For milling - How to get a level surface on a round object?

[ssdesigner]

I'm a visual guy so I need drawings

Excuse the quick and dirty mockup of my first setup for making this part. I have the slitting saw cutting just below the halfway on the ring.

Looking for feedback to make sure that I'm reading what is being advised.

 

[ssdesigner]

@Flyinfool - Are you saying that the hinge pin lines up with my first cut which splits the ring at the halfway point? Illustrated with the red lines here:

 

[Flyinfool]

Yes your mock-up drawing is correct.

Yes the red line is the true center line of the part. If you set the depth of cut so that the finished surface is right on the center line then that end will need no further cleanup. The hinge end must be cut high enough to machine the hinge parts. The top part that is cut off is the scrap part, it will be to small to make another part. The bottom that is in the vise is already set up perfectly level for the 3 holes and for the hinge machining.

The tricky part will be holding the part for drilling and/or reaming the hole for the hinge pin.

 

[ssdesigner]

Im probably overthinking this but, once i make my first cut on the right side along my dashed red line, i need to rotate the part to add the length of the male end of the hinge. If i setup everything in a v-block and lock it in the vise, i shouldnt have to move the x or y axis after cut one and before cut number two, correct? Am i thinking correctly? I should be able to just loosen the vise and spin the bracelet enough to add for the male hinge depth, yes?

 

[ssdesigner]

As for the hinge pin, yeah. That will be a challenge for sure. It’s a 1mm hole.

I think that the plan of attack will be to cut the notches for the hinge and before I round off the parts on the male end, I’ll press fit them together with a little loc-tite. Without rounded off edges the parts should fit really snug while I drill them out.

 

[Flyinfool]

Yes you are over thinking this a bit.
Make both cuts with the slitting saw in the same setup, just change the Z for the second cut. This way you do not loose your position and can go right to milling the slots and drilling the holes. You will have to round off the outside of the hinge side anyhow so the tiny fraction of a degree that it is off will never be noticed.

 

[ssdesigner]

Yes you are over thinking this a bit.
Make both cuts with the slitting saw in the same setup, just change the Z for the second cut. This way you do not loose your position and can go right to milling the slots and drilling the holes. You will have to round off the outside of the hinge side anyhow so the tiny fraction of a degree that it is off will never be noticed.

I don’t doubt that you are right, but I’m having a difficult time seeing how raising the z axis won’t give the surface that gets the hinge a weird angle. But I get what you’re saying. Since I’m rounding it anyway it’s negligible.

So the other question is, on the 2nd half ring that has the female notch for the hinge, I won’t be able to do it the same way on the second cut. There are no round offs on the female side of the hinge.

Thanks again for your time. I really appreciate it!!

 

[Flyinfool]

Unless you are making the notches extra deep both sides will need to be rounded off the same amount.

To move up that 1/8" or so for the hinge side, the angle difference will not be noticeable to the naked eye.

 

[ssdesigner]

Thanks again to everyone here that posted. I have a clear direction to move forward, and that includes a couple of hundred in new tooling It's a good thing because I need more excuses to get more efficient and comfortable on my mini mill. I feel like I can close my eyes and visualize most setup steps on my lathe for a project, but not so much with the mill. To learning!