Collet confusion.

Hi , I have been surfing sites like Chronos , RDG and RHR looking for some tooling and I noticed the number of different collets available ,
this is leading to some confusion on my behalf.
Just wondering why there are so many differnt collets , there are ER 32, ER35, ER40 etc and probably a heap more that I have not seen or heard off . What are differences and advantages one over the other.?
The ones I remember from my trade days were threaded and were drawn into the lathe spindle using a draw bar and hand wheel on the out board end of the spindle. (Hope I'm not telling my age here.)
I'm not looking to buy any , as I have a full set of what I think are Myford collets and a chuck that came with the Super 7 . There is one "ring in" in the set it has Hardinge stamped on it and is slightly different in the profile (concave)on the front face. I don't use them a lot ,but if you are machining lots of parts from small diameters they would make life easier.
Thanks .
--
Kevin (Bluey)
"I'm not young enough to know everything."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The great advantage of ER collets is that their double taper means they can close down by 1.0mm (0.5 for the very small sizes) and still maintain excellent grip and concentricity. Collets with a single taper will only work efficiently for material of the exact diameter of the collet; even normal mild steel (usually a few thou under nominal) can be a problem with single taper collets.
This means that a set of ER collets will grip anything within their range - you don't need a metric set and an imperial set, for instance. They will grip milling cutters effectively. The collets themselves do not need a drawbar as the double taper holds them in; it is the collet chuck itself that needs a drawbar, at least when holding milling cutters.
The different numbers are just sizes. ER25 (the set I use) goes from 1.0 to 16.0 mm; the larger sets have a correspondingly larger range.
David
--
David Littlewood

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

David , Thanks for clearing that up . I thought it was some evil conspiricy to extract more folding green from our pockets by having to buy a set of each because of some manufactured difference.
--
Kevin (Bluey)
"I'm not young enough to know everything."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Just to make sure there is no confusion, I should explain that the different sets are different in size. They are not interchangeable between sets. I think it would be unfair to say this is done to extract more money, just that there is a set appropriate for your equipment. Thus, for my lathe (S7) and milling machine (Emco FB2) the ER25 size is about right; the holders for the larger sets would be inconveniently large for the 2MT spindle. The "25" in ER25 refers, I think, to the widest part of the chuck taper, the actual collets are about 26mm at their widest point.
Don't let the profusion put you off, just find the right size for your machinery and buy a set, you will find them invaluable.
See, for example:
http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collets-Collet-Chucks
Not sure, reading my previous post, that this was clear.
David
--
David Littlewood

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David Littlewood wrote:

All clear and understood.
I had that link bookmarked , and will check it out again.
Not sure I'll buy a set just yet ,I still have the Myford collet set ,But these below would be able to fit my drill press and a future mill with the MT 2 chuck. I have some other tooling I want to get first
Found this set on the Bay ,price is good ,not sure on the quality , made in the Peoples Republic of C .
http://cgi.ebay.com.au/FULL-ER25-COLLET-SET-15-PCS-CNC-MILLING-LATHE-NEW-A05_W0QQitemZ110265889934QQihZ001QQcategoryZ25294QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262 and the MT 2 chuck , http://cgi.ebay.co.uk/ER25-MT2-3-8-COLLET-CHUCK-CNC-MILLING-LATHE-NEW-A68_W0QQitemZ110265134618QQihZ001QQcategoryZ12584QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262
On the collet page if you scroll down he has a handy chart with all the collet sizes etc.
Thanks again
--
Kevin (Bluey)
"I'm not young enough to know everything."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well the price is certainly attractive. Some of the cheaper sets have been reported to have slightly higher run-out (lack of concentricity) than they should, but for the holders at least it is possible to clean them up in the lathe you will be using it on (see correspondence here a few months ago). Not much you can do if the collets are out of true. Try looking at the seller's feedback to see if anyone has complained, or asking around.
David
--
David Littlewood

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Kevin(Bluey) wrote:

http://cgi.ebay.com.au/FULL-ER25-COLLET-SET-15-PCS-CNC-MILLING-LATHE-NEW-A05_W0QQitemZ110265889934QQihZ001QQcategoryZ25294QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

http://cgi.ebay.co.uk/ER25-MT2-3-8-COLLET-CHUCK-CNC-MILLING-LATHE-NEW-A68_W0QQitemZ110265134618QQihZ001QQcategoryZ12584QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262

Missed this post.
The cheap ones can be pretty good, I bought an ER25 set all of which have a TIR within a single 1/100 mm division on a normal dial gauge.
Which is pretty darn good.
YMMV,
-- Peter Fairbrother
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David Littlewood wrote:

AET stuff is nice, but for ER25 collets
http://cgi.ebay.co.uk/FULL-ER25-COLLET-SET-15-PCS-CNC-MILLING-LATHE-NEW-A05_W0QQitemZ120273119058QQcmdZViewItem?_trksid=p3286.m20.l1116
is pretty good quality, and a quarter the price - and at under 18 for the full set there's no VAT or customs fees to pay.
(satisfied customer only)
-- Peter Fairbrother
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David Littlewood wrote:

