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Loose Tenon Joinery

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Chris Knight

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I like loose tenon joinery because the Woodrat makes it easy to do and it saves wood.

I have just calculated the saving on a project I am in the process of designing which is based on post and panel joinery - hence fairly heavy on M/T joinery. The answer for my framework as shown below is 10%. This isn't going to make a huge difference to me on this project - which I shall probably use hand tools for anyway but I did think of Aragorn's lovely kitchen and all his joints. I guess there is no reason why loose tenon joinery can't be done with the Leigh FMT? That would make it a real time and money saver for you pros out there I guess.

 

Woodythepecker

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Chris nice one. As you said 10% may not make a diffence on that project but look at how much you would save over a year.
This would be noticed even more if you run your own company and were using hardwood day in and day out.

Regards

Woody
 

Aragorn

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Hi Chris
That looks good! Is that a sketchup drawing?
Yes, the Leigh FMT does a great job of loose tenons, and I have used it for them on a couple of occasions.

I was wondering about any saving though. I can't see how that would happen: each joint would take a third as much time at the jig - two mortices and one loose tenon, as well as cutting down the tenon to length, as opposed to just one mortice and one tenon and the joint is complete.
Also, the loose tenon takes stock too, and for the Leigh to get a good grip of it, it would need to be long enough below the cutting plate for the clamps to hold it, perhaps a minimum of 8-9cm? So for stock, there is no saving either. :cry:
Presumably this would be different on the Rat?
Of course, you could make the loose tenons separately to the Leigh jig, on the thicknesser and router table (this is probably what you had in mind?) But each tenon needs to be twice as long as a tradition M&T so that it enters equally into both mortices.
I don't think their would be a time saving, and overall, you are using slightly more timber, because of the longer tenons.

Hmm. Perhaps I'm missing something?
 

jasonB

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I find that the tennon can be cut from the extra length that I leave on a piece of timber for planer snipe allowance so no real saving in material unless you have a lot of short components that can be cut from one length and there are no defects to cut out.

Jason
 

Alf

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Hmm, interesting thought. Like Aragorn I'm not sure that any timber saving wouldn't be gobbled up in extra time taken as far as the professional is concerned. But from an amateur wood-challenged stand point it has a certain allure. But I've never actually done any loose tenon work, so what's the drill? Do you run up vast lengths of tenon stock in timber X and use that regardless of what timber is used in the project or what? And if so, what's timber X? Oh, and Chris, what cutter/s do you use on the 'Rat for the mortises? I've been meaning to ask that for ages, so while I'm here... :D

Cheers, Alf

P.S. What you making? Something with carved panels?
 

johnelliott

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If I was to do M&T joinery I would use birch plywood for the tenons, and use whatever thickness was appropriate to the joint. I would then cut the mortices to suit the ply thickness
John
 

Chris Knight

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Some good points there!.

I make up loose tenon material from any suitable wood (ie strong enough) on the table saw and router table (saw square edged and rout with a half rounder or bullnose cutter that matches the mortice). Since I typically use tenons of fixed widths and thicknesses (like say half an inch by one inch or one and a half inches; a quarter by an inch and so forth) I can make up lengths beforehand whenever I have suitable off cuts of ply, or whatever wood I am working. Ply is usually great because there is almost always stuff left over from a sheet cutting exercise that is big enough to make useful tenons and the grain direction is not normally a problem).

The tenons/mortices in the design I showed (done in Solidworks, not Sketchup) are all half an inch thick. The best cutters I have found for morticing are not (as one might expect) spiral cutters but KWO replaceable carbide insert cutters. They leave a very clean cut and cut very quickly.

Aragorn, to be honest I was not counting the cost of the tenons, because I am comparing (in this case) Walnut for the frame with scrap for the tenons.

Jason, I don't leave allowance for snipe. My planer (Scheppach HMS 260) does not give me much trouble in this regard and I always finish plane by hand. My rough cut dimensions are usually a quarter of an inch overlength and an eighth or so on width and thickness, depending on how much I judge timber movement might be between rough milling and joinery/assembly.

Alf, I am going to make a sort of Andy Rae Tool cabinet ( http://www.skillspublish.com.au/Amer-Plans-ZI-Large.jpg - homage to the new plane!) I may try carving the front panels but am just as likely to veneer and inlay!
 

Alf

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waterhead37":dy20g5n8 said:
The best cutters I have found for morticing are not (as one might expect) spiral cutters but KWO replaceable carbide insert cutters. They leave a very clean cut and cut very quickly.
Well I'll be blowed. That's a surprise. Is that based on those against other replacable insert types or as against straights and spirals? In other words, is it KWO or nothing? Okay, so I'm thinking Wealden here; been very impressed with my first order from them.*

waterhead37":dy20g5n8 said:
Alf, I am going to make a sort of Andy Rae Tool cabinet ( http://www.skillspublish.com.au/Amer-Plans-ZI-Large.jpg - homage to the new plane!) I may try carving the front panels but am just as likely to veneer and inlay!
Mmmmmmm, nice. WIP pics I hope? :D

Cheers, Alf

* I'm genuinely afraid I may be turning into a Normite. :shock:
 

Chris Knight

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Alf,

I am comparing the KWO with straights and spirals (both up and down spirals) I have tried them all and like the KWO best for morticing.

Yes, WIP pictures in due course. However, before I lay hand on wood, there is still a lot of design to do to get what I want in the thing and to get the whole caboodle in my workshop!
 

ProShop

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Chris,
I make a lot of loose tennon joinery, even doors, internal and external. and framing etc. I just make the tennons from scrap timber on the saw table, using the roughness of the saw blade to help with the bonding of the glue. Gives a much better key, than planned etc. I've never had a joint fail yet (touch wood :) ).
Now that I have a spindle moulder I will use it to make some fixed tennons, but I'll still make loose tennons as well.
 
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