Using stainless steel nuts for rings? how to tell?

[stioc]

If you wanted to use a CNC Mill, then you would just use a small ball end mill and mill the contours in 3D. No form tool needed.You will still need to work out workholding and have to flip it at some point in the operation but that is true for both CNC MIll or Manual Lathe. I like the idea of the formtool on the lathe.

Ok, that's what I figured i.e. I'd have to flip the ring over and do the contour one half at a time. Plus on such a small part I'm sure the contour will leave steps...though I could sand them even.

If I were making the "comfort style", I would tse the lathe to cut the ring from ther end of a piece of round stock. Bore the i.d. first and turn the maximum od.. I would use gravers to do the contour work first the i.d. and then the od. Clean up both surfaces with increaswingly finer grits of wet or dry followed by polishing with diamond paste. The final operation would be parting the ring and sanding and polishing th last edge. I have made a mandrel for polishing my ring using a pice of pvc pipe and some duct tape. The ring is slid over the duct tape and has a tight enough fit towithstand the sanding and polishing forces.

Thanks RJ! interesting, never even knew what a 'graver' was. However, going this route means learning and acquiring more stuff before I can do the actual work. I think I'm going to try the form tools first. I've been meaning to make small boring bars that take HSS inserts so this will be a good time to make that happen.

Great tip on the pvc/duct-tape mandrel, I was thinking of making an expanding one out of alum but pvc one sounds much easier/faster.

 

[Boswell]

Plus on such a small part I'm sure the contour will leave steps

Some surface finish would be required. With CNC you can control the resolution (step-over) of each pass at the trade off of process time. Once you get it fine enough, then sand, polish, tumble, buff, or some combination to get the surface finish that you would like

 

[stioc]

So I started making a small boring bar and insert. The boring bar is a 5/16" 12L14 and the insert is a broken #1 HSS center drill shaped using a diamond bit in a Dremel.

I think I'll face it off a bit more and use a shorter set screw so the bar doesn't stick out as much and I may even turn the diameter down at the top.

 

[stioc]

I posted it in the POTD thread but thought I'd close this thread with the results. I did do the outside contour but didn't do the inside because I goofed on the sizing and didn't leave room to cut the convex shape on the inside! doh! but nonetheless I'm pretty happy with the results. Thanks for everyone's help especially suggesting 303 stainless, while it was tough for the HSS contour bit (smoke and squealing) but my carbide insert tooling cut it pretty easily.

It's quite small, 2.5mm wide and 1.2mm thick which includes the convex contour on the outside.

 

[westerner]

The ring is slid over the duct tape and has a tight enough fit to withstand the sanding and polishing forces.

Well said! It is this appreciation for the forces at work that separate hacks like me, from the pro's like you.
Superglueing your part to a faceplate, and then actually getting something done.....
I gain further understanding every time I log on here.
Thanks to all of ya!

 

[pontiac428]

Stoic, be aware that some small percentage of the population has an autoimmune reaction to the nickel in stainless steel jewelry. It usually starts with a rash under the ring for those poor folks. Titanium is non-allergenic, which is why you see so much jewelry in that material. Nice work there, that's a rather small part to make!

 

[stioc]

Thanks for pointing that out, I didn't know about the reaction and I wouldn't have thought of it considering most medical equipment is made out of stainless steel. I'll let the owner know to watch out for any rash.