1/8" plywood problems

[Scott Woodson]

I've purchased 1/8 baltic birch plywood now from three separate vendors. Although the price has swung dramatically (from $11 a sheet to $28 a sheet) I've noticed an increasing problem getting a good cut with my 45 watt epilog. There seems to be more glue (probably filling voids in the inner core) that chars and doesn't cut through. You can even see the laser turn colors when it hits this material. Is anyone else out there noticing this? I'm trying to compensate for this by slowing the speed of the cut (using 25 spd, 100 pwr at this point) but am now noticing more burning and of course it is costing me time. I've checked to see if my tube is losing power (cuts through 1/8 arcylic with factory recommended settings) so I don't think the tube is losing power. I've also fooled around with the HZ setting, but still can't find a sweet spot (moved from 500Hz to 2500Hz). Looking to see if it's the supply chain up here or if this is a universal problem with others.
Thanks in advance.

Scott

[Steve Clarkson]

I'm wondering if you're on to something............two years ago, I could cut 1/8" baltic birch at 100P/35S.........and for the past few months, I had to drop it to 100P/27S to get the pieces to completely cut through..........I too was thinking that my tube was going.........

[Chris DeGerolamo]

Scott, from my experience, slowing the laser down does not solve the issue. As you found, you get more charring and the glued areas may or may not get cut. Depending on your application, I would recommend scoring the wood with a exacto knife or similar once it is done to remove it. You should be able to pick out the problem areas by visual cue alone. Try this too: spray the board with Pledge. Do some tests and see if it works for you. I have found that it helps a bit, I am unsure why. Good luck.

[Larry Bratton]

Plywood never does cut as well for me as solid wood. I know for sure my tube is not going because I can cut 1/8" acrylic with 10s/45p/500f and get a clean cut. (The manual recommends 15s/100p/5000f) I cut some 1/8" baltic birch plywood last week at 30s/100p/500f. It took 2 passes to get through it. However, the cut was clean with little charring. I surmise the reason is the different glues and I there is probably no way to standardize the veneer layers.

[Michael Kowalczyk]

Hey Scott and others,
The 3mm (1/8') Genuine Baltic Birch plywood we use cuts fine on our Trotec and I have actually been able to increase the cutting speed by tweaking the settings a little. So my settings are 100% power 1.15% speed and 5000 Hz. The pics shows the edge quality.

Make sure you are getting Genuine Baltic Birch plywood by checking the stamp in the corner.

[Michael Hunter]

And check that it is interior grade too - the WBP waterproof stuff has the laser-proof glue.

[Darryl Jacobs]

I too have seen vast differences between grades of Baltic birch lately and I have found a bit better results with playing around with the frequency and speed. Too slow and hot and it chars and then the problems start.

I have also had some 1/16" that cuts worse then some of the 1/8th that I use. I used to like working with the stuff, but I just hate it now to get decent cuts.

[Scott Woodson]

Thanks all for your input. I was beginning to think it was me only. I did check the plywood and it was a green mark in the corner indicating B/B. I think I'm going to continue to play with my frequency and speed settings to see if I can get acceptable results. I've found a source for $11 a sheet so at least this will lower my costs some and make up for the slower production.

[Mike Null]

It is very important to check flatness when cutting plywood. It is quickly affected by humidity changes and can result in areas being out of focus with your laser.

[Richard Rumancik]

The problem with cheaper plywood is that it may be Chinese plywood, not Russian birch or Baltic birch. Apparently the quality is much poorer. You may find internal voids, and there may be excess glue inside. Also some of it uses non-birch softwoods for inside the inside ply layers. Let us know how you make out with it, but perhaps it is better to pay more and get something that works reliably. A place that supplies cabinet shops would have a more consistent supplier. The big-box stores will buy the cheapest and change suppliers based on price. Plywood is plywood, right?

Even the best plywood will have some internal knots however and the laser can have trouble cutting through these.

[Kay Bengtson]

I cut 1/16" Baltic/Russian birch ply regularly and I also have found that it varies more than I would like. Some sheets cut like butter but others take two passes or end up being a total loss. Sometimes, the thickness varies and they have much more knotty areas on one side which causes the laser not to cut through. If it chars at all, additional passes just won't work. It seems that quality control is slipping in just about every product nowadays.

Kay

[Scott Woodson]

Kay, I would agree. I've purchased 1/8 from three separate vendors with 3 separate price points, but recently not matter where I get it I've encountered this problem. It was intermittent at the beginning, but now all the sheet exhibit the same problems. I was told the 5X5 sheets are the standard Russian Baltic Birch, the Chinese products were normally coming in 4X8 size. All the plywood I've purchased is from hardwood suppliers to cabinet shops vice big box home improvement stores (who for the most part won't sell less than a skid).

[Bill Cunningham]

If your using a Epilog, Drop your frequency to 150..
I cut 1/8 @ 100power/10-15speed and 150 freq., and get a clean cut with no char.. 500 is high, 5000 is 'way' to high. Forget the book...

[George Brown]

I bought some Baltic birch 5x5 sheets, and have the same problem. Most of it cuts easily, and then it hits areas what WILL NOT cut, no matter how much power is used. A cut through that area with a saw revealed a different appearance of wood, maybe a void filled with a biscuit of some sorts. I may try some Finnish birch, maybe it will be better?

[Ron Chapellaz]

I just finished cutting 1/8" Baltic Birch last week and managed to tweek my settings for the better. I used to cut at 70 speed 70 power and now I am cutting at 100 speed, 100 power, and cut through on one pass with my 35 watt. I finished off the last batch of wood I had in stock and I just picked up 5 more sheets. I'll be cutting again next week. It will be interesting to see if I'll be able to cut at the same settings. I'll post my findings to the forum. I wonder if humidity might play a factor in the ability of the laser to cut through. Could the energy of the beam become absorbed by the moisture in the wood? Maybe others can chime in with their expertise...