Ware, How, And If To Start Milling Small SS Watch Parts

[mabmojo]

Hi guys, Looking for a little advice on a couple things. Basically as of right now i have a Harbor Frieght Micro mill stock. However it was used for one project and now is collecting dust.

I am looking for some advice on the How and if to start machinning parts similar to the following picture. The material will be 316 Stainless Steel.


I do want to make parts similar to the picture above. I do not require this to be a mass production or a fast machining process. My questions would be, what type of machine do you think I would need to be able to handle the stianless steel.

Also do you think that one machine would be able to complete the milling of a peice like this. ?

How many axis mill do you advise the mill be?

Also any other advice on my project.

[larry53]

It would be possible to do this machining on a manual mill if you have alot of experence and some add ons, like a rotary table. However you would be better off using a small cnc mill.

[mabmojo]

thanks larry, Yes i am definatly not that skilled on this manual mill. I was wondering if this would be a good idea to convert to cnc or start with a new setup for SS. I was under the impression that milling ss can be a bit of a bear.

[larry53]

Machining 316 will be tough. 303 or 416 is alot easier. you would have to get a answer from someone who has changed a manual mill to a cnc. But I think that is the way to go on what you want to try.

[mabmojo]

Hrmm. I guess i will have to get more familiar with steel grades. I assumed 316 was softer than 416.

Regarding the axis, how many do you think I should need.

[larry53]

go for what you can afford. A 3 axis mill with the option for the fourth would be what you would need.

[miljnor]

I started business machining almost 95% 316 and 316L and I thought it was easier to machine than 304 and is definitely easer to machine than 416.

I think its all in what your used to.

Those type of watch parts are usually done with allot of cool fixturing in a lathe then milling the odd features. And allot of polishing after completed.

If you don't like polishing you should maybe find someone who does. Its a dirty business (polishing).

[mabmojo]

Yes, I dont mind the polishing, Ha spent about 3 hours behind a buffing wheel today.

Regarding the the fixturing int a lathe. Could you elaborate, Sorry Im a newb =)

[miljnor]

The circular interior of the watch looks almost polished, And from experience and a cost perspective it is a waste of time and effort to polish a part on the inside for shear looks as its cost prohibitive (there are reasons to do this but not looks). So to get a ripple free (from cut chatter) you have to turn it or use a boring set up (manual operation instead of CNC.

To fixture it is rather complicated but if you were doing the first operation in a lathe then the part is most likely square and can be chucked up in a 4 jaw chuck and machined. I would actually lean to doing the lathe op's last do to the shape of the part, the fixtures would then be based off of the ears (band holding) part of the watch.

Fixtures are an art form, some, though crude, perform elegantly and others, while pieces of art, are temperamental and inconsistent. It takes a certain kind of craziness to make complex fixtures as you never know if the will work as built.

But since you don't have a lathe and are probably very low production (or probably one off) then do everything in the mill as you can always polish the heck out of it to make it purrty!

[larry53]

I do not understand about 416 being hard to machine. I provide a company with parts all made from 416. It machines like butter. It is known as a free machining stainless because of its sulfer content. 316 and 316L has low carbon content, steel used for welding purposes but has alot of molbdenum in it and for me is harder to machine.

[mabmojo]

@miljnor: Yes your right in the photo that piece is probably done with a lathe. Mine does not have to be that pretty on the inside =).

@larry: Yes I was reading up on steel grades last night. Seems like somthing you really need to work with every day to ge a real handle on. Yes i read that to that 416 was great for machining. The only thing that worried me is that it said it was completely unuseable for marine applications.

Now My idea is to make a dive watch or at least parts for dive watches. Do you see any problem with 416 for this application.

Cheers Thansk guys for all your help.

Mikey B

[miljnor]

well your probably right on the 416 as I have machined that alloy maybe once and it was years ago.

I tend to lump the alloys that piss me off into a group, full well knowing that certain ones in that group are alloyed to machine/weld/not rust (whatever their purpose may be) and I machine 410 and 420 SS all the time (but not enough to really get a good handle on tool life) and its a BIG UGLY BULL DIKE to machine (I apologize to any BUBD's that are out there in advance )

So if its not similar to the other 400's then forgive my ignorance!

400 series stainless needs to be heat treated to 40Rc (somewhere about there) to be corrosion resistant and will still be nowhere near 300 series when it comes to corrosive abuse. And salt water is very harsh so thats why it isn't good to use.

316 is the stuff that is typically used in pumps for Salt water so that probably your betty!