Dog/Holdfast hole size tolerance

[ian maybury]

This is what an adjustable engineering hand reamer for tuning the tolerance of holes in metal (e.g. the bore of bronze bearing bushes after they are pressed into place) looks like: http://www.newmantools.com/reamer/expanding.htm Much cheaper these days than used to be the case, but still well over $100.

One key feature is that the cutters form a long enough cylinder for the tool to remain properly aligned with the axis of the starting hole.

I wonder if a low cost version of any such tool for use on wood exists?

ian

[Jim Koepke]

Where is the post? It didn't make the trip.

Oops, it has been added to the post.

It can also be found by its title here or through Google, "A Bit About Augers."

jtk

[Jim Koepke]

I wonder if a low cost version of any such tool for use on wood exists?

I think it is called, "a bigger drill bit."

I recall buying a an expandable reamer back in the early 1970s for about $20. It was needed to ream the bushings for my VW buss's steering pivot pin. My recollection was finishing the job a little after 2:00 am with frost in my mustache. The improvement in the steering was worth the effort and the ream was sold at cost to a friend who wanted to do his.

More recently another larger one was acquired from my brother who picked up a bunch at scrap metal prices.

Oink! Oink! The tool pig moniker should be worn proudly!

jtk

[ian maybury]

That rings a few bells Jim, only in my case it was the small end bushing on a Triumph Tiger Cub motorcycle back in the late 60s.

A bigger drill bit is one route - but running a slightly larger one through a previously drilled hole isn't always ideal given the risk of grabbing. Guess i was just thinking that something adjustable and less aggressive would be nice - it'd allow a sneaking up on the ideal dimension for a given holdfast. Probably not robust enough, but there's definitely a tapered variety about with a wooden body and an adjustable blade....

[Jim Koepke]

Probably not robust enough, but there's definitely a tapered variety about with a wooden body and an adjustable blade....

Sounds like a project for a day when one finds an old bandsaw blade and a dowel...

jtk

[ian maybury]

Exactly. The thought was in the context of how to set up to test just what hole diameter and hole length works best for a given holdfast. It'd be interesting to run the issue to ground and produce some fact rather than relying on hearsay. I've started my (very slow moving) bench - I'll probably run a few trials and report in due course .

[Matt ONeill]

Well, I can only give you my personal experience. I've got 4 of the grammercy holdfasts, and a 4" thick ash bench. At first, they worked great out of the box. After a couple years, they barely worked at all (and I counter bored my holes from the bottom). However, I purchased some lie-Nielsen holdfasts, and they worked great. The difference? The LNs are cast, and have a rough shaft. My opinion is that the holes get burnished over time, and a rougher shaft overcomes this.

- Matt