dbane883 Posted August 28, 2014 Report Share Posted August 28, 2014 Guys, I need a way to hold a watch case on a lathe or other machine tool. I will need a mandrel of some sort that can expand on the inside of the case and hold firmly in place using a collet of some sort. Something like this home-made unit I scrubbed from the internets: Is this something that is ready made somewhere? Or is fabricating it myself the preferred path? I think something that expands from 27-30mm should fit most Rolex cases I imagine. Link to comment Share on other sites More sharing options...
GenTLe Posted August 28, 2014 Report Share Posted August 28, 2014 It shouldn't be that difficult to do it yourself if you've a lathe and are good with the saw (or, better, have a belt one). Important is to make the thread before splitting the large part and also to create a conic bolt to insert. Link to comment Share on other sites More sharing options...
automatico Posted August 28, 2014 Report Share Posted August 28, 2014 On rolex style cases... If you need to mount the case from the back side you can usually mount it using a four jaw chuck inside the case. It will not damage the threads unless you really crank the jaws out or leave it too loose and allow the case to slip on the jaws...or it is a gold case. If you need to mount it from the front side you can usually get by with using the four jaw chuck over a crystal (no bezel) to keep from scratching the case neck. This will work as long as you do not apply excessive tool pressure to the case and force it out of the jaws. Be careful not to apply too much clamping force to the case neck. I have some stainless steel bezel blanks made out of 316 seamless tubing and can machine the id of one to press over the case neck with a crystal mounted if I need to...it takes a while to machine the id to fit so I usually skip it and just clamp the jaws over a crystal. I made one for late DJ cases but not for 5512/13/1680 yet. The main problem with a four jaw chuck is set up time. A three jaw 'self centering' chuck is Ok for mounting something that will be machined from start to finish and does not have to be exactly on center for the first cut. As for mandrels...you might make one out of aluminum with a flat surface to mount against the case front or back with a precision step machined on it that will fit inside the case with a post machined on it to allow mounting it in the lathe. Make a washer to go on the other side of the case with a hole bored through it for a bolt to screw into the mandrel with threads cut in it to clamp it all together. It may not be a super precision fit and you will have to use a four jaw chuck to mount the mandrel and case. Most of my hair brained projects take longer to make the cutting tool, holding tool etc than to do the job. Link to comment Share on other sites More sharing options...
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