0:14Welcome to another Lightblade Learning Lab in today’s session we’re going to make a
0:20new addition for this machine now I’ve been advised that quite a few people are
0:27having trouble with their either Bofa, or their Purex filter unit
0:32when they’re cutting MDF the debris and the smoke has been quite heavy and
0:39they’re blocking their filters up quickly I’ve been asked to look at the
0:42possibility of copying somebody else’s pre-filter well I’m afraid that’s in
0:50itself a bit of a challenge because I don’t like copying other things
0:53if there’s a problem I like to think about the problem and try and find a
0:57cost-effective solution so that’s what I’ve done hopefully I’m going to make
1:01a very simple cost effective pre-filter for this machine that will be
1:07easily either replaceable or washable which is the ultimate goal you don’t
1:13have to ever buy new filters what I’m going to do is dive straight in
1:17and cut the pieces then we’ll put them together and see how the thing works, Now I’m making this out of
1:24nominally five millimetre Perspex it’s white Perspex which I just happened to
1:28have some spare of so it’s whatever it is but you could make it out of a five
1:35 millimetre plywood or five millimetre MDF I don’t think it really matters
1:39now I’m using a two inch lens on here and I’m cutting this at maximum power
1:48running I think about eight millimetres a second
1:52well there’s our first pieces cut all the pieces are just falling apart which
1:58is very nice
Transcript for Make Your Own Pre Filter for MDF Fumes (Cont…)
2:01and yeah they fit in there nicely I’m only just about fits on the table I
2:06think it’s about 395 or 398 back-to-front so yeah this is a tight
2:13squeeze to fit this onto the table okay my second piece of material that I’m
2:18going to be cutting is big enough to do the job but it’s a very odd shape as
2:23you can see underneath it so what I’ve done I’ve purposely cut my first piece
2:28out of a nice square item where I can see exactly where it’s going to go and
2:33now what I’m going to do is to register where the start point is and make sure
2:38that this aperture fits over the material so I now know that the
2:45cut is going to fit onto that piece of material there we have the last part
2:50cutting and yes it’s going to come out of that funny shape and there we go
2:54that’s all fallen out nicely
2:57even all those little three millimeter holes
3:03if you’re making it from wood you might well be putting just ordinary wood screws or
3:09some self tappers in these little pilot holes I’m going to tap them m4. Up to now I’ve
3:16purposely been trying to hide what I’m going to do we’re going to start showing
3:21you now how things work now look these two pieces here have got some
3:28interesting cutouts in them these cutouts here are flexible tongues
3:33they’re quite stiff but they do flex and the idea is that that’s these two pieces
3:40click together like this and then they will actually go in the extract tube at the
3:48back there and they’ll go in easily until they reach those little barbs when
3:54I shall have to go and push it in so once the whole thing is assembled that
4:00will sit snugly in there but you’ll be able to take it out so that begins to
Transcript for Make Your Own Pre Filter for MDF Fumes (Cont…)
4:09give you a little bit of a clue as to what I’m trying to do now we’re gonna
4:16build the next part well here are the eight parts that are going to make up this
4:21filter now I need to assemble them in the right manner so I need to start with
4:29that one and as I said these crossover they will poke
4:37through there
4:41like that they are quite loose but that’s because this material can very
4:47anything from 4.5 to nearly 6 milliliters so it’s incredibly difficult
4:53to get these holes to fit perfectly I made the holes four point seven knowing
4:59that quite a lot of this material was undersized but I came across some stuff
5:03that was nearly six mil I think the first thing we do is to pop this piece
5:06on we’ll put it on first and we’ll glue it on from this side so using my PDTG
5:14glue which seems to work extremely well on acrylic now I’m not going to be too fussy
5:20about the glue this time because nobody’s going to see this piece okay so
5:25that’s it sits nicely on my box now I can put just another little bit of glue
5:31along the bottom corners here as well I mean this is an incredibly simple
5:36assembly what we’re now going to do is just drop that on there like that these
5:45are all exactly the same and they just work they way around nose to tail
6:00like that now if i’ve got all these bits designed correctly this bit will now sit
Transcript for Make Your Own Pre Filter for MDF Fumes (Cont…)
6:09on top here and there we go that’s the complete assembly. Now all I’ve got to
6:18do now is to go around and just glue these joints and the whole thing will be mmm
6:28almost finished just give these another few minutes to dry another minute or so
6:37then I can turn the whole thing over and I can finish off the tabs underneath and then
6:45just to make sure it’s nice and really strong I’m gonna run a bead of glue
6:54around the edges and when that’s dry I should do this edge here as well I
7:02should wait for that to fully dry before I assemble the last parts well here we
7:11are next day and I’ve just been and bought what I thought were going to be
7:16the ideal thing to fit on there that’s what I’ve designed and then these things
7:20which are standard computer filters the day plan was to just stack nine of those
7:29up but now that I’ve got them and I take them apart and have a look at the
7:36filter material look you can see it’s probably pretty next to useless it’s
7:44probably fine for taking lumps of sugar out of the air but not for very fine
7:49particles of MDF smoke so plan A in the bin but fortunately I always did have a
8:01plan B when I designed this but Plan B involves making a few more pieces now I
Transcript for Make Your Own Pre Filter for MDF Fumes (Cont…)
8:09didn’t have enough material to make that in one piece so I have to make it
8:15in two pieces but what we’re going to do is we’ve got these extra pieces as well
8:29so let’s make sure we get them all the same way because there’s a long end and
