The Framers Forum

When the clamp comes down on a wedge-shaped moulding, it pushes the bits apart.

If you make a reverse shim it has the same effect, indeed it's like a wedge being pushed into the joint.

What techniques do people have for reducing this problem?

Thanks

One of those funny ones.

It's because the clamping point is too far offset from the v-nail insertion point. You can't get it dead right or it would mean
the nail being too near the back edge. I've pinned this shape a few times but it was to making a spacer inside a frame so I could
get away with a shallow v- nail as the spacer frame didn't need to be super-strong.
I think you might have to get out the hammer and nails. And you'll need a mitre vice.

I have a piece of 18mm MDF, around 5" square with a bit of loop fabric glued to one side.

I assemble the glued joint in the underpinner, fence locked to the outermost wedge, put the MDF block over the entire joint and then pin it. The MDF block spreads the load and stops the pinner head pushing the 2 sticks apart.

You can position the MDF in such a way that you can see if the joint is tight. Once the outer edge is pinned, it's simple enough to add more wedges - just apply light lateral pressure to ensure the joint is nicely closed and pin as before using the MDF block.

Or you could glue and throw a strap clamp round and cinch it up as tight as possible. Then pin it.

Agree with Prospero, that's the way to do it. Use Tiebond3 overnight and pin it the next day.

prospero wrote:Or you could glue and throw a strap clamp round and cinch it up as tight as possible. Then pin it.

That's what I do, seems to work...

I'm with Glimpse on this

If you use a strap clamp on it, does it not foul the clamps also you can damage the outer corner of the frame with the strap clamp , which ok if it's a spacer in another frame is no a problem but if it is the frame , then you're bu&&ered

That's what polyfilla is for. That's why I don't touch factory-finished frames.

I'm not one for having half-finished jobs kicking around the place, so the MDF block trick wins hands down - get it pinned, get it assembled and get it paid for!

Try it, it works perfectly every time - no need to over-think it!

I do the same but with a triangle of wood faced with cork and wrapped in handy wrap. You're right in saying
it spreads the load but with this moulding it may be tipping as the v-nail pushes the middle while the clamp
pushes the back. I would have thought on a narrow moulding this wouldn't happen but something is amiss.
It's the only explanation I can think of.

Unless James has got his v-nails in wrong way up.

Let's remember that James is using a barewood moulding and would most probably have no interest in a sharp, unmarked outer corner. The time spent joining his frame is irrelevant to the time and care spent creating his finishes.

Start at the back and move forward, works for me