Cutting 10mm cast acrylic

[Graham Taylor]

I have an 80W speedy 300 and need to cut some 10mm cast acrylic.


Can someone please help me with the best settings to start with so I get the best cut edge and also the best way to get a clean edge that is perpendicular?


I think I need to lower the focus point but am not sure of the best way to do this so it is repeatable so I get the same result each time I run the job.

thanks in advance

[Chris J Anderson]

Hi Graham,
Ideally you would use a 4" lens so that the cut is as close as possible to perpendicular.

But regardless of lens, you should set you focus, then raise the bed closer to the lens by half (or just under) of the acrylic thickness, in this case 5mm.
This will set the focus in the middle, and in theory make the cut as straight as it can be with that particular lens.

For power and speed, you should experiment first, but to get a nice polished edge, go high power, and really low speed...

[Graham Taylor]

Thanks Chris, I should have said I would be using a 2.5" lens


Hi Graham,
Ideally you would use a 4" lens so that the cut is as close as possible to perpendicular.

But regardless of lens, you should set you focus, then raise the bed closer to the lens by half (or just under) of the acrylic thickness, in this case 5mm.
This will set the focus in the middle, and in theory make the cut as straight as it can be with that particular lens.

For power and speed, you should experiment first, but to get a nice polished edge, go high power, and really low speed...

[Jiten Patel]

Hi Graham,

Try 100% power, 0.19 speed with an offset of -2.5 to -4.0 and see how you get on. Try cutting small pieces (5cm x 5cm) until you get the optimum setting for your machine as every one is different.

[Scott Shepherd]

Hi Graham,
Ideally you would use a 4" lens so that the cut is as close as possible to perpendicular.



Are you saying that in theory or from practical experience? I've cut a fair amount of acrylic. I cut a total of (5) 4' x 8' sheets last week, with most of that being 1/2" thick, and one sheet being 1/4". I have tested lenses fairly extensively, along with settings and methods over the years, and I have never seen a 4" lens cut thick acrylic successfully. The lens is too far away from the work and the air (on machines with co-axial air assist) will not reach the cut, causing the worst potential for flare ups and fires with the 4" lens. Every time I have tested the 4" lens on acrylic, I've seen flare ups.

Are you getting a different experience than that?

Graham, make sure you have "Send Bezier Paths to printer" turned on in Corel, and when you send it over, make sure you have "Enhanced Geometry" turned on in the driver. That'll help with the best cut quality as well.

[Jiten Patel]

Scott, with Enhanced Geometry, have you tried this using illustrator? I get really wierd results, therefore never use it. For example, if I flip the artwork in the driver, I get some bits unflipped and other flipped, so get a jumble of vectors. Also the time it takes is painful. Without it on, some of my files take for example 5 minutes to cut. With it ticked on, they take 8-10 minutes. It splits the vector paths into thousands of tiny parts which the vector ordering cannot sort out.

Graham, I use my 2" lens to cut 10mm. I don't do it often as it is slow, but get a good cut.

[Scott Shepherd]

Scott, with Enhanced Geometry, have you tried this using illustrator? I get really wierd results, therefore never use it. For example, if I flip the artwork in the driver, I get some bits unflipped and other flipped, so get a jumble of vectors. Also the time it takes is painful. Without it on, some of my files take for example 5 minutes to cut. With it ticked on, they take 8-10 minutes. It splits the vector paths into thousands of tiny parts which the vector ordering cannot sort out.

I have not Jit. I don't have Illustrator on the machine that the laser is on. I haven't heard of anyone using it with Illustrator successfully, but I haven't spoken to many people about it. I do know that it works well with CorelDraw. You just turn it on, send it over, it sends the job over nice and clean, and it never takes longer to cut. If you have an item sent over without it on, and click on it when it's on the plate, you might see 30 nodes. Send it over with Enhanced Geometry and it'll only be a couple of nodes showing.

I think it has something to do with the fact that CorelDraw has that option of turning Bezier's on for sending to printer. That option doesn't exist in Illustrator that I know of, and I've been told that Illustrator doesn't need that turned on, because that's how it sends things any way, but that might not be true at all. I don't have any way to test it, so I can't do any research on it, but I do know it works well with CorelDraw.

[Glen Monaghan]

make sure you have "Send Bezier Paths to printer" turned on in Corel

I searched CD's help, searched SMC and googled it, but found nothing on that subject (except this thread!)... How do you turn that on?

