor is at the root of this issue but that the patterns are a symptom of another problem interacting with the stepper motor.
  • Crude demonstration of stepper /servo motor principles
  • The importance of removing elasticity from a drive system
  • Detail look at the design of the head drive system
  • Sponginess of the rubber timing belt teeth
  • Accelerometer tests were unsuccessful at seeing resonance
  • Can we see system resonance with my crude mechanical resonance detector?
  • Back to using acrylic as a means of detecting beam velocity
  • Carry out a series of reference tests before making changes to the machine.
  • Different belt material. Polyurethane with stiffer teeth and steel cords.
  • Repeat and analysis of the acrylic reference tests
  • Repeat of waggle meter tests and trying to relate stepper sound to the acrylic head velocity patterns
  • We have proved that a rubber belt was producing resonance and that the new belt has narrowed those velocity spikes to a much narrower range.

118 One Piece Tube and Mirror Mount Design

118 One Piece Tube and Mirror Mount Design
  • The design work has already been done for the Lightblade machine but for various reasons has not been fitted
  • This session is all about adapting that design to suit the China Blue machine
  • Examining the various critical dimensions around the machine that will dictate the design.
  • Lots of boring CAD video with explanation for various design decisions.
  • Programming the parts for cutting
  • After doing lots of acrylic cutting of the parts the cooling water temperature is around 41C. Not over worried about the high temperature because power has not decreased.
  • Assembly and gluing the parts together.
  • Using one of the new mirror mounts for mirror 1
  • Adding a red dot pointer to the assembly (the mk7 design.)
  • Assembly complete ready for installation and testing next session.
  • How to use a laser cutter tutorial

119 One Piece Tube and Mirror Mount INSTALL

119 One Piece Tube and Mirror Mount INSTALL
  • Removal of the old clamps and mirror 1
  • Jiggle the new tube mount into place without disconnecting the tube
  • Make some in situ adjustments to miss tubes and wires
  • Put fixing slots into machine
  • Use the red dot pointer to test the alignment of the new mount
  • Demonstration of how simple it is to align the beam onto mirror 2
  • In an attempt to get the beam aligned onto mirror 3 my frustration at the troublesome adjustment system on mirror 2 finally boils over
  • I design and manufacture a new mirror mount for mirror 2
  • Success at mirror 2 !!!!
  • Remove the red dot pointer and set the beam properly with the scorch method
  • Setting the X and Y axis is simple now
  • The importance of setting mirror 3 onto it’s “sweet spot”
  • Aligning the Z axis
  • Summary of the project success.

120 Strange Properties of Acrylic

120 Strange Properties of Acrylic
  • Demonstration of the light pipe principle using a laminar flow water stream to show the beam being turned away from a straight line exactly like fibre optics.
  • Discussion of what might happen when we fire a 60-watt beam through a 1.5” FL lens at the surface of an 80mm block of acrylic
  • Test 1, Wow. Explain what you are seeing. How is this possible?
  • The same tests with a 2” FL lens
  • Observation of the effect of lowering the focal point into the material
  • Discussion about the hot gas cloud the happens as the acrylic evaporates.
  • The gas cloud effect that causes cut striations on the edge of acrylic.
  • The difference between static and dynamic effect on acrylic.
  • How to use a laser cutter tutorial

121 Is this CURTAINS for CURTAINS

121 Is this CURTAINS for CURTAINS
  • Summary of what curtains are is there any way to get rid of them
  • We concluded that the problem was a replication of the timing belt pattern
  • Could it be that a lead screw fixes the problem? Too expensive and complex to implement
  • How about a rack and pinion drive system? No, BUT this triggered a lightbulb moment!
  • Let’s remove the timing belt
  • Let’s reverse the timing belt ….Mad or not ????
  • My temporary smooth roller bracket demonstrates the principle of using the belt almost like a rack and pinion system. and showed that the belt was a fraction too long
  • The Mk2 design was made of steel and fixed a couple of problems identified with the temporary mk1 design.
  • Because the belt has been reversed, the direction of motor drive has also reversed so the vendor properties must be changed to reverse the X motor.
  • Various repeat tests of the curtain parameters demonstrates clearly that the CURTAINS have gone!!!
  • A smug summary of my success

