watch makers jig borer, jig grinder

[refinery mike]

I had never seen such a thing before but there it was on Ebay. But where to come up with the 900 dollars. Well it didnt really matter because when the dust had cleared the thing went for over 8 grand. Two smaller watch jig borers where on ebay too. both at over 4 grand, not including thousands of dollars of accessories offered for them near by. Pardon me, i am drooling with envy. The question i have is just how small of a hole can you actually bore. Or are these things just very accurate drill presses. with microscopes.

[Harold_V]

The smallest hole I've ever bored was 1/16" (.0625"). I dare say, with care and skill, one could bore something as small as .03".

A jig borer is far more than just a fancy drill press. They typically offer the ability to locate within tenths, to say nothing of the ultra precision spindle that is fitted to the machine.

Harold

[ctwo]

How did that old joke go? The Americans sent their smallest drill bit to the Swiss, and the Swiss sent it back, with a hole drilled through its center...

[SteveM]

I had never seen such a thing before but there it was on Ebay. But where to come up with the 900 dollars. Well it didnt really matter because when the dust had cleared the thing went for over 8 grand.

Link please!

Steve

[refinery mike]

just go to WWW.EBAY.com and look for watch jig borer.

[refinery mike]

Yes Harold, the dials on this thing were like 5 inches in diameter. And it had some sort of micrometer viewer as well. the dove tails were massive cast iron, probabaly weighed 300 pounds, and i think it only had 150 millimeter travel. It was absolutely a beautiful piece.
What does a boring tool look like for boring such tiny holes as you were talking about. I can not Imagine how one would go about that.

[SteveM]

Is this the one:

http://www.ebay.com/itm/291630366307

Attached is a pic, so it won't disappear once the ebay listing is removed.

Pretty neat machine. I know the seller; he's not far from me.

Steve

[pete]

That Hauser and the Leitz machine that's still up sure makes me drool. I still haven't found the right project yet, but I've got a solid carbide boring bar with a 3/8ths shank and it's got a .047" wide cutting tip. So I figure it should be good for holes starting at a finished size of around .050" Can my equipment and even more important, can I even bore a hole to that size without instantly breaking a $45 boring tool. But a buddy in the U.K. has sent me links to a few European tool makers where the boring bars go a lot smaller than what I have. They also cost a hell of a lot more. So one of those very fine Swiss or European made small jig borers would be ideal I think for that type of tooling. They might be lacking in enough rpms tho.

Pete

[Harold_V]

What does a boring tool look like for boring such tiny holes as you were talking about. I can not Imagine how one would go about that.

It's been a long time (more than 33 years ago), but if memory serves, I used a small drill or drill blank as a boring tool. Drills are hard slightly beyond the flutes, so that portion can be used with success. Think of a D bit and you'd be close, although with top rake ground as a chip breaker. Not much different from boring larger holes, although feed rate is almost zero, as is the depth of cut with each pass. It's hard to determine if you have proper geometry because of size. Magnification, especially now, for me, would be a huge benefit.

One of the problems of grinding small tools is breakage. If the shank is quite heavy, you risk breaking the tool in grinding. For that reason, I, typically, use a small size, adequate for the task at hand, but no larger.

I recall hand grinding threading tools for 80 pitch threads in tungsten (which were inspected, by the way). I could see back then. Now? Ain't gonna happen.

Harold

[jerry kieffer]

Most small older manual Machine tools designed for watch size parts came from the old watch factories or instrument shops. Since most of the machining that I do is micro machining, I have owned several of these machines over the years. While of superb quality and a joy to observe, you quickly learn that they were designed for a specific purpose in production as were many of the older machines. As such, If one attempts to use a single machine for general purpose one off type work in a home shop, it can be a long row to hoe as they say.

For small one off watch size parts in a small shop setting, the current production Sherline and Cowells type Mills are far more versatile with readily available accessories. They also incorporate much more efficient methods of holding both tooling and work pieces that are compatible/ interchangeable with a like size Lathe.

The following is a typical example On a Sherline Mill.

The part shown on the coin is an escape wheel machined as a replacement for a valuable watch. For the most part it was machined with a .020" Endmill.
The other Photo shows the Mill as it was setup to machine the teeth on the part. Installing the CNC rotary table and Microscope took about 15 minutes and the part was ready to be machined. Versatility allowed the part to be positioned so the machining process was directly in front of the scope. This in turn allowed the old wheel to be duplicated to be mounted on the front of the wheel blank. Again this in turn allowed the Endmill to be positioned under the microscope using the old wheel as a guide requiring no measurements. The machining process as shown in the photo took just under four hours including setup. On my older specialized machines, setup and jigs for a single machine could have taken four days before machining.
What was not included in the four hours was parting the wheel off in the lathe and squaring the corners of the spokes with an escapement file. And of course the center hole needs to be drilled.

While I would not give up my older small Jig borers etc., they are just to time consuming to be efficient for the type of work that I do. But then a joy to look at and play with once in a while.

Boring bars are available from Micro 100 for ID down to .025"

Jerry Kieffer

[pete]

Hi Jerry.
Very happy to see you posting here. A lot in your post I hadn't considered before about the watch makers jig borers. I still lust after a BCA though.

Pete

[little giant]

The smallest hole I've ever bored was 1/16" (.0625"). I dare say, with care and skill, one could bore something as small as .03".

I have bored a .014 diameter hole in a Hardinge GT CNC lathe using a .010 wide boring bar and made a .004 diameter hole in a EDM sinker with a .002 electrode... not fun jobs!