Hip Roof Model 2, mailing 2: keta intersection

An on-going study exploring traditional carpentry layout techniques.
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Chris Hall
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Re: Hip Roof Model 2, mailing 2: keta intersection

Wed Jun 21, 2017 8:46 am

Yeah, it's a joint with long interfaces, which is one of the reasons it is such a strong connection. For ease of disassembly you should ease the mortises in the long keta piece at the very least. A chunk of wood and a small sledge can be helpful for knocking the parts away from one another.
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Brian
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Re: Hip Roof Model 2, mailing 2: keta intersection

Wed Jun 21, 2017 11:21 am

Beautiful joint Derek. I am correct in assuming those pull together with shachi pins?
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Re: Hip Roof Model 2, mailing 2: keta intersection

Thu Jun 22, 2017 7:58 am

Very nice, Derek!
Locking forward to the intersection with the Hip-rafter.
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Re: Hip Roof Model 2, mailing 2: keta intersection

Thu Jun 22, 2017 5:01 pm

Thanks Chris,
when the joint is closed up tight there would seem to be no bearing surface against which to apply force without marring surfaces. Are you suggesting levering the morticed Keta piece (with the long open mortices) away by knocking it away from the morticed side, thereby allowing the mitred surfaces to bear the leveraging forces?

I have inserted and removed the tenons from the mortices a couple of times and they are a little easier to insert however the tenons still require a lot of persuasion to insert to depth in the through morticed piece.

Brian, thanks for the kind words. You are correct, the next step will be to cut the mortice pockets for Shachi Sen. It will be my first time cutting that type of joinery.

Marc, thank you also for your comments. The hip rafter intersection will come in due course, if you can bear with my slow pace of work. If this sort of thing interests you then the build thread for Hip Roof Model 1, also on this forum, may be worth reading through. The Keta/Hip rafter intersection is totally different to this model.

Regards
Derek
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Re: Hip Roof Model 2, mailing 2: keta intersection

Fri Jun 23, 2017 8:50 am

Ok, so a very judicious thinning of the tenons and a bit of a clean up of the through mortices on the large Keta piece and this joint is going together much easier now:
DSCF4431.JPG
DSCF4431.JPG (208.04 KiB) Viewed 6372 times
Albeit, a little error in the length measurement of the tenons is now obvious. A little more fine adjustment of the mitred abutments still required before it will close up completely as can be seen on the other side of the joint:
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And from above:
DSCF4433.JPG
DSCF4433.JPG (201.05 KiB) Viewed 6372 times
Onwards now to the Shachi Sen.
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Chris Hall
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Re: Hip Roof Model 2, mailing 2: keta intersection

Fri Jun 23, 2017 9:20 am

Yeah, I thought from your previous set of pictures that the tenons were looking a hair long (or the mortises short). Be sure that when the connection is drawn up tight that there is a little space between the end of the tenon and the mortise end wall, 2~3mm typ.. I think, but I'm not sure without rereading, that I mentioned that detail in the last mailing - or it is at the very least, readily deduced from the sketches and the indicated dimensions for the parts. LMK if that's not how it's adding up for you in the layout.
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Brian
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Re: Hip Roof Model 2, mailing 2: keta intersection

Fri Jun 23, 2017 2:48 pm

I followed Chris' layout for the shachi and it makes them very straight forward to get a nice tight fit. They look difficult in the abstract but not so much in reality, just leave enough length for compression. If you saw in my last blog post my mentioning having made two sets, the first ran out of length too quickly, the second set was better. Always surprising how much softer woods can compress (Honduran Mahogany is not very hard).
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Re: Hip Roof Model 2, mailing 2: keta intersection

Sat Jun 24, 2017 8:43 am

Mortices too short as it turns out - I had referenced the measurement off the end of the piece, not the mitre line as the drawing showed, hence 10mm short. All rectified now. Chris, you have made reference to the need for a couple of mm clear space at the end of the tenon at various other points in time so there was no doubt about that fact. Many thanks.

Brian, thanks for the encouragement, I have had Chris' volume three of the carpentry drawing series on the laptop today re-reading the section on the shaping of the Shachi sen in preparation.

How the joint is looking now with the open mortices correctly dimensioned:
DSCF4441.JPG
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A little trimming still required on the mitres but getting close:
DSCF4440.JPG
DSCF4440.JPG (192.61 KiB) Viewed 6357 times
Some stray 'just shy of 6mm' stock that was minding its own business when I went looking for wedging material:
DSCF4438.JPG
DSCF4438.JPG (205.04 KiB) Viewed 6357 times
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Re: Hip Roof Model 2, mailing 2: keta intersection

Sun Jul 02, 2017 4:36 am

Well, I don't have much to show for myself at the end of this weekend. I spent what seemed like a lot of time trying to fine tune the mitred abutments for the Keta crossing, feeling mostly like I was going backwards. Lot's of variables go into that joint closing up nicely and it can be tough determining which is the limiting variable.

Otherwise I have some stock cut into the required parallelogram size and shape for the Shachi sen. I wanted to have the Keta intersection as tight as possible before cutting the Shachi Sen mortices.

Hopefully I will make more progress during the week.

Derek
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Chris Hall
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Re: Hip Roof Model 2, mailing 2: keta intersection

Sun Jul 02, 2017 8:15 am

Yes, 4-way mitered connections are a tricky matter and it can feel a lot like you are chasing your tail at times. As you do them more and more, they seem to get easier.

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