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Angled mortise and tenon help please


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So I've been striking out on what I think is a common technique.  I can't wrap my brain around the process and oddly enough I can't find a single reference on the ol' internet- and I haven't been able to get to the library.  Maybe I'm looking under the wrong topics?  Would love a reference and/or discussion.  


A bit of a two part question- the first leads into the real project...


Part 1

How do you make an angled mortise and tenon joint?  This seems to be a common technique in traditional stairway pickets in order to maintain a nice joint while keeping the picket nice and vertical and the handrail at it's correct angle (that is without the handrail cap).  It's really a question about the shoulder I think; I can make a nice 90 degree joint, but how do you make that joint a different angle without bending the tenon and ending up with a sloppy looking joint?   


Part 2

Ok, so the project I'm working on is a firewood holder (and sorry, no pictures yet and we'll see how far my description goes).  Think 2 half circles next to each other with the ends/top being closer than the base like a cradle- or two tires leaning on each other if that makes sense.  The circles would be joined with stock tenoned on both ends flush with the inside of the two circles.  The Upper joint would be perhaps 1 foot wide, and the base/feet would be riveted at about 1.5ft.  I know I could just rivet some stock on the outside of the circle with this spacing, but would like to figure this out.  


Oh-  I'm using 5/8 square and looking at a diameter of about 3.5ft wide and about that tall (we'll see if I fall back to 1/2''!)


Hope this isn't to confusing, but appreciate any thoughts and suggestions!

Thanks a whole bunch! 

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Part 1 - pre-bend the bar to the angle that would put the tenon in the correct plane then block out the tenon across the tangent points and finish.  Bear in mind the balance of the bar will swing up and down while rotating it - you might hit the floor or other equipment with insufficient clearance.


Part 2 - not sure I am following you on this one but I'm thinking to make the two half circles then lay out on a table and draw out the assembly with chalk.  Should be easy to line up the two elements then take your measurements for the balance of the parts.  If you are worried about putting the holes in the wrong place, make one sacrificial piece out of lighter material and take measurements from that master.


A drawing or sketch will help...

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ok, I'll try to get a sketch in. I guess the ultimate question is about the angle of the shoulder of the tenon. The normal monkey tool type thing will give a 90 degree shoulder, how do you make a different angled shoulder? Hmm, well to the drawering. thanks!

Might need to try to flip the image


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That sketch isn't what I thought you were asking about.


All the angled tenons I've seen done on stair railings, the tenon is 90 deg to the top/bottom rail as I drew on your sketch. I know I working on one in one of my classes, but I can't remember how right now it was explained to me when I was asking about them. I'll keep racking my brain trying to remember the sequence.



For what ever reason It's not letting me attach the file right now, I'll try again later.



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When punching/slitting for the mortice, punch from both sides of the bar and offset/overlap the punch locations to get an angled mortice.  Back up with an angled bolster when drifting to prevent distortion.  


Angled tennons are harder to get exactly right.  You can cut the desired angle onto the end of your monkey tool, but where the tennon springs from the end of the bar will change as you hammer the sloped shoulders onto the bar, the tennon gets driven towards the side with less resistance.  You can grind or file on the angled shoulders but then you get a different look.  Some people drill a hole into the end of the bar, cut the angle, then insert a pin to act as a tennon.  


Mark Asprey's most recent book on joinery covers this pretty well.

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First the tenon. Calculate the required angle of the bar. Leave enough to form the tenon on the bars centerline. The monkey tooling is angled to the calculated angle you need.

Now the slitting of the bar. To offset the angle slit or punch has to be offset. Once the offset is established you drift to the correct tenon dia.

The trick is in the lay out. Do a few test pieces to make sure you are getting the angled hole right. On the old railings that used this design, they frequently had a top cap that covered the end of the tenon wher it was peened into a countersunk opening so it was flush. The punched rail isn't pretty and I think the top cap was designed to both offer a smooth surface and cover up the roughness of the punched bar.

I think Francis Whittakers book Showed the angled monkey tooling you need to make.


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Alright, there happens to be some confusing info on this particular subject, first off if, your talking pickets on railings or sloping fence you wouldn't(shouldn't ) be inclined to punch an angled hole as that making a straight tenon with an angled shoulder is a bit of fussy work. Angled shoulder + angled mortise= Too much work. You would use an angled shoulder if you were drilling the hole at an angle, as that is so fast it makes up for the fussy bits. The old timey way of making that connection is to punch the mortise as a straight hole and pull the tenon off the bar at an angle. In this instance your standard monkey tool would work because the TENON is 90 degrees to the shoulder, but that shoulder is at a specific angle to the center line of the picket,ya follow? Going back to the first example, you would drill a hole at an angle (drill press fixture required) butcher your tenon at something close to that angle forge,swage, and monkey it with your very specific monkey tool. That tool is your standard monkey tool with its end cut at whatever angle is required. like you drill a 3/8 hole in the end of a 6" length of 1" square as deep as will clear your prospective tenon, with a drill press or lathe, and then lop the end off at an angle with your cut off saw. Hope this helps some, Take care, Matt

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