First sub 0.5mm pivot replacement

Dells

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Hi all
I didn’t know best place to post this but as it’s a Schatz 1000 day repair I thought I would post here , the Schatz 1000 day clock had the mainspring jump out of the arbor causing extensive damage, but luckily Schatznut has sent me the replacement parts i need ( very helpful man ) , anyway I thought as an experiment I would repair the smaller pivot ( third wheel ) as I had never done one that small 0.49mm , I have done a video of me doing it but ignore the size I quote because I got it totally wrong , I should have said 0.49mm pivot and a 0.45mm drill but you will see what I said, I am happy with the outcome but I need to make a sensitive drill for my Pultra.
Dell
693CB7C7-EB0F-4383-B2E1-E886FDC65F1F.jpeg
 
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Wayne A

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Nicely done by hand! Also have done a few of these but used those small carbide micro drill sets that step up for easier holding. Used the tail stock to drill and its not to difficult. Most difficult thing is holding the wheel.

Wayne
 

Dells

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Nicely done by hand! Also have done a few of these but used those small carbide micro drill sets that step up for easier holding. Used the tail stock to drill and its not to difficult. Most difficult thing is holding the wheel.

Wayne
That’s a good idea stepped drill bits, and I quite agree regarding holding wheel.
 

Dells

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Hi Dells,

You might find this post from Jerry Kieffer interesting. I've used this method for pivots down to 0.2mm with short flute carbide drills.

Regards,

Graham
Thanks gmorse
That’s very interesting and informative but my lathe is a English Pultra 17/70 with a leaver tailstock that takes the standard 10mm collets and I could have used that but I find I don’t get the feel I want with it with very small drill bits, also I don’t think I can adapt Jerry’s approach to suit my tailstock but will have a look to see if I can find a runner type tailstock because I know they were made.
Dell
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gmorse

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Hi Dell,

I see what you mean about the tailstock feel being imprecise for this sort of work. I have a 6mm Geneva pattern lathe with a plain tailstock which works very well. With the short flute carbide drills in these small sizes being pretty expensive, I can't afford to risk breaking them, apart from the trouble of getting them out if they do break!

Regards,

Graham
 
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Dells

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Hi Graham
I try not to use carbide although I haven’t done much re pivoting, I have heard lots of stories regarding them but I do use a carbide spotting drill.
Dell
 

Bernhard J.

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I have a device like this one for drilling pivot holes in pocketwatch wheels. The rotation is generated using a bow. The "revolver" is for guiding drills of various diameters. It is long ago that I used it and I recall that it takes really long until the hole is drilled to the necessary depth. But one has plenty of "feel" and the risk of breaking the drill is rather low. Since then I prefer watches with intact pivots ;)

Zapfenbohrmaschine.jpg
 

gmorse

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Hi Dell,
I try not to use carbide although I haven’t done much re pivoting, I have heard lots of stories regarding them but I do use a carbide spotting drill.
As with most things, not all carbide tools are created equal . . .

The drills I use are not the ex-PCB things you can buy on eBay, they're industrial grade bits which in the smaller sizes can cost as much as £20 each, (delivered), so I need to take care of them.

Regards,

Graham
 

gmorse

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Hi Bernhard,
I have a device like this one for drilling pivot holes in pocketwatch wheels. The rotation is generated using a bow. The "revolver" is for guiding drills of various diameters. It is long ago that I used it and I recall that it takes really long until the hole is drilled to the necessary depth. But one has plenty of "feel" and the risk of breaking the drill is rather low.
I have a couple of these but I rarely use them any more, it's impossible to see what the drill bit is doing with this design. I prefer Jerry's method. This is a 0.24mm drill.

DSC01765.JPG
Regards,

Graham
 
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Jerry Kieffer

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Thanks gmorse
That’s very interesting and informative but my lathe is a English Pultra 17/70 with a leaver tailstock that takes the standard 10mm collets and I could have used that but I find I don’t get the feel I want with it with very small drill bits, also I don’t think I can adapt Jerry’s approach to suit my tailstock but will have a look to see if I can find a runner type tailstock because I know they were made.
Dell
View attachment 720283
Dell
If you wish to use the system suggested in the post referred to by Graham, you would not need to purchase a different tailstock.

