Acrylic Cutting Myths 

Thanks . That is a great tip.and less agressive than my method of hitting it with a ball pein hammer. You can laser cut thin polycarb (maybe up to 3mm )but it produces horrid brown fumes and leaves a brown edge. It's fine for prototyping but is not a viable production process. For years I have worked with metals but upon retiring and acquiring a laser machine, acrylic is a great substitute for many projects where I would have previously used metal. PET is a reasonable substitute for polycarb in many applications and it cuts much cleaner. Best wishes Russ

Hi Thanks for the thought. I have already been there and tested it. Yes, it works but there are better ways to achieve the same results. You may like to watch this video and specifically at 45:29. I hope I am not appearing to dismiss your comment because that fact two people can indepenently invent the wheel is just the way the world works and is a demonstration of how independant thought works. see ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-79VZjMdfBmI.html

@@SarbarMultimedia No worries about dismissing 😊 I'll have a look at the video you mention, and I guess you've thought about a lot in this domain. I'm grateful you share your knowledge since I'm not going to do these deep investigations you do, but I'm interested.

Hi There was a time when new laser users started with a 40 watt CO2 laser but in the last few years diode lasers have swept new users up with slick advertising and the promise of doing so many things at a budget price and with almost zero knowledge. It is the limited knowledge requirement and the word LASER that captures newcomers imagination. As you have now found out, there are serious material limitations to working with light at 455nm wavelength. Thanks for jumping into my video but this is the wrong place for you to be. I have never been a big fan of diode lasers but just recently I decided that with so many people interested in the technology and so little REAL understanding available,I have decided to disect the technology in detail so that you can do more than fiddle with parameters and watch videos to see what others have achieved by blind experimentation.. If youunderstand the science behind the technology you are using you may be able to gain more form it and make sensible decisions about materials and parameters.. Can I suggest that you search for Diode Lasers...Under the Hood on you tube. Start at number 01 and work through with me. . From all my experience with CO2 and Fiber lasers I have a good backgound knowledge about laser technology, materials and lenses but I am a student when it comes to diodes but I have no interest in the trickery that people use to try to achieve results despite the materials saying "NO!!!". Your problem with clear acylic is typical of the sort of problem people encounter. Your solution is the sort of experimentation that many hav unsuccessfully tried because they fail to undersatnd the basic principles of damaging material with light. The first 3 sessions in my diode series expain the science in simple terms. This may not be scientifically perfect but it's the ideas that are important. Understanding that the laser beam is NOT a beam of heat but a beam of light that has no termperature is a difficult concept to accept when you clearly see that damage is caused by heat. Watch the seies so far and then please ask questions see the first video here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-wermWuSbK4w.html Good luck and welcome to your journey into the world of lasers.

@@SarbarMultimedia I see your point and agree to a large a extent. Though I'm not very experienced in laser cutting I'm not totally ignorant with technology. I've already seen that you have a d diode series but I have still to watch it all. My suggestion was simply an idea that I got when you explain how acrylic is actually "boiled" away, and that this could be utilised even on a diode laser, since some materials and settings produce a lot of heat - some "air jet" with that could possibly make some (probably not very pretty) rough cutting in clear acrylic, but experiments are off course needed, and failure is a very possible outcome 😁

Thanks for the comment . In some instances you are correct that stress induced by cutting can immediately be relased with IPA and cause cracking. Acrylic is a weird material because of the way it cuts (boiling and evaporation like water) The way in which the edge cools down can have dramatic effects on the residual stresses. I am not into production so have no need to make my cuts as fast as possible. so I rarely use air assist as this causes fast cooling of the liquid phase that follows the cut. I have experienced cracking when I first started working with acrylic and in particular I remember wiping a plain sheet of acrlic with IPA. It was not until about a week later that I discovered it was crazed all over so I have never used it on acrylic again.

@SarbarMultimedia yep, I discoveres it the same way. There is for example mirror acrylic material whivh i cut a lot and it needs that active cooling otherwise the mirror film burns at edges. Sometimes i burn with 3m film applied too, so these applicaion need good active cooling for a good cut unfortunately. Interesting that I am supposedly always buying "cast" acrylic on amazon, and apparently it is extruded then... 🤷🏻‍♂️

@@VladOnEarth Hi Vlad The 100% giveaway is the raised edge burr on exrtrded after cutting

@SarbarMultimedia its strange, I dont have raised edge on mines, but other that rhat they do act like extruded. Does the raised edge occur only when unforcused, or does it happen on normal cuts too?

