Posted 5 years ago
ChaseCan
(35 items)
Mystery solved by Bruce99, (thank you) A vintage set of smoothing/cutting broaches used by watch/clock makers or repair people.
Description:
They range in length up to 5.75".
All are 5 sided, and seem somewhat sharp edged.
They vary greatly in diameter. The smallest size smaller than a needle.
The image didn't come out showing that they're all shiny. Possibly hardened steel of some kind.
They came with the wooden holder and plastic case.
My guess from the 60's or 70's.
Who made them, I don't know.
Hello ChaseCan.
I believe you have a set of cutting broaches there. They are typically used to size the inner diameter of newly placed bushings. They are tapered to cover a wide range of sizes, but the trade-off is that they cut a tapered inner diameter. That is off-set slightly by cutting from both sides. Some Horologists still prefer not to use them because of this short-coming.
The significance of the resulting tapered cut is of some debate since the thickness of the plates is often in the neighborhood of somewhere between 1 and 2 millimeters.
Folks who want to cut an inner diameter with perfectly parallel walls might use sharpened pin gauges instead which is an elegant alternative.
Pin Vises are most often used to handle these tools and apply them to the work at hand.
I'm not sure about older tools but today, "Swiss Made" Cutting Broaches are most valued. Which "Swiss" Company is generally no specified by Clock Supply & Tool Suppliers in their catalogs. No doubt they could tell a Buyer if he or she really wants to know.
Thanks for sharing.
Thank you Bruce,
Yup, they're smoothing or cutting broaches.
I still don't quite understand what they're used on given the 5 sides. You can't cut or smooth a square hole with them. Perhaps they're used on the gear teeth maybe? Or the gear spokes?
I'm sure a clock or watchmaker will know how to use them.
Another one for give away pile as I'll never use them, but someone else might have a use for them. At least I know what they are now.
Thanks again for the info.
Cheers...
They are cutting broaches. They are 5-sided to make them better at self-centering in a hole that is out of round (center around the largest part of the hole).
They are typically used to broach bushings to size which are placed to restore worn pivot holes in clock plates.
Does that make sense?
Hey Bruce,
Okay.. I think I'm understanding... Almost anyway. Lol
It's my lack of knowledge of the workings of clock repair that's interfering.
I have knowledge of broaching a keyway. Which the cutting broach is squared on the sides to the cutting face. Which the broach action is a fore to aft cutting movement.
I understand now about the 5 sides and it's use to self center in the hole.
I'm assuming then, the cutting action for these broaches is rotating or drilling action rather than a fore to aft filing action.
What's losing me is, why they would taper the entire length. I could see a taper up to the point of the size hole you're after, then I would think, ideally you'd want it to be the exact diameter for a good portion. That way the hole you broach doesn't have a taper to it. Even a slight taper, given the metal in cock's and watches aren't that thick.
Unless you're suppose to run these all the way through when broaching a bushing. Which would eliminate the taper.
I searched for a video in hopes of someone showing then in use but.. nothing so far.
Now if these are cutting broaches, which in my Google search the ones that came up looked all the same yet some descriptions labeled them as "smoothing/cutting" broaches, while others just said "smoothing" and still others said just "cutting" broaches.
What's the difference between a smoothing broach and a cutting broach... And a smoothing/cutting broach?
They all "looked" the same in the pics they showed.
Yes, the cutting action is rotational. The taper allows custom sizing of the pivot hole (inner diameter) of the new bushing. Some may determine the desired size of the broached hole, and place a stop (or marker) at the appropriate spot along the length of the broach to achieve the right dimension.
Cutting broaches have the five sharp corners of a pentagon. Smoothing broaches have a circular profile with a matte finish. The smoothing broaches are used to remove any potential burrs or to help work harden the inner diameter of the bushing.
I hope that makes sense. If not, let me know and I'll try to explain it better.
Regards,
Bruce
Hey Bruce,
Aah...Now I understand.. Thank you very much for the time and the explanation.
:-)
Cheers...
THANKS SO MUCH to both ChaseCan for showing these fascinating little precision tools, and to Bruce99 for the clear and concise explanation of what they are and how they'd be used. <applause> What FUN stuff to be learned by hanging around CW!! :-) :-) :-) :-) :-)