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home-made lathe accessory




Hello,
As you may have read on the vintage watches forum I recently aquired a second lathe. After not being too sure whether to keep both or sell one I decided to use the european type lathe for finer work.
So I decided I'd start work on some accessories for balance staff polishing. I also wanted to try some advised tool angles in my more general use lathe and so below is the result.
It isn't finished yet, still to do is the drilling so that staffs may fit part way in, for polishing the ends. I thought I'd show it at this stage as I tried some perlage of my own using brass filings as an abrasive, just it might get spoilt later.
J Grainger

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Interesting device, I haven't seen anything like it before. What exactly is it used for? And how? Is the back bit in the centre for holding a graver?
Nice touch with the perlage.
-Jonathan

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Hello,
When the holes have been drilled, the balance staff to be polished will be placed, one end in a centre fitted in the headstock, the other end of the balance staff will be placed in a hole which fits the staff with the tip potruding. The tip can then be polished/ re-shaped.
The part which goes in the tailstock just has a dimple at the moment, I might drill it out to a small size to hold some tiny centres I have without the brass peice attached. I do have to make a jacot drum still when I find some steel
J Grainger

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Perlage is used to snag lightweight material and hold it from becoming detached. Casebacks are perlaged so dust that accidentally gets in the case is trapped on the back and cannot drift loose into the works.
On a tool that will be exposed to generated filings, I'd think you'd want to avoid perlage since you want the removed metal to disengage and leave the area. I'd think a mirror polish is a more appropirate finish here.
What was your criteria for choosing this finish?
>< gts I've been posting on here for 12 years.
My all-time best postings can be found at
professorguy.com/blog.

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I wasn't planning to do any perlage, however, I was improving the finish of the brass using the table of the bench drill and it seemed as good an oportunity as any to try it. I thought the shape at the back of the brass would fit nicely in a cut out on the drill table so as to allow it to be rotated reasonable accurately.
Another use for perlage (as well as other patterns) is to distract the eye from noticing a slightly uneven surface.
J Grainger
J Grainger

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Perlage is a word from French that has recently made its way into English and pushed out the older word "spotting" which used to be used to describe this type of decorative finish.
Spotting, Perlabe or whatever you want to call it, is just another form of decorative metal finishing and falls into the engine turning category, in all probability.
This is the first time I have heard of its ability to retain dust or anything else. If it did have this capacity, why are movements so often perlaged ("spotted")? this seems not to be very sensible.
Could you offer some proof please? Spotting is usually no deeper than micro thickness, and I would think it has no effect at all, but I speak against correction and would like to hear more about this.

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I also recall reading that the pearlage inside watch backs was as an aid in fine particle retention.
In Minerva timers, from WW1 til after WW2 it seems that the inside of dust cover was spotted; inside of back was not. This suggests to me that it just might have been thought useful to retain fine particles. From around the 50s, spotting was done on both til the hinged double back was discontinued.
What I can tell you for sure is that when we build hard disk drives, we like very smooth surfaces as they easier to get really clean of particle contamination.
Cheers, Ch@rlie

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Interesting, it wouldnt seem to make sense though decorating movements from the perspective of service life.
J Grainger
J Grainger

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I am not disagreeing with what you said about perlage. Yet, I have a somewhat related question. I had once been told that the purpose of perlage (it was called "jewelling" when the finish was applied to the surfaces of machines larger than watch movements) was to retain or localize lubricants, i.e.: to prevent them from migrating too far afield from the places the oils were needed. The application was to surfaces that slid against or through each other with significant force. When the swirls were shown to me, in some cases, the application was not as fine or as decorative as the perlage we see in watch movements or cases but in other cases it was just as fine and decorative. Indeed, when it had much rougher edges, it would seem more likely to snag foreign materials, as you said. On the other hand when it was a fine finish that was lubricated, perhaps it did serve to retain the lubricant. Do you think there is any validity to this idea of perlage ever serving the purpose of reservoir for lubricants in watch mechanisms? I must admit that its apparent regular use on the cadrature, case backs and rotors would not seem to require nor serve any lubrication functions.

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Very interesting discussion.
Hope that you can show us the complete finished tool in the near future.
Machiel.

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I think I will do, though I'm not sure whether the perlage is there to stay.
J Grainger
J Grainger