Box joints in plywood

[Grahamshed]

I have been trying to make box joints ( finger / comb joints ) in plywood for a drawer but the ply is just 'shattering' all the time.
I have tried half inch baltic birch and 3/4 inch far eastern ply, both look to be good quality. I have also tried a backing piece and front piece which help but not that much.
I have tried the router at high, medium and slow speeds but no real difference.
Joints in solid wood seem quite good.

Equipment is a shop made table, Steve's jig, wealdom 8mm straight two flute cutter.
Any ideas anyone ?

 

[Phil Pascoe]

Give up trying to make finger joints in plywood?

 

[No skills]

Well I was thinking it, Phil posted it... Still nevermind, must box joints be used for what your doing? could you use a sliding dovetail instead??

Wonder if a spiral cutter would be any better, haven't used them myself.

 

[Grahamshed]

I dont HAVE to use box joints but I would like to. I have a small cupboard in the house made from 1/4 inch ply with box joints and that looks good.

I was also thinking upcut spiral and it says it is for ply etc so maybe I will have to try that.....

 

[custard]

I've done finger joints in baltic ply for drawer boxes and they've been okay, little bit fuzzy without a backing board but easily cleans up during sanding. I use a spiral bit and the best quality ply I can find (currently Chudova birch ply from SL Hardwoods), it pays to use the best because any small voids or tiny patches of delamination and ply will spelch for England!

 

[Jacob]

Wrong tool for the material and joint? TS a lot better. Or a different joint.

 

[fluffflinger]

I agree with Jacob, although not impossible to get the fit and finish you want from the router table I'd definitely plump for the TS solution.

 

[Steve Maskery]

I've not used ply for this so I can't help, but if you go the TS route be aware of the added dangers. Apart from the general guarding issue, you have to lean a long way over the saw to operate an equivalent jig on a TS. One of the most common accidents on a TS is people falling onto the blade at the end of the cut. Not as common as lost fingers, perhaps, but quite common nonetheless.
Cheers
Steve

 

[Grahamshed]

Thanks all. I do not have a table saw ( and with my eyesight the way it is I have no intension of getting one ) so I will have to try the upcut spiral. They do seem expensive and hard to find though. The size I want is out of stock at Wealdons and Axi.