But i am not sure if this is known or has been written down somewhere, but playing with my GF now for a week or so, i realized that the proofgrade material is actually a single 1/16 inch ply of the wood on both sides, with a draftboard core measuring 3/16…
I couldnt for the life of me figure out why the etches werent coming out with a wood grain look… its because the default etch settings takes the 1/16th off leaving the draftboard/mdf like material.
Not sure how this makes me feel… almost… cheated? not really, i just assumed it was a really high quality plywood, but it’s not the case.
“With hardwood plywood, any material can be between the face and back veneers and still be called plywood. The core material is specified separately from the face, so you can have maple plywood with a veneer core (which is similar to construction-type plywood) or with a particle- board or medium-density fiberboard core”
"Particleboard core or MDF (medium density fiberboard) core are the other common types of plywood cores in use. In professional cabinetmaking, they are the preferred materials for quality work because they’re flat and of a consistent thickness. "
Proofgrade is a larger category than just what you are describing. You are only describing the proofgrade plywood, which is an mdf core plywood versus a wood core like what most people are used to. There is also proofgrade hardwood which would give you the wood grain you are looking for as it is solid wood throughout.
I had some of the first beta Proofgrade that had a core of wood. It worked for some things and others it didn’t. Often when we think of high quality plywood, we think of the layers as being all wood because it gives the most strength across a wide variety of use cases.
When it comes to making a consistent product that works in a small CO2 laser for a variety of use cases, the values that go into calling it quality are different from cabinet grade plywood.
For example. Trying to get a consistent base surface engraved into an all wood plywood is very difficult. With an MDF core you can be assured that the inlay will go in flat.
I had a conversation with someone the other day about plywood being an inferior “cheap” thing to make cabinets our of. The best he said were the old cabinets that were of solid wood. I told him that I would prefer using high grade plywood because of the stability that it brings. But definitely no chipboard stuff with vinyl facing. That really isn’t plywood.
Another issue is needing the plywood to remain dead flat in the bed for precision cutting and engraving with defaults. Often veneer cored three ply plywood can be unpredictable in how it behaves in low and high humidity environments.
Getting an inner core veneer that is consistent, integral, no voids, knots or other surprises might have kicked up the price, I don’t know.
These aren’t all the issues but recognizing that there are other values and end cases to consider that might be better served with an MDF core and the decision isn’t made because it is cheaper. Although that might be a consideration.
My experience with Proofgrade is that it is a quality product that works great in my Glowforge. I haven’t found anything that so predictably works like this. Especially in that it is finished.
Just to come in late to the conversation (as usual), let me second what others have said, it just all depends on the use. multiply (alternating layers of wood laminate) is used almost exclusively in construction because of its strength, but MDF core pannels also get used a lot in cabinet making and other “fine” woodworking projects because of its consistency. And just a personal preference, I love the contrast the charred MDF gives when etching through the veneer of the plywood If you are wanting the grain to show in the engraved parts, then you would be much better off using solid wood and not a ply.