Because holdfasts are the primary workholding device on my French oak workbench, I am quick to investigate things when the holdfasts stop working well.
This week I noticed my holdfasts were getting stuck in their holes. They were difficult to get in and out. After a little investigating I found two things had gone wrong.
As the thick slab continued to dry, the holdfast holes had distorted enough to create an interference fit with the shaft of the holdfast. The distortion isn’t something you could see, but you could definitely feel it when you pushed the holdfast into its hole.
Second, the end of one of my holdfasts was a few thou too big for the holes. How did this happen? Easy. When the holdfast holes started to distort and the holdfast began to stick, the only way to release the holdfast was to strike it from below the benchtop with a metal hammer.
Surprisingly, this hammering upset the end of the holdfast and caused it to swell at the end of the shaft. And it was enough to make the holdfast even more difficult to insert and remove.
At this point in the blog entry I should insert a few proctology jokes. And something about a swollen shaft. But I’m feeling too classy this morning to go to that dark place.
To remedy my distorted holes and swollen shaft, I turned to two electric tools: A corded drill and a grinder. I put a 1”-diameter Wood Owl Nailchipper bit into the drill and reamed the holes. One of the holes – the most distorted one – gave up a spider web and two mummified houseflies.
Then I dressed the end of the holdfast on the grinder until everything worked well. The shaft dropped smoothly into every hole and the holdfast returned to its normal grabby self.
— Christopher Schwarz
Note: The shaft of my vintage holdfast was made so its shaft is the same diameter along its entire length. Not all vintage (or new) holdfasts are like this. Some taper along their shaft. This makes them immune to the above problems, but I don’t find they are as easy to set.
Chris,
The proctology jokes, and the exploding raney jokes, are the main reason (oh, besides the reams of invaluable information) that I read this column every day. Don’t hold back! Freed from the editorial restraint required at your previous job, you regularly inject high quality lowbrow humor into woodworking content. Lacking this you would likely be a staff writer at BHG Wood, an unenviable endeavor. Thanks for the chuckles, even the implied ones.
Hope your two “test nickels” haven’t given you trouble.
I have also found that finishes can affect the way they hold. Oils and wax reduce friction and friction is what makes a holdfast work. The few times i have had someone complain that they couldn’t get theirs to hold, that turned out to be the problem. I learned this early because they do look so much better with a nice wax finish on them. But they won’t hold at all if you do that. Once I put them back in the forge and burned off the wax, no more problem.
Who are you, and what have you done to Chris?
Chris and Daniel have switched places. Now The History of Wood is going to contain 11% more poop jokes.
Snort
If only Roubo could post here.
1″ diameter? Isn’t 3/4″ the usual holdfast size?
Older holdfasts were bigger.
Older holdfasts ran 10 miles to school in blizzard conditions uphill both ways in a bikini and still got there in time to ace the math test and could grow a full beard in two minutes flat with 11% more poop jokes.
I don’t know where I’m going with this. Beer good, holdfast bigger.
Chris, perhaps a urologist would be more helpful in making jokes about a swollen shaft and a proctologist would be more appropriate with the distorted holes.
Although you have some wood shrinkage, the Wood Owl Nail Chipper is not actually 1″, it is a metric undersize. We ran into this when we putting together our Easy Dog Hole Kits. We were providing 3/4″ router bits and 3/4″ Wood Owl bits to chase the holes through deeper benches. We ended up getting a ledge and realized that the Wood Owl bits were metric and undersized. It made a difference in weather the dogs fit or not.
Garth@timewarptoolworks.com
Garth,
The WoodOwl bits are indeed metric, it says so right on the package. So it is a 25mm bit, which measures .950″. That is definitely close enough to 1″ for a holdfast.
I sort of have the opposite problem, where my holdfasts won’t grab in a couple of my bench holes. I suspect the problem is that I bored out of plumb or even with a slight curve as I tried to correct on the fly. My holes are 3/4″. Any suggestions there?
Easy. Dimple the shaft of the holdfast with a pointed punch. Richard Maguire showed the world this trick on his web site. Works like crazy and fixes every holdfast I’ve done this to.
I’ll give that a try.
I wouldn’t think that a slightly out of plumb hole would be a big problem. There are some ratios that seem to make a difference, The arm of the holdfast should be about 1 1/2 times longer than the bench is thick. For a 3/4″ hole an 11/16th shaft is a good fit and 5/8th is probably a bit loose. For a 1″ hole 7/8th seems to work well. lots of the comercial ones are made for fairly thin benches. Chris’s idea of dimpling the shaft should help, if the top is very thick counter boring from the bottom may help, also roughing up the shaft with some 80 grit paper, around the shaft not in line, would help. If the holes being out of plumb is the problem you might have to rebore then go to a larger shank holdfast.
My solution thus far has been to try enlarging the bottom of the hole a bit, Counterboring might work, too. Now I have a couple suggestions to try. Thanks!
One of the first thing I learned in a shop is, you never strike the holdfast with a Hammer, always with a wooden mallet and if your holdfast don’t hold, rub the inside of the hole with chalk.
And what would be a shop of busy woodworkers without some proctology jokes to relieve the tension!