Universal Laser doesn't cut film completely. Advice?

[Lisa Conyer]

Hi all,

We have two lasers. One is a Universal and the other is a Franken-laser that was built for us using a Universal laser with a different ui/driver combo.

In general, they work well for our purposes. We cut mylar and other thin films. The major problem we have is that we often get hanging chads on both lasers. Not sure what else to call them.

Say for example I was going to cut a letter O. As the laser beam cuts around the letter O, it seems to stop a hair shy of the origination point, leaving the tiniest fraction attached to the main sheet of film.

Sometimes a vigorous shake will dislodge the pieces, but not always. We have high labor cost due to this weeding process. Some of the designs we cut are extremely intricate and I can understand the hanging chads on those files, but we also run into this problem cutting san serif fonts like Arial and Helvetica.

Is there anything we can be doing to correct this problem? We're in a sweet spot with PPI, speed, and power. We run into melt issues if we get the laser going much hotter and that doesn't really seem like a solution anyway.


The only solution I can think of is maybe running our files twice, if we could somehow print the file and have the laser start and stop firing at different origination points on each vector object. I have absolutely no idea how to make that happen though. We use Illustrator, for reference.

I am a total laser novice, but I would really like to cut our production hours if possible and any help is totally appreciated!

[Kev Williams]

You need a program that will create a tangential entry/exit point. See the picture, this was done using my old Casmate, notice the 'tails', this causes the starting and ending points of the actual piece to overlap, leaving no "chads". The sample shown was for some vinyl numbers I did, but it would work just as well when cutting with a laser. You just have be sure to the entry/exit points on are the side of the part your throwing out! (Casmate does this automatically once you choose) I've watched video of a plasma cutter in action, and tangential entry/exit is pretty much necessary to prevent overburn at the cut's point of origin.

http://www.engraver1.com/erase2/tangential.jpg

[Mike Lassiter]

Out of curiosity, have you tried cutting some other material to see if this happens with just Mylar or all materials.It doesn't add up to me needing to overlap nodes to get a letter to cut completely out. I understand concept but consider you laser spot is say 0.005" in diameter. You start and end on the same node so you would have a theoretical overlap already of 0.005" or 1/2 spot size starting and ending. That's not much when you think about it, but it proves to be enough to completely cut out things. Cutting text like true type fonts you shouldn't have to do what what suggested. If you have open paths that don't connect it does make sense. I use Corel Draw which lets you do a fill and change outline around letters as text and also if you convert text to curves.
This to me almost seems to be a mechanical issue like maybe a belt drive pulley that is slightly loose that is causing some lost motion to carriage that is creating incomplete travel by a sight amount due to shaft rotating slightly in pulley to start carriage moving. Driver nor software can compensate for looseness that creates lost motion. Don't know if I am getting my point across as I mean. Check for some slightly loose pulleys on drive motors on xy axis motors are my thoughts.

[Lisa Conyer]

You need a program that will create a tangential entry/exit point. See the picture, this was done using my old Casmate, notice the 'tails', this causes the starting and ending points of the actual piece to overlap, leaving no "chads". The sample shown was for some vinyl numbers I did, but it would work just as well when cutting with a laser. You just have be sure to the entry/exit points on are the side of the part your throwing out! (Casmate does this automatically once you choose) I've watched video of a plasma cutter in action, and tangential entry/exit is pretty much necessary to prevent overburn at the cut's point of origin.

http://www.engraver1.com/erase2/tangential.jpg

This is very intriguing. Can this be done with Corel or Illustrator? I would give up Illustrator in a hot minute if we could cut better in Corel.

[Lisa Conyer]

Out of curiosity, have you tried cutting some other material to see if this happens with just Mylar or all materials.It doesn't add up to me needing to overlap nodes to get a letter to cut completely out. I understand concept but consider you laser spot is say 0.005" in diameter. You start and end on the same node so you would have a theoretical overlap already of 0.005" or 1/2 spot size starting and ending. That's not much when you think about it, but it proves to be enough to completely cut out things. Cutting text like true type fonts you shouldn't have to do what what suggested. If you have open paths that don't connect it does make sense. I use Corel Draw which lets you do a fill and change outline around letters as text and also if you convert text to curves.
This to me almost seems to be a mechanical issue like maybe a belt drive pulley that is slightly loose that is causing some lost motion to carriage that is creating incomplete travel by a sight amount due to shaft rotating slightly in pulley to start carriage moving. Driver nor software can compensate for looseness that creates lost motion. Don't know if I am getting my point across as I mean. Check for some slightly loose pulleys on drive motors on xy axis motors are my thoughts.

Believe me, I don't think it should be happening either. We don't have any open paths and yes, all text is converted to outline (that's what Illustrator called it).

It happens on paper and fabric as well. It's not as prominent as when we cut on film because the film is much more rigid if that makes sense.