You can lock your tailstock spindle, remove the drawbar and utilize the spindle drawbar hole since the headstock spindle creates tool holding alignment accuracy.

If your not equipped to fit or make the parts, there are many model engineers in the UK how could assist you. They seem to be a very friendly and helpful bunch.

After rereading the thread referred to by Graham, I see an error in post #5. In this post I made the statement that I drill .0001" holes using a Sherline Lathe. While National Jet has made .0001" drills that are utilized in their A7 drilling machine, it is unlikely it will happen in any machine not specifically designed to do so. The statement should have read .001" ten times larger

Jerry Kieffer
 

Dells

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Dell
If you wish to use the system suggested in the post referred to by Graham, you would not need to purchase a different tailstock.

You can lock your tailstock spindle, remove the drawbar and utilize the spindle drawbar hole since the headstock spindle creates tool holding alignment accuracy.
Jerry Kieffer
Thanks Jerry I never thought of that ,but as the tailstock spindle has a taper for a 10mm collet won’t that effect the accuracy?
 

KurtinSA

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After rereading the thread referred to by Graham, I see an error in post #5. In this post I made the statement that I drill .0001" holes using a Sherline Lathe. While National Jet has made .0001" drills that are utilized in their A7 drilling machine, it is unlikely it will happen in any machine not specifically designed to do so. The statement should have read .001" ten times larger

Jerry Kieffer
Jerry -

I would go find that post and report it to the admins. Ask them to change your number for future reference!

Kurt
 

Dells

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Just had a look at my tailstock spindle it has a key for the keyway in the collet so I don’t think that will work.
Dell
 

Jerry Kieffer

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Just had a look at my tailstock spindle it has a key for the keyway in the collet so I don’t think that will work.
Dell
Dell
A keyway slot can be machined or reduce the diameter of the end of the runner to clear the key per attached sketch.
Jerry Kieffer

AB1202C2-7670-45F6-93B2-FE4439303B4B_1_201_a.jpeg
 

gmorse

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Hi Dell,

Well, maybe it could be an advantage. One of the key features of Jerry's method is that once you've drilled a hole in the tailstock runner to mount the drill, the runner mustn't rotate or the truth of the centre could be lost, so a milled keyway to engage with that pin would be an ideal way to prevent that.

Regards,

Graham
 

Dells

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Have asked a friend to grind a keyway in a length of silver steel for me so all I have to do is get the steel.
Dell
 

Dells

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I have measured the inside of the tailstock spindle and it has three different sizes so that makes life difficult, but I have an old 8mm id 10mm od collet that if I fit to spindle but only tighten drawbar enough to stop it moving a 8mm length of silver steel will slide quite freely, that should work I think, thoughts please.
I removed video because it had so many mistakes but here is edited version

Dell
 
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Jerry Kieffer

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I have measured the inside of the tailstock spindle and it has three different sizes so that makes life difficult, but I have an old 8mm id 10mm od collet that if I fit to spindle but only tighten drawbar enough to stop it moving a 8mm length of silver steel will slide quite freely, that should work I think, thoughts please.
I removed video because it had so many mistakes but here is edited version

Dell
Dells
Without your tailstock spindle in hand ,it is difficult to make suggestions.

With all of this in mind, to make a long story short, it is doubtful the use of a collet for this procedure will produce satisfactory results.
In order to to get accuracy and repeatability, a long straight round hole is required.

Again with nothing in hand, I would suggest the following.

I would first suggest replacing a tailstock lever hinge pin with one that is easily removed. By removing one of the hinge pins, the tailstock spindle can now be easily removed exposing the spindle hole or opening in the tailstock. This opening is straight, round and long enough to be stable for successful use of the drilling procedure in question. Or at least should be.

Jerry Kieffer
 
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