[Scott Shepherd]

Glen, go to "Tools", "Options", then follow the tree in the photo attached. On the top right, click the drop down and select Trotec Laser, then the boxes shouldn't be grayed out and you can check the one for sending Bezier's over. I can't show you that on this machine because I don't have Job Control installed on this machine.

Any questions, just ask.

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[Richard Rumancik]

. . . I think I need to lower the focus point but am not sure of the best way to do this so it is repeatable so I get the same result each time I run the job. . . .

I can't quite make out the construction of the focus probe for the Speedy but perhaps you could construct a special probe for that that specific material. For some lasers, the probe is a simple pin with a stop on top so it is easy to make a special probe from rod and a shaft collar (or alternatively, add a collar/spacer under the normal probe head equal to focus offset.)

The picture I have of the Speedy looks a bit more complicated and I can't make out the detail of the probe and don't quite understand the procedure I see.

An alternative is to use a focus plate - focus on 5mm material and then swap in your workpiece. (You can shim the 5mm to optimum height once you find the sweet spot.) The downside with this approach is that you can't easily do a re-focus with your workpiece on the table, if the table is completely covered. You need a clear area of the table to locate your focus plate and re-focus. It depends on if you have any free table space left.

Your beam alignment needs to be very accurate for thick material or you will get angled cuts. Thin material is forgiving but it can be very obvious with thicker material. Even with the best alignment, you will probably still end up with some angle to the cut, but it should be the same angle all around.

[Scott Shepherd]

I can't quite make out the construction of the focus probe for the Speedy but perhaps you could construct a special probe for that that specific material. For some lasers, the probe is a simple pin with a stop on top so it is easy to make a special probe from rod and a shaft collar (or alternatively, add a collar/spacer under the normal probe head equal to focus offset.)



No need to make anything, it has a programmable Z Axis. Just go into your color for that material, select the Z Offset and enter -.060, -.090, or however much you want it to go down. When the machine starts, the table will rise up, it will cut the job, go home, the Z will go back to zero, and it'll be ready to do the next piece.

See the Z Offset where I put it here....

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[Jiten Patel]

Richard, Job Control (the software) does it automatically. You can set the offset to be a minus or plus figure (raises or lowers the z axis in mm) according to what you put in. Save the setting and hey presto, set to the same level for that material every time.

[Mike Lassiter]

one thing about using the software that I discovered is you need to routinely check that the calibration is set correctly. I set the z height to zero using the focus tool on the cutting table and then always set the height in the driver when cutting as mentioned previously. At some point I started seeing a wider kerf being cut and maybe an incomplete cut thru the material. The material was exterior siding that my biggest customer seems to keep needing me to cut. At best it cuts poorly. Gaps in the inner plys and glue pockets so I thought the problem was the siding (cutting from bad to worse) and had to cut twice sometimes three times for complete cut. Got rather frustrated over it all. For some reason I actually did check the z height and discovered it was off about 0.3" and after I recalibrated the z height in the software the cutting improved going from worse back to bad.
I don't have a answer why it changed but it did. I still use the driver and set cutting height, but I now check to make sure I am getting what I think I am ocassionally. I did find a few weeks later the height again was off, but not very much. Quick recalibration again. Didn't see cutting any different that time, but due to using a 3" lens there was enough margin in the focus that it was still cutting ok.

[Ross Moshinsky]

Getting back on topic, part of the benefit of buying a Trotec machine is the materials database. I'd start there and then tweak. As for the offset, I'd figure about 2mm would be a good place to start.

[Scott Shepherd]

one thing about using the software that I discovered is you need to routinely check that the calibration is set correctly. I set the z height to zero using the focus tool on the cutting table and then always set the height in the driver when cutting as mentioned previously. At some point I started seeing a wider kerf being cut and maybe an incomplete cut thru the material. The material was exterior siding that my biggest customer seems to keep needing me to cut. At best it cuts poorly. Gaps in the inner plys and glue pockets so I thought the problem was the siding (cutting from bad to worse) and had to cut twice sometimes three times for complete cut. Got rather frustrated over it all. For some reason I actually did check the z height and discovered it was off about 0.3" and after I recalibrated the z height in the software the cutting improved going from worse back to bad.
I don't have a answer why it changed but it did. I still use the driver and set cutting height, but I now check to make sure I am getting what I think I am ocassionally. I did find a few weeks later the height again was off, but not very much. Quick recalibration again. Didn't see cutting any different that time, but due to using a 3" lens there was enough margin in the focus that it was still cutting ok.

