Nasty collets

[Jonathan Coates]

After I made myself a lathe nose taper adapter to Morse 3, I was surprised how much runout I was getting when using an ER32 collet adapter. Well I got to the bottom of that after finding that the finishing staff in the Chinese collet factory clearly don't exist. Here's a photo of some of the nastiness I found inside the 20mm size collet. After removing the offending curly bits the runout has almost disappeared. What's your best method for cleaning these up, as I found poking about with a steel rule was not very successful and not an appropriate use for precision equipment.

 

[pete]

I would have instantly returned those back to whoever I bought them from. They keep manufacturing and selling garbage like this because people keep buying it. But If I ever had to deal with something like those internal burrs, any steel scale and especially what I'm paying for mine sure wouldn't be the tool to use. That takes something that will cut to remove them and a blunt edged scale sure won't. It still depends on what you already have as far as recommending what to use. A Noga type de-burring tool might get most of it, that would depend on just how hard those burrs are. I suspect not very hard. I'd then use a thin fine stone angled at about 45 degrees along each slot just to double check there's nothing left. Properly manufactured, that collet should have been finish ground for size and the correct angles on both the ID & OD after it's heat treatment. Obviously that wasn't done or those burrs wouldn't be present. So are they even heat treated. In theory, each of the collet segments close and exert the most grip between those slots. I'd be careful and understand exactly what I was trying to accomplish before I started, but a Dremel and with one of there very small diameter fine stones gently stroked along each slot would also remove those burrs. Admittedly they were fairly expensive, but I can say for sure none of my European manufactured ER collet sets came with any issues like that.

 

[timo_gross]

I would have instantly returned those back to whoever I bought them from. They keep manufacturing and selling garbage like this because people keep buying it. But If I ever had to deal with something like those internal burrs, any steel scale and especially what I'm paying for mine sure wouldn't be the tool to use. That takes something that will cut to remove them and a blunt edged scale sure won't. It still depends on what you already have as far as recommending what to use. A Noga type de-burring tool might get most of it, that would depend on just how hard those burrs are. I suspect not very hard. I'd then use a thin fine stone angled at about 45 degrees along each slot just to double check there's nothing left. Properly manufactured, that collet should have been finish ground for size and the correct angles on both the ID & OD after it's heat treatment. Obviously that wasn't done or those burrs wouldn't be present. So are they even heat treated. In theory, each of the collet segments close and exert the most grip between those slots. I'd be careful and understand exactly what I was trying to accomplish before I started, but a Dremel and with one of there very small diameter fine stones gently stroked along each slot would also remove those burrs. Admittedly they were fairly expensive, but I can say for sure none of my European manufactured ER collet sets came with any issues like that.

Buying garbage is part of our hope to find a treasure . Worst case, I do not want to accept the loss and start "fixing" it.
Problem is that returning things is often more expensive (time, money and lost trust in mankind) than just accepting the loss.
I bought some collets that were 80USD (a piece) A full set really would have blasted a hole into the money bin.
For some strange reason bigger money bins are easier to fix than small ones and when full, the flow is restricted by the weight of the money on top, so the outflow is automatically stopped.

p.s. you can have run out on the collets or you can run out of money (whatever comes first)

 

[NORTONS SHOP]

Buy once, cry once.

 

[BaronJ]

After I made myself a lathe nose taper adapter to Morse 3, I was surprised how much runout I was getting when using an ER32 collet adapter. Well I got to the bottom of that after finding that the finishing staff in the Chinese collet factory clearly don't exist. Here's a photo of some of the nastiness I found inside the 20mm size collet. After removing the offending curly bits the runout has almost disappeared. What's your best method for cleaning these up, as I found poking about with a steel rule was not very successful and not an appropriate use for precision equipment.

Your not the only one to discover that these collets have not been cleaned up.
Basically they have not been tumbled as they should have.

I used a Stanley knife blade to clean mine and found that they were much much better afterwards.

 

[pete]

Collets are supposed to be properly hardened and then tempered back to a spring condition. That's due to how there designed to open and close while staying out of the metals permanent deformation range. There's a few warnings online about not trying to fully close any ER collet without the minimum diameter tool shank in it or possible damage or even segment breakage may happen. My ER's due to the absence of any internal tool marks are I suspect internally ground after heat treat, then the OD would be ground on a high precision mandrel so both the OD & ID are then as concentric as possible. At that point any remaining burrs within the slots may be mechanically or less likely hand de-burred given the numbers involved. CNC and a diamond or CBN wheel could easily do automated finishing of those slots.

