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Sunburst jig for making a sunburst finish on a watch case.

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God day, I have designed a 3 part jig for adding a sunburst finish to a watch case restoration available here:

1) Jig:


2) Anvil:


3) You will need 1 of the the following bearings:


Here is an example (not my watch) of the type of finish this tool is designed to achieve on the case of the watch:



A tool to add a sunburst finish to a watch restoration. you need to add a bearing (see Below) to the anvil and then attach this to the jig, this should allow you to turn the watch 360 degrees. Then using a needle file (sideways) in the groove(s) you can apply a sunburst in a sawing motion as you turn the watch.

Details of bearing to be used:

Skateboard Bearings: 608-2RS ball bearings Size : 8x22x7mm, rubber sealed deep groove.
Available on amazon

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Posted (edited)

I love the idea 👍

Perhaps it is complete and I don't fully get it jet, or it needs some expansion?

As I understand your description, the bearing slides over the Jig's pivot and the anvil goes on top, between the two post of the jig, allowing it to rotate.

Than, I assume, the watch floats (?) on top of the anvil. The slots in the jig are there as a guide for the needle file (?).

The way I understand how to make a sunburst, the needle-file has to be at a constant angle (the exact same angle as the to be "sunbursted" surface), rotating around the center-line of the watch-case, or, the watch-case has the able to rotate around its center-line.

What I fail to see at the moment is how to assure that the watch-case is perfectly centered & secured in place and how to assure that the correct angle of the needle file is maintained during the process?

It would be very nice to have a DIY tool 😉


Edited by Endeavor
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Thanks for the feedback, I'll tackle your observations one at a time 🙂

7 minutes ago, Endeavor said:

the bearing slides over the Jig's pivot and the anvil goes on top, between the two post of the jig, allowing it to rotate.

This is correct

8 minutes ago, Endeavor said:

Than, I assume, the watch floats (?) on top of the anvil

yes the watch sits on top of the anvil, I secured mine with a lump of rodico. I contemplated integrating some kind of movement holder (like a 4040), but when tightening it you would draw one half of the holder closer or further away from the other, hence, moving the center point of the watch relative to the center of the anvil causing it to gyrate as it turned and guaranteeing that you would have an off center burst.

12 minutes ago, Endeavor said:

The slots in the jig are there as a guide for the needle file (?).

Yes the slots are there to ensure that the individual strokes that are made to make the burst are always in line with the center of the watch (taking the above into account), this ensures the constant angle (as long as the watch is correctly centered [+/- ]on the anvil)

15 minutes ago, Endeavor said:

What I fail to see at the moment is how to assure that the watch-case is perfectly centered & secured in place and how to assure that the correct angle of the needle file is maintained during the process?

This is the hardest bit, I incorporated a cross-hair on the anvil to make it easier to judge the watch case centricity relative to the center of the anvil. My hope is that this will reduce the error as much as possible, but I agree that it is still dependent upon human judgement. But, that being said, I think and error created by doing it this way would be minimal and not noticeable, especially compared to manually going at it.

I did contemplate catabolizing some kind of self centering mechanism like those used in a diving watch case-back remover (see below), but I thought that this would be overkill especially as I think the manual method above (whilst not technically perfect) gives the best cost/benefit ratio. However, I am more than happy to try improve the design if you have a better solution 🙂 


I was also toying with the idea of using some kind of pusher arm (like on a hand setting tool) on the same or a similar jig to make a radial finish... but my wife was already upset with me for spending too much time 'playing' on my CAD software, so that's an idea for another day... but happy to take any ideas that are out there!


Something like this???


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Posted (edited)

I've been contemplating a design, but never got any further than that , which is based upon a Lansky knife sharpening system, which I own for keeping our kitchen knives (razor) sharp.