122 Let’s Make a Rotary Engraver

122 Let’s Make a Rotary Engraver
  • This project will be two sessions. The first will be the design and manufacture of a motorless rotary engraver and the second will be testing it.
  • I claim no credit for this design idea, I am just adapting the principle to a more suitable design for my machines.
  • Yet another plug for the benefits of a solid steel table
  • Step by step assembly and gluing the parts together (with tips)
  • Having assembled the frame we now discuss the design of the special wheels that I am making myself.
  • When assembled the wheels did not live up to expectations so I had to design a mk2 design with 2 bearings to remove the wheel wobble.
  • Discussion and step by step assembly of the mk2 wheels
  • Assembly of the live end stops
  • Demonstration of the simple principles of this design
  • How to use a laser cutter tutorial

123 Let’s Test our DIY Rotary Engraver

123 Let’s Test our DIY Rotary Engraver
  • Our first test will be to engrave a biscuit making pattern on a rolling pin
  • Creating the pattern in RDWorks
  • We need a flat surface in the machine to make the device work
  • Adding the pusher bar to the machine
  • Why elastic bands?
  • Understand the max size for your graphic
  • Setting up the rolling pin in the fixture
  • Setting the origin point
  • Success 1 with wood
  • Engraving a glass bottle.
  • Principle of etching glass
  • Tricks for glass engraving that people advocate.
  • I use molybdenum disulphide spray as a heat moderator
  • Choose a suitable photo image and modify it to a sensible resolution based on our previous photo engraving experience
  • Set the rotary device to suit the bottle
  • Set the origin and define the cutting parameters.
  • Check the result. Reasonable 1st attempt
  • Modify picture resolution and parameters for a much-improved 2nd attempt
  • Great first step to exploring glass engraving along with the perfect proving trial for the non-motorized rotary device

124 How can we get Smaller Dots?

124 How can we get Smaller Dots?
  • A simple test pattern
  • Using acrylic to burn an unfocused beam track at different speeds
  • Analysis of the results
  • Examine the beam energy distribution.
  • The effect of the beam depends on the absorption and damage threshold of the material that it is fired at
  • Explanation of why line width changes as speed increases
  • What happens to the beam profile after it has been focused?
  • Can this be used to decrease dot size and improve photo engraving resolutions for “harder” materials?
  • We shall find out as we explore different materials in future sessions.
  • How to use a laser cutter tutorial

125 Hunting for my Sweet Spot

125 Hunting for my Sweet Spot
  • I know that the Lightblade machine has a cut squareness issue when working with thicker materials such as 8,10 and 12mm materials
  • Demonstration and analysis of the problem
  • Rotating the air assist /lens through 90-degree increments shows that the problem remains the in same direction regardless of the lens position
  • Using a red dot laser pointer to show how the focused beam is VERY sensitive to beam alignment
  • What is the sweet spot?
  • Having accurately measured the Lightblade head and drawn a detailed CAD diagram of where the lens axis intersects the mirror, I know that the centre of the inlet port is the correct aiming point to hit the sweet spot.
  • A scorch test on the inlet port shows the beam to be about 1.5mm high.
  • The only way to lower the beam by 1.5mm is to drop the tube down by that amount. Possible, yes, but that runs the risk of upsetting the whole beam alignment.
  • With no vertical adjustment on this head mount I decide to shim the head UP by 1,5mm to catch the beam at the correct position.
  • Using a centring jig, I establish that the Z beam alignment is now central and axially true
  • Back to cutting a test square and evaluating the result
  • Stressing the importance of understanding if the head design sets the sweet spot at the centre of your inlet port. DO NOT ASSUME THE DESIGN IS CORRECT.

126 3D Engraving Is this the FINAL Chapter Part 1

126 3D Engraving Is this the FINAL Chapter Part 1
  • Discussion of the strange links and discoveries that will eventually lead to 3D engraving success
  • Discussion of beam energy distribution.
  • Our beam is NOT a beam of heat but is a beam of LIGHT
  • Energy transfer mechanism…… VERY IMPORTANT
  • Etching stainless with MoS2, then sulphur powder then engine oil
  • Observe the bright white “flame”
  • A chemical reaction is occurring between the stainless and sulphur at very high temperatures
  • White light is not for free . The Kelvin light scale says about 5000C
  • Discussion of how wood burns, sublimating the carbon at something over 3000C
  • Running a test matrix of varying power on MDF at different speeds
  • Review of matrix results for 3 different lenses Trying to find. to determine how we can get a burn free removal of material.
  • Discussion of how to linearize the power characteristic so that we get linearized power burn as we do our 3D engraving
  • Source for 3D engraving images.
  • How to use Photoshop to distort the greyscale levels to allow for the power nonlinearity
  • How to use a laser cutter tutorial

