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Ed Maloney
07-17-2007, 5:56 PM
Thought I would share an experience that I had the other day...

Finally got around to trying out Tom's LaserBuzz files. I popped in a 1/8" birch sheet into the laser, set the vector power settings for same, and sent the job. Didn't cut through the material. Damn. I just replaced my tube and I thought it wasn't as hot as my original one. Lowered the speed and the results are shown in the first picture.

After thinking about it for awhile I decided to try a scrap sheet that I had success with before. Sent a small rectangle to the lower right of the sheet with the original power settings suggested for the 1/8". No problems. Switched in the crispy crittter sheet, sent the same job, and it didn't cut through. Comparing the two sheets I noticed a difference (picture 2.) The sheet (bottom of the picture) that didn't vector through was missing a middle ply like the one I had no problems with (top sheet in the picture.)

I'm thinking I ordered the wrong one or the vendor sent me the wrong one. I assume the one without the middle ply has some type of different glue that didn't like the laser.

Joe Pelonio
07-17-2007, 6:07 PM
Did it flame too? I only had that happen once, when I was trying to use a piece of exotic African Mahogany that a customer brought in. Flames were shooting up even with 40lbs of air assist.

Michael Kowalczyk
07-17-2007, 7:15 PM
Hey Ed,
At first glance i would think you were out of focus or the lens was not in. Also I have not seen a 1/8" or 3mm ply that had 5 plys like your top one.

That looks like Luan to me. Hard to tell when it is horizontal. You will see a big difference with the 3mm I sent you.

I am cutting mine on a 60 watt Trotec so I do not know what your settings should be. I have several settings for mine. Some with clear coat, some raw for laserbuzz tributes, some with 4 colors to do engraving, then vector marking, then 1st vector cut for accurate position of hole, then final vector cut for actual outline to be cut last. You know how it is that sometimes after you cut many small parts out the material may rise a little in one area. I do not have a vac table to hold it down just a wonderful grid from Mike Null. Sometimes when you clear coat one side it will warp a little and cause the above to happen. Sometimes I can tape it down on the edge but it only happens once in a while.

Look forward to seeing your projects after your shipment of 3mm ply arrives.

Lee DeRaud
07-17-2007, 7:35 PM
That looks like Luan to me.Second that. That burn pattern looks like some (solid) mahagony I've tried to vector. Even worse, the edge-on picture of the stuff looks like some kind of MDF-core stuff, and I've always needed more oomph to get through MDF than the same thickness of plywood.

Michael Kowalczyk
07-17-2007, 8:53 PM
Hey Ed,
My settings are 100 % power and .80 speed. Now since you have a new laser tube and mine is about 4-5 years old you may have to adjust the % value a bit. I think you have about 1.7142857142857142857142857142857 times the power of yours. So I am guessing you have about 58.3% of my powerI am not sure how to convert my speed. My raster is 140IPM but I remember reading that the vectoring is never the same as the raster speed. So even if you take say 58.3% of .80% of speed you would have about 46.64% of 1.4 IPM or let say we round it off to .7 IPM or some other number that you will use on yours. Boy does that sound slow to me. Is everyone confused yet? Well that number will have to be determined by you since I do not know how your laser works for power settings and what it's IPM is. Curious to here what your speed ends up. Mine takes about 4-5 seconds to vector cut a 1.75" diameter circle. It could be a little faster but I do not like to lose parts that do not cut all the way through in one pass and if you clean it out with and exacto knife the edge shows up different and it takes too much time.

Here are a few pictures from my cell phone for you. You will see the front and the side. These are untouched as they come from the laser. We only have to clean the keyring hole with a damp towel to get the residue off of it. Usually one swipe and it's gone. Enjoy

Leigh Costello
07-17-2007, 11:27 PM
Ed,
Where did you get your substrate? I had the exact same thing happen to me on some wood I had ordered from a scrollsaw supplier. I now use the remaining sheets for other things. I always use Baltic Birch plywood for my Laserbuzz stuff. I get it locally at a hardwood supplier.

Mike Null
07-18-2007, 7:18 AM
Michael

Look at Job Control, Settings, Options, Engraver and it tells you that the maximum raster speed is 140 IPS and the maximum cutting speed is 31.5 IPS.

Ed Maloney
07-18-2007, 8:25 AM
Another thing I forgot to mention. I got through 1/4" solid maple with no problem at all. I add this because I noticed on the order form from the vendor that I requested maple plywood, not birch. So I am guessing it's the interior material that was the issue.

Michael Kowalczyk
07-18-2007, 1:41 PM
Michael

Look at Job Control, Settings, Options, Engraver and it tells you that the maximum raster speed is 140 IPS and the maximum cutting speed is 31.5 IPS.
Yes you are correct. I knew I saw it somewhere but just couldn't put my finger or mouse on it at the time I was thinking of it.
Thanks!

Neal Schlee
07-19-2007, 11:25 AM
Looks like Phenolic glue (exterior waterproof type) was used in the ply, it can and does react inconsistently when lasered.

Neal

Ed Maloney
07-20-2007, 10:52 AM
That looks like Luan to me. Hard to tell when it is horizontal. You will see a big difference with the 3mm I sent you.

....

Look forward to seeing your projects after your shipment of 3mm ply arrives.

Michael - The plywood arrived faster then I expected. Thanks. Did a test run as well and everything is good with the world again!

Thanks!