1/4 ply question

[Jim Reinhard]

I was trying to cut 1/4 midwest model plywood .I was having a tought time with it and many passes .I then came in and started rereading some old posts and see people cutting with 150 or 200 ppi .I was trying with full ppi constant on.I will try 150 and 200 tomorow but was wondering why less is more for cutting.?

[John Noell]

For me, 150-200 is a bit low but I often use 500 or less for wood. If you think about it, having that many holes per inch pretty much cuts through your ply, while using 2500-5000 simply means that you are going to be heating/burning a lot more times per inch -- and so close together that it heats the wood more, and therefore is more likely to burn the wood (= black char edges). So, a lower ppi can mean less charring. It won't cut better in my experience, but there is less charring.

I should add that if you are having a lot of trouble cutting through 1/4", maybe it is the glue? Exterior plywood glue is nasty to cut. Interior (with PVA) is MUCVh easier to cut.

[Craig Matheny]

To add to Johns notes I found that as I lowered my freq / ppi it also burned hotter more energy per pulse making it cut better and cleaner with the low ppi. With that said cutting 1/4" ply on a 40 watt unit is going to be painfully slow 1/4" solid wood at best is for me 10% and 1/8" Baltic birch is 16% so making it 1/4" ply maybe 4% and if it is exterior glue forget it that creates its own issues. Good luck

[Douglas J Miller]

I cut the old 1/4" Baltic Birch ply on my 40 watt at 30% speed, 100% power. A lot of charring, but goes right through it. The new glue they are using now I have to go down to 20% speed, though. :(

[Kimmy Armstrong]

Midwest is not the best product for lasers. Believe me I know. Revell is better. The problem is, in the middle layers there can be knots. The adhesive used for Midwest is a pain to cut through, and a lot of times ends up not cutting the bottom layer of the veneer. The best 1/4" to use is Columbia Forest Products A-1 birch. They may sell it at your Home Depot, but you can special order it, or call the company. They use soy based adhesive and cuts like butter. When I used Revell- we cut at 100% power, speed of 10, and a frequency of 2,500. The lower freq. did not work for us.

Epilog mini 50 watt

[Jim Reinhard]

Midwest is not the best product for lasers. Believe me I know. Revell is better. The problem is, in the middle layers there can be knots. The adhesive used for Midwest is a pain to cut through, and a lot of times ends up not cutting the bottom layer of the veneer. The best 1/4" to use is Columbia Forest Products A-1 birch. They may sell it at your Home Depot, but you can special order it, or call the company. They use soy based adhesive and cuts like butter. When I used Revell- we cut at 100% power, speed of 10, and a frequency of 2,500. The lower freq. did not work for us.

Epilog mini 50 watt

Yep the midwest is what I was having trouble with.I am trying to cut parts for rc aircraft engine mounts .So I figured it would be best because of the strength.tales me 2 passes at .07 100 power and 200 ppi.chars up but not as bad as it was with full ppi.
I can cut the HD 1/4 ly with little charing.

Even the 1/8 midwest is hard to cut.

[Craig Matheny]

Sounds like it is exterior grade ply