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View Full Version : 5C Step collets and step chucks, closers ?



nheng
06-22-2004, 04:48 PM
I have an assortment of 5C step collets and noticed that Royal offers them but Hardinge does not (they offer step chucks with closers).

Where do you draw the line on what a step collet can hold safely? Would the closing force roughly be the 5C closing force reduced by the ratio of the workpiece circumference to the actual 5C collet circumference(and more)?

Den

[This message has been edited by nheng (edited 06-22-2004).]

Spin Doctor
06-22-2004, 05:21 PM
A few of the smaller size Hardinge step chucks do have closing tapers to engage the normal 5C collet closing taper. Up to around 1-1/4" I think. The use of a Closer ring requires the use of either a 4d Hardinge Taper, the Hardinge thread size on the spindle for the H series chuckers or some of the closer rings made for A series CNC lahes. At one time when I was ordering a collet closer set-up from Royal for a machine at work I asked if was possible to get one with the 4d nose taper and was told flat out no. I believe the exact quote was "we are not in the business of promoting another companies product". But the last time I looked at Royals collet closers on the web it looked like they where now manufcturing them with the 4d nose taper ????. As for what's better. I'd say the Hardinge ones. Yes they require an extra piece of hardware but I have never seen a part come loose in a Hardinge step chuck. But then I haven't seen one come loose in a Royal either. I just don't like the idea of the collet body doing the work holding out spinning in the air with no back-up. I fact in the whole Hardinge 5C collet system and all the products that are offered in it I have yet to see anything that does not prform as avertised. And we've got normal, extended nose, super precision, extra deep step chucks to 5" in emergency and 3" in hardened and ground at work.

Just my slightly opinionated $.02

INTERPOLATE
06-22-2004, 06:16 PM
I was wondering this too.
So if I have a A2-5 spindle and want to purchase a 5C collet closer and use step collets, can I find/use step collets with closer rings?
I trying to imagine how springy a 5"-6" step collet held only by the taper would be. Can't be good.

[This message has been edited by INTERPOLATE (edited 06-22-2004).]

RobDee
06-22-2004, 07:19 PM
The rule on collets is .005 over and under from about an 1/8 up. Royal makes a pretty good collet and I've pushed them but accuracy suffers.
Hardindge Bros. always made a good product too but I've only used them on watch lathes. Are they still selling collets?
RobD

Spin Doctor
06-23-2004, 06:06 AM
Monday when I got back to work from vacation I had some Hardinge collets in recieving. 2.125, 2.375,2.625 and 2.875 to with our other hardened and ground collets. A lot of people will insist that a Hardinge is nothing more tham a glorified watch lathe but with proper tooling they will do work far beyond what most of us would assume. But in reality any thing over 3.00" is about the upper limit for anything serious.

DR
06-23-2004, 08:09 AM
I've got the Hardinge step chucks and closers, my biggest is the 6" size. Couldn't live without them.

Once I tried an import step collet on some thin 3" diameter steel blanks. This is a generic type with no closer ring. In the CNC I spun it up to around 2500rpm and and one of the collet segments bent out due to centrifugal forces and the blank went flying. Cracked the Lexan window of the machine. Last time for me without a closer ring.

INTERPOLATE
06-23-2004, 11:00 AM
So if one doesn't have a Hardinge then step chucks with closers are not available?

nheng
06-23-2004, 02:57 PM
From the Hardinge workholding catalog:

(re: closers) "taper or threaded nose for 5C models or A2-4, A2-5, A2-6, A2-8 spindle noses"

They do mention, under some deep emergency collets, a list of ONLY Hardinge machine that they will work on.

Hardinge says no step chucks without closers, period. Does this limit the Royal and other step collets to only very light and thin work?

Den

DR
06-23-2004, 08:29 PM
"Hardinge says no step chucks without closers, period. Does this limit the Royal and other step collets to only very light and thin work?"

From my Hardinge collet book....."Closer required for all step chuck applications"

But, they show collets up to 2"dia x 1/2" depth with the small closing angle. These can be used without the closing ring. The 2" extra depth don't have the small closing angle.

There's a slight contradiction there.

Also, until about 5+ years ago they put the small closing angle on over 2" step chucks. Must have been some liability issue involved here.

My collection of extra depth, 1-1/4" deep, step chucks all have the small closing angle because they're old.

In answer to your question, be careful using larger than 2" step chucks without a closer unless the rpm is very low.