127  3D Engraving is this the FINAL Chapter Part 2

127  3D Engraving is this the FINAL Chapter Part 2
  • Discussion about the best resolution for the picture.
  • Setting the SCAN parameters
  • OUTPUT DIRECT switch must be set for greyscale engraving
  • Multiple passes will be required. On this version of RDWorks as there is no option to run the program multiple times When you read this there may be an updated version that does allow repeats
  • We take a look at a small, simplified matrix burn test pattern
  • The first test with MDF. Pretty granular.
  • Change to acrylic test material and run a matrix test
  • Put the table down by 10mm to try and create a polished final cut.
  • Did I get the calibration adjustment correct or could I make some fine adjustments?
  • Matrix test with white maple
  • White maple is still a bit granular
  • I adjusted the calibration correction, and the results are staggeringly better
  • Back onto acrylic with the revised calibration settings
  • Soft wood proved to be very unsuccessful
  • When the woods are washed, the results are amazing.
  • Admission that running slowly may not be the best parameter. Running faster is actually better
  • Review of what changes I made to get the better results in Photoshop. I.e., revised resolution and tweaked calibration graph.
  • Final test with revised parameters.
  • Comparison of 300 dpi and 600 dpi. With some great results
  • How to use a laser cutter tutorial

128  Are Acrylic Striations Stepper Driven

128  Are Acrylic Striations Stepper Driven
  • Making a crude mechanism to try and get steady (non-step) motion for moving acrylic under a fixed head/beam.
  • The results are abysmal
  • Despite the terrible results it does show up a sort of layering effect with horizontal striations.
  • The horizontal striations are also there for normal stepper motor cutting
  • Restatement of the energy transfer principles yet again.
  • Demonstration of water being boiled by a beam of light
  • Understanding a scientific definition of temperature
  • An explanation of the energy transfer mechanism
  • Proposed explanation for horizontal layer evaporation process within acrylic
  • Possible reason for better striations with the stepper motor.
  • Still more work to do on this.

129 The Mechanics of Wood Cutting

 129 The Mechanics of Wood Cutting
  • Revisiting the burning matrix test with three different lenses
  • Comparing colour and depth of burn.in white maple.
  • Observed depth of cut more with a meniscus lens.
  • Demonstration of wood burning with a blowtorch and that burning effect reducing as the beam moves faster over the wood.ie the energy per unit of time gets less so the damage to the wood gets less
  • Using an unfocused laser beam, we can demonstrate the destruction of cellulose in wood to leave a film of carbon on the surface.
  • The carbon film glows white hot as its temperature rises to 3600 before it turns directly into gas
  • Demonstration of wood removal without burning.
  • Comparing burns prior to and after the lens.
  • Speed and increment have significant effect on cuts.
  • Possible explanation of why cutting with max power as fast as possible produces the cleanest non-charred edge..

130 Engraving anodised Aluminium

 130 Engraving anodised Aluminium
  • Anodized aluminium offers the prospect of high-resolution engraving
  • Description of the anodizing process.
  • What happens to the matrix burn test on anodized aluminium
  • White is caused by evaporating the dye.
  • Testing various parameters and resolutions …not too successful
  • Using SPECIAL MODE engraving seemed to work quite well
  • Using oscilloscope picture to show what special mode is doing.
  • Single dots may not get full power.
  • Beware the dangers of overdriving your tube in special mode.
  • Microscope view of dots done in special mode
  • Comparison with common mode dots
  • Dots done with different lenses
  • To be honest no results looked good with my dot test.
  • Picture comparisons for different modes, resolutions, and powers.
  • Running at 1000dpi seems to give a great result in special mode’
  • A look at the numbers involved to create such an image.
  • The scanning and resolution numbers don’t make sense when you examine the microscope images.
  • Checking the scanning step with a digital calliper.
  • The numbers don’t match but the pictures seem reasonable quality
  • Once the dye has been removed the dot colour is white. Even if you burn the dot again it cannot get any whiter. Thus, unlike organic materials where multiple burns cut deeper and blacker, anodized aluminium is impervious to the effect and appears to be capable of 1000dpi images although in reality that cannot be true.
  • How to use a laser cutter tutorial

131 Dohicky Power Meter Update

 131 Dohicky Power Meter Update
  • Review of power meters and how we measure watts
  • The alternative DIY version
  • The compromise you must accept for the DIY version.
  • A better K type alternative thermocouple
  • Look at the original K type cable.
  • How to modify an existing dohickys to take the new alternative probe
  • Daniel Roberts Arduino version of the e-dohicky.

