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Could I make this joint better?

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Anonymous

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I'm just completing the first of a series of projects with lots and lots of 3 way joints - about another 80 to go. These will mostly be around drawers which sit on the side rails which will be rebated (rabbeted?) to about 1.5mm above/below the front rails before final assembly - marked with the pencil lines in the picture.

I've made them as horizontal mortise & tenon with an extra small M&T between the front and side rails to help stop the side rails twisting.







I thought of doing these as double vertical M&Ts but was worried that the innermost tenons would be too short. Also, the pieces are not huge - front rails are 20x30, uprights are 36x36, side rails are 30x50 less the rebates.

Could I make these any better/stronger? I've thought about bracing the internal corners between front and side rails but as for side to side and back to front loads there is no cross-bracing so these joints have to me as strong as possible.

Thanks to Charlie for help uploading the images :D
 

Aragorn

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MP":24oajcna said:
Also, the pieces are not huge...
Something that can't be said of the images you've posted!!!!
Any chance of editing them a lot smaller so that we can see wha't going on.

Ta!

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Anonymous

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Think I'll have to beg Charlie to shrink them or re-post them for me - they are up on the forum website rather than linked to anywhere I have direct access
 

Aragorn

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That's better!
I would probably make this joint a different way. The orientation of the tenon doesn't give the maximum amount of strength, although once glued up it may not matter if there isn't much load.
So a couple of ideas come to mind. I'd probably use twin vertical M&Ts, mitred. It doesn't matter that the wood is quite small - a twin M&T has a very large surface area compared to the size of the timber, so plenty of gluing surface. The vertical tenons maximise the strength. The inner short tenon still provides gluing surface area and will keep the piece from racking.
Also, how about making the rabbeted piece out of two pieces of wood - the main piece that joins onto the upright plus a baton glued and pinned onto that to form the runner?

80 of these? Wow. What are you making??

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Anonymous

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2 bedside tables (just glueing up) then 2 tall chests of drawers and a dressing table. Then probably the free-standing mirror, new bed, and anything else the power that be decides she wants to fill the bedroom with once she works out how much space is left. At the moment I've got a transit-van load of cherry roughly cut to size and stacked under the bed to get used to the central heating. Should be enough to keep me going all summer long. Still, at least by not paying for shop-bought furniture I justified the cost of the toys, sorry, tools :)
 
A

Anonymous

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Ok, i've been thinking about the double-tenon option over the weekend and come up with one key question: how to cut out between the 2 tenons?

Given the size of timber and need to keep away from the edge of the upright, i figure I can go down to 8mm wide tenons/mortises with a 6mm gap between them. 30mm deep from the end, and 20 or 30 mm thick depending on the workpiece.

handcut/bandsaw is, for me, fairly inaccurate.

30mm is way too deep for the groove blades on my spindle moulder. Could get a dedicated groover or wobble saw but didn't really want to spend that sort of money on one. There was a thread a few weeks ago about using a circular saw blade on a spindle moulder for cutting drawers/boxes to height, but that struck me as being very scary as the smallest 30mm bore blades I've seen are 200mm diameter and so way too big for the guards on my machine.


6mm router bit in from each side of the timber in the router table - would require multiple passes and then clean up the bottom by hand. 30mm is too deep for my router bits from the end of the piece

double pass over the table saw like a dado/finger joint cut. Would need a fair size jig to hold the work vertical and slide and also act as a blade guard as the original guard would need to be removed. Would also need a fine adjustment to move the work over accurately.

anyone have any thoughts or other suggestions? at the moment I'm leaning towards the table saw option...

cheers

m
 

Aragorn

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Of course this would take about 20 seconds in my Leigh FMT :!: :!: :!:

Sorry - not very helpful. :oops:
Without the Leigh, I'd use a table saw for this cut (without the guards - sshhh, don't tell Charley).
My TS has a micro adjust on the fence and I used to use a very simple jig - safe and effective:
It is a piece of 3/4" MDF about 500x500mm with a box section attached to the side so that it very snuggly fits over the rip fence of the TS. I then attached a baton at 90° to hold the workpiece. You can add slots for clamps as well if need be. This jig simply runs along the rip fence at the required distance from the blade, holding the workpiece in a vertical position. Because of the size of the MDF, your fingers never go any where near the blade.
This would give you very accurate cheek cuts, and you could clean out the waste in the same way or by hand.
Let me know if you want a photo of all that!

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Anonymous

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sounds pretty much like what I was thinking of, but I don't have the micro-adjustment on the rip fence so I was looking at basing it on the T-slot and having a couple of bolt adjusters from that to the main body of the jig

BTW your comments on my glueing up questions on how well-formed joints should pull the work square were spot on. Finished glueing up the first of the main carcases of these bedside tables last night and as I clamped up it all came miraculously square and even - not a millimeter of rock . This is definitely the most carefully machined work i've done to date and it looks like it has paid off :) :) :)

thanks

m
 

Aragorn

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Hey M
Yep - a really accurate and well made joint is a treat to glue up. Takes all the pressure off when things slot together nice and snug but not too tight and the clamps are just there to hold it rather than force it into position.

As for the tenoning jig, I've used this method on a TS without a rip fence micro adjust and it can be done just fine - dimension some scrap stock down to size and just make small test cuts. I found that just by nudging the rip fence over you can make really small adjustments.
When it's in the right place - pass through all 80 of your pieces (!) and then make the new adjustments on the scrap piece and go at it all over again.

(Or just buy the Leigh FMT!!)

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Anonymous

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the other thing I sometimes use for fine adjustment is some little stepped plastic wedges that i got in a laminate floor kit once from Ikea (spit) - they move over at about 0.2mm at a step so can come in handy.

Definitely planning to do all the pieces at once production line style. and this time I'm also going to make a few spares just in case

at the moment I'm trying desperately not to spend any more money on machines, jigs, bolt ons, etc as I'm just about to start down the whole L-N slippery slope with a block plane... the Leigh jig looks the absolute mutts but I really can't do it. No. Must resist. Must be strong. Must not give into the dark side...
 

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