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What are 'spring' collets?

For that matter, what are 'Finger' collets

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Ian P21/08/2019 21:10:55
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I have always wondered what people were referring to when they mention spring or finger varieties of collets.

I just Googled 'what are spring collets?' and the first definition from Google itself is this,

Spring collets are perishable tools for fixing a workpiece at the processing, or fixing cutting tools, and used as some parts of a machine or a conveyance machine. ... On the other hand, when we use spring collets, a workpiece is clamped as wrapping in with the number of flexing slot of the collet.

So now I know!

Not that I am any wiser

Ian P

Michael Gilligan21/08/2019 23:34:49
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Ian,

As I understand it; Spring collets are the ones that are:

  • only split from one end
  • usually pulled in by a draw-bar [but other arrangements are available]
  • only handle a specific diameter [or section] of material

Watchmaker's style ... but available in many sizes

ER collets, by contrast, are 'soggy' because they are split from both ends.

MichaelG.

.

Edit: Here is some bedtime reading

http://www.rotagriponline.com/datasheets/5C.pdf

Edited By Michael Gilligan on 21/08/2019 23:41:49

Michael Gilligan23/08/2019 09:27:34
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In case anyone is wondering [which it would appear they are not]: Adjectives such as 'spring' are included for clarification .... because 'collet' also has other meanings [e.g. in armoury, jewellery, and horological work] where it is merely a ring/band/collar, rather than an an adjustable device.

MichaelG.

Ian P23/08/2019 09:42:14
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The Rotagrip document that Michael gave a link to does contain some information about spring collets. I've not quite worked out what differentiates them from outwardly identical but non spring versions of the same collet.

Nowhere does it mention finger collets though so I'm no wiser on that score.

Ian P

Michael Gilligan23/08/2019 09:47:53
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Posted by Ian P on 23/08/2019 09:42:14:

...

Nowhere does it mention finger collets though so I'm no wiser on that score.

.

The splits in a 'spring collet' divide it into 'fingers'

MichaelG.

Andrew Johnston23/08/2019 09:52:28
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I would regard 5C collets as spring and finger collets, whereas ER collets are spring collets only. A spring collet relies on the springy properties of the body material unlike collets such as the Burnerd multisize series, which have a series of separate tapered wedges that slide within the body as the collet is closed. Or rubberflex collets which have a series of metal wedges connected by moulded rubber.

Andrew

Ian P23/08/2019 09:54:06
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Posted by Michael Gilligan on 23/08/2019 09:47:53:
Posted by Ian P on 23/08/2019 09:42:14:

...

Nowhere does it mention finger collets though so I'm no wiser on that score.

.

The splits in a 'spring collet' divide it into 'fingers'

MichaelG.

I always regarded the individual sections as 'Tines'.

ER collets do not really have Tines though (as the finger is attached at both ends)

Ian P

Michael Gilligan23/08/2019 09:58:03
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Posted by Ian P on 23/08/2019 09:54:06:

I always regarded the individual sections as 'Tines'.

ER collets do not really have Tines though (as the finger is attached at both ends)

.

  1. That must be because you're Posh
  2. Agreed

MichaelG.

.

P.S. the 5C 'emergency collets' are not very springy, because they are intended to be further machined to requirement, by the user.

Edited By Michael Gilligan on 23/08/2019 10:01:40

Michael Gilligan23/08/2019 11:41:24
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Posted by Andrew Johnston on 23/08/2019 09:52:28:

I would regard 5C collets as spring and finger collets, whereas ER collets are spring collets only. A spring collet relies on the springy properties of the body material unlike collets such as the Burnerd multisize series, which have a series of separate tapered wedges that slide within the body as the collet is closed. Or rubberflex collets which have a series of metal wedges connected by moulded rubber.

Andrew

.

An interesting distinction, Andrew yes

But I am left pondering ... Does the 'spring' necessarily have to be integral to the body material ?

  • Multisize incorporates wire springs
  • Rubbeflex incorporates rubber springs

Not arguing ... just wondering

MichaelG.

Tim Stevens24/08/2019 16:06:32
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Might finger collets refer to collets comprising sets of individual (matched) fingers - so that the collet could be used in cases where a more conventional collet would not go over an obstruction? In other words, take an ER collet for example, and grind away the connecting bars between the fingers (having first, I guess, marked each finger in number order?).

And in my view, an ER collet is a spring collet, just not a very strong spring.

But what do I know?

Cheers, Tim

Michael Gilligan24/08/2019 17:15:53
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Posted by Tim Stevens on 24/08/2019 16:06:32:

[ ... ] And in my view, an ER collet is a spring collet, just not a very strong spring.

.

Can't disagree, Tim

I simply offered an hypothesis, to get others thinking about Ian's question.

Perhaps Neil [who wrote the dictionary] will be along to provide a strict definition.

MichaelG.

Michael Gilligan24/08/2019 17:27:58
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For what it's worth: This article includes the term "finger collet" [and some pretty pictures]

**LINK**

https://gearsolutions.com/features/tooling-workholding-making-out-of-round-parts-round/

MichaelG.

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