pinned bridle joint question

[Brian Holcombe]

I'm building a dining table in which I plan to attached the legs to the table top supports with bridle joints. In order to have the table able to be easily knocked down I would like to use a tapered dowel.

The supports are running just shy the width of the table top (split top), they will be attached to the top with sliding dovetails and somehow pinned in the center of each half (haven't determined the style of pin just yet, but its unimportant). These support battens will be white ash, cut to 1-1/4" thick and the legs are 1-3/4" x 2-1/4". The part that acts as a tenon and the supporting mortises will each be 3/4" thick.

My issue is that I'm unsure of how tall to make these battens, at the current height I expect to have 7/8" of material above the pin. In your experiences is this enough material? The total height of the tenon will be 2.25".

[Terry Beadle]

I've read your description a couple of times and I'm not sure of your design terms. However, a good rule I follow is to make mating pieces close to the same thickness. If you are going to use a tapered dowel to anchor the bridle joint pieces, I'd go a little thicker.

Maybe some one else will know your nomenclature a little better. Even better would be to post a sketch of the pieces and joint you are designing.

Regards and good luck,

Terry

[Brian Holcombe]

I'm probably making this sound more confusing than need be.

Here's a sketch;

http://i27.photobucket.com/albums/c181/SpeedyGoomba/0c749863-3adc-405f-8fc1-ebedd3abc885_zpsecae9031.jpg

[Sean Hughto]

Personally I don't like this concept for a large heavy (ash) table. When the table is lifted by the top, the only the short grain running from the top that dowel to the top of the leg is taking all the stress and might pop. What if you use the same design, but make the batten with angled sides - like a dt that slides into the leg?

[Brian Holcombe]

Sean, sounds like you're more concerned about when it's coming apart, rather than in regular use.

I see mortise and tenons that are draw bored often have the dowel offset toward the shoulder of the joint, which seems to be to allow as much material after the dowel as possible.

this is what I'm talking about;

http://shard3.1stdibs.us.com/archivesC/upload/8718/98/dining_table_large_005.jpg

I like your idea, but I'm worried about how difficult it will be to take apart over time, and I still have to peg the thing to keep it in place.

[Sean Hughto]

You notice in your picture how the bridles are extra long, right? I don't think that's just a design choice. It's for the same reason that folks leave rails or styles long when chopping mortises by hand - it's really easy to break out that short grain at the end, so they cut it to length later.

Think about tusk tenons in stretchers on a classic trestle table - take a look at how much meat they leave after the hole that sports the tusk.

I'm not speaking from experience on your particular design. Just noodling. Someone here may have done something close enough to tell you I'm worrying needlessly. Maybe do one joint as a test and see if you can break it. I do lots of tests like that in the course builds. It's time well spent.

[Brian Holcombe]

I appreciate your thoughts, they mirror my concerns as well.

I did notice that and that's likely the case that it is not a design choice, but based on the maker's exp. I've built tusk tenons in 8/4 rock maple recently with 3/4" thick tusks, I probably left 4" after the tusk, there was no reason to make it less so I left as much as possible. The difference being that when I assemble my bench I tap those in pretty good.

I could rearrange things to get about 2" of material above the dowel. I'm going to make a mock up at that dimension to see how it goes.

[Brian Holcombe]

Here's george's solution to a similar problem. I don't really like this for my table, since my stretcher is much lower on the leg, but I thought i'd post it up.


284660

[Sean Hughto]

I like GN's solution for the dowels - all long grain and super strong. I'm not sure I'm understanding the stretcher joint right, but it looks like some kind of tapered dovetail tusk? If so, he again avoided any short grain issues. Nice.

[Brian Holcombe]

Yeah, it looks like a tapered sliding dovetail, pretty slick.

The mental wheels are turning...