I'm not sure that it's the double taper so much as the fact that there are eight gripping segments, rather than three in a normal collet.
In a three-segement collet the inside of the segments is round, and if it is used to grip a tool which is slightly smaller than the hole then each segment will only touch the tool on a thin line.
With eight (or perhaps sixteen) segments an ER collet will grip on 8 or 16 lines, rather than 3.
Also, as there are 8/16 gaps, they can close up more than i=f there are three gaps.
-- Peter Fairbrother

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The eight slits help improve grip, of course, but I believe it is the double taper and the fact that the slits are alternately from front and back. This means that on closing down the collet grips the work or cutter at front and back (indeed probably all the way along) instead of just at the front. Some text books even show this diagrammatically.
David
--
David Littlewood

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
David Littlewood wrote:

Yes, it's most helpful having the contact surfaces go all along the length (rather than squeezing one end of the tool shaft at the point where it leaves the collet, and leaving the other end inside the collet wobbling about).
This happens because the inside of an ER collet remains parallel to the tool when compressed, because the main taper acts along all the length of the collet. Move the collet in a bit and both ends move in, rather than just one.
A collet with a single taper would do this too.
I'm not sure what the second, front taper on an ER collet does? Makes the front end grip hardest? angles the compressive force properly?
Anyone?
-- Peter Fairbrother
Some text books even show this diagrammatically.
You read the instructions?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

It may be that it allows easy changing of collets from the front without need for a drawbar (apart from the one on the collet chuck, of course). But I think the front taper, as you say, improves the grip at the front.

Well, more that I just noticed it somewhere. Actually, there is a little subtlety in loading an ER collet into the closing nut, so RTFM is not a bad idea in this case.
David
--
David Littlewood

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Peter Fairbrother wrote:

David , Thank you for your in informative explaination ,its has been most helpful. This news group is one of the best on usenet , and the people friendly and helpful.
--
Kevin (Bluey)
"I'm not young enough to know everything."
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
hello Kevin, just one thing to point out - although each closes down by up to 1mm - it a good idea at the outset to decide if you are 'imperial or metric' - it isn't true to say that a set will hold all cutting tools within the range of the set. If you look at the link below, you will see that the 14mm collet will close down to 13mm, but the next one down is a 12mm collet - so there isn't a collet to hold a 1/2" tool - ditto 1/4". So you might need to buy extra collets to fill in - or go one way or the other from the start! http://cgi.ebay.co.uk/ER32-Collet-Set-12-Piece-MT3-Metric_W0QQitemZ320199826872QQihZ011QQcategoryZ12584QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262
Hope that helps without adding to any confusion! rgds Hugh

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Hugh
Correct for the "part" set that you provided a link for but the normal "full" set for ER32 includes 18 collets and does cover the full range and the ER 25 full set includes 15 collets and does likewise.
http://www.chronos.ltd.uk/acatalog/Chronos_Catalogue_Sets_of_ER_Collets_131.html
Regards
Keith
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
from "Hugh"

http://cgi.ebay.co.uk/ER32-Collet-Set-12-Piece-MT3-Metric_W0QQitemZ320199826872QQihZ011QQcategoryZ12584QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262 > Hope that helps without adding to any confusion!
It will cause confusion in-as-much-as the information is incorrect (I'm sure many others on the group will also reply). ER collets are made to cover the complete range of potential capacity. In the case of ER32 that is 2mm to 20mm.
The eBay item cited is a set of 12 whereas the complete range would be a set of 21.
JG
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

http://cgi.ebay.co.uk/ER32-Collet-Set-12-Piece-MT3-Metric_W0QQitemZ320199826872QQihZ011QQcategoryZ12584QQtcZphotoQQcmdZViewItemQQ_trksidZp1742.m153.l1262
However http://tinyurl.com/6qjjws Shows enough to cover the whole range from 1 to 20mm
Henry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dragon Wrote:

Be careful of these direct from Hong Kong sales. Read the current feedback, some is in other languages but the trend is for customs to start checking these parcels.
When you get hit with a VAT and duty bill plus no redress on faulty goods it's a risk you have to take. Fine on a 2 laser pointer but on precision gear I'd like to see what I'm buying.
There is still some rubbish out there and it's bound to filter down to the lowest priced goods. At least with Warco, Chronos and Arc you do have some redress.
P Riedie.
--
P Riedie
------------------------------------------------------------------------
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks for the pointer though I was not about to purchase and used the link to demonstrate the full range.
I used the EBay negative feedback site to check the supplier I quoted. It seems folks are content with the collets but got caught by 'officialdom' which pushed up the cost. Also seems the supplier is not communicative.
Henry
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dragon wrote:

Keep the price below 18 and there is no VAT - actually it's the 8 (PO) or 10 (DHL) charge for collecting the VAT which gets you, not the VAT itself.
There are two or three HK sellers, they seem communicative enough though they don't reply to "it isn't here yet" comments until several weeks have passed. You have to be patient.
Not the world's best quality, but everything I have bought has been perfectly adequate - and the price is right.
-- Peter Fairbrother
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.