How to Use a Laser Cutter - Lightblade learning lab 31 make your own pre - Filter for mdf fumes

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