SPRING BARRELS WITH STEEL CAPS

John P

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Sep 17, 2010
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Deep cuts in barreled mainspring arbors where steel caps were used.

We see a lot of this coming thru the shop now, and i wanted to explain to rebuilders how we repair the worn mainspring arbor.

We are sleeving this arbor with a brass bushing and the using the mill to open up the steel cap to accept the new sleeve.
The milling, using a rotary table rounds up the hole. The arbor, with new fitted bushing slips nicely into the cap.

How long will it last is unknown but the clock is saved for now.

This For the gear end of the barrel, we also round up the worn hole with the mill and use a hard brass washer, tamped into the barrel and then machined to fit that end of the arbor.

This repair process works very well and saves money, time, and parts that are no longer made.

BIG PLUS...I have a chance to do some nice work with the Sherline mill.

Johnp
 

wow

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Jun 24, 2008
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Nice work, John. Many Hermle barrels I get have this problem. I do the same as you on the gear end but on the cap I have had good luck making a brass bushing for the cap with a thin lip on the outside. I polish the arbor where the bushing contacts it. I have not tried the sleeve approach. I use my mill for bushing barrels often. That seems to be one of the most common power loss problems in modern movements.
 

John P

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The high cost of replacing clock movements has forced us to re-think the process of bringing old ones back to life.
If we are able to save the mainspring barrels, that alone could save the movement from the scrap pile.

Here are some pictures of the basic process
MILL SET FOR BARRELS (4).JPG MILL SET FOR BARRELS (7).JPG MILL SET FOR BARRELS (1).JPG
 

Willie X

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Feb 9, 2008
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If you are speaking of Hermle movements, the arbors, sleeves, and caps are available for around 10 bucks per train.
Then you can make some money on your jobs and return the worn out parts to the customer. Customers like that ...
Willie X
 

John P

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I believe the mill is the incorrect tool for this job. The single most important thing is to drill a hole that is centered. The lathe is tool designed to do this.
Could you explain why you feel the lathe would be a better tool for this work?



The Sherline Mill is much more fun to use than a lathe and far more accurate for this type of work. IMHO
My Waltham watch lathe will not accept caps of that size even using a 3 jaw chuck and our 1955 Logan lathe is too large for the accuracy I want.
Drilling out the worn hole does not allow for bushing size you plan to use. Drill size dictates that.
Drill bits have a tendency to walk toward the wear.
Cutting out the worn hole is controllable and easy to fit the bushing size you plan to use.

Re- sizing the bush for the arbor, no need to relocate part or change tooling.

The mill throws the chips out of the work for a beautiful, straight finish.

Rotary table with controller will cut any speed you select, or you can hand feed.
Cutter will spin any speed you select.

Trimming bushing thickness is a breeze with a mill and looks professional.

We can also run the cutter around the outer teeth area to clean up burrs and teeth replacement. Same tooling you have been using.

Besides, we have a large investment in the mill and tooling, Why not use it?

johnp
 

Mike Mall

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Oct 27, 2021
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If you are speaking of Hermle movements, the arbors, sleeves, and caps are available for around 10 bucks per train.
Then you can make some money on your jobs and return the worn out parts to the customer. Customers like that ...
Willie X
Hey Willie,
Can you tell me where these are available?
I find arbors and caps, but not sleeves.
 

Willie X

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Feb 9, 2008
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Mike,

The sleeves I have now came from BFI. There are two large versions and two small (130 series) versions.

I don't use Timesavers anymore but I have purchased these sleeves from them in the past.

I have also scrounged the sleeves from scrap movements. The wear can be anywhere between 0 and .006". Don't accept any noticable wear. Because once the wear starts, it goes south really fast.

Willie X
 
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