Mike, one thing that can mess that up is if you stop the job before it goes back to home. I have a bad habit of opening the lid once it starts to go back home. If you do that and it's not allowed to go back home, then it'll adjust itself by the offset from where it's at. Over time, you can have a real mess (or a crash) depending on which direction you are offsetting. I complained about it years ago but I don't think anyone ever understand how insane it was to allow that to be able to happen.

[Graham Taylor]

thanks for all the advice guys - its much appreciated as I am very new to this laser lark having only had the training a couple of weeks ago so I am still trying to get my head around all the terms and everyrthing else.

I will have a play when the material turns up either tomorrow or Monday.

thanks again all

[Mike Lassiter]

Mike, one thing that can mess that up is if you stop the job before it goes back to home. I have a bad habit of opening the lid once it starts to go back home. If you do that and it's not allowed to go back home, then it'll adjust itself by the offset from where it's at. Over time, you can have a real mess (or a crash) depending on which direction you are offsetting. I complained about it years ago but I don't think anyone ever understand how insane it was to allow that to be able to happen.

Scott I appreciate the tip. And yea, that's probably the cause of it. I often raise the lid before the carriage has homed. I have to cut the sheets of 49" wide and slightly over 24" high to table size of 24"x48" and have a file saved in the driver permanently that I use over and over to do it. A cut from the top right down then across the bottom right to left. When it finishes I generally will open the lid and start removing the cut off part while the carriage is returning to home position.
That file has a little higher Z height due to the MDF sitting on the edges of the cutting table, then the actual file I need to cut reverts to the material thickness that I set in the driver. I was dumbfounded to understand how the cutting table calibration came to be off by 0.3" inch. The setting in the driver was the same, but the laser wasn't.

[Scott Shepherd]

Hopefully that explains what's causing it Mike. Here's how it works :

You either set the material thickness in the material setting and you have it automatically go to the top of the part when you hit start (or you hit the focus button). It's at the top of the part. You have a -.060" Z Offset to make it focus down into the work. You hit start, it raises the table .060", and cuts. Everything is great. Then it's supposed to finish, go home, and the Z returns to the top of the part, removing the negative z offset. If you open the lid it never gets to the part when it comes itself again. So it's at Z-.060". Hit the start again for the next piece and it's going to increment the Z another .060". Do that a couple times and you'll crash the head into the work.

What SHOULD happen is that you zero it, when you hit start, it raises the table by .060" (Z-.060"), and then you open the lid early because you are impatient like me, put a new piece in, and it SHOULD know that it's at Z-.060". When you hit start, it SHOULD drop the table down so it's at zero again before it starts. If you finished a job and lowered the table by 1", then when you hit start, it should know you did that, but it doesn't, unless you have the automatic stuff fully turned on and are using it.

It should just be a simple test, logic wise, to know where the Z position was when you started the job, and it should always start in that same place.

The Universal's do that. Doesn't matter what you do, it knows where to go. Why Trotec doesn't do it, I don't know. It would be great if their engineers in Austria actually read and participated in forums like this to get real life feedback from users.

[Mike Lassiter]

I have a Universal ILS laser. It doesn't work as you described exactly. I do the set z height either in the driver or with the tool as you stated. Mine NEVER has changed the Z height after cutting back to the calibrated zero height. Everything happens on mine on the start, either I set it manually or in the driver (unless the z height is disabled in the driver with intentions of doing it manually - but forgetting to do so). I agree with you about the Trotec. It's odd to me they would move the table AFTER cutting. If you had the same thing to do over and over it waste time and unneeded wear on machine moving up and down.

So, that may not be my problem after all. I use to check EVERY time I cut something, but that gets old when you think the software will handle it for you. I have a digital caliper right here beside the computer to check material thickness to enter into the software. That all works great if the table is where it's suppose to be every time.

[Scott Shepherd]

I have a Universal ILS laser. It doesn't work as you described exactly. I do the set z height either in the driver or with the tool as you stated. Mine NEVER has changed the Z height after cutting back to the calibrated zero height. Everything happens on mine on the start, either I set it manually or in the driver (unless the z height is disabled in the driver with intentions of doing it manually - but forgetting to do so). I agree with you about the Trotec. It's odd to me they would move the table AFTER cutting. If you had the same thing to do over and over it waste time and unneeded wear on machine moving up and down.