Our Frankenlaser has had belt issues before, so that's definitely plausible and I'll check it today. I do notice on some letters like cursive B and cursive L that our upper left curve is a little "soft" and that was a belt issue in the past.
The thing that's weird is we have this problem on both lasers. I don't typically operate our real Universal, so I don't know if it has had a belt tuneup since it was purchased though.

[Ross Moshinsky]

Have you tried not converting to outlines and simply changing the stroke on the text? It shouldn't make a difference, but it might.

[Dan Hintz]

Kev is correct on this one... during initial entry, you're not getting complete burn-through, which leads to a tiiiiny little pieces that doesn't cut completely. If the substrate was wood or something similar, it would immediately snap off and you'd never notice it... since it's pliable plastic, it doesn't always snap. Mechanical issues should be checked out, of course, but I think you'll find this is a cutting issue.

All of that said, I hope someone jumps in with a convenient way of adding lead-in/-out sections in Corel... I've never had to do it, so I can't suggest a way. If you have to do it manually, it will get extremely tiresome when it comes to a lot of text or other vector art. G-code machines (like plasma, CNC, etc.) almost always support lead-in/-out by default as it's a known issue, but Corel not so much.

I'm curious to see the final (speedy) solution someone comes up with. I imagine a macro would work in most cases, though... searches an entire document for beginning/ending points of vectors and adds in a short lead-in/-out.

[Guy Hilliard]

A piece of sticky tape may help. :)

Adjust the tack until you find one that catches all the "hanging chads".

I never had this issue with my X660 (or my new Speedy 400) cutting SMT stencils from 0.003" Mylar. But the settings are as you said very sensitive to get in the "Sweet spot".

[Scott Shepherd]

It's a belts/bearings issue. Replace the belts, bearings, pulleys with the maintenance kit they offer and it'll solve the problem. Been there, done that.

[Lisa Conyer]

It's a belts/bearings issue. Replace the belts, bearings, pulleys with the maintenance kit they offer and it'll solve the problem. Been there, done that.

Went out there, looked on the side, one of our belts was sagging, took it off to examine, torn almost 3/4s thru in a spot.

Doesn't explain why our other laser has the same prob, but the problem is definitely more pronounced on this laser. Going to check the belts on that laser later today!!

[Lisa Conyer]

I want this macro!

[Scott Shepherd]

Doesn't explain why our other laser has the same prob, but the problem is definitely more pronounced on this laser. Going to check the belts on that laser later today!!

Because that belt/bearings/pulleys are worn too. We have to replace ours every 12-15 months or we start seeing that. They have a kit for it. It comes with all the belts, bearings, and pulleys. Takes about 1 hour to replace it all, then you'll be good. That's my opinion. It's always best to call Universal's tech support and get their take on it before spending any money.

[Kevin L. Waldron]

You might try programs like CoCut for Corel or Flexi-sign......... they will have many of the needed features, and include some that could help on weeding.....but it does come with a price.

http://www.cocutusa.com/products/compare-product-features/

http://www.thinksai.com/vinyl-cutting-software

Both these programs will work with laser's...... the later is more powerful but the price reflects this.

Blessings,

Kevin

[Mike Lassiter]

Any update on what you've found?

[Dan Hintz]

Any update on what you've found?

Yeah, I'm interested in hearing about it... I just assumed the obvious things like belts were checked when I said the issue was the substrate. If it turns out to be the hardware, well...

[Jerome Stanek]

Could this be because the material expands and then contracts do to the heat

[Mike Lassiter]

Don't think so Jerome.

[Mike Lassiter]

An update would be nice.

[Lisa Conyer]

I'm so sorry guys. A huge reorder came in, I've been absolutely swamped. Room to breathe now.

The belt was about 3/4 torn on left side of laser and about to blow. It was a year to the date that we had replaced the old belt, looked at email chain from our universal rep to check! So whichever PP had said check your belts, bang on.

Not everything falls out of the mylar perfectly when I pull it off the honey comb table, but about 90% of san serif fonts like Arial and Helvetica are falling out, which is where we were at before BeltGate.

I am really exploring the tangential point of entry concept, I need to go back and look at those links that were posted.

I looked at casmate, is the software in Italian? I was a little confused.

http://www.fcsrl.com/en/download.html

[Lisa Conyer]

Kevin, you're a wizard.

Just talked to Jim at CoCut. He was so nice and we have been looking for his exact product for years. I can't believe it actually exists.

I can't thank you enough.

[Brian R Cain]

It's a belts/bearings issue. Replace the belts, bearings, pulleys with the maintenance kit they offer and it'll solve the problem. Been there, done that.

That was my first thought. I've seen this a couple of times but more exaggerated than described. In one instance the belt had been changed but not tensioned, in the other the belt teeth were badly worn. The machine was ten years old and had never been serviced. For a short-term fix I turned the belt around, i.e. so the section that normally runs round the gear ran round the idler instead.

It isn't just the belt teeth that wear. Those on the gear will as well, so ideally that ought to be replaced too. The belt picks up abrasive particles and over time grinds itself and the gear down, rounds the corners off and you end up with backlash which is causing the start and end points to be in slightly different places.