Probably not a recommended machining practice

[DPittman]

I had to take off about another 40 thousands of inch on the thickness of these little half moon shape spacers. I had done some hand filing but was getting crooked on them (and tired) and they needed to be fairly accurate.

I couldn't figure out any other way to hold them to skim off some material with the mill. View attachment 11826View attachment 11826There was an existing 3/16 hole in the pieces already and I used loctite to hold a small piece of rod in the hole which I could then clamp onto with the vise.

Pictures will explain what I did better.

I knew it was risky but didn't figure I would ruin anything other than the part if it didn't work. It worked like a charm. I took only maximum 10 thou cut at a time cuz I was scared to bugger it all up. I think the reason it worked is because pretty much all the pressure was down ward across the face of the piece evenly.
The part is for a moving cocking mechanism on an air rifle.

 

[RobinHood]

Good solution to your problem. You basically ended up with your vise jaws acting as a V-block to support the half cylinder. The rod was the fixturing device.

Another way items like that can be made is with “machining allowance stock”. In this case using square stock and turning the cylinder while leaving the ends square. You can split the whole thing and still be left with the square ends to hold in your vise for second op machining.

Once you have the required dimensions for your cylinder halves, just cut off the ends. The cylinder halves can easily be held in the vise for end machining.

 

[DPittman]

Good solution to your problem. You basically ended up with your vise jaws acting as a V-block to support the half cylinder. The rod was the fixturing device.

Another way items like that can be made is with “machining allowance stock”. In this case using square stock and turning the cylinder while leaving the ends square. You can split the whole thing and still be left with the square ends to hold in your vise for second op machining.

View attachment 11829

Once you have the required dimensions for your cylinder halves, just cut off the ends. The cylinder halves can easily be held in the vise for end machining.

Oh thank you for that suggestion, I would have never thought of that. I better write that down cuz I'm forgetting more these days than I should be and I end up doing alot more unnecessary machining and mistakes than I need to be because of it.

 

[RobinHood]

You are welcome.

This principle works very well also for machining odd shapes that need to be held in various positions and set-ups; and long, flat tapers (ie making a new gib).