Some pieces are badly cut

Hi, I want to ask. I am looking for the optimal cutting speed of beech plywood (3 mm). I tested a speed of 150 mm / m with 3 layers. That was good, but it seems pretty slow to me. Then I tried a speed of 350 mm / m with 5 layers. It was better, I save on each cutout approx. 30 seconds. The pieces are cut out perfectly, but the problem is that some don’t, and then they don’t go off. And I don’t know why.

Any advice on that? Could it be the base, adhesion or unevenness of the plywood? Do you have the same problems?

A common problem I have with cutting any of the plywood that is out there? The slightest warp in the material will keep the laser from cutting all the way through. I have been working on making jigsaw puzzles with the many caveats involved. I stopped using spray glue to attach photos to one side since it is so messy. Now use water based contact cement we have used for many years to build commercial furnishings. Glueing the photo to one side makes the plywood warp bad! I spray the uncovered side with soda water. Normally within fifteen minutes the plywood will be nearly or completely straight.

Lowe’s carries a plywood that is of plantation grown trees, supposedly of Poplar. Unless they use some poplar as interior layers there is obviously no poplar on either side. Top and bottom veneer is extremely thin as in paper thin and you can sand by hand and go completely through it. That said it is 5mm x 4’ x 8’ and is very consistent in thickness. Lasers well. I can cut it with my 60W Omtech CO2 speed of 15mm/sec and power of 45%. With a photograph glued to one side it will require a speed of 12mm/sec and power of 55% with air assist of 45 psi. Next to no residue on top bare side and very little on the photograph with it being on the bottom. Soda water removes what is on the photo easily.
I have a 3W diode laser. Never even tried to cut with it. Does a great job of engraving.
Some question in my mind as to who sells a Diode Laser that is actually 60W.

I have a tendency to believe very little of what most Chinese manufacturers say about their products. Over the years we have been involved with buying some expensive machinery.
Difficult to decipher so called instructions.
The one exception to this has been our Omtech. They go through the equipment when they receive and set it up.
Mine worked perfectly from very beginning and still does.

That ‘90 watt’ device is powered by 12v @ 2.5A… Even the placard states an output of 5.5 watts which is probably pushing it.

“90W effect laser beam shaping technology:” :crazy_face:


Funny, they show a picture of the ‘fine line’ it produces…

I can easily and consistently produce 0.1mm dots, even a bit smaller if I want to work at it… on my 50 watt co2.

It’s too bad they can get away with the stuff they pull…


Hi JMichael,

  1. yes, Im using air assist.
  2. Sculpfun S6 have 60W diode laser.

So can I straighten bent plywood by pouring soda over it? Interesting… thanks.

Dry soda wouldn’t help the bend.
I use
A spray bottle with soda water
Soda water is in the bottle for cleaning the
Photo side so I use it on the warp also

Don’t have a photo or video exactly how to do it? Should it be submerged, or just spray and let it work? How long?

If you only glue something to 1 side of anything, (Ply, Mdf, solid wood) it will want to cup the material, this is why when veneering a panel you always veneer both sides, pretty veneer on face side and balancing cheap veneer on the back.
The reason it cups is when the glue dries it pulls on the surface, cupping the material (if it was because it was getting wet it would expand and bow the surface) which is effectively what you are doing by wetting the opposite side to straighten it temporarily, however when it dries it will go back to the cupped shape. once cut into small jigsaw pieces this cupping will be very small of course, but it will still be there.

I would suggest you glue both sides using a paper balancing sheet glued to the back.

My purpose for the wetting/dampening the back side was to get it straight long enough to cut the puzzle. With my limited use of this system I find little to no warping of the puzzle pieces.

BTW: Spray bottle works best. I let the plywood adjust to the water for about 15 minutes before beginning the cut.

Yes I understand why you are wetting the backside. I was explaining why you wouldn’t need to if you did the job correctly. But if you get the desired results thats ok.

Well, I have to disagree with your assessment of my process. Obviously you have not had the success I have with the water additive.
Man! I hate it when someone looks down their nose at me.

Sorry for the rant!

Firstly, no one is looking down their nose at you or your process, I said if it works for you that’s ok, there are many ways to achieve a result.

I’ve been a professional cabinet maker for 35 years and I veneer boards all the time, I was trying to give you the benefit of my experience, with the knowledge of why the board bends and how to fix/stop it.

If you choose to take offence at people trying to help that’s your issue not mine.

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Strictly how your comment came across.
BTW: I built most of the furniture in our log home as well as all of the cabinets.
Have been building residential and commercial cabinetry for 65 years. I do know something about wood working.

Then why are you bodging the job in the first place by veneering only 1 side of a job and then having to find another bodge way around the bending by spraying it with water??!!

Someone with 65 years of woodwork should know better than to give such poor advice. You say you know something about woodworking.
Do you have to spray the underside of all your home furniture once a week to keep is flat LOL.

And at this point now I am “looking down my nose at you” (As you say) and it’s a long way down.