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Forum topic by newwoodbutcher posted 01-25-2021 07:00 PM 571 views 0 times favorited 16 replies Add to Favorites Watch
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newwoodbutcher

849 posts in 3858 days


01-25-2021 07:00 PM

I’m building this desk
I’m using some really nice Genuine Mahogany. It’s pretty dense and hard for Mahogany.
The problem I’m struggling with is the M&T apron to Leg joinery. The legs are 1 3/4” square. The aprons are 7/8” thick.
The “plans” call for a 1/2” deep 1/2” wide tenon with 1/4” shoulders. I really want this desk to last and those tendons in the plan look shy of sturdy to me. If I make them 3/4 or (my preference) 7/8” deep and 1/2” thick they interfere with each other. I’ve considered multiple tenons with haunches between them that miss each other in the mortise. But using only half of each tenons width seems as weak as shallow tenons. Each of the eight legs will have two sets of apron mortises and two stretcher mortises.
I’m babbling.
I guess my question is as a compromise, does it create a better joint with a shorter or narrower tenon?

-- Ken


16 replies so far

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Mosquito

10915 posts in 3301 days


#1 posted 01-25-2021 07:20 PM

What is your area of concern? It looks like the photo of that desk there has everything as being draw-bored or at least pegged tenons, I don’t think I’d be to worried about them pulling apart if that’s the case.

I also wouldn’t be too concerned about 3/4” tenons either, but 7/8” and you’d just be making through mortises in the legs, which I probably wouldn’t do.

Are there cross braces from front to back for the four legs in the middle of the desk? That may have been another consideration with the plans being at 1/2” deep.

Truthfully, with modern glues and tight joinery, I don’t think I’d be that concerned about the 1/2” tenons if they’re pegged/draw-bored together, unless you foresee a lot of racking stress on the desk in its future. But, I’ve not built a desk like that, so I’ve not had first hand experience (the proverbial “grain of salt” disclosure)

-- Mos - Twin Cities, MN - http://www.youtube.com/MosquitoMods - http://www.TheModsquito.com

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splintergroup

4672 posts in 2231 days


#2 posted 01-25-2021 07:52 PM

You can get by with 3/8” tenons just as well as they’ll still be plenty strong. If you are adventurous you can offset them to the outside a bit to gain room for more length.

For the intersection inside a mortise, a common approach is to bevel the ends of the tenons to 45 degrees. They then fit together like a mitered corner and have the full length glue surface on the outside face. (leave a slight gap at the ends where they meet inside the mortise).

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newwoodbutcher

849 posts in 3858 days


#3 posted 01-25-2021 07:58 PM

Mosquito,
Thank you for responding. My main concern was strength, over the long haul. Future generations will most certainly abuse this in unknown situations. So I want to make it as durable as I can. Your input has me feeling better about the 1/2” tenon. I use 1/8” bamboo sticks for draw bore pins. But considered not using them on such a short tenon but you have changed my mind. Pinned nice tight joinery with good glue coverage and 1/2×1/2×4” tenon should be fine. Thank you

-- Ken

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newwoodbutcher

849 posts in 3858 days


#4 posted 01-26-2021 08:29 PM

Ok I guess I’m once again over building. Thank you for responding

-- Ken

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EarlS

4305 posts in 3356 days


#5 posted 01-26-2021 08:47 PM

This looks like the Aurora table desk that Darrell Peart has in his G&G books. I’d trust his construction methods every time.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

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newwoodbutcher

849 posts in 3858 days


#6 posted 01-27-2021 03:05 AM

Thank you Earl, personal experience?

-- Ken

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Lazyman

6636 posts in 2396 days


#7 posted 01-27-2021 03:37 PM

I think that I would make sure that the aprons are not quarter sawn. Pegs so close to the end could tend to pull out with QS boards. You want the pegs to go into flat sawn grain to make them a little stronger.

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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drsurfrat

476 posts in 195 days


#8 posted 01-27-2021 05:08 PM

I think you are all set with advice, so I will give some more :)

You might just try your 1/2” tenon in scrap, glue up a T, let is sit for a day, then try your hardest to break it apart – you probably won’t even able to get it to budge til you hold it at an angle and stand on it. But you will know firsthand that your one joint is tough; three per side will be bulletproof.

-- Mike (near Boston) ... Laziness is the mother of invention, necessity is the mother of exhaustion - me

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Robert

4440 posts in 2489 days


#9 posted 01-27-2021 07:25 PM

Double tusk tenons are the traditional way to join thin aprons or dividers to a leg.

I’m kind of with Mosquito, I think you’ll be fine since there are 8 legs in this thing.

-- Everything is a prototype thats why its one of a kind!!

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newwoodbutcher

849 posts in 3858 days


#10 posted 01-27-2021 08:09 PM

Once again, Lumberjacks members are helpful, thoughtful and responsive. Thanks for all your responses. Here is where I’ve landed. I’m thinking once again that my tendency to over build for strength has become counter productive.
Sounds like a well made, good fitting, pinned 1/2” x1/2×5” mortise and tenon connection is going to be plenty strong enough and that is how I’m going to proceed. Probably after I do the test Drsurfrat suggested, including the pins, you know, just to be sure

-- Ken

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newwoodbutcher

849 posts in 3858 days


#11 posted 01-27-2021 11:15 PM

Thanks Robert,

-- Ken

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EarlS

4305 posts in 3356 days


#12 posted 01-28-2021 03:16 AM

Ken – Darrell Peart is probably the top G&G furniture maker in the country. He also occasionally posts on LJ and teaches a fair bit too, though I have not been fortunate enough to attend one of his classes. I think he has 3 books out. If I recall, this was in one of them. He also goes into the G&G history quite a bit too. All in all, they are interesting to read. There are numerous LJ’s that have built his designs from the books so you should be able to get plenty of commentary from them.

-- Earl "I'm a pessamist - generally that increases the chance that things will turn out better than expected"

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newwoodbutcher

849 posts in 3858 days


#13 posted 01-28-2021 03:54 AM

Thank you Earl,
I took the G &G Details class with Darrell up in Washington a few years ago and have read all his books. I’ve made his design of the Blanket Chest and have been wanting to build this desk for several years. So far it’s coming together beautifully.

-- Ken

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newwoodbutcher

849 posts in 3858 days


#14 posted 01-28-2021 06:54 AM

Lazyman, been thinking about your point. None of the aprons are quarter sawn but since my pin of choice is about 1/4” diameter I’m thinking draw boring might be too much for such a short tenon. My test joint came out good and strong with two bamboo pins drilled and hammered home without the added stress of draw boring. I haven’t really stressed the test joint yet, waiting over night for a good dry glue up. But my feeling about that joint is that it will be plenty strong for many years. So I went ahead and cut all the apron and stretcher cheek and cheek shoulders 1/2” deep and 1/2” thick. I’m cutting the mortises in the legs and finishing the tenons tomorrow. Thank you all again

-- Ken

View Lazyman's profile

Lazyman

6636 posts in 2396 days


#15 posted 01-28-2021 03:54 PM

I agree. I actually meant to but forgot to add that I would not draw bore these dowels since they are so close to the edge and ends, even without the concern of quarter sawn grain .

-- Nathan, TX -- Hire the lazy man. He may not do as much work but that's because he will find a better way.

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