Cheap holdown (the kind which wedges itself in a 3/4 dog hole)

[jimhanna]

I was intrigued by the idea of using a batten with a birdsmouth notch to hold a piece against a single dog for planing after seeing a video demo ( at http://www.theenglishwoodworker.com/?p=1434) . It looked really effective at holding the stock for diagonal planing, yet the stock can be lifted and flipped over very quickly.
An essential for using the birdsmouth batten is some sort of holdfast to clamp it down to the bench.
The large solid metal holdfasts which you fix with a hammer are too pricey for me as is the Veritas Bench holddown with the screw tightening.

Also all of the above have long stems which stick down below the bench when holding thin stock, I don’t really want to lose my underbench shelving.

I found a design online using an F clamp with the head removed and a swivel added to the end of the bar. Unfortunately any F clamps I have with a decent sized throat are much too big to go through my ¾ dog holes.

Then I found the Sjoberg QSH holdfast, it doesn’t protrude below the bench and looks a bit like an F clamp with the head removed and a kink in the stem to wedge it in the bench.

To make something like this I drilled out the pin on a large F clamp to remove the head, then drilled out another hole further up the shaft offset enough to give me a kink something like the catalogue holdfasts.
I used a 4” long ¾ UNF bolt as the stem to enter the bench. After knocking down the threads a bit the bolt is a good fit in my ¾ dog holes, it locks down the work solidly in my 2 ¾” thick pine bench, total cost very little.

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My holddown made from the F clamp and ¾ bolt was so useful that I’ve made a second one. The washer on the bolt is just a repair washer drilled and filed out to ¾. It’s nothing to do with the wedging clamping action, it’s only there to stop the end of the clamp bar dinging the bench when I push the bolt into the dog hole (DAMHIKT) :U

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Regards

Jim

[GraemeCook]

Good Morning Jim

I like your idea of using a bird-beak push stick to corral errant timber on the bench; hope you don't mind me poaching.

With respect to your hold down with a bolt welded to an F-clamp, perhaps you are using a sledge hammer to crack a peanut!

I just use Quick Grip clamps. Just knock the split tube out of the end of their bar, slide the clamp off the bar, stick the bar through the doghole and reattach the clamp. Easy peasy. And it works a charm.



Fair Winds

Graeme


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[jimhanna]

I like your idea of using a bird-beak push stick to corral errant timber on the bench; hope you don't mind me poaching.

With respect to your hold down with a bolt welded to an F-clamp, perhaps you are using a sledge hammer to crack a peanut!

Graeme


Hi Graeme
The simplicity of the bird mouth stick surprised me the first time I saw it, unfortunately I can’t claim any credit for it.

I’d agree with you that a through the bench fixing is much simpler if that can be achieved. I was driven towards a wedged in clamp because my garage workshop is small and my bench has to be against the wall. I have no problem dropping a bolt or small clamp through the front dog holes if I want to secure my drill stand, however for planing support I usually want a clamp towards the back of the bench and it’s a real pain lifting out the bench hook and shooting board which live on the shelf underneath and then trying to grope in with a nut or clamp head.
The wedged in clamp is good because it doesn’t need any under bench access.

A wedged clamp needs a substantial construction. Before I used the ¾ bolt I’d tried a bit of M12 threaded rod down the middle of a ¾ dowel and a 12mm square steel bar faced with shavings from the dowel to make it fit the dog hole. Both of them wedged OK and didn’t try to lift out but they bent as I tightened, the forces on a kinked wedging holdfast are considerable.
304724First attempts, both of them bent in use.
Regards

Jim