My best guess is the highest precision ER collets are probably lapped after slightly undersized grinding for exact size, concentricity and roundness since there's quite a jump in price for those guaranteed highest precision collets. Tumbling might remove some of the outer edges of those burrs, but it wouldn't be capable of removing that hardened steel without affecting there other dimensions. If your removing those burrs with a Stanley knife blade, then there not that hard. I can't say for sure, but the cheaper one's may or may not be manufactured using a pre hardened steel such as 4140 PH which is only about 28-32 Rockwell C. Or for all I know some might be left soft. But those tool marks and burrs or lack of give some obvious clues about how there being made and finished.

The better collet manufacturer's don't seem willing to show there final finishing processes, which is probably understandable. But there are at least a few YT videos showing the basic shaping of the OD & ID and slotting before there hardened. Rego-FIX the inventors of the ER collet design have a very good YT channel with great information about ER collets, the different types that are available and how best to use them. For something as simple looking as they are, there's quite a bit more to these collets than some seem to think. And the minimum tool shank length each collet series requires is just one of those details because of how there designed to grip a tool shank at each end of the collet.

 

[BaronJ]

Hi Pete,

I 100% agree with you !
The Rego-fix collets that I only have a couple of, are obviously very much better made and finished than the cheap ones. Your right about the hardness, a Stanley knife blade will easily mark the metal of the collet. However since all the straggs of swarf are inside, the blade does a good job of removing them. A tiny stone, like those Dremal ones used by hand and carefully rubbed down the inside of the slot will clean off the tiny sharp bits left.

 

[Jonathan Coates]

I'll have a look at Rego-fix after work this evening and edjumacate myself I think. I'll probably try a file on my collets as they may not even be heat treated (or metal, for that matter considering the source).
I bought the cheap collet set as it was in budget (which is based on what I could spend on a hobby without excessive guilt, rather than anything else) as I didn't think I'd be needing the micron level tolerances of the "real" ones. If deburred they'll get me close enough for what I want most of the time and, after looking at some more of my set, the rest so far have been cleaned up already. It's a learning curve getting back into what they showed me in Technical College forty odd years ago as I now have more issues to contend with. The kit was all there. all new, there were racks of tooling and most of all I could see it.
Different issues arise as ones kit gets worn on the machines as well as the human body but at least it's all fun and entertaining and keeps the thinking going. Thanks for the input guys.

 

[Bazzer]

I'll have a look at Rego-fix after work this evening and edjumacate myself I think. I'll probably try a file on my collets as they may not even be heat treated (or metal, for that matter considering the source).
I bought the cheap collet set as it was in budget (which is based on what I could spend on a hobby without excessive guilt, rather than anything else) as I didn't think I'd be needing the micron level tolerances of the "real" ones. If deburred they'll get me close enough for what I want most of the time and, after looking at some more of my set, the rest so far have been cleaned up already. It's a learning curve getting back into what they showed me in Technical College forty odd years ago as I now have more issues to contend with. The kit was all there. all new, there were racks of tooling and most of all I could see it.
Different issues arise as ones kit gets worn on the machines as well as the human body but at least it's all fun and entertaining and keeps the thinking going. Thanks for the input guys.

Some of these bad collet sets are just not worth bothering with, some run out nearly as much as a three jaw chuck.

In England (where you are) there is a company in Oxford called DJ Workholding and they sell the Fahrion collets, you will not be disappointed in those and you don't need to buy a full set as they sell individually.

I have 3 Fahrion sets (2 x ER25 and 1 x ER11)

 

[Ken I]

I had a similar experience :-

Chinese ? Junk !

What bothered me was it was very well made junk - I suspect that the manufacturers failed to grind their mounting hardware every time it was mounted. (Batch-wise manufacturing with frequent tool changing).
Obviously this "wears" the tooling out and requires replacement, instead they simply allowed it to get further and further out of whack with use.
Everything was precisely ground and utterly useless.

I returned them and the next set was worse - I went to the suppliers premises with my own equipment to show them how bad it was - I even trolled through a whole bunch and everything was horrible.

Typically 100micron / 4 thou runnout - I can "eyeball" a 4-Jaw better than that - so no point whatsover in using it.

A case of the ship being ruined for want of a Ha'penth of tar.

I went to a different supplier - problem solved.

Regards, Ken I