132  Photo Engraving Mineral Materials Part1

132  Photo Engraving Mineral Materials Part1
  • Review of what minerals are, and the properties required for successful production of dots.
  • Geology lesson….yawn!!!
  • Starting with slate we use a 2” meniscus lens and run a test matrix
  • Also run a matrix test with Special mode
  • Wide range of parameters will work for slate
  • Marble seems quite good
  • Limestone OK but not brilliant
  • Granite seems to produce glass in one of its constituents
  • Quartz, a man-made stone is bound together with some sort of polymer binder and burns black. However, the black brushes away . No good contrast.
  • Cimstone, another quartz, man-made product needs further investigation under the microscope.
  • Review of each material to see if there is a good colour difference to produce a binary image.
  • Slate is the only obvious material that seems capable of picture work.
  • Microscopic view of what happens when you engrave slate. It is not a sharding mechanism but a glass conversion process.
  • How to use a laser cutter tutorial

133 Photo Engraving Mineral Materials Part 2

133 Photo Engraving Mineral Materials Part 2
  • Before starting photo engraving on slate, we must find the smallest dots possible by choosing the best speed and power
  • Microscope pictures help us determine what size dots we have achieved
  • We must set the resolution to match the dot size.
  • Although, again, because this is a binary material you cannot get over burning and it looks as though we can do hi-res pictures when in reality we are fooling ourselves.
  • A look at different resolution results
  • How a bigger picture at lower resolution appears to produce s better picture
  • Testing with higher resolution but at slow speed
  • Comparing hard Chinese slate to softer more expensive Italian slate
  • A comparison with a fine granite. …a poor alternative
  • We rejected man made quartz but there may be a way of exploiting its properties for certain applications
  • Block engraving on green slate and granite will be successful where phots will fail.
  • Photo engraving a piece of white man-made quartz material we rejected earlier. Wow what a surprise.
  • How to use a laser cutter tutorial

134 Max Min Power Revisited

134 Max Min Power Revisited
  • This time of looking at Max/Min power I understand more about the way the machine works and have my little USB oscilloscope to help me see what’s going on.
  •  Look at the scope signals for cutting a normal square with max and min set equal..
  • Look at scope pictures for some “magic” numbers
  •  You can now see that there is a power ramping taking place which is proportional to speed as square drives in and out of each corner.
  • As this first test shows, if the magic number for min power is too low then corners remain uncut
  • Reset min to 10% and problems are almost solved
  • Jump to 20% and all the benefits of min power a lost
  • The range of setting for effective use of this min power is very narrow and will always require you to experiment with the material and lens you are using at the time.

135  Finding and Exploiting Low Energy Density.

135  Finding and Exploiting Low Energy Density.
  • Quick review of matrix burn tests
  • Can we get dark colour for organic engraving without charring?
  • Repeat of the wood burning mechanism by IR light
  • Understanding the difference caused by the high energy density core of the focused beam and the low energy outer part of the beam.
  • We are looking to just scorch the surface with delicate control of power.
  • More matrix tests with 2” meniscus lens, concave side down.
  • Matrix tests with lens flipped upside down and focus reset to 3mm more.
  • Results show the flipped lens has “softer burn characteristic
  • Can we get an even softer beam using special mode ?
  • Demonstration of the surface charring mechanism of a deep cut.
  • Defocusing along with special mode shows great improvement
  • Back to common mode with an out of focus beam but at very low power 13%
  • How to scorch the surface without material removal?
  • Maybe a 2.5” lens flipped will give an even softer beam.
  • More out of focus, decreased power and speed.
  • Finding the optimum speed for scorching
  • Works well for MDF but not for card
  • Faster speed and more defocus for paper is a bit better
  • Great results overall.
  • Demo of almost black depthless logo engraving on MDF

