Messages Archive

Subject:
Re: Bench dog hole repair

William Duffield
A lot of the advise I see here, and your drawing of the plug, are specific to dog holes only used for holding dogs, tools and work lights. The requirements for dog hols used for holdfast are a lot more stringent, since the holdfasts put an immense amount of lateral pressure at two points: the top of the hole at the back of the holdfast, and the bottom of the hole at the front of the holdfast. Of course, these points change as the holdfast is rotated to hold stuff at different locations on the bench top. Therefore, my recommendations are as follow:

Drill a large diameter hole all the way through the bench top. This will get rid of any wallowing bt the holdfast.

Use hard maple for the plug, it deforms and splits much less than oak. Turn it in the shape of a cylinder, without any steps, with the grain orientation you would use for a bowl. It would also probably help a little to align the growth rings of the plug with the growth rings of the bench top. This alignment, of course would need to be done before mounting the plug for turning. This will stress the wood of the bench top much less with the change of the seasons. Make it as long as the thickness of the bench top, unless the bench top is more than about 3" thick. Holdfasts don't hold as well in very thick bench tops because they aren't tilted at as large an angle, and the pressure they develop against the sides of the dog hole is not as great.

Replace that junk cast iron holdfast with one or two by Gramercy Tools, and consider adding a doe's foot (shop made) to your work holding arsenal.

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