1/4" Plywood Strength Choices

[Adrian Anguiano]

I stopped by home depot tonight for some 1/4" plywood but left undecided.

I need the strongest plywood as far as:
if i bang an edge with a hammer, which will dent the least.
if i side kick the middle of the 2ft x 4ft panel, which will have the least amount of permanent damage, cracking/splitting/etc.

Looked like my options were BC Plywood, Birch Plywood, Utility (Underlayment) Plywood, Sandply Plywood

Which will fit my specs the best? Needs to be from these choices, as I'm not driving 30 minutes and taking off work to go get baltic birch and dont want to pay the extra.

PS: The birch at homedepot is MDF center. .19thickness. BC Plywood looked closer to .25

[Kent A Bathurst]

May I ask the intended use?

[Adrian Anguiano]

1) The bottom of pinball machine cabinets between 1940s-1980s. (Side kick proof is related to the heavy use of lift carts pinheads use to move their machine puts a lot of stress on 1/4" panels.) and yes it has to be 1/4" due to the way they are built without having to do major restoration woodworking.

2) Face of the head on pinball machines. Dent proof because Pinheads love to buy and sell and take to shows etc, and the travel gets lots of dings, and being on the head makes it visible. ANd yes it has to be 1/4" because pinheads want them to be the same thickness as they were originally which was 1/4".

Ive been using 1/4" Birch plywood, but was wondering based on my specs on my original post if the other options would be better.

[Henry Kramer]

Would 1/4" Masonite (Hardboard) meet your needs? In some ways it is more durable than plywood.

Hank

[Jamie Buxton]

For strength, thicker is better. And MDF core is not as strong as real wood. So of your choices, it seems that the BC ply is the best. But do you have a visual preference? If this panel is where users can kick it, won't they also see it? If so, wouldn't you want something prettier than BC fir ply, with all its knots and patches?

I make drawer bottoms with 1/4" ply, but when I need more strength, I glue 1/4" offcuts to the underside. The bottom layer doesn't need to go all the way to the edge of the top layer. Where the bottom inserts into the dados in the drawer sides, it is 1/4" thick. But most everyplace else, it is 1/2" thick. It is much much stronger that straight 1/4" material. Could you do the same thing to your pinball panel?

[Adrian Anguiano]

Would 1/4" Masonite (Hardboard) meet your needs? In some ways it is more durable than plywood. Hank

Cant use it for the head since it wont glue well on the rough side unless sanded and that's too much extra work, and I don't trust its kick in strength

For strength, thicker is better. And MDF core is not as strong as real wood. So of your choices, it seems that the BC ply is the best. But do you have a visual preference? If this panel is where users can kick it, won't they also see it? If so, wouldn't you want something prettier than BC fir ply, with all its knots and patches?

For the bottom panel of a pinball machine prettiness doesn't matter. Strength does. It wont get kicked but I said that as a metaphor for the lift carts that get used on the bottom panel put a lot of stress on them.

For the head panel, they get painted, so patches don't matter, but it must be smooth.


For all these reasons is why I suggested between BC Plywood, Birch Plywood, Underlayment Plywood

[Kent A Bathurst]

...It wont get kicked but I said that as a metaphor.....

I can personally assure you that there are plenty of pins from the early 70's that have been kicked.

[glenn bradley]

I would choose 1/4" baltic birch ply if you have a lumber yard nearby. Double-sided service tempered hardboard (smooth both sides) in 1/4" is some pretty stout stuff. It is heavier than 1/4" ply but, quite resilient.

[Jim Dwight]

Unfortunately within those general descriptions you can have quite different products. The inner plys are where a lot of strength comes from and the material makes a difference. Softwood is the least desirable. But more layers is better than less layers. Luan underlayment plywood is thin (really 5mm) and only three layers if I remember correctly but it isn't softwood so that is positive. Sandeply isn't softwood either but it is pretty soft. If there is one with more than 3 layers I would probably go with that and if there are multiple, I would choose the one with non-softwood layers.

[Adrian Anguiano]

I would choose 1/4" baltic birch ply

"Needs to be from these choices, as I'm not driving 30 minutes and taking off work to go get baltic birch and dont want to pay the extra."

[Adrian Anguiano]

Unfortunately within those general descriptions you can have quite different products. The inner plys are where a lot of strength comes from and the material makes a difference. Softwood is the least desirable. But more layers is better than less layers. Luan underlayment plywood is thin (really 5mm) and only three layers if I remember correctly but it isn't softwood so that is positive. Sandeply isn't softwood either but it is pretty soft. If there is one with more than 3 layers I would probably go with that and if there are multiple, I would choose the one with non-softwood layers.

From what I could tell the Sandply, Underlayment, and Birch Ply were all 5mm. I know the Birch was MDF Core, I cant remem on the Sandply and Underlayment. Im sure the BC was all pine, but It had about 5 plys and was a true 1/4"

[Bill Orbine]

Get the 1/2" plywood...run a rabbit along the edges to make the 1/2" fit into 1/4" groove if that's what your trying to do with the 1/4 plywood.

[Adrian Anguiano]

Get the 1/2" plywood...run a rabbit along the edges to make the 1/2" fit into 1/4" groove if that's what your trying to do with the 1/4 plywood.

1/2" Plywood Eats into my tiny profit.

[Art Mann]

I have bought B-C grade SYP plywood at Home Depot a time or two and it never fails to disappoint. It works okay for underlayment but I wouldn't use it anywhere that requires any strength. The MDF core plywood looks a lot nicer but it has even less strength. Birch or Sandeply are your best bets. However, I once tried to make bookshelves out of their premium grade 3/4 Birch plywood. I ripped off the sides and started cutting a 1/4 by 23/32 dado for a shelf and there was so much voiding and rotten wood in the core of this material that it was unusable. I took it back. At other times, I have bought "premium" plywood from HD and it was quite nice. I believe they must buy in vast quantities from the lowest bidder without any regard for structural integrity. You are always going to take a chance.

[Robert Engel]

I've glued rough side of hardboard with contact cement no problems.
Use a double coat on rough side.