136 Photo Engraving with Lightburn.

136 Photo Engraving with Lightburn.
  • Quick review of how the machine creates single black engraving dots for dithered images.
  • Response time of power supply is key to rapid single dots
  • Summary of what in store for this video
  • Lightburnsoftware.com for 30-day trial
  • Create a scanning offset test program
  • Use this pattern to assess the response time of your HV power supply
  • Step through the Russ Formula with small modifications to allow for the NEW response speed of the power supply
  • Close look at the dot test with 2.5” lens to get the best focus/power/speed.
  • Microscope examination of results comparing different card types for testing
  • Results just mediocre so change to 2” lens
  • Microscope results better but still not good. Swap to 1.5” Lens
  • Much better dots even at 200mm/s so the calculated response of the power supply seems to be proven.
  • Quick look at the Lightburn software and its great features, especially the photo engraving features.
  • Examination of the various dither options available in Lightburn
  • Emphasis on getting the right DOT quality for the material you are using BEFORE you attempt any photo engraving
  • OOPS……Forgot to correct the scan line offset that we used to assess HV power supply response speed. This MUST be corrected, or the dots will be mis-registered line by line and creating a fuzzy image.
  • It is important to set the test speed to that of the scanning speed you plan to use for your image scanning
  • You will need to go to Config, System setting to add the Scanning Reverse Offset factor and then repeat the test until you get near perfection.
  • First picture comparison is pretty good. Just the right tone
  • Further review of factors in Russ Formula to test an increased resolution.
  • Comparison with an RDWorks image.
  • Close examination of all the dither types
  • The magic effect of picture size
  • Microscope examination of the dots for each dither system
  • How to use a laser cutter tutorial

137  Compound Lens Facts and Fiction

137  Compound Lens Facts and Fiction
  • Hi res photo engraving relies on producing VERY small crisp black BURNT dots with our laser technology.
  • Single lenses seem to hit a brick wall at about 0.2mm i.e., 127dpi…..a fairly low resolution
  • A quick look at different lens mounting systems, i.e., in nozzle or tube
  • A look at lens shapes and the reason why a meniscus lens may be the best for producing small dots.
  • Small dots may be produced by just kissing the very high density at the centre of the focused beam, but the chances are there will still be low energy around it to produce a scorch halo.
  • Certain materials cannot be over burnt or scorched.
  • Thunderlaser sell an expensive compound lens assembly claiming to be capable of burning 1000dpi, but I have no idea of the lens combinations used, or the internal spacing configuration
  • I have designed my own special nozzle to experiment with combinations of two different focal length lenses. The principle being to use a 4” lens to reduce the beam size before it passes through a second shorter focal length lens.
  • We are now hunting for the smallest possible clean burnt dot.
  • Using acrylic with my standard dot test to see if we can produce halo-free dots
  • With experimentation with speed and power and a meniscus 2” lens it seems possible to get 0.1 dots (just)
  • Can we find a better result with Special Mode?
  • Yes it seems better, so I use Lightburn to run a 254dpi picture
  • Testing with cast and extruded acrylic the results were disappointing
  • Change to Newsprint dither pattern at 254dpi Results look good
  • Then at 508dpi for pretty good results
  • Move to wood for testing. At 508dpi
  • Slightly different woods and different grain directions create massive final image differences
  • Did I damage the 2nd lens by concentrating the power to a high energy spot?
  • I have not been able to get anywhere near the Thunderlaser 1000dpi claim
  • Challenge to Thunderlaser owners to make 0.025mm dots with their HR lenses.
  • How to use a laser cutter tutorial

138  The Quest for 1000dpi

138  The Quest for 1000dpi
  • Trying to give some visual cues as to exactly what a 0.0254mm dot (1000dpi) looks like.
  • Review of some background tests that I had conducted changing lenses and distances between lenses.. Shorter spacing gave better results.
  • Testing the idea of obscuring the low energy part of the beam and only allowing the higher energy central part to reach the lens.
  • Quick and dirty results with various size orifices indicate the obscuration of any sort does not help get better dots.. The smaller the orifice the worse the dot.
  • More dot tests using acrylic. Results showing great 0.1mm dot consistency.
  • A closer look at newsprint dithering and why it seems to work at twice the predicted resolution for a given dot size.
  • Comparison of picture on different card types. and different dithers and different parameters.
  • The promise of an owner’s Thunder laser lens loan may allow us to solve the claim.
  • How to use a laser cutter tutorial

139  Designing a Compound lens System

139  Designing a Compound lens System
  • In my search for the smallest dot, my normal methodical approach seemed to have been hijacked by progressive small successes.
  • I recognised a pattern of decreasing dot size with decreasing distance between lenses.
  • Review of the Parallax Technology treatise on lenses forces me in another direction .
  • Demonstrating the refraction effect and how Snell had created a law to calculate it. It is the basic principle of how rays pass through a lens.
  • With zero previous experience, how hard can it be to calculate rays for different compound lens configurations?
  • After a few hours some interesting patterns begin to emerge
  • It requires another special nozzle design to house the revised lens configuration.
  • Trying to find the new focal distance and the best parameters by using the dot pattern
  • We are starting to get better dots real 0.1mm diameter or a bit less.
  • Test this new lens with a more demanding picture.
  • This is an amazing image at 254dpi and makes you wonder why you would want 1000dpi?

