Best wood for not warping?

[techyg]

I have been using some Amazon purchased Baltic Birch, that is about 3mm or 1/8" thick. I am not really that happy with it. Just about everything I have cut with it larger than a few inches (25-30 mm) ends up with serious warping. I have not had any warping problems with the PG draftboard, but I know that’s just MDF.

The BB plywood seems fine for really small things like earrings (which is good, because I still have probably 15 sheets), but not for anything larger. I was surprised it warps so much. My basement, where I have the GF, is about 60% humidity year round (at least until the dead of winter, when it might drop to 30-40%). That may have something to do with it.

I haven’t really experimented much because I didn’t want to order a bunch of material until I had some practice, and I feel like I’m at that point now. My GF only came with two different types of wood- draftboard and medium basswood plywood. I haven’t tried the basswood plywood yet.

Just looking for some more info on what your “goto” general purpose material is, ideally 1/8". I am going to be traveling off and on over the next two weeks, so I could probably put an order in to GF for PG materials, but I’d also like to know if there is a good supplier on Amazon that’s worth getting. I hear a lot about “Woodchucks” but haven’t tried their stuff yet.

My next project is to cut some turkey napkin rings for Thanksgiving. They are fairly good size, maybe 3" or so wide by 2" high. I am still tweaking the design so the engraving turns out how I like it. It turned out pretty well on the draftboard, and I could use that, but I don’t know if I have enough to complete the project (probably need about 30 or so of them). I think my BB plywood is going to warp too much to use.

Thanks in advance!

[evansd2]

Warping how? In storage? Post cut? Post finishing/cleaning?

In general plywoods should be pretty warp resistant by their nature. Maybe a bit more detail?

[techyg]

The sheet seems to be relatively flat (it’s a 12x12" sheet), and it’s held down by magnets. I notice the warping after I get done cutting it.

Here is a picture of something I just cut, which is probably around 8" or so in diameter.

[evansd2]

Sometimes engraving can cut through the layers and expose new layers which then suck up available humidity and expand, giving you that taco shape. If you cleaned the engrave, the solvent can definitely cause warping. Did you clean it?

You might also be releasing internal stresses between the layers which then shift and warp. Hard to say.

[techyg]

That makes sense, thanks for the explanation. I didn’t clean it, so it must just be the engrave going a bit too deep (causing the internal stresses). Maybe what I can do is lower the engraving setting and go a bit lighter to see if that helps any.

[evansd2]

I’ve had some severely warped engraves that settled down and went back to flat after a day or two. I might lay it flat and see how it goes for a bit.

[techyg]

So I just lowered the engrave power (from 80 to 50, speed=600) and tried a smaller piece. No noticeable warping… Engraving quality isn’t quite as good, but it’s not bad. Do you think it’s possible the heating of the more powerful engraving was causing it to warp/curl?

[evansd2]

Possibly, yeah. It’s really hard to really figure this stuff out, there are a lot of complicated forces acting out all at once. Isolating the root cause is sort of academic in that light, and results are king. Engraving is a complicated mix of factors, I’d say do a few small test engraves at lower power until you find what you like. Slower generally = darker, more lpi generally = darker. If you are trying to get a dark engrave without beating the wood too much, a shallow slow engrave might do what you want.

The problem is that slower and more LPI = muuch longer engraves. Especially upping LPI is a huge time suck. Youd 8" engrave will go from a nice half hourish to 2 hrs plus just on changing settings. Finding that balance is key.

Another possibility is to glue a few layers of ply together and then do the engrave. The strength of the other layers might prevent the warping. Kind of depends on your intended use, but it might work.

[techyg]

Yeah, there are quite a few variables at play, it seems! I am keeping a spreadsheet of all my tests.

I just tried again at engrave power = 60, all other things constant, and it seems to be a good balance of no visible warping, but a good engrave. Hopefully it translates well to the larger size. This particular design is about 40 minutes of engraving at the 8 inch size… I’m not planning on doing more than one of these (aside from my previous attempts) so I think the longer engrave time is OK.

Thanks again for the helpful info!

[jbmanning5]

I think a common theme of woodworking (as far as warp) is if you do something to one side, it’s best to do it to both sides - or something like that. Ie staining one side can produce warp, treating both sides would be more desirable.

That doesn’t really help in this case, I don’t suppose though. Planing too vigorously from one side can do the same (warp) - which would be more akin to what’s going on with engraving. One solution, like you discovered, is less aggressive engraving.

I’d also suggest to maybe let the wood rest a while after (a day or two), weighted down. Let it acclimate again in its new form.

[brokendrum]

notice the warping

Wood that has warped can also be trained back flat before sealing it.
Water will work, but alcohol is better since it evaporates quicker.
Give it an alcohol mist, then place it under a flat board with a weight upon it. I also layer a paper towel between the boards (to help absorb the excess alcohol).

Not magic, just science. The moisture allows the fibers to stretch and give without shear damage.
Some lacquer or Poly seal to prevent further moisture issues should color it done.

There may be other things people do, this works for me though.

[evansd2]

Not magic, just science.

SORCEROR! GET HIM!

[techyg]

The full 8” engrave at power 60 seemed to do well with a decent engrave and minimal warping. Thanks to all who chimed in!! I do like the power 80 engrave a little better so I am going to leave it under a pile of wood and see if it straightens out. I may also try the spray alcohol and will have to do some more research on that. I think it will come in handy for future projects.

[kittski]

I back my deep engraved pieces with a layer of acrylic. In addition to helping the warp issue, it gives a clean, finished look to the piece. I know it’s not a viable workaround for a lot of projects, but thought I’d just throw it out there.