• It's time to cast your vote in the January 2025 Turning Challenge. (click here for details)
  • Conversations are now Direct Messages (click here for details)
  • Congratulations to Alan Weinberg for "Elm Burl Bowl" being selected as Turning of the Week for January 27, 2025 (click here for details)
  • Welcome new registering member. Your username must be your real First and Last name (for example: John Doe). "Screen names" and "handles" are not allowed and your registration will be deleted if you don't use your real name. Also, do not use all caps nor all lower case.

Is plywood OK for glue block/jam chuck

Don C Davis

Don C Davis

Joined
Feb 15, 2018
Messages
256
Likes
64
Location
Canton, GA
I am wanting to build some glue blocks and some jam chuck blocks currently--a couple for jam chucking some bowls, and also some center drilled and tapped with my Beall spindle tap for glue blocks. My shop expansion is nearing completion, and there happens to be a fair bit of 3/4" interior finish CDX plywood leftover that is big enough for these if I glue up like 3 pieces together--question to those who know, will building some 4-6 inch stacks of this plywood make a reasonable block for these pieces. I have seen some folks on YouTube making such pieces but they used Poplar or Birch of such. I don't have any 12/4 pieces of such wood, so I was hoping using some of the leftovers from my shop expansion would be OK.

Thanks for any advice/input--Don
 
This will work, the multiple layers provide strength but also require a sharp tool to cut thru the layers of glue. The multiple layers are in different grain directions which adds to the stability of the finished item. The only disadvantage may be small voids that you may run across while turning the CDX piece. You can always fill these with wood glue or wood putty if you want them to look nice when complete.
 
Be aware that inexpensive plywood (actually none of it is inexpensive anymore) will have voids. This can be a problem for glue blocks because you don't know they are there. Not much of a problem for making jam chucks. Most of the time you can simply turn past them or fill them if necessary. For jam chucks I prefer to glue up 4 or 5 2x4"s. You have enough thickness to turn a lot of jam chucks before you finally have to toss it.
 
I agree with John....plywood glue blocks can delaminate, coming apart. You would be fine for jam chucking, but not glue blocks. Stresses from turning can make a plywood block come apart and that flying blank could hit you square in the face........please use only solid hardwood for glue blocks. On smaller things, you could use a glue block from 2x4 or 2x6 construction lumber, but for larger turnings, either use hardwood or faceplate, or a good chuck with tenon turned to match the jaws.
 
Plywood can work okay for a jamb chuck, but not for a glue/waste block. I did it once.... You may have better results with Baltic Birch ply or Apple ply, but pine or poplar give a more secure mount...

robo hippy
 
Like Reed says do not use plywood for glue blocks, they can and will split along the layers, DAMHIKT :oops:, if used as faceplates with screws going through they are OK, I usually use pine barn boards, they do work well or some scrap end construction 2X6 or 2X8 lumber.
 
Ditto

plywood good for jamb chucks & donought chucks

Plywood bad for glue blocks.

I like hardwood ( maple, cherry, walnut ) for glue blocks.

Ideally you want dry wood.
I have made several from almost dry wood that have served well.
 
Thanks folks--I didn't think about that feature for glue blocks--I guess I'm going to have to break down and buy some 12/4 wood online--or find some locally--there are a few lumber suppliers that may have this stock.

Thanks for the help folks!
 
@Don C Davis i have made all my glue blocks from bowl scraps I have dried.
If you can find a solid piece of firewood it should serve nicely.

Do you really need a glue block? I consider glue block to be fairly advanced which you may be.

Generally I use a 4 jaw chuck for almost all the bowls I do and some of my hollow forms.
Most of my hollow forms I do with faceplates.
Also I am working almost exclusively with wet wood from local trees.
 
I think that 1X and 2X lumber are fine for glue blocks as well as using scraps of free wood. I hardly ever throw away pieces of wood that are large enough to be used for something. If you put a piece of brown paper sack between the pieces of wood, it will be easier to remove the waste block using a chisel.

I don't use waste blocks very often, but sometimes theere isn't any wood to spare for a mortise or a tenon.
 
I'm going to say no.
No because it means you are trusting the laminate and glue. You will already have your glue joint to be concerned with; why add to the equation?
 
You must log in or register to reply here.
Back
Top