Shaping Crown Guards?

[dbutlerman]

I need to modify one of the crown guards on my recent 1680 Franken. My question is, what do you guys use to maintain the inside curvature of the crown guard. It'd be easy to make them flat, but how to create the curve on the inside, that's another story. Any help is greatly appreciated!

[highoeyazmuhudee]

(symmetrical, camera angle may make them appear not)

practice and observation

i use the triangle file, flat file, and round file, first i roughly trim away what i dont want with the flat edge files, this is often done squarely, then i trace the contour out like a semi circle and use the round file to achieve the the correct interior contour around the crown...hmm hard to explain in words. then i use sand paper to finely make them symmetrical and smooth and to eventually finish them before a deep polish... my advice is look at a lot of pictures from many angles , hold the gen in your hands if you can and observe it in 3D space. when you go to mod your piece visualize what you want removed from the stock CGs and maintain that image in your head until youre satisfied that it matches up. i find drawing cutaway spots on the actual case to be ineffective

[dbutlerman]

Thanks man! That is exactly what I wanted to hear...

[freddy333]

Not sure why you are worrying about curves inside the CGs? The bottom corners should be squarish anyway. Simply (gently) clamp the case in a vice & use a flat file to grind down the inner-sides (inside) of the CGs to match the gen you are using as a model. Then, smooth things out with a dremel & sandpaper, & polish. Not really rocket science

[dbutlerman]

That makes it sound easy. I'll start working on it and post some pics when done...

[highoeyazmuhudee]

remember there are many many variations between years as well

[dbutlerman]

Yeah - but since one of my crown guards is already modified, I am just going to match the other one to it, I may be slightly limited to what I can and can't do. Mainly I am just trying to increase the space between crown and the lower CG.

[freddy333]

Try this

[dbutlerman]

Thanks Freddy! Printing them out as references now!

[Nanuq]

I tried JMB's automated method to reshape the inner curves with a drill press, but I'm just not getting a good result.

Maybe it's my tools?

[dbutlerman]

I think that one should work perfectly Nanuq, that is, based on your other aging processes. Personally, I'll stick with hand tools:

[JEKS]

I remember seeing a thread somewhere on one machinist who would align to the center of the crown hole and then plunge down with a taper mill. The taper of the mill would provide a round but decreasing diameter cut. That would seem to be the best option, but a file will work as well.

[dbutlerman]

I am pretty sure it was JMB who wrote about it, but since I don't have a mill, I'll be sticking with the grinder method...

[jmb]

I tried JMB's automated method to reshape the inner curves with a drill press, but I'm just not getting a good result.

Maybe it's my tools?

Now, I really LIKE this tool!!!

[cjjoyce1]

Crown guards are like ta ta's. We all have an ideal of what we think is perfect, and they're all just a little bit different from one another

Edited September 30, 2011 by cjjoyce1

[highoeyazmuhudee]

this might actually help you out. i discovered a use for DLC rolexs awhile back. no reflection of the metal makes it easy to see the exact shape and contour of the case. check out those CGs, much easier to see and understand.