Friday, May 6, 2011

Clamping Strategy

One of my favorite parts of making chairs the way that I do is that there is almost no clamping involved in the assembly. I always disliked the scrambling to set clamps during complex glue ups. But one place where I have expanded my use of clamps is during bending.

When the wood comes out of the steamer it's soft and quick to take impressions of the form, and more detrimentally, the clamp itself.  In most applications where the workpiece presents a flat surface to the form and the clamp, the soft clamp pads that come on my Irwin clamps protect the workpiece from clamp dinging just fine. 
But lately, I have been bending turned pieces and the round surface loves to flatten from the pressure. I solved the form side of the problem by cutting a v notch that houses the bend. To protect the clamp side, I've started playing with hard felt pads.

In the image above, you can see that the workpiece has left it's impression in the felt, rather than the other way around. Much better!!

On simpler portions of the workpiece, I've found that I can reduce distortion by simply cutting a v notch in a clamp block.

These days, I find myself wanting to bend turned pieces more and more, and these simple techniques nearly eliminate hassle of reworking them to remove clamp damage. I have ordered some larger (and cheaper) pads from Duro-Felt in Arkansas that I plan to cut up and use. I ordered some 1" thick stuff and some 1/2" thick, thinking that I might also line some of my forms.

The block should be harder felt than you might think would work ( I ordered the stock with the H notation), but remember, the steam and moisture coming from the wood acts on the felt to soften and mold it to the shape. I'll post more results as they happen.


Anonymous said...

Have you tried using Homasote, it might be another option.

John said...

I am like you... Not a big fan of projects where clamping becomes harder than the project itself.