It's basically a clamp which clamps onto the back of your knife. Both "legs" of the clamp (on either side of the knife) do have equal degrees holes which allows you to sharpen the knife-edge, on either side, to a desired angle. Different grits grinding stone can be attached to a rod, and the smooth rod slides in the clamp-hole and the grinding-stone rest on the knife's edge, assuring a constant angle. There is a commercial (bla-bla-bla) video on Lansky's website: https://ad.knivesandtools.eu/en/pt/-lansky-professional-sharpening-system.htm

so you get the drift of the system. For knives this system work excellent.

The whole idea is to keep the grinding stone at a constant angle to the to be grounded surface.

Now I'm just brain-storming;

if it was possible to make an in high adjustable center-post (which would act as one of the Lansky's clamp-legs), the angle of the grinding stone can be seamlesly adjusted and set constant.

Either the center-post has to be able to rotate, or as with your design, the table or anvil has to be able to rotate around the center-post.

I made a quick and dirty sketch for the basic idea;


If the table (or anvil) can rotate, the center post could be made of a threaded rod, "fixed" to the jig, but you have to be able to adjust the height (to obtain the correct angle) and to lock it in place (with a counter-nut?). Perhaps a higher base of the jig with a nut for the center-post included?

This still leaves the centering and fixating of the housing 🤔 Also, my idea is an inconclusive expansion on what I already have, namely the Lansky grinding stones. But even the coarsest grinding stone in my set, is too fine and too wide for a sunburst. It has to be a needle-file, but with a smooth end so you don't wear out the hole in the center-post.

Feasible of just wishful thinking?

EDIT; what if when you clamp the housing from the inside ?? Kinda a head of a lathe? With a 3-claw lath-head you can clamp on object inside the claws, or you can clamp a hollow object with the outside of the clamps. Of course, in a lathe head, all 3-claws are moving simultaneously, ensuring centrality.

EDIT EDIT; One could perhaps also have a fixed center-post, fixed to the jig, and make the table adjustable in height (with shims underneath the bearing?) 🤓






Edited by Endeavor
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Posted (edited)

I had another idea, still based upon the "Lansky-principle", but perhaps more simple to build?

Forget about the scale and proportions in the sketch, it's just to convey the idea.


The center-post in the previous drawing doesn't have to be in the middle of the rotating table, it can be moved to somewhere else on the jig. What is important however, that the file runs through the center of the rotating table and through the center of the watch case. One side of the existing guide post in your current design can stay, it will make sure that the file stay in line with and directly over the center-line.

The now moved "center-post" has to be adjustable in height (telescopic?), so the angle of the file (with a rod-extension) can be adjusted to the correct angle of the "to-be-sunbursted" surface.

The rotating table has to be able to rotate, with or without a smooth running ball-bearing, but it is very important that the table is stable (not allowed to wobble) and stays in the center.

The file used can be extended with a smooth rod, running through a hole, or a slot/slit, in the in height adjustable post. The width of the slit between the two guide post should be wide enough the accommodate the width of the file, but not much more than that.

One thing vintage watch collectors-freak out about is when the shape of the case is altered, or previous sharp edges are rounded due to polishing. For cheap watches this is not a problem.

I'm looking at Sunbursting an Omega 1975 Speedmaster Mark II case, so that has to be as precise as possible. Of course, it's a DIY tool, never matching the professional ($$$$) equipment, but since we are in the design phase, we may just as well give it our best shot 😉

Once the concept idea is established, dimensions and angles can be determined.

Still hanging in the air is that little pesky problem of how to fix the watch-case in the center of the rotating table. Most watch-cases do have a circular inside, which seems to me a more sensible approach than clamping onto odd outer-shapes.

I'm sure that there are some very bright minds on our forum who have some simple & smart idea's how to centralize and fix the watch-case.

I do hope that they will chip in ! 😇

What do you think? 🤔



Edited by Endeavor
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Posted (edited)

Hi there, sorry I didn't get back to you sooner, but life gets in the way 🙂

I think that our two designs are moving closer together, but I do like the idea you have to keep a constant angle on the arm that applies the finish. Perhaps something as simple as a small (wing)nut and bolt and washers fitted in the vertical slot under the arm would stop it moving down to maintain the angle and remove the need to have a height adjustable/telescoping center rotating mount for he case?