140 I Forgot to Focus on the ELEPHANT in the ROOM

 140 I Forgot to Focus on the ELEPHANT in the ROOM
  • Upon reflection, maybe there is another way to get a fine dot and that is to filter out all the low energy fuzz at the focal point by grossly exaggerating the spherical aberration rather than cancelling it.
  • Stepping through the thought process and logic for my new direction.
  • Using a meniscus lens as the second lens
  • Lots of test patterns …..very boring but showing some great results.
  • Testing again with the demanding image . Superb results at 363 dpi. (0.7mm)
  • Dot size is king and determines the resolution of the picture, however different materials will give different dot sizes and require different parameters
  • Don’t attempt a picture until you have found the correct focus and parameters with the dot test
  • THE DOT SIZE DETERMINES THE PICTURE RESOLUTION
  • Repeat the picture on acrylic so we need a negative image.
  • Reason for reversing the image
  • Amazing result for acrylic
  • Now to test a piece of glass. Not bad
  • The Mk2 compound lens pushes the dot size to 0.07mm
  • We seem to have proved the principle of exaggerated spherical aberration as a power filter.
  • How to use a laser cutter tutorial

141  Testing More Dotable materials

141  Testing More Dotable materials
  • You can make a 0.2mm dot on most materials but not all materials allow dots as small as 0.1mm or less
  • Main aim is to see how well I can photo engrave on some foil covered PETG and Acrylic
  •  The first sample failed its focus/dot size test and had to be abandoned.
  • Second sample just a bit better so decided to run it at 127dpi
  • A satin finished gold foil scored very highly as did a black woodgrain foil.
  • Silver foil on a white background posed and interesting positive or negative engraving question,
  • Photoengraving test on Formica Wow. Superb at 245dpi
  • Why do we need to chase 1000dpi?
  • How to use a laser cutter tutorial

142   Looking for the 0.05mm Dot

142   Looking for the 0.05mm Dot
  • Recap on the disruptive principles I am pursuing to produce a halo-free dot
  • Explanation of the reason why I would want to put a 1” focal length lens to guide light into a meniscus lens
  • Finding the new focus point and power settings.
  • Measure the ramp line to characterise the lens
  • Measuring the dot test looks as though we can achieve 0.05 dots on acrylic
  • Now to test on anodized aluminium.
  • In the absence of anodized aluminium, I am trying to simulate with black painted marble. Not too successful.
  • Maybe it would perform better on my 1mm thick beer mat card
  • Change of colour as the picture progresses would indicate that the lens is becoming fogged.
  • Lens examination proves that is so.
  • Lens cleaned and colour restored. Comparing the 350dpiresults with our best 254dpi picture still leaves that lower resolution as the best compromise.
  • One final lens configuration produces even better 254dpi results
  • The new combination puts the meniscus lens and the plano convex touching each other.
  • In summary even though a 0.05 dot is achievable on certain materials it is so weak that is not of any real benefit. 254dpiwith 0.1mm dots id the real practical limit and cam produce stunning results.
  • How to use a laser cutter tutorial

143 Acrylic Fest Myths and Truths Part 1

 143 Acrylic Fest Myths and Truths Part 1
  • I have designed a temporary linear non-stepping drive system so that we can create silky smooth head motion for test cutting acrylic
  • The previous attempt was rather crude and misleading.
  • Using a piece of acrylic, I run a speed test. The power is constant so if we get a level bottom cut it proves that we have uniform speed.
  • Breaking the front face of the cut away allows us to see inside that test depth cut. There are obvious striations on the cut face but why when the speed was absolutely constant?
  • Demonstration of the energy density profile of the laser beam and how it is only the low energy outer part of the beam where the liquid phase of acrylic can exist.
  • Demonstration of what appears to be an unexplained and weird property of acrylic. Despite the beam expanding and losing its energy density below the focal point it can drill a virtually parallel hole deeper and deeper into the acrylic
  • It has been suggested that this phenomenon is due to the laser beam being internally reflected (as in an optical fibre)
  • Demonstration of how I think beam drag is generated. Done in discrete steps to simulate the action of a stepper motor you can observe gas/liquid dynamics happening within the cut and the settlement of and cooling of liquid on the wall of the cut to form marks that may be the mysterious striations.
  • Now a look at punching 20ms pulses into a block of acrylic at different distances above and below the focal point.
  • Using a piece of thin card, we can see the high energy core of the beam at the same 20ms pulse, create a 0.2mm diameter hole. That same 20mm pulse creates a 0.5mm hole in the acrylic.
  • Break for a physics summary about how light transfers its benign energy into hear energy by stimulating molecular excitement in the material it impinges upon.
  • A reasonable explanation of the hole difference between burning card and burning acrylic is a gas scouring that takes place around the beam to make the acrylic hole oversize.
  • When the beam moves there is no immediate solid to erode so the cutting action is by definition intermittent. And it is the artefacts of this intermittent NATURAL cutting action that leaves small striations.
  • How do we “hide” these striations? Buy leaving heat in the cut.
  • Lots of cutting tests on cast and extruded acrylic without and with air assist.
  • To try and emulate the high frequency pulsing of “expensive” rf driven machines I am running dot mode to produce pulse cutting.
  • I now fool the machine into thinking it is engraving. That way I can invoke Special Mode where I can use the PWM signal to turn the beam on and off at 20,000times each second. This is a close simulation of an RF driven tube.
  • Looking at all the samples . All have the same fine pattern of striations despite there being no stepper driven cause. There is little difference between with and without air assist. There is a noticeable difference between cast and extruded acrylic, but all have these fine striation pattern.
  • Summary: Those that insist that striations are stepper driven are partially correct BUT take away the steppers and we have clearly demonstrated that there are still natural striations .generated during the cutting of acrylic.
  • How to use a laser cutter tutorial

