# Wedge through mortise and tenon joint

 Forum topic by Frazeran posted 09-05-2018 11:20 PM 1418 views 0 times favorited 10 replies
 Frazeran18 posts in 1090 days 09-05-2018 11:20 PM Hello fellow woodworkers! Building a small stool out of Nick Offerman’s “Good Clean Fun” book. In the book he uses wedged through mortise and tenon joints for the stool legs. My question is around the geometry with the wedges and the mortises. I have heard that the rule of thumb is 3 degrees but I am having a hard time wrapping my head around that and how specifically to make the wedges the right fit. Below is a picture of where I am at so far. Any help/advice is much appreciated!

## 10 replies so far

 bandit57124440 posts in 3295 days #1 posted 09-05-2018 11:38 PM Hmmmm Hmmm.. Just food for thought… -- A Planer? I'M the planer, this is what I use Frazeran18 posts in 1090 days #2 posted 09-06-2018 01:54 AM I appreciate the picture of the finished product. I am trying to figure out the math to make the angled mortise opening and the wedges wuddoc354 posts in 4329 days #3 posted 09-06-2018 02:18 AM This may give you some guidance: https://www.woodworkersinstitute.com/furniture-cabinetmaking/techniques/joints-cabinetry/tenons/through-wedged-tenons/ and this site has a formula:http://www.craftsmanspace.com/knowledge/wedged-tenon-and-mortise-joint.html -- Wuddoc HokieKen12031 posts in 1750 days #4 posted 09-06-2018 02:40 PM Personally, I cut straight slots in the mortises, no angle. Then I cut my wedges so that the bottom end is slightly smaller than the slot width and the top end is about 125% of the slot width and the length of the wedge is about 90% of the length of the slot. So, if your slot is .1” wide and 2” long for instance, I’d lay out the wedge with 3/32” at one end, 1/8” at the other and with a length of around 1-3/4”. Hope that makes sense. -- Kenny, SW VA, Go Hokies!!! EarlS3436 posts in 2959 days #5 posted 09-06-2018 05:02 PM I use the bandsaw for my wedge slots and taper them slightly into the relief hole. The wedges start out flat and are sanded to a taper until they “fit” in the slot. Generally, they wind up being ~1/8” at the top of the wedge. It’s all highly scientific. -- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected" OpensideFlanker14 posts in 920 days #6 posted 09-06-2018 07:17 PM Agree with Kenny; straight slots, tapered wedges. Having had the slots (tapered or not) propagate a crack beyond the depth of the cut, I now am very careful to not overdrive the wedge and often I first drill a small round hole at where the base of the slot will be to further prevent the crack chattering into a visible location. bandit57124440 posts in 3295 days #7 posted 09-06-2018 09:04 PM Mine were done mainly like this… Wedges cut on the bandsaw….from as thin as I could to less than 1/8” at the fat end….don’t want them tooo fat, as they will cause a split to happen. -- A Planer? I'M the planer, this is what I use Frazeran18 posts in 1090 days #8 posted 09-07-2018 02:49 PM Thank you for all the great advice! I am going to start with straight mortises and wedged tenons and see how that goes. Used my friends mortising machine last night and man! can that thing chew through some wood. 1.75” Cherry. Now time to clean up the edges with my old friends the chisel and the mallet Frazeran18 posts in 1090 days #9 posted 09-10-2018 02:16 PM Progress shot! Went straight mortise and tenons with it. Now to make the wedges, sand and finish! Frazeran18 posts in 1090 days #10 posted 09-10-2018 02:18 PM