@@VladOnEarth Cut extryde actylic at ant speed and even with air assist and oits thermal properties will always produce a liquide phase on the kerf wall 2 or 3mmfollowing the cut. This will produce a burnished finish undr alsmost ant conditions. Not so cast acrylic. Brelow 5mm iyt is diffucult to hget a burnishe d edge unless you run at 50% speed or less.. I have never seen any extruded acrylic cut without a burr. even thick 8mm stuff.

Hi Keith It's a great question that is nearly impossible to answer without knowing more about your system. You may not have the flexibilty with your lens tube and lens holding system to overcome the problem. The simple principle is to have a large air gap below your nozzle, a large hole in your nozzle, very little air assist flow and a cutting speed that ensures you cut through cleanly with a single pass.. Cutting acrylic is always one of the most dangerous materials for cutting on a CO2 laser.please watch these two videos ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-n54uNRs8Ydk.html and ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-eaz9ZEjwjfs.html This is meant to be cautionary rather than terrifying. Just understand and respect the material. Any upwelling fumes are reheated by the incoming laser beam and can ignite so it is important to either blow them away with CROSSFLOW air or send them out of the bottom of the cut.. As the two videos show, out of sight is not necessarily 100% safe. Here is a short video I did for another guy to show how a big airgap can be used to reduce surface browing on plywood. The same principle applies for acrylic. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-HwVw_TzyGrM.html Please shout again if you need more help Best wishes Russ

Hi Thanks for the commentIf you saw my last video you will have seen my vast collection of acrylic offcuts I have acquired. In 7 years of playing with various thicknesses and colours of acrylic I have never encountered a cracking problem with IPA. However, to be honest, I can't imagine many circumstances when I would have used it.. As you have found out for yourself, there may be a few special products that are more susceptible but the IPA test is not THE definative test that the myth suggests just as the acrylic cement is not a relable indicator of cast or extruded acrylic. The simple raw beam test is a quick and positive indicator and (as in the video) often surprises me. I am sure that others will find exceptions that also crack with IPA, o thanks for sharing your experience. Best wishes Russ

@@SarbarMultimedia When I cut acrylic it gets all the muck from cutting MDF all over it (really should clean the bed), I clean that off by putting it in a tub of IPA. No cracks. Thinking about it I've had mirror crack in all colours, can't remember if normal silver (or gold) mirror does weird stuff but I think it does. I've had clear craze but that was too long ago to remember why.

@@j.f.christ8421 Ah,, so you think its not the cut edge but the general material surface? If so that's not exactly what the myth claims, its supposed to be the stresses caused by cutting that induce the cracks when wiped with IPA. However, that's an interesting finding. Thanks

@@SarbarMultimedia I don't cut much acrylic under 3mm, but I don't recall IPA causing any problems except with the thin coloured mirror. That would suggest it's the coating causing the cracks, not the clear itself cracking. How that would work I don't know. And yes, it cracks at stress points (sharp corners etc), nowhere else. But yes, I've seen IPA crack thin mirror acrylic. Can also eat away the coating in a way that looks like cracks, very odd stuff it seems. Pretty though. I now keep IPA away from mirrored acrylic, this tiny exception might be the source of the myth.

At work we made a bunch of acrylic racks that were cleaned in a machine that sanitized with IPA. We discovered that the racks would only last a few months before they would just fall apart from all the cracks that would form. I think we used extruded acrylic, but I'm not sure. Keep in mind, these racks were being washed once or twice a day 5 days a week, but alcohol definitely had an effect. We were all so glad when that project ended.

Hi This error happens when you stop a program maually/part way through. If you press ESCAPE, it will clear the error and your head will reset to its start position. If it does not then we will need to research further.

@@SarbarMultimedia thanks for getting back I have done a reset and still have the same problem

Hi The The escape/reset buttons will always fix the issue for me but there must be another underlying cause in your case. This error always indicates that there is an unfinished program in the machine that has either been paused or has not finished properly. Let me first check the obvious. There are two USB ports on the side of your machine, one only reads from a memory stick (FAT32 format) and the other reads from yoir PC. They are not interchangeable. Can you save your program to UDISK (save it to a memory stick) and then transfer it to the machine via the UDISK port? An unfinished program will probably also prevent you from loadibg this file to memory.

. Two problems with your thought. First you would have to flip the program and second how would you guarantee perfect alignment with the first cut.

Hi Alan That's an interesting observation. They are both chemically exactly the same but as I demonstrate, the extruded seems to have a lower damage threshold which means it may produce MORE fumes,. That may account for the stronger smell. It's not something I have noticed because when I'm not filming I have the lid closed and my fumes are ripped away by the tornado that blows through my machines.