wedged through tenon

[Glenn Lewis]

i tried wedged through tenons for the first time today and thought it went pretty well until i realized the cut i made for the wedge kept going and split the wood beyond the tenon.

i drilled a hole at the base of the cut as i read you're supposed to do to alleviate the stress of the wedge but it still split. did i just get too aggressive driving the wedge in or did i not drill a big enough hole?

in a tenon that's roughly 7/8"long by 2"wide by 1/2" thick i drilled a 3/16" hole. any advice is appreciated.

Glenn

[glenn bradley]

I think your hole size is OK. Your mortise allowed too much spread as the wedges went in. You can laminate a piece of veneer to the outer edges of the tenon to reduce the gap (if not too late).

[Cliff Rohrabacher]

Well that was lesson #1.
Don't create a situation where you have the wedge expanding the Tenon much. Really all you need is a scosh just to snug it all together. Like Glenn said: you can piece your tenon to eliminate excess expansion

[Chris Friesen]

Woodworking magazine did some tests with just saw kerf, kerf and hole, and just a chisel split, then sawed the joints apart to see what they looked like inside. Basically they concluded that the hole does nothing, and that if the joint is sized appropriately just the chisel split gave the tightest joint.

That said, I agree that if your tenon piece is splitting your mortise may be too loose. Alternately, the wood may simply be very brittle. (I wouldn't want to try and wedge ebony, for instance.) Some woods react better to using two wedges, one near each end of the tenon.

[Matthew Voss]

You must also consider the grain direction. The wedge must be oriented so that it applies pressure against the grain, not across it.

[Matthew Hills]

You must also consider the grain direction. The wedge must be oriented so that it applies pressure against the grain, not across it.

I thought that this was for the piece with the mortise in it?
(doesn't the slot for the tenon pretty much always run with the grain?)

[Matthew Voss]

Yes, you're right. I misunderstood the op. thanks.

[Robert Miller]

The trestle base of my workbench had 24 wedged tenons to make.:eek:
This is way I do them, but I'm sure everyone has their own preferences.
I laid out the mortises in the 12/4 white oak and cut them with a chisel. I used a 1/8"line on each side of the actual mortise and chiseled halfway down each side of the mortise to restrict the amount the tenon could spread. I used a large chisel to spit the tenon in the mortise and drove in the ebony wedges with a steel hammer.
I use a steel hammer because you can hear the difference in the sound when the wedge is drivenhome, a rubber mallet won't. Be sure to drive evenly and don't beat the thing to death. My tenons were all shouldered and I never drill a relief hole in the tenon. I use this technique a lot because its strong and it just looks great.Hope that helps.

http://i55.photobucket.com/albums/g148/robmill54/P1010051.jpg