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Nov 07, 2019, 10:53 AM
Neophyte hacker
portablevcb's Avatar
Lenses. They last longer if you keep them clean. The gold coating is VERY soft. When wood dust gets on it the sap will eat at the gold. If you get enough on there it will absorb the laser power and the extra heat will make the problem worse. Cutting a lot of ply is bad too as the burned resin gets in there. Good 'air assist' and evacuation is a must.

Get a bunch of GOOD qtips and lens cleaner. Clean carefully. The coatings on these things are more fragile than good camera lenses. We used to go through a full set of mirrors/lenses in less than a year.

charlie
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Nov 07, 2019, 11:16 AM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
Quote:
Originally Posted by CloudSniffer
Besides the 80w having up and down Z to focus is very important. Also compressed air blowing out the nozzle to blow the cut clean and keep smoke away from lense. I added a little valve on the line to adjust the nozzle air pressure flow. If you cut small parts completely out full pressure will blow them out and they can get damaged landing in the laser path.

Clean and aligned mirrors makes a huge difference.
When I was having Charlie cut parts for me, he asked me to add small breaks in the lines every so often to keep parts in. I have found that in balsa even a .020" break will keep the part in, and yet still allow easy removal.

Quote:
Originally Posted by portablevcb
Lenses. They last longer if you keep them clean. The gold coating is VERY soft. When wood dust gets on it the sap will eat at the gold. If you get enough on there it will absorb the laser power and the extra heat will make the problem worse. Cutting a lot of ply is bad too as the burned resin gets in there. Good 'air assist' and evacuation is a must.

Get a bunch of GOOD qtips and lens cleaner. Clean carefully. The coatings on these things are more fragile than good camera lenses. We used to go through a full set of mirrors/lenses in less than a year.

charlie
Yes!!! I have been cutting some 'Home Depot' Luann mahogany plywood for some tugboat kits I sell, and I could not believe the amount of residue that I found on the exhaust fan!!!

SteveT.
Latest blog entry: My shop....
Nov 07, 2019, 11:39 AM
Registered User
I got the CU mirrors because everything I read says they are more durable and almost as reflective as SI. The coating seems to have been etch away ( like fungus on a camera lens ), so sounds like what you describe. I will try and be more diligent about keeping them more clean moving forward. This also should be improved by the fact I have improved my exhaust system recently. When I first built my system, it was fine with cutting, but could sometimes be overwhelmed when engraving. I added a second exhaust fan. I'll see if that helps with mirrors.

I find with grayscale 3D engraving wood, finding the right nozzle air flow is key, too much and the smoke gets pushed up too far. It all eventually gets drawn out but not as fast. Surface engraving ( for lack of a better description ) isn't much of a problem.

Quote:
Originally Posted by portablevcb
Lenses. They last longer if you keep them clean. The gold coating is VERY soft. When wood dust gets on it the sap will eat at the gold. If you get enough on there it will absorb the laser power and the extra heat will make the problem worse. Cutting a lot of ply is bad too as the burned resin gets in there. Good 'air assist' and evacuation is a must.

Get a bunch of GOOD qtips and lens cleaner. Clean carefully. The coatings on these things are more fragile than good camera lenses. We used to go through a full set of mirrors/lenses in less than a year.

charlie
Last edited by joel_l; Nov 07, 2019 at 11:59 AM.
Nov 08, 2019, 08:23 PM
Registered User
I didn't have 1/8" but I have 1/4" dense birch ply, 10mm/S and 70% power. I had some medium density 1/8" birch ply, 50mm/S 40% power. This is with fresh mirrors.

Joel

Quote:
Originally Posted by SteveT.
Yeah, I'm thinking for the majority of the stuff I am doing, I also will not be cutting at high power. As noted, it seems something happened with my laser as one day it was cutting fine, but the next, not. And from the research I did, it seems the power supply in these lasers tend to go out, so, if I was going to buy a new power supply, I might as well get a more powerful one and a power powerful tube to go with it. I do want to be able to cut at least 1/8" aircraft grade ply and mine, while it would, was at 70% power and down to 3mm/s. I have my tube now, but have to fabricate an extension to cover the tube.

SteveT.
Nov 08, 2019, 08:54 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
Thank you Joel!

SteveT.
Latest blog entry: My shop....
Nov 09, 2019, 11:16 AM
Neophyte hacker
portablevcb's Avatar
Aircraft ply is the toughest wood to cut with a laser that I have seen.

Just about anything with a resin in it is tough on mirrors and lenses. Depron, while easy to cut, also lays deposits on stuff that build up quickly.

charlie
Nov 09, 2019, 05:09 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
Yes, I agree about the toughest, but didn't know about the depositing. I wonder if the laser cuttable (melamine resin/adhesive) stuff from Aircraftplywood.com does the same? I know it cuts very well.

SteveT.
Latest blog entry: My shop....
Nov 12, 2019, 05:00 PM
Neophyte hacker
portablevcb's Avatar
It will build up, just not as fast as acft ply. Liteply does too.

If you really want a 'mess' try etching through the resin layer on big areas of ply.
Nov 12, 2019, 11:34 PM
If it flies, I can crash it.
rocketsled666's Avatar
MDF is a curse. Damn the wood gods that it's so cheap. The stuff doesn't burn as much as "atomize" and the dust sticks to everything. I just did about 4 hours of cutting 1/4" MDF and the inside of my machine looks like it's covered with a grey colored snow.
Nov 13, 2019, 12:19 AM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
Yeah, I would imagine so as it is nothing but sawdust and resin. Like I said, the Luann Mahogany I use in the tug boat kits I sell is horrible also.

SteveT.
Latest blog entry: My shop....
Nov 13, 2019, 01:45 AM
If it flies, I can crash it.
rocketsled666's Avatar
Yeah. But I carved up 16 square feet of the stuff and it cost me $12 in material.
Nov 13, 2019, 04:35 AM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
Mine even less.. 32 sq feet for $11.42 plus tax..

SteveT.
Latest blog entry: My shop....
Nov 13, 2019, 09:33 PM
If it flies, I can crash it.
rocketsled666's Avatar
I went to Home Depot. They might have had some that was a little cheaper, but I liked that the stuff I got was "light honey" colored and the sheets were relatively flat compared to the cheaper stuff... But you got a much better deal than me.
Nov 13, 2019, 09:38 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
Thread OP
It works, but it sure does put out a lot of residue!!

SteveT.
Latest blog entry: My shop....


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