I kept meaning to reply to this thread, just reminded me.

Anyway, I was seeing similar things, though it's been weird. For, example, when I was cutting the chess set, one spot on the board was always a single pawn that wouldn't drop quite right. It's almost as if there's a smudge somewhere in the optics and things are off just a tad bit around there.

I cut acrylic the other day perfectly. The 3/16" stuff we got at Piedmont. Settings were 6%speed, 100% power and 5000 frequency. I did two passes and it came out beautifully.

But that was all cuts in the top left, not in the almost-bottom left where that pawn would never cut cleanly.

The Epilog user's manual says that the optics should be cleaned at least once a week. How often are they cleaned at TechShop? If I could get myself cleared to do it, I'd be happy to clean it the next time I'm at the TechShop. It says you need the cleaner that came with the Accessory Kit and some cotton swabs.

Thanks again!

Matt

Update: after talking to Aoife, I hear (2nd or 3rd hand, mind you) that the optics were cleaned just the other day, like Monday/Tuesday.

I know we clean it fairly often. Mike or Dennis should be able to tell you. I don't think it is cleaning. There seems to be a small crack in the lens and that might have something to do with it. We're ordering some replacement parts soon. Like tomorrow if I can get to it.

We want you to get your stuff done quickly too. We'll make it right soon.

Thanks,

Scott

I noticed some of this as well - the other thing is that the bed appears damaged / uneven (hit too many times with the laser?) and loose in it's seating. I'm not positive but it also seems like the exhaust fan might have less suction than it used to.

As far as multiple passes on plywood goes, that's typically problematic, even on a good machine. Basically, the first pass creates alot of charcoal that sits in the cut - remember that if the laser isn't cutting all the way through, there isn't an effective escape for all the hot ash and heat produced by the cut. This effectively insulates the wood from being further cut on subsequent passes. I think the heat also hardens the plywood glue, making it even more difficult. With enough power you can blast through, but a good general rule is to always try cut plywood in one pass. Side note, it's a similar effect that makes cutting at slower speeds and lower frequencies produce cleaner cuts - there's more time for the material to cool off, so it chars less.

but yes, the laser needs some work.

Maybe a clear policy on what we should leave for scraps. I've been leaving anything with more than 1 square inch available, because I thought people might like to experiment with my material (especially the fluorescent green) and that it would be helpful for the SBU students. If that isn't necessary, then we could put up a sign.

I've noticed that the laser cutter manual suggest that any cutting be done over the heavy one-inch-spacing table top with "a bed of nails" supporting the pieces. This could cause problems with cuts that will end up being unsupported as they will droop as they get close to the end, but I was surprised that we weren't encouraged to do it that way. Without the "bed of nails," using the heavy table top would save the grid, but I'm not sure how the air flow would work. One option I've been thinking about would be to use the heavy table top, but then to put a piece of doubled-up window screen in between the top and the piece to be cut. That way we'd still have some airflow and the damage would only be to a cheap piece of screen. (Some vacuum formers use a screen instead of the one-inch-spaced vacuum tops.)

Any status on the replaced pieces?

Thanks!

Matt

I think behind the computer, on the right side wall works well, but I think it's getting used as personal storage, right now. Maybe just throw up a sign and maybe make a rack out of scraps from the pile in the wood shop.

Speaking which, Scott, how do you feel about members putting materials up for sale in & around TechShop? I have a huge pile of acrylic earmarked for the Makerbot project, but I'd have no qualms with putting it all in the laser room with a price tag on it for folks to buy & use when they need it. We're not going to use it all right away... so someone would get use out of it, it'd clear up the makerbot table some and we'd just get more when we were ready for the next batch (and I'd have something to do with the excess).

I was thinking T-track for some bolts. Originally was going to route something out of MDF, but now I'm thinking something like http://www.microrax.com/, it's 1mmx1mm 80/20 aluminum stock. That way I could use it as a support for various jigs, etc, that would let me hold down blanks in place.

Though, I just picked up some stainless steel mesh at J&D recyclers, it's practically like chainmail. I'm thinking that might work really well as a support material for wood, since that doesn't seem to have as much issue with flashback underneath itself. I'll bring it by, hopefully it's not too heavy to mount on some kind of bed and set it in place of the vector tray.