Could someone nice check my m/tenon dimensions?

[Bm101]

Leg mortice tenons for a bench.
I have a 25mm auger bit but was wondering if I should widen the tenon a bit more, maybe 35mm? They seem a little narrow to me at 25mm. 45mm depth with 5 mm play possibly for 1/2mm drawboring if i can manage it. :?
Shaded area is the leg, tenons are on the bearers of course. Its keruing. Theres approx 1.2m between the legs and full length of top is about 2.3m.
I'd be glad if some could enlighten me before I start cutting. If I was to widen the tenon what would be the minimum width you'd leave on the mortice to be safe? Bearers and legs are flush fitting. (in theory at least! )
Cheers
Chris

 

[Chrispy]

Personally I would make them smaller, 18mm and give your self a shoulder one the inside, a joint like this gets a lot of it's strength from the shoulders.

 

[Steve Maskery]

Chris
Your rails are very thick at 45mm, but a 25 or even 16mm (5/8") would be quite thick enough. 5/8 is still 1/3 of the thickness.

It's not a good idea to have them bare-faced as you do. You can put them centrally, or, even better, closer to the front of the leg than that. That will enable you to have them longer, and therefore stronger. And whilst you are right to see that they meet inside, if you have them further out, they won't collide til they are much longer. You can even make them longer still and mitre them.

HTH
Steve

 

[Bm101]

Many thanks for taking the time to reply.
I've been taking plans and adapting from Chris Schwarz book and he shows a bare faced tenon. Having said that, I don't recall ever seeing one in my limited experience. I will definitely be adapting the plans. I was aware of the one third rule but it was worrying me a little. I need to get a 19mm auger bit anyway for the dog holes so its no loss and a stronger bench to boot. Your advice is much appreciated!
I was just looking at the size of the stretchers and thinking bigger must be better. Always glad to stand corrected!
Cheers again!
Chris

 

[RobinBHM]

Also a shoulder at the bottom and haunch at the top, is good. As mentioned above the shoulder add a lot of strength due to their ability to resist racking of the joint.

 

[Steve Maskery]

Chris S knows what he is tlking about, I should think. Does say why he chooses a BF tenon? Personally I would want a shoulder on both sides, not just one. The tenon doesn't have to be central, but it is the most common arrangement.

+1 for Robin's comment.

 

[RobinBHM]

I would tend to think that in a conventional table, the bearers are set back from the face of the leg. The tenon is then set closer to the outside face, allowing a longer distance before the tenons collide and more meat on that internal corner of the leg.

 

[Amateur]

The OP doesn't say what sort of bench this is or what he is making it from?
If its for his greenhouse plants to sit on its fine,
If its for a work bench that's different.
One of the problems is making the bench too light so that it ends up walking round the shop.
I'd be inclined to increase the thickness of the rails rather than reduce them, and if your fitting a couple of vices will give substantial support.
A workshop bench is probably better over designed and bulked up, than finishing it and its far too light.
But that's just my experience.

 

[RobinBHM]

The OP doesn't say what sort of bench this is or what he is making it from?
If its for his greenhouse plants to sit on its fine,
If its for a work bench that's different.
One of the problems is making the bench too light so that it ends up walking round the shop.
I'd be inclined to increase the thickness of the rails rather than reduce them, and if your fitting a couple of vices will give substantial support.
A workshop bench is probably better over designed and bulked up, than finishing it and its far too light.
But that's just my experience.

Thats true, we may all have been think something woodworkey related, whilst the intended purpose might be flower arranging

 

[Bm101]

Like this for the haunched and bottom shoulder Robin?
Many thanks.

Steve, the only bit I could find was on using blind tenons to join the top to the legs. I think in the newer version of the book and a youtube vid I saw he is now doing 'through' tenons (?)

Hopefully not breaking any copywrite posting this.

It's the witching hour here at the moment with my kids so I'm back and forth a bit! trying to keep up!
Yeh its a workbench! For making wooden flowers! Possibly! And the legs have to be flush with the front of the top.

Posted this a while back, its the specs. rouboish-bench-build-advice-dimensions-deadman-question-t92506.html

Phew! This is tiring me out! Thanks for the advice.

 

[James-1986]

The legs on my (unfinished) bench are 6" x 5" because of having the joints coming into the leg at the same level. This way you can place the joints wherever you like and you don't have to limit the length of your tenon on the stretcher or fuss about, its a bit lazy but...meh. The rails have a 2" tenon draw bored, the stretchers have a 3" or 4" tenon which I secured with a big fat barrel bolt that goes through the middle haunch (I saw them on those Richard Maguire benches and liked the idea). The rails and stretchers are 42mm x 140mm and have shoulders both sides. I used 3/4" tenons, as I already had the chain on the machine

If your rails are 45mm then I assume you have got some 2" stock? So a big leg is easily glued from that.

 

[Steve Maskery]

I'm afraid I don't have anything else to offer.

 

[woodenstx]

Looks like a slimmed down version of what I made a year ago.

Legs were 100x100 (ish, after PAR) and the rails were 75x75 (again ish), with a 25mm Tennon at about 75mm length to overlap in the corners. Way overkill but that thing isn't coming down :lol:

 

[Bm101]

Thanks for all the replies. One last question, is there any disadvantage to offsetting the end and side bearers slightly. I was wondering if i raised the end bearers just above the side bearers if it would have any advantage by extending the tenons further. I plan on doing the haunched and 3 shouldered tenons suggested by Robin, thanks for the advice everyone.