 144 New Laser Head

 144 New Laser Head
  • Apologies for not continuing with acrylic fest part 2 but decided to remake the head mounting bracket while it was off to refix the belt I had previously removed.
  • Never been in love with the existing head so I have designed my own Mk1 design made from ACRYLIC sheet!!
  • Cutting and assembly of the pieces
  • I even make a new mirror plate from acrylic
  • I have made a set of pre-set lens tubes
  • Mounting the new head
  • Quick re-polish of my copper mirror
  • Setting aids to ensure precision Z
  • But first setting procedure for X axis i.e., mirror 2
  • Having set X axis true to bearing rail we need to move the head (on its adjustment bracket) so that it “catches” the beam onto the target centre.
  • Now comes the VERY important Z axis setting procedure
  • Having set the beam perpendicular to the table We can now adjust the whole head to catch the beam onto the mirror 3 “sweet spot”
  • It is crucial that we set the beam to pass through the axis of the lens.
  • One final check at the 4 corners to sees us requiring small resets in X and Y
  • That in turn requires a final adjustment in Z
  • 1.5” lens cutting 10mm plywood for a final test.
  • Sticky tar residue (condensed fumes) that would normally stick to your honeycomb table
  • Instant table cleaning with acetone
  • Mk1 lens module demonstration
  • Quick review of advantages of the new head design
  • Is this it? Or will there be a mk2?
  • How to use a laser cutter tutorial

145  The 1000DPI Mystery Solved

145  The 1000DPI Mystery Solved
  • I watched a Thunder laser video about how they claim to be making 1000dpi images with their 1000dpi HR lens system
  • I choose a difficult image to process and load into RDWorks
  •  IMPORTANT!! A pixel appears on a computer screen and a dot is what we burn onto a surface The first is defined as PPI and the second as DPI.
  • To get faithful reproduction of the NON-OVERLAPPING pixels on the screen, we must have NON-OVERLAPPING dots also
  • Therefore, if the best dot size you can make is 0.2mm then the resolution for your picture must be 25.4mm/0.2mm=127PPI
  • Choosing dot graphic converts a greyscale image into a binary image with various density dot patterns that fool the eye into mixing white and black to simulate the greyscale that was there before.
  • Now that it is a black dot pattern on a white background we only must copy the square pixels with same size round black dots
  • Ok, lets reset the picture resolution to 1000PPI.. This time we will use Net Graphic to process the picture into a binary image
  • Playing with the conversion parameters as Thunder laser do. We arrive at a picture that we cannot copy. Simply put, the dots in this processing system are various sizes and that cannot be copied by our “one size dot” laser machine.
  • Lots more analysis of the way the Net Graphic system works .
  • We know we cannot burn much better than 0.1 dots on most materials so let’s see what Thunder laser are using for their lenses.
  • They have 3 lenses 4” , Standard ( which turns out to be a 2” lens) and HR.. The 2” claims a dot capability of 0.1mm which without overlapping dots will give 254dpi.. They claim a capability of 500dpi. The HR lens system claims a DOT size of 0.05mm (508dpi) for which they claim phot engraving to 1000dpi (not ppi)
  • Having created their 1500ppi image thunder laser dump you and do not advise you how to set the scan interval because any attempt to scan at other than 1500 lines per inch in Y will result in aliasing patterns
  • This is clearly demonstrated with several pictures at different scan intervals
  • So, the 1000dpi photo engraving claim is misleading and impossible.
  • How to use a laser cutter tutorial

