Any ideas?

[Barb Macdonald]

hey all, does this sound like my tube is going? Or the focus is lost? i.e. the bed isn't totally level, even though I leveled.
After vectoring 0.375" acrylic, at speed 6, pwr 100, freq 5000, perfectly, last week.
This week, rest of the job to do, after cleaning mirrors and rails, because it seemed to be "not going through" on one pass, needed two vector passes, which was odd.
Had three duds to do, they had a "hammered" appearance. I like it, but it's not what I showed the customer. Just a simple acrylic base.
First piece, rastered fine. Vector, (4 speed) it went through, but not over the entire piece. The last 6" or so, not quite through, like the frequency went lower by itself..

epilog 60 watt, legend ext.
yes, tube's new since Jan.07. Guess that means it's two years old..

ho, boy..

thanks, and Happy February:)

[Margaret Turco]

Sorry I haven't had enough experience to help you Barb. I have that problem sometimes on plywood, but that's most likely because it's not always really flat. If the raster is ok near the same place on the table I would think the tube is ok.

[Scott Challoner]

Similar to what Margeret said... I did a job a few months ago that had a large engraved area. I ended up putting so much heat into the acrylic that it warped and didn't cut properly. Is your material flat?

[Stephen Beckham]

Barb,

I'm not sure - but I'll tell you I go through this from time to time with my .25 acrylic. What I have found is that depending on the company who made it and the quality of the acrylic, they have a wide berth of variance on thickness. I take the caliper out and verify, but most times my .25 seems to be more along the lines of .3.

I slowed my laser down two more percent and it goes through everytime now. Yea it's slower than the book states, but I don't like having to run it twice.

I too worry about the laser tube going out, but everything else seems to work fine. The only other test I did was to take some 1/16 romark and run the laser three percent faster than the recommended speed, then two percent and then one percent to see if I was getting even cuts. Their thickness is a lot more percise and I was able to see a good cut all the way through it - so come up with some 'control' scrap to verify your cut will work on something you know is good.

[Richard Rumancik]

Barb, what's the temperature like in your shop? Is it tightly regulated or does it get a bit cool in February? Maybe a long shot, but if the tube is on the cool side it might not be performing as well.

I noticed recently with one job that my laser wasn't rastering well, and yes, it was cool in the shop. I opened the back and warmed the tube with a portable heater. It seemed to help. I looked up the spec on the Synrad tube and spec'd with a 15C-40C operating temp. My shop may have dipped to 15C-16C. In any event, warming it up seemed to make the problem disappear.

[Joe Pelonio]

I have had two tubes go out. It started as you described, but as it got worse the beam weakened as it got farther from the source. Eventually I was adjusting speed and power daily, but only able to run on the left size. Turned out that my 45 watts had run down to 10.

Call Epilog, there are several other possibilities from power supply to mother board and they can walk you through the troubleshooting.

[Stephen Beckham]

Barb,

I was thinking of one other thing that could be causing it - along with the variance in thickness, you've only got a 1/4" of focus.

Are you focusing right on top of the acrylic? If so, then it's possible the spreading of the beam by the time it gets to the bottom of the plastic may be weaking it's effect. I always put my 1/4" acrylic two or three clicks high on the focus so that (I think :confused:) my focus is more towards the middle of the plastic than on top of the plastic.

I'm thinking this because I off focus my 1/4" by 10-12 clicks when I'm lodging coins in from the back. By cutting from the back and having it way out of focus, it gives me a wedge cut so that the coins can go in from the back, but when the acrylic is fixed to the wood, they won't come out the front. See picture for example...

ANYWAY.. to the point.. When I cut like this, I notice I have to slow down at least 3% more than normal to cut all the way through... You may be having the same issue of having to slow down because the beam is not in focus all the way through your plastic. Are you getting a flat or sort of a chamfer cut on the edge? I'm sure there's some expert out there that will weight in to say if I'm crazy, spitting in the wind or maybe just a little bit on to something...

Take care