I was wondering the best way to drill, or chisel the angled side of the mortise for this joint. I have looked a the drill guides that timberwolf tools sells and the chain mortisers, all look like great tools but a little pricey for me right now.

You could go ahead and drill perpendicular to the face where the tenon runs through so all that is left is the wood running to the angle. Then you could simply chisel the remainder. I would recommend transferring that "interior" angle to the faces of the post for alignment ease. If you clean out the cut part of the mortise just mentioned I guess you could take a hand rip saw to the sides and cut to the angle as well. That might make the chiseling easier

tack or clamp a straight board on the timber to (visually) guide your drill. on the end of the timber works pretty well, or on the adjacent face to the mortice.

with a boring machine you can prop the base of the machine up with a wedge. the angle of the wedge is then the template for the dovetail tenon. easy. whistle a song while you're drilling. yet another reason why boring machines rock.

How many do you have to do? Is this for a personal project house or are you trying to feed your family by cutting these? Do you currently use a mortiser or drill for mortises?



One thing to help with the cleanup is to cut a block the required angle to register the back of your chisel on while tapping.

GH

In Doug Fir anyway, you can angle a hollow chisel mortiser to cut the taper with minimal clean up.

Gabel were you suggesting that the wedged half dove tail requires extra time and there for not worth a client or your families valuable time, when you typed this...personal project house or are you trying to feed your family by cutting these?. I have seen two examples in production shops where they don't use this joint, due to the fact it " takes to much time". This bothers me in some way. The wedged half dove tail is a very strong joint and there for is the joint of choice over one with out a wedge and half dove tail,when used on a tension member. I believe it was the joint which broke Ben Brungrabers hydraulic press.
Other details I am interested in is the direction the wedge goes Inside/outside and why? Number of pegs, size and placement? Where else is this joint used King post and Tie beams?
I have read that the wedge goes in from the outside. The shrinkage issue is solved for the most part by having the small end section of the timber (the tenon) naturally/pre dried in comparision to the rest of the timber so on assembly there isn't much drying left and very little shrinkage after that. There for the wedge is inserted from the outside not the inside where it can be tightened later by taking up the flooring and driving the wedge even more. I also don't use anchor seal on any of my joints, this would prolong the drying process.
I have gone to one 5/4" peg in addition. I was looking at a old barn and noticed the tying joint had had pulled away by about 2" on closer inspection there was no peg as back up, but the building had great amounts of stress added to it as it was in a state of collapse.
Futher comments would be great. Tim

Tim,

With my questions, I was trying to get a sense of how many of these per week/year/lifetime the original poster was going to need to cut, as well as what tools he currently had.

To my mind that pretty much determines whether to use tools he has, even if they are slow, or spend money on an expensive tool.
There is a big difference in how I approach cutting 2 vs. cutting 200.


I have no issue with the wedged half dovetail tenon. I think it is a great joint. We don't use them often, but that isn't because they are hard to cut or take too much time.

I'm also interested in what the best way to detail this joint is. As well as how much tension capacity can be developed if it is properly detailed.

I have seen an old frame where the wedges could be removed easily by hand. They were loose. I have also seen an old frame where the wedges were gone in some trusses. They had fallen out because they were loose. It seems to me that you want those things tight -- that is why I think it best to have the wedge on the inside as mo drew it in another topic. If the wedge is taller than the floor is thick, you could tighten it without taking up the floor. But if it is hidden in the wall, you'll never know how tight (or loose) it is.

I like these discussions about detailing joinery -- I would like to hear more people's point of view.

Gabel

Hi Gabel,

Having been through thousands of domestic and agricultural buildings, I have yet to see one of the joints that is described above. That is not to say that these do not exist but that their usage is not immediately obvious in the vernacular building landscape.

You have identified its major weakness i.e. the possibility for wedge loosening, or worse still loss, and that just about says it all. I would suggest that unless you are dealing with a structure that is known to need to be taken apart, aligned and / or tightened on a regular basis e.g. a like a mill, then this type of connection is best avoided.

Ken Hume P.Eng.

I think Ken may be suggesting the WHDT is an American joint. Which makes sense, being, it is used mostly in the dropped tie configuration, with common rafters. Ken, do you see that set up on your side of the pond? I have a book, Recording Timber-Framed Buildings: An Illustrated Glossary By N.W. Alcock, M. W. Barley,.... It shows a half dove tail with a wedge. No detail so I am guessing but the wedge looks like it has no taper. This book is a recording of English joints. It is on page F-28. So there may be examples on you side of the pond, Ken just rare.

On one of my own first buildings I used the WHDT on the foot of the king posts (6 trusses 30') In the recient past I noticed one of the wedges was not present! I can look right up through the wedge slot, the joint shows no gaps to speak of. There is no floor loads either. I should jam in a new wedge. These joints were cut incorrectly. My wedge side had no taper, and some of the wedges went in from the top, some bottom, it is a bottom wedge which is missing. In a king post set up, I put the wedge in from the top now. This is the same as going in from the inside as with a dropped tie. I also like the ratios Jack Sobon talks about 1:5. I would think a wedge with even less taper would be better yet. So, on a 10" post the wedge would be something like 2"-2-1/2" in 10". How about putting a nail in the wedge so it can't fall out? This would have to be pulled to tighten later.

Another situation I have come across is where the king post was square ruled into the top of the tie by about 1", this housing prevented the half dove tail from fully contacting its seat before being completely assembled. The joint needed some futher adjustments. I had to extend the housing/reduction on the tie to allow the king to seat onto and than slide over to the half dove tail. A haunched shoulder eliminates this problem on the dropped tie. I now only use the top of the tie as reference in a king post truss. For futher info on that, I used the bottom as ref. so I wouldn't have to reduce at the posts, Trial and error. Tim