Dog hole sizes & holdfasts.

[Apollo]

I am planning to put some dog holes in a workbench. Most of the holdfasts seem to be designed for ¾ inch (19mm) holes, I was wondering if these holdfasts would work in a 20mm hole as I would like it to be compatible with the Festool/MFT accessories.



When researching this question, I have come up with conflicting advice, from definitely No, to it may not be as tight and cause damage to holes.


Any real life experience out there to guide me.

[orraloon]

As I cant say for sure if thay will hold try a test hole in a scrap bit of wood.
Regards
John

[BobL]

As I cant say for sure if thay will hold try a test hole in a scrap bit of wood.
Regards
John

I would suggest using a piece of wood that is the same wood type and thickness as the bench. You also need to try it repeatedly e.g. many dozens of times) in different directions in the hole (i.e. against end grain and side grain) to see if the holdall/benchtop angle is too shallow which will crush the bench top wood fibres more easily and damage the hole quicker than usual.

[IanW]

With my wooden holdfasts, a mm difference wouldn't make an iota of difference - they'll hold firmly in much sloppier holes than that! About the only problem I can see is that metal shafts might accelerate wear on the edges of your dog holes if too loose a fit, but possibly not to any significant degree when they are that close. I imagine the holes wear anyway, with constant use, so it's probably well worth the risk for the convenience of having a one-size-fits-all hole!

Cheers,

[Apollo]

Tanks guys.