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Collet closer draw force ratio?

turnworks

Cast Iron
Joined
Dec 12, 2018
Seemingly simple question but can't find the answer.

Trying to find the ratio on just the run of the mill manual ones. I swear I remember seeing something like 100:1 but that seems really high.

Any help would be great.
 
You could put a semi hard piece of rubber in a collet.Put a dial indicater on the face of the collet. When the clamping starts,see how far the colllet moves back.Now measure how far your hand travels ,when it moves the handle.. Hand movement divided by. collet movement is overall ratio.HOWEVER,NOT ALL CLOSERS ARE DESIGNED THE SAME. ALSO most of these are not a simple pivot . They have an over center action with a constantly changing ratio. Edwin Dirnbeck
 
Seemingly simple question but can't find the answer.

Trying to find the ratio on just the run of the mill manual ones. I swear I remember seeing something like 100:1 but that seems really high.

Any help would be great.

What Edwin said. "Gross motion" depends on the collet family and actuator design.

I'm partial to 100% nose-mounters. Skinny spindle-bore thing.

A Hardinge "loop" closer for 2J needs a Hell-for-stout anchor. It has more Iron in its idiot-stick than the final-drive axles on my 295 BHP Jaguar.

Over-center? Bet your ass it does!

Same again a(ny) rear-lever and drawtube. No other safe way to hold-in as a hand WHEEL and drawtube can have!

No need to make a problem out of a solution on a closer.

Just insure it has a decent range of adjustment and set it up so it comes good for the tasking to-hand.

Collets can vary. Even brand-new. So, too, the stock.

We JFDWT.
 
Its the cam that gets me taking measurements. It doesn't seem to be a linear ratio movement.

Not trying to reinvent stuff but got caught up in a spirited debate at work.

I believe a run of the mill standard rear mount 5c collect closer with draw bar could be used with a power 3 jaw chuck. Figure since a cnc lathe can use collets and power chucks with the same psi(air/oil) then a manual collect closer should be able to do the same.

Figured Id do the math to double check and got stuck on the ratio.

Thanks for the replies.
 
I believe a run of the mill standard rear mount 5c collect closer with draw bar could be used with a power 3 jaw chuck. Figure since a cnc lathe can use collets and power chucks with the same psi(air/oil) then a manual collect closer should be able to do the same.

Figured Id do the math to double check and got stuck on the ratio.

If you have one, try it. If you don't have, it doesn't matter. "Technically", power closer can take either approach. Toggle action over-center. Or not.

Most simply "sustain" a specific set force the whole while.

Personally... I'd want to it the other way' round. Use a power-closer for both, same as the CNC does.

Yah can dial-in whatever force yah need, each tasking.

And a human arm would not get as tired!

:D
 
Figured Id do the math to double check and got stuck on the ratio.

It's not simple math. Try a regular drawbar collet closer for a lathe, without the thrust bearing. The collet
can barely hold anything even with real armstrong effort.

Then try it with the thrust bearing back on - the difference is amazing. In both cases it's still 26 TPI on the parts. Same ratio,
vastly different behavior.
 
Jim you lost me there. You talking about friction difference?

5c collet blocks with the simple ring on the back and a spammer wrench can lock up some stock tight. I was trying to figure the force applied with the cam style closer. It’s dumb and stupid and more important things to do but was curious and keeps my mind working.

Maybe I’m not understanding how it works yet.
 








 
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