8:33there’s a short end as you can see so I need all the long ends working the same
8:38way so that I can put them in long end log in that way we should just turn that
8:48over and assemble at the other way because I can’t glue it this way okay so
8:57now we’ll just pop some glue on those and get that held together now the most
9:02important thing at the moment is probably these joints here because
9:07goodness me that’s raining outside now I can just hear it
9:14so I should just hold those two joints together
9:23just make sure they press together and then I should be able to just gently put
9:32a little bit of stuff along those joints there to get those to bond together
9:42right so now that we’ve got that upside down or just do what we normally do and
9:47just run round all these joints here just to make sure that we’ve got them
9:53nice and strong well okay what’s it cost us so far
10:00some design time and either some MDF and maybe a few screws now screws are
Transcript for Make Your Own Pre Filter for MDF Fumes (Cont…)
10:08the interesting thing because I happen to have some very nice M4 plastic
10:14screws which is why I designed these holes with M4 just look I’ve got a bag
10:19of these that’s been kicking around for about twenty years so I have to find
10:23useful on sometime when my other filter system failed I went to a store which
10:33I’m sure you’ve all come across called Dunelm
10:36now it’s not the sort of place you’d normally go for engineering equipment
10:41but look what I’ve got for four pound I bought a meter and it’s material that
10:53they use for quilting but look it’s absolutely amazing it’s exactly what
11:01we’re looking for by way of a filter material and I’ve got all this a meter
11:09of it for four pounds so that’s the only real cost of this project and I’ve got
11:18enough there to make probably six filters or replace the filter that’s in
11:24here six times whichever way you like to look at it so I don’t think it has to be
11:28cut all that accurately because it’s sufficiently flexible that
11:31it’ll push inside my frame here and if it doesn’t I’ll just trim it off looks
11:37like that might need a little bit of a trim but no big deal now I’ve made this
11:52dimension here 10 millimeters thick but this looks to be about probably 12 to 15
11:56millimeters thick so it will squash down you’ve only got to increase this by
11:59another 10 or 20 millimetres and you can put three or two thicknesses of this
Transcript for Make Your Own Pre Filter for MDF Fumes (Cont…)
12:04material in there I mean it’s just literally almost invisible to airflow
12:09what I have to do is just trim the corners off just to clear my screws I think I’m
12:19only going to need the four corners to hold this on and my over-enthusiastic
12:25use of holes is not in the least bit necessary that works perfectly okay with
12:32just four corner screws now what you’ve got to remember is that each one of
12:36these holes is the same size as the extract duct so the velocity of air or
12:43volume of air through these holes will be 1/9 of what it is down the extract
12:49duct so there’s virtually no air resistance through this filter at all so
12:53because there’s so little pressure loss across here you won’t need an additional
12:58extract motor you can use the fan that’s already there which is why this will
13:02just disappear in the machine and it will be seamless now this is so
13:06relatively cheap to make you could technically have two of these so that
13:11one of them is in your machine and the other one is out being replaced but it’s
13:17only going to take what, 20 minutes to take this out of the machine and put a new
13:21filter in it? okay well let’s take a look in the machine and see where we’re going
13:27to fix this now you had a bit of an idea because you saw me trying this little
13:32piece at the back here this is very asymmetric so we’ve got to fit it in one
13:36way only and it goes in this way but we have to be careful because at the top
13:42here there’s a bit of a ridge and so what
13:46I’ve got to do I’ve got to put it in basically flat like that get it beyond
13:50the ridge and then tip it upright and that will then get me past this belt
13:57there we go – clicked into place and you can now see the reason where I’ve got that little
Transcript for Make Your Own Pre Filter for MDF Fumes (Cont…)
14:08foot there just to keep it level we’ll just turn the extract system on to make
14:13sure that the filter doesn’t go off and suck in
14:26now I’m just going to do a 25 millimeter test square on some it’s it’s hard board
14:32which is sort of MDF type material
14:47we can see the fumes being drawn backwards
15:07that cut can go a lot faster because it smells smoky
15:12it smells smoky and it looks smoky and look it’s leaving marks on my hand
15:19just clean my fingers
15:25still a little bit
15:28but not as bad
15:33just try pushing it a little bit more 22 maybe or 24 lets try 24
15:42it hasn’t dropped out but it will pop out
15:49and now let’s try a clean finger
15:57there we go 24
16:01maybe it would go to 26
16:06just only just making it, look it’s pushed the bottom out now
16:14so that is not a good cut looks to be about 24 millimeters a second is the
16:19good speed to go for but the whole point there was we’re trying to generate some
16:24smoke now I doubt whether I’ve generated anywhere near enough smoke to see anything on
16:29the filter but let’s have a look I don’t know where it’s come from but
16:35we’ve definitely got some bits of debris on these two here which is approximately
16:42underwear we were dragging the the fumes from so this is something that I think will
16:47have to be field tested by somebody that uses a lot of MDF all day well I hope
16:53you found that another interesting session a practical problem and a
16:58practical solution I’ve enjoyed the design challenge and I think we’ve come
17:03up with something which is very cost effective and simple for virtually
17:06anybody to adapt and fit as I mentioned earlier the drawings will be available
17:11on the Thinklaser website so you can take those drawings and make it fit your
17:15own machine I’m certainly going to be leaving it attached to this machine
17:20because it can’t do any harm whether it’s going to do any good will be for
17:24other people to tell me so until the next session I’ll say cheerio