But as you state, we still have the issue of securing the watch case, I was looking at the polishing case holders (somehow) mounted vertically:



However, there are 3 issues with this; the first is that we are in huge violation of the K.I.S.S. principal of engineering and the second is that they are CRAZY expensive ($300+) and finally, they would only work on round watch cases.... hopefully there are some other brains looking at this who will come up with the "how come I didn't think of that" solution 🙂



Here is my bad drawing of the bolt angle system, who needs CAD ha ha 🤣

Edited by Waggy
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Posted (edited)

Yes, the wing-nut is a good idea, seamlessly adjustable, simple & idiot proof.

The Horrortec idea is good, but way too expensive. We need something far more KISS.

And this type of solution will indeed only be for watch-cases which are internally round. But how many square / oval cases (internally not round) are there with sunburst compared to internally round?

As for centering the case, again for internally-round cases, I had an idea but it has its flaws 😞

If one were to incorporate a conical ring in the center of the rotating table, the watch case would centralize itself. Perhaps the conical side, as shown in the sketch, has to be far less steep, allowing for different casing-sizes and such that the watch-case doesn't sink too far over the ring, avoiding that the edge of the conical-ring interferes with the path of the file.

However, this conical ring would not prevent the watch-case from tilting / tipping over. The watch case has to be kept horizontally.


Edited by Endeavor
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30 minutes ago, Endeavor said:

If one were to incorporate a conical ring in the center of the rotating table

I like this idea, but I agree that if the watch has a large ID then it will slip quite far down the cone, if I understand you correctly this would mean that a lot of cone will poke out of the top which could interfere with the polishing arm...? Time for another sketch, like this?:


Perhaps an 'adapter' ring/cone could be used for larger watches with larder ID to push them further up to keep them in range of the arm without interference, like the below:


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Posted (edited)

Yes, perhaps, however loose rings tend to go missing and if that would be the way to go, we still haven't solved the problem of tilting / tipping and a way of getting the watch-case in the perfect horizontal plane 🤔

It would be ideal if the case would rest on its lugs ......fixed and centralized (minor detail)

There has to be a way; Let's think and back to the drawing board 🥸

Rome wasn't build in a day either 🙂


Edited by Endeavor
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Posted (edited)

OK here we go..... how about if we take inspiration from the tool below and combine it with our current design:


to give you:



so cone centers the watch, but you can slide the table up and down to support it and keep it level


Edited by Waggy
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I still see some of the same problems as we had before. The size of the cone-tip is limited to a few internal diameter sizes. Assuming that when loosening the grub screw, the variable table can be lowered to centralize the watch-case. In that case the cone starts to stick higher up, possibly interfering with the file.

Also, I question the idea of using a bearing. It all adds to the play and "wobbliness" of the rotating table. If the rotating table would just rest on the base (jig), being centralized by a tight tollerance pivot, it shouldn't be that hard to turn the table (friction between plastic-and-plastic?). I my mind there is no need for a smooth, free spinning table. The "sunbursting" is a slow process, turning the watch-case each time in small increments. The table has to be hold stationary with each file stroke. The more stable the table, the better. I think it is way more important to minimize the play in axial and radial direction.

We also have to bear in mind, that in our current "paper-design", the diameter of the rotating table may be much small than with your initial design. What the diameter of the rotating table will be, is determined by the diameter of the watch-casing, the height of it and under which angle the file has to operate. The smaller the diameter of the rotating table, the more wobbly it may get. IMHO, leaving the bearing out simplifies the design, safes cost and reduces the overall play.

Another question which one could ask is; has this tool to be universally designed for any watch-case (shape & size) you may possibly ever encounter (men and ladies watches) or stick to a certain range of watch cases, say men's watches with a round internal? Which group would benefit the most of such a sunburst-tool? The question deviates from our current design questions / idea's, but then again it has everything to do with it. 

Needles to say, an universal "can-do-it-all" tool is way harder to design than a tool for a specific range of watch cases.



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