On Wednesday, 25 July 2018 22:29:36 UTC+1, newshound wrote:
On 25/07/2018 10:41, tabbypurr wrote:
On Wednesday, 25 July 2018 09:44:15 UTC+1, wrote:
On 24/07/2018 21:28, John Rumm wrote:
On 24/07/2018 15:15, wrote:

I have a large shed with 6" x 3" timber uprights resting on a stub
block wall. The bottom 2-3 feet of the posts is rotten so I want to
splice-in some new timber. I can't think how to cut a decent lap joint
in the bottom end of the remaining upright so I'm tempted to butt join
the timber and add steel plates (fish plates?) on each side - at a
guess these would be around 150 wide 450 long and a few mm thick.

Suggestions welcomed for how to cut a lap joint on the bottom of a bit
of timber that's waggling in the breeze, or for a source of suitable
steel plates.

A scarf joint would be easiest - just a long straight cut on the
diagonal with a handsaw - match the same angle on the new bit, then glue
up and screw through the face into the joint a couple of times.

If you want a half lap, then as you said - repeated cuts every few mm
with a circular saw, then knock out the waste, and plane/chisel flat.


I'd discounted a scarf joint because it's dependent on the glue and
screws to resist the shear force, whereas if I shim the ends of the lap
joint then I've got half the thickness supporting the load, as well as
the glue and screws.

it is, but you can get plenty of strength from glue & screws if done well.


NT

Agreed; the reason I didn't suggest a scarf joint is that, away from a
work-bench, it would not be so easy to cut the upright neatly and
accurately. Although you could clean up a "rough-cut" with a sanding
disk on an angle grinder.

the existing upright could be doe with a handheld circular. Scribe the position of the cut ends onto fresh wood & cut with a mitre saw.


NT