Easy way to cut a form tool, .210” O-Ring?

Janderso said:
Boy, I made a fool of myself.
I need a .210 diameter form tool and I need to plunge in .105"
Back to the drawing board :)
What's my line? If you aren't making mistakes you aren't learning......

Better >>>>> Except I need to grind more side relief, whew, chatter box. It could use some positive back rake too.
Click to expand...
To reduce the chatter you don’t have to use your form tool till your at or about full depth. Try using a cutoff tool or the one you previously ground. Get yourself close to dimension. Then take your form tool and clean up the groove. Ive had good luck with a smaller tool and freehanding the radius in the part till it’s to your liking.
 
Janderso said:
Boy, I made a fool of myself.
I need a .210 diameter form tool and I need to plunge in .105"
Back to the drawing board :)
What's my line? If you aren't making mistakes you aren't learning......

Better >>>>> Except I need to grind more side relief, whew, chatter box. It could use some positive back rake too.
Click to expand...
Can't figure out how you made a fool of yourself. Form tools do chatter especially if cutting on both sides. I try to go slow and apply stead pressure. The minute I think I am about to chatter I back off, or go a little deeper... I'm no expert. Sometimes I will just be a little smaller on something like you are doing so I can take a little more off each side one at a time. I also flood it with oil.
 
Cadillac said:
To reduce the chatter you don’t have to use your form tool till your at or about full depth. Try using a cutoff tool or the one you previously ground. Get yourself close to dimension. Then take your form tool and clean up the groove. Ive had good luck with a smaller tool and freehanding the radius in the part till it’s to your liking.
Click to expand...
I knew about this trick. I didn’t incorporate it until I reground the tool. It worked much better with most of the material pre-cut.
I’ ll get there in the end.
The motivation for this thread was to ask if there was a trick to it. It appears grinding the form tool is the way of it.
Thanks fellas
 
As for chatter, a form tool is like a cut-off tool - lots of lube is required - and it will still chatter some.
 
Don't use an "O" ring belt......they have too much drag. It is much easier to go with a serpentine belt, and it's much easier to make pulleys for. The belts are dirt cheap and have 25% less drag.
 
Jimsehr said:
Jeff
I just went out to shop and tried one of my crazy ideas.
About an hour ago. See time on my last post.
I turned a 1/4 dowel pin too .210 dia about 3/8 along pin dia.
Then I took a piece of scrap alum out of my junk pile.
Drilled a 1/4 hole thru and drilled and tapped thru side to grip dowel pin.
Ground end of dowel flat on belt sander.
Put a piece of stock in collet and used a height gage to check top of stock dia.
Took half of stock dia to find lathe center.
Set turned .210 so that top belt sanded edge was RIGHT on center of lathe.
There is NO clearance on turned down dowel pin.
People will say I’m nuts and it won’t work.
But if you look at video you will see two formed radius on the piece of steel.
Click to expand...
Jim, what video?
I’d love to see what you described
jeff
 
derf said:
Don't use an "O" ring belt......they have too much drag. It is much easier to go with a serpentine belt, and it's much easier to make pulleys for. The belts are dirt cheap and have 25% less drag.
Click to expand...
Shoot, I ordered a package of bulk oring.
I don’t know anything about the belts.
The reason I thought to use the oring material was because I’ve seen these fixtures using them??
 
I think the o-ring will be good for what you’re doing
 
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