Epilog 45W won't cut 3/8" acrylic

[Amanda Davis]

Hi all,
After lots of browsing through the forum, trial & error, replacing my lens, exasperated sighs, checking the table height, and adjusting the alignment, I'm hoping there might be some alternate suggestions for why I can't cut through 3/8" acrylic with my mini 45.

2 passes at 3/100/5000 will, in fact, cut through, however it leaves the backside horribly rough around the edges and warped as shown in the photos.
(The 2nd pass I focus deeper into the material)

My fear is that after 5 yrs, it's finally time to replace my tube, but was assured by Epilog Tech Support that alignment would more than likely solve my issues.

Any advice on what I'm doing wrong or if it might actually be due to a loss of power?
I've seen others comment on successfully cutting through this thickness with a 45w and am curious what else I should try differently...

Thanks

[Kim Vellore]

Amanda,
Have you tried cutting squares or just a straight line.
Kim

[Joe Pelonio]

Cutting through 3/8" with 45 watts is pushing it. If you want to do this on a regular basis a more powerful laser would be better.
You may have some issue that tweaking could help with, but for small circles it's going to take two passes unless you are lucky enough to have a 45 watt tube that actually exceeds that. Even when my current tube was new it would run 3/8" cleanly with two passes at
4/100/5000 for straight lines or larger curves, but for small circles I might have to do a third pass. You can copy and paste the vector images onto themselves and get it to run both passes without having to re-run the job. If you cannot cut 1/4" in one pass at about speed 6, then I'd be more concerned about the alignment, mirrors, lenses and tube.

[paul mott]

I have found that there is a big difference between clear acrylic and coloured acrylic when it comes to cutting through 10mm stuff. Perhaps it's the pigment filler perhaps it's the laser wavelength but clear and green I have no problems with but red and similar causes me trouble above 6mm thickness.

Paul.

[Mark Ross]

We have a 45W epilog EXT and when things start going all non cutty on us, we first check the beam alignment and if that does not solve it we clean the mirrors and lens and if the problem still exists, we replace the mirrors and lens. Only after going through all that do we replace the tube. That all being said, we just replaced our tube. Third time in 6 years, but this time it is an Epilog tube, not a Coherent so we are hoping to get some life out of this thing. We cut 8-10 hours a day, 5-6 days a week. Not raster, (well not much) almost all vector.

Be careful what you clean the mirrors with.

[Martin Boekers]

I'm sure Epilog ran you through the basics. A quick way to check beam alignment is to put a piece of masking tape over the entrance circle to the lens
and fire the laser. See how centered it is in the circle. Check to make sure the air assist nozzle isn't in the way of the beam. If you are using auto focus
check focus manually. Make sure all mirrors and the lens are clean. It looks like the acrylic is painted is it. Is this a different paint than normal. Like Paul
said colored acrylic esp black takes more power. Is the table level and acrylic flat? Is there a possiblitity of the acrylic moving? One thing to test the power
of the laser is to use TNR text at about 4 or 5 points at your normal setting for painted brass and see if it hold the fine lines like the tail on the y.
I know you probably did most of these things, but I thought I'd toss them out to see if you may have missed one. Good Luck!

[Amanda Davis]

... but for small circles I might have to do a third pass. You can copy and paste the vector images onto themselves and get it to run both passes without having to re-run the job. If you cannot cut 1/4" in one pass at about speed 6, then I'd be more concerned about the alignment, mirrors, lenses and tube.

Joe,
Thanks for the suggestion to overlay the shape on top of itself instead of re-running the job; I'd never thought of that! Luckily, I can still cut 1/4" at 5 or 6 speed fairly easily so that gives me a bit of hope. One question, would 3 passes without manually focusing the beam deeper into the material each time prevent the warping/melting on the backside of the shape?

It looks like the acrylic is painted is it. Is this a different paint than normal. Like Paul said colored acrylic esp black takes more power.
One thing to test the power of the laser is to use TNR text at about 4 or 5 points at your normal setting for painted brass and see if it hold the fine lines like the tail on the y.
I know you probably did most of these things, but I thought I'd toss them out to see if you may have missed one. Good Luck!

Martin,
I'm using 3 pieces of stacked 1/8" pink acrylic, which the beam is basically melting together when cutting through, and finishing with some acrylic adhesive. No paints. Perhaps I'd have better luck with a solid black or white 3/8" material, but unfortunately I have a customer wanting this thickness in this specific color. I had success cutting lines and boxes but anything else, including a small circle, seems impossible to achieve thus far.
I have not tried the TNR text "test" yet (that was a mouthful ) but I will do so today. Thanks for your input!

[Frank Corker]

I have to be honest, 3/8 acrylic with a 45w should be a breeze. I regularly cut 10mm and bigger without any issues. Looking at the curl on the edges of your acrylic I think there is evidence of alignment, the kerf should barely be noticeable almost 90 degrees. All clear acrylic is pure, coloured acrylic has additives to give it colour and makes them more dense, but even that at 3/8 should be an easy cut. I'd do the usual checks like mirrors and lens cleaning. Make sure that the lens has the flat part facing downward and the curved facing into the oncoming beam, it fits both ways so very easy to put it in the wrong way.

[Rodne Gold]

Multipass cutting of acrylic is a big problem , you really need to cut in a single pass. The issues are that melt generated from the earlier passes has no where to go and either messes surfaces or resolidifys in the cut groove. apart from that , acrylic expands/warps a lot when heated and the expansion makes the next cuts in the multipass cut (which puts more heat in and allows retained heat) not line up perfectly.
Cutting layered stuff can also be problematic , especially if you use adhesives to layer , even if you dont , there will be a "gap" that opens up between layers , thus leading to less effective cutting.
Im not sure of this , but Acrylic acts as a wave guide , IE it allows the beam to act as tho its like this || and not this ><. It might be that with stacked material , the back edge of the layers you cutting thru then allow the beam to diverge before it hits the next layer and thus spot size changes per layer.