 146 If not 1000DPI is 500DPI achievable

 146 If not 1000DPI is 500DPI achievable
  • Testing of Laser Tiles
  • The importance of having a responsive power supply before attempting dot work
  • Comparing typical response specs from top to bottom of the price range
  • Quick calculation to show that ANY power supply cannot deliver 1000dpi pulses unless you scan at very slow speeds
  • The importance of using the right lens to achieve the smallest dot size, which in turn relies on a critical combination of speed and low power.
  • Microscope pictures of compound lens tests on the Laser Tile
  • Examination of the first test picture at 300dpi to see what success my settings had.
  • Black areas were not as black as they could be more of a grey halo.
  • Just change resolution to 500dpi
  • I draw your attention to the white light emitted during scanning, and indication that the surface temperature is exceeding 2000C
  • Thoughts on how these Laser Tiles are performing their magic. It’s all to do with ceramic wizardry.
  • Proof of the idea by heating the glaze to red hot without it turning black.
  • Microscope pictures of the 508dpi image.
  • Still not black enough, really needs to run slower to allow more power per dot and stay within the power supply response rules
  • Sadly, running at 50mm/s means the stepper motor is setting the head into resonance and .causing strange patterns.
  • How do we unravel this puzzle? By making the lines wider and darker by increasing the power.at 100mm/s from 14% to 16%?
  • WOW!!!! LOST FOR WORDS
  • So 508dpi IS achievable but under very special circumstances.
  • This is truly the brick wall. So where does this leave the Thunder laser claim?
  • How to use a laser cutter tutorial

147  China Blue Head Transplant Part1

147  China Blue Head Transplant Part1
  • Having used the MK1 head very successfully there were many requests for the drawings. Upon reflection and with a 3D model in front of me to, I decided that making special lens capsules was not the right way to proceed because everything was bespoke.
  • Mk2 was required but and would be based on standard lens tube and nozzle technology.
  • Cutting and assembly of the Mk2
  • Note. This design is only suitable for machines with an adjustable table
  • How to use a laser cutter tutorial

Although this design uses standard lens tubes it still requires a special nozzle and modifications to the lens tube.

148  China Blue Head Transplant Part2

148  China Blue Head Transplant Part2
  • Fitting the MK2 head to the machine
  • Demonstration of flex in the head mounting bracket
  • Attempted acrylic replacement bracket turned out to be junk
  • However, without this junk bracket the strange test pattern results I saw earlier on my Mk1 head may have been harder to track down.
  • Continue to set the MK2 head in Z as we have demonstrated with the Mk1 head
  • We now carry out the focus test with the Mk2 head and get even worse wobbly test results
  • The acrylic bracket and the new aluminium bracket are the culprits.
  • Need to design a steel stiffer bracket system.
  • While the bracket is being made I have remade the head so that it is projects a little lower and also bodged a stiffening bracket for the original aluminium system that runs a nice steady dot test.
  • New bracket arrives and is fitted.
  • Go through the Z setting procedure again
  • 2 more days have passed and more thoughts about how you will be able to make this for yourself have been troubling me.. Oh dear, I feel another change is coming!!!
  • Welcome to the Mk4!!!!!!
  • How to use a laser cutter tutorial

It uses a standard UNMODIFIED lens tube system.

149  Let’s Zoom in on Lenses Part 1

149  Let’s Zoom in on Lenses Part 1
  • Review of a bit of lens and beam theory
  • Different lens mounting systems and nozzles
  • Where to buy lenses and what material should I choose?
  • What are those materials used for lenses?
  • Now lots of tests to look at what sort of dots each lens will produce
  • How to use a laser cutter tutorial

View some interesting results under microscope comparing each to an ideal compound lens reference.

150 Let’s Zoom in on Lenses Part 2

 150 Let’s Zoom in on Lenses Part 2
  • This session is all about assessing the % power transmission through the lens
  • Look at the method I am using
  • Look at the calculation strategy I am using to assess transmission efficiency
  • A close look at the gallium arsenide lens very shiny anti-reflective coating makes you wonder if this can be true, surely something so shiny must reflect?
  • An analysis of the results puts gallium arsenide as best performer and a few other surprises.
  • How to use a laser cutter tutorial

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