Plywood questions

[h2simms]

If I were to build a 4' by 2' by 18" cage, out of 1/2 plywood, and I want the back piece to fit inside the top, bottom and sides would it be 47 1/2 inches long by 23 1/2 inches tall? And what kind of stain could I use? Is there a certain brand of alot of colors? Thanks,
Trent

 

[EShell]

Using 1/2" plywood for the sides, we would need to deduct 1/2" off for each end panel, so your "drop-in" length would be 48" - 1" = 47".

The same thing with the height, we deduct 1/2" top & bottom sheets, so the height of the drop-in back piece would be 24" - 1" = 23".

I've used MinWax stains for most of my own woodworking, but you should be careful to choose a water based stain, so that it will not leach toxic fumes for the next century or so. It still needs to be sealed with something moisture resistant. I have used polyurethane, but there may be some easier to handle and less potentially toxic one can use.

You may already be aware, but plywood comes in varying grades for surface finish, glue type (interior/exterior), material species and treatment for either fire or decay. Most of these variations are described using letter codes.

The better surface grades are "A" (stain grade) or "B" just as smooth, but it is permissible to fill the voids with "footballs" and thus it is considered paint grade. Plywood surface character is denoted by letters for descending grades. You will usually see two letters, one describes the first side, the "face", and the other describes the back. A piece of plywood graded "AA" would have top grade material on both sides. "AB is a more commonly seen type, with a nice outer face and a slightly lesser interior finish. "AC" would be used where the back is not seen at all. This provides a very good surface finish, but a utility grade back that cannot be finished acceptably.

For an animal enclosure, you'll want exterior glue, signified by an "X" in the identifying number. One might see "ACX", which is a cabinet grade face (A), utility grade back (C) and exterior glue (X).

I prefer to work with birch plywood for cabinet grade work, and they refer to it as "luan". It provides a decent stain surface, and can be had in "fancy" grades with nicer grain.

Plywood can also be had with cherry, oak or other hardwood veneer faces that provide very nice stain effects.

HTH,
Ed

 

[h2simms]

Thank you, that's great information and will keep that on hand! Thanks!

 

[JeffSimpson]

If I were to build a 4' by 2' by 18" cage, out of 1/2 plywood, and I want the back piece to fit inside the top, bottom and sides would it be 47 1/2 inches long by 23 1/2 inches tall? And what kind of stain could I use? Is there a certain brand of alot of colors? Thanks,
Trent

In general, 18" wide is considered the minimum depth and maybe too small for a large BD. Most people seem to agree (right or wrong) on a 4x2x2 enclosure. Are you dead set on only 18"?

I prefer to work with birch plywood for cabinet grade work, and they refer to it as "luan". It provides a decent stain surface, and can be had in "fancy" grades with nicer grain.

I've never heard of birch plywood referred to as luan. Generally at the big box stores if you ask for luan, you are going to get a 1/4" plywood that chips pretty easily and is generally used for subfloors. Birch or Oak both take stain very well, and are readily available at HD/Lowes, etc. You can of course paint them as well, but it would be cheaper to buy a sheet of cheaper grade pine plywood and simply sand it down.

In regards to stain, ideally you want something water based and non-toxic. Minwax is usually found at most places. As for sealing it, again you want something water based, NOT oil based. Due to the off-gassing of vapors from oil-based products, long after it dries and there are no fumes, can apparently cause problems. I don't have any personal experience with this, but the concern seems to be pretty consistent.

 

[h2simms]

No, 4' long by 2' deep by 18" high.

 

[EShell]

...I've never heard of birch plywood referred to as luan. Generally at the big box stores if you ask for luan, you are going to get a 1/4" plywood that chips pretty easily and is generally used for subfloors...

Understood and no argument. This is probably a "BC" grade you're seeing, used for, as you suggest, flooring underlayment. Underlayment must be very smooth (hence the "B" face), but surface appearance isn't an issue since it's covered. An "A" faced sheet, still luan, will have the noticeably better surface.

With regard to chips, there are three factors that come to mind:
1) Big box stores, with their high stock turnover, and high employee turnover, tend to handle their merchandise rather roughly and/or in an unskilled manner. Corners are often chipped and edges bruised before the customer does one little thing to lift the chip or make it delaminate.
2) Hardwood veneer faces, such as birch, are indeed inclined to chip if they are mishandled (as above)
3) Big box stores have many ways of keeping their pricing down. Buy bulk, hire unskilled people for certain material handling jobs, import goods..... One other way is to use a pine substrate behind the hardwood veneer face. Pine does not glue as well, nor is it as structurally stable. One will see much more attrition in pine products, but, the important thing is they are cheaper....I guess. Fir plywood runs a few more dollars a sheet for what seems to be the same product, but fir will be a much nicer product, the sheet will lay flat, the material will stay glued and temperature/humidity changes don't distort it as much as pine.

 

[EShell]

No, 4' long by 2' deep by 18" high.

Then I've given the wrong dimensions above.

Sorry, I misunderstood. FWIW, construction dimensions are normally given as L x H x D and I read the height as the depth in your first post. Then, your idea of the back piece being 23-1/2" kinda sealed it for me...LOL.

If the enclosure is 48" long and 18" high, then your sheet of plywood for the back inset would be 47" x 17".

Same math applies, you're just subtracting the 1" (1/2" + 1/2") from the 18" outside dimension instead of a 24" outside dimension.

 

[h2simms]

Woops, k j got it now, yes I messed up above with the demensions, sorry.