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Discussion Starter #1
I think I've figured out how to properly restore the unique factory machining marks on the 6139-7100. I'm awaiting a case form Ramon to confirm.

Long story short, I made an accessory for my mini-lathe carriage to add a third axis of cutting tool motion. Most lathes have but two axes unless one partially disassembles the carriage. Time consuming PIA at best and at worst a huge pain to determine and set the angle of motion.

Ugly it may be but there is no lash in any of the parts and all components were on-hand...





Don't worry boys and girls, no living Seiko cased have been harmed during this production. The case on the lathe is one that was very poorly and quite improperly "refinished".

"Here at East Tech Manufacturing we don't make 'em pretty but we sure do make 'em work."
 

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Discussion Starter #4
LUW said:
Could show us before and after pics? It would be a lot easier for us feeble minds to understand what you were trying to accomplish.
Once I have the case from Ramon to work with, I'll get more pix posted.

In the second photo you can see the results of this effort. Most refinishing of this model winds up being a heavy brush or satin finish rendered with abrasive cloth or paper like this one from the Photo Database:



The factory finish is difficult to photograph but here's a couple more borrowed pix...

[img]

In this one you can really see the nature of the machining...

[img]
 

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Interesting and ingenious, Jonathan! One thing that's always puzzled me (and I know it's not a Japanese watch but the 'helmet' case design is suspiciously similar), how does Omega get this machined radial finish on its Flightmaster?
 

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Discussion Starter #6
Sir said:
Interesting and ingenious, Jonathan! One thing that's always puzzled me (and I know it's not a Japanese watch but the 'helmet' case design is suspiciously similar), how does Omega get this machined radial finish on its Flightmaster?
The Flightmaster's radial brushing is a lot easier than the concentric machining on the 6139-7100 and was used by Seiko on several '60s and '70s models. Even so, the process is an expense vis a vis set-up time and effort, thus this finish is not as prevalent as others.



Here it is, somewhat coarse on a 1967 8305-7000...



And a bit finer on this 6106-9010 from 1969...

[img]http://www.csce.uark.edu/%7Ejgauch/photos/dir1/seiko_6000/6106-9010/005.jpg

It is done while the case is spinning in a lathe and a spinning abrasive wheel, as opposed to a cutter, is applied at a 90 degree angle to the diameter or perpendicular to the circumference of the case the case. I've done this successsfully but the set-up is absolutely critical. A degree or two off and the applied lines begin to slant away from perpendicular to the case with a visual effect similar to the rotating ring of the "sawtooth" dive watches. Interesting but only for a wacky mod.
 

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Jonathan,

That is a professional set up you got there. It appears that you will be applying the finish line by line, I am curious how you would be to achieve uniform spacing between the lines !! PLEASE show us your finished case !!

I love these case restoration articles by you !

Cheers!!

Jim
 

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I was a little curious as well, how will you time the rotation of the case to the rotations of your new jig? It seems like they would have to be synced up to achieve the proper finish. (I am in no way second guessing you Jonathan, I just want to know how you are going to make it work.)
 

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Discussion Starter #11
aladin_sane said:
I was a little curious as well, how will you time the rotation of the case to the rotations of your new jig? It seems like they would have to be synced up to achieve the proper finish. (I am in no way second guessing you Jonathan, I just want to know how you are going to make it work.)
To answer you and Jim, I'm not sure a synchronization is necessary. In working with this case at a relatively slow rotation, the lines are effectively a spiral with the spacing dependent on the speed at which I feed the cutter along the case. Slow, even feed equates to even, closely spaced lines. My biggest concern is the carbide cutter whose tip is not a point but ever so slightly rounded.

I am at a stand-still until Ramon's case arrives. I will follow-up as soon as I have the next results.
 

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A question, how does the new jig adapt for ever increasing circumferences in the case's concentric circles? Do you have to ad each increase manually?
 

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Discussion Starter #13
Isthmus said:
A question, how does the new jig adapt for ever increasing circumferences in the case's concentric circles? Do you have to ad each increase manually?
Despite the case being a truncated cone, the side surface is essentially dead-flat at the point where the cutter makes contact. The issue I have solved (hopefully) is that of setting the precise angle for the cutter to remain in even contact with the case as it is fed along the side surface.

After doing case refinishing for so long, I discovered most case details are made up of planes that are flat on one axis. The 6105 and 6309 dive cases are, of course, an obvious exception but most of the same rules of tool application apply to these.

The key to refinishing without killing the creases is to try to establish the sequence with which to apply the tools. Of vital importance is the use of rigid tools, ie. hard felt buffing wheels or abrasive material backed up by wooden blocks. Most guys use soft buffs in their polishing machine, hand-held abrasive sheets and the small wheels of a Dremel or flex-shaft tool. These all conspire to kill the detail lines of a watch case no matter how careful one might be.
 

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Jonathan, has anyone ever told you that you really need to take on a few apprentices so as to save all the metal working knowledge for future generations? O0
 

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Discussion Starter #15
Isthmus said:
Jonathan, has anyone ever told you that you really need to take on a few apprentices so as to save all the metal working knowledge for future generations? O0
In the big scheme of things, I know virtually nothing. And everything I do has come from trial and error learning/experimentation over many years. I wish I had the patience to teach but alas, I do not.
 

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Jonathan, at first I was going to ask, why don't you just use the compound and set it at the angle of the case?

But then I noticed that you have the compound slide set parallel to the Z-axis. So, you need the precision of the lathe compound in order to position the tool properly?

I tell ya, you were a full-on toolmaker in some other life. Kudos!
 
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