Sorry Mike, you lost me there. When you said "It doesn't work as I described", were you referring to the ILS or the Trotec?

Both of them do the same thing if you leave the lid shut until it finishing. Plus, there's a couple ways to do the focus on the Trotec. You can go manual, semi automatic, and automatic, depending on the options you have selected.

[Dan Hintz]

I have a Universal ILS laser. It doesn't work as you described exactly. I do the set z height either in the driver or with the tool as you stated. Mine NEVER has changed the Z height after cutting back to the calibrated zero height. Everything happens on mine on the start, either I set it manually or in the driver (unless the z height is disabled in the driver with intentions of doing it manually - but forgetting to do so).


Sorry Mike, you lost me there. When you said "It doesn't work as I described", were you referring to the ILS or the Trotec?
I believe he's talking about the ILS. I remember my PLS would only change Z height when I hit start, as Mike describes. If the last part left the table too high to get the next piece in there, I had to manually lower it via the keypad. On the next press of start it would raise/lower to the proper height... but as you said, Steve, it remembered where it was regardless of when the lid was opened or what you did at the keypad. Seems like a simple (and expected) thing for the machine to do.

[Chris J Anderson]

Are you saying that in theory or from practical experience? .
.

Hi Scott,
Thats complete theory mate, not from practise.
I'm glad you posted that information, I never thought of all those issues.

cheers,
Chris

[Mike Lassiter]

Sorry Mike, you lost me there. When you said "It doesn't work as I described", were you referring to the ILS or the Trotec?

Both of them do the same thing if you leave the lid shut until it finishing. Plus, there's a couple ways to do the focus on the Trotec. You can go manual, semi automatic, and automatic, depending on the options you have selected.

ILS
Yes, I didn't open the lid until the job was done, but the carriage was moving back to home position.

[Scott Shepherd]

I believe he's talking about the ILS. I remember my PLS would only change Z height when I hit start, as Mike describes. If the last part left the table too high to get the next piece in there, I had to manually lower it via the keypad. On the next press of start it would raise/lower to the proper height... but as you said, Steve, it remembered where it was regardless of when the lid was opened or what you did at the keypad. Seems like a simple (and expected) thing for the machine to do.

Gotcha, I never had that be an issue on the Universal, since it's always going home at the end of the job (I have that option turned on). Since it's home, and when it starts, it moves, so it's not like it's ever going over the work at the wrong height, right? Or have you experienced something different? I guess if you had the "return to home" turned off, then yes, it could be an issue and get in the way. On the Trotec, however, you can certainly crash it if you do repeat jobs and open the lid before it goes back to it's origin.

[Richard Rumancik]

OK, I suggested to Graham how he might manually accommodate a z-axis offset on the Trotec. I am am not a Trotec user. But with all due respect to Jit and Steve who pointed out there was a programmable option, the glitch that was identified (with the Trotec losing its z-axis zero reference) would make me reluctant to use the programmable z-axis offset.

On my laser I often open the lid before the laser carriage homes, so I am sure I would experience the same issue. At least my manual table stays where I put it for the entire job. I can still tweak focus on-the-fly in seconds if need be.

It's too bad that something so simple to correct in firmware wasn't quickly addressed by the company. Here they have a potentially great feature and then blow it on the details. The effort to correct the firmware glitch would seem pretty trivial. Trotec isn't unique in this respect.

[Scott Shepherd]

Richard, it's kind of a glitch because most people aren't quite using it right. The right way would be to turn autofocus on at start of job, and then it'll focus correctly before it starts, which makes the issue go away. However, most people don't use that function, so we're sort of using it in semi-automatic mode, which I think is where the issues come in. A perfect example of things designed in a lab environment and not the real world. I'd love to have the people who write the software work for me for about a week. I can promise you, they'd have a new found take on how things should work versus how they do work.

[Dan Hintz]

A perfect example of things designed in a lab environment and not the real world. I'd love to have the people who write the software work for me for about a week. I can promise you, they'd have a new found take on how things should work versus how they do work.

You can always tell the the engineers who have worked in the real world and those who have worked only in the lab (at least in my line of work). Real-world experience teaches a different set of problem-solving skills.