On 25/07/2018 09:44, 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,

The glue alone will be stronger than the wood itself. The purpose of the
joint is to give a large long grain contact area for the glue.

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.

Nothing wrong with a lap either - but both will do the job just fine.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/