Contributor
I was told to not hit them with a metal hammer because you can cause metal fatigue.... So i always hit them with things that are not metal. I am not well enough to say one way or another in that regards.
I can say that I do not need to beat it to make it stick. Mr. Cohen has it right I think.... but I think he also said you can hit it with metal.
I suspect that even if you are causing metal fatigue with metal on metal it would take a long time to manifest.
Contributor
I smack them with the mallet below. It's a cast iron body with a drop through handle in a thru mortise. It goes together just like a joiners mallet. The striking faces are white oak that I carved to fit (no lathe). I added a leather disc to one for a softer blow. I'll bet it once had rawhide faces but when I bought it at a flea market it didn't have any. I've never seen anything quite like it. It's heavy like a lump hammer. There are no markings of any kind. I'd like to learn more about it if anyone has any ideas.
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Sharp solves all manner of problems.
Contributor
I use hard face of the Thor hammers like Paul Sellers uses on his chisels. Works great for me.
Contributor
Like about a thousand years.Originally Posted by Andrew Pitonyak
Member
Thanks Frank, you have me ROTFLMAO.
ken
[OP]
Member
Thanks fro the great info. So on some of my dog holes I can just push down and get a satisfactory grip for anything other than banging out mortices, but on most I can't. I've never really figured out what the difference is.
Contributor
The thicker the top, the more slop you need in the hole, to a point. My top (hard maple) is just over 3.5" thick, the holes are exactly .75" and that combination seems about perfect for the Gramercy holdfasts. A much thicker top would need holes just a little bigger.
Contributor
Or, chamfer the holes from the underside (to "reduce" its thickness) if the bench is greater than 3 1/2" thick (my bench is 3 1/2").
Regards from Perth
Derek
Contributor
Hilton, not a lot, although it depends with whom I am talking. I have lived here most of my life. Nearly 35 years in Perth, and Sydney before then. It’s hard to leave Cape Town behind.
I tend to be soporific, regardless
Regards from Perth
Derek
Contributor
You're not exaggerating. From a metal fatigue standpoint the those particular holdfasts are very well designed; long story short, unless there's some kind of internal flaw in the metal you'd almost certainly destroy your bench in short order hitting the holdfast hard enough to even consider approaching the fatigue limit*.
*Fatigue limit: the cyclic load limit, below which a steel object will never break no matter how many load/unload cycles it goes through.
Contributor
I don’t use holdfasts these days very often, certainly not as much as most of you guys. But, I have a pair of Taiwanese holdfasts that are at least 15 years old. Every time I use them I swat them with a hammer. I can barely tell they have been hit.
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My Gramercy holdfasts definitely don't hold that easy. I have to give them a good wack with a hammer or mallet to get them to hold tightly. I guess my set up is the issue, but how do I know what about my setup is the problem?
Contributor
How thick is your bench? What did you use to drill your holes? How smooth are they? Note Derek mentioned his holes are slightly larger than the shafts of his hold fasts allowing for room for the shaft to bind. He also noted the walls of his holes are rough. In my 3.25 inch thick maple bench the holes were bored using a router bit. This resulted in extremely smooth holes. The Gramercy hold fasts would not hold until I abraded the shafts a little. I can now set them by hand but prefer to use a leather faced jointers mallet.
Contributor
I wonder if the geometry, metallurgy, and the placement of the setting blow has more to do with it then the type of hammer used or bench thickness.
Contributor
My answer would be yes. Just pushing my holdfasts against the work will secure it without a bash from a mallet.k
This has me wondering also. A holdfast needs to have a bit of slant to hold in the dog hole. There are three points of contact to fix a holdfast. The front of the rod, the back of the rod and being lightly sprung on the work have to all be working in order for the holdfast to hold securely.
If a dog hole is too slick along with a super smooth holdfast it likely will not hold as well. Another problem would be the holdfast being almost the same size as the dog hole. The thicker the top of the bench, the less of a slant for the shaft of the holdfast.
jtk
"A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
- Sir Winston Churchill (1874-1965)
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