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View Full Version : Need help! What tolerances to use for tight plywood joinery (dog bone)



bjl.ward
10-11-2012, 05:19 AM
Hello everyone,
Im new to this site and am in need of some help. I am currently designing some furniture to be made out of plywood with a lot of slot together joins and need to know what sort of tolerances to put on the outer join to allow for a tight join with the 'dog boned' slot that will hold without the use of fasteners! any help is much appreciated!

I am using 17 mm ply so if I were to make a join to be stiff but not too stiff so its difficult to put together.
I am eagerly awaiting a reply!

Dylwad
10-11-2012, 07:27 AM
I think its one of those things that you have to test cut/fit. CAD drawing aside the fit will be different depending on feeds and speeds, and moisture content/humidity/condition of the bit/accuracy of the machine.

Are you going to be doing the cutting or sending it off?

bjl.ward
10-11-2012, 08:08 AM
I will be cutting myself, on a shopbot PRSalpha. How tight would it hold together if I offset it by 0.2mm?

bjl.ward
10-11-2012, 08:09 AM
0.2mm larger than 17mm, which is the thickness.

nachin11
10-16-2012, 02:15 PM
0.2mm larger than 17mm, which is the thickness.

I did 0.2mm on a 20mm plywood sheet and it was to tight, very dificult to insert to 5 mm depth and almost no place for the glue.

Will be 1 mm tolerance to much, glue included?

If the idea is paint.........Which tolerance for hardware?

ger21
10-16-2012, 05:16 PM
Is the plywood actually 20mm, and is the dado actually 20.2mm? Just because you program for a certain size doesn't mean you'll actually get it.
Also, the plywood we get usually varies in thickness more than .2mm, so you may get some sheets that fit perfectly, and some that won't fit at all. If you need to add glue, I'd probably go .3-.4mm larger.

nachin11
10-16-2012, 07:14 PM
Is the plywood actually 20mm, and is the dado actually 20.2mm? Just because you program for a certain size doesn't mean you'll actually get it.
Also, the plywood we get usually varies in thickness more than .2mm, so you may get some sheets that fit perfectly, and some that won't fit at all. If you need to add glue, I'd probably go .3-.4mm larger.

So, 20mm plywood and 20.5-20.6 mm dado?

Why did you say we will not get the measure we programe?