ER16 Collets from Ebay

[SillyOldDufferModerator @sillyoldduffer]

Posted by B Tulley on 22/04/2022 20:46:05:

Posted by JasonB on 22/04/2022 18:51:40:

Well I suppose you get what you pay for and if you are happy with that and it's for holding drills then all well and good.

I'd be looking for more like 0.0005" half a thou which can be had for not a lot of money.

Ah, you have a point – I was getting confused between mm and inches….

So my 0.005" (worst collet measured) equates to 0.127mm; Arceurotrade sell 0.015mm (0.0006" collets in a set (12 collets – I got 10) for double what I paid. Was any of the runout measured due to the way I was doing it – almost certainly, because I had a collet holder (ER16) held by another collet holder (ER32) so twice the opportunity for runout to be introduced. Not sure how else I can check the collets though?

Absolutely right to question how the measurements were made, because it's difficult. All bets are off in my opinion because the arrangement involves a stack of collet holders, a drill shank of unknown accuracy, and a Dial Indicator.

• The stack accumulates all the errors from spindle to the drill shank; it's not measuring the run-out of the final collet.
• Drill shanks may not be particularly straight or circular.
• How smooth is your Dial Indicator's mechanism? I have two Indicators, almost identical, but one of them has a slightly sticky mechanism. It tends to move the needle in a series of misleading jerks.
• How firmly is the Dial Indicator foot held to the drill shank and is it square? Likewise is the stand as solid as possible, avoiding having the Indicator at the end of a spindly set-up?

The 0.005" error could be explained by the bullet points above. The only thing that can be said with confidence is that the collet run-out is less than 0.005", perhaps a lot less.

I prefer not to confuse myself attempting precision measurements. Metrology is fascinating but hard to get right. Too easy to get wrapped round the axle in a self generated fog of confusion. (Don't ask how I know!) Instead I find it simpler to use the tool to cut metal and diagnose faults only if they matter. I don't worry unless the set-up as a whole fails to do the job. In the event of trouble in the Tulley workshop, too-cheap collets are an obvious suspect, but not as much as a collet chuck held in another collet chuck.

Consider the faulty set-up shown below:

Run-out measured at the chuck-jaws would be much lower than run-out measured at the far end. However, not only does the long rod amplify the true run-out, it adds more due to the rod bending under its own weight, and it will whip around when spun. The risk of whipping in this arrangement is a serious safety issue: bad enough to fly out of the chuck damaging the lathe and spifflicating the operator.

Dave

[Nick WheelerParticipant @nickwheeler]

Posted by Peter Greene 🇨🇦 on 24/04/2022 01:54:45:

Also, lets not forget that these collets were designed for industrial use not for model engineers. If the requirements for their use are onerous in this latter context, it's up to the ME to adapt.

How many MEs are using their collets in 10hp machines turning £200 tools at 15,000rpm to machine multi-thousand £ castings with the lights out?

How many of us have actually measured the runout of our collets to a reliable standard unless the parts they make aren't up to our relatively basic requirements?

After all, it's not that long ago that most MEs did all of their milling in a vertical slide using basic tool holders(and measuring equipment!) yet they produced useful parts.

[HopperParticipant @hopper]

Posted by Nicholas Wheeler 1 on 24/04/2022 11:04:47:

After all, it's not that long ago that most MEs did all of their milling in a vertical slide using basic tool holders(and measuring equipment!) yet they produced useful parts.

Not long at all. Less than a week ago for some of us. And holding the milling cutter in a 65-year-old three-jaw chuck.

[Nick WheelerParticipant @nickwheeler]

Posted by Hopper on 24/04/2022 11:10:04:

Posted by Nicholas Wheeler 1 on 24/04/2022 11:04:47:

After all, it's not that long ago that most MEs did all of their milling in a vertical slide using basic tool holders(and measuring equipment!) yet they produced useful parts.

Not long at all. Less than a week ago for some of us. And holding the milling cutter in a 65-year-old three-jaw chuck.

You know admitting that will make the Guardians of Myford(formerly the Model Inquisition) come and poke you with long travel DTIs until you repent your sins against Model Engineering?

[HopperParticipant @hopper]

Oh No! Not … The Model Inquisition.

[JasonBModerator @jasonb]

Posted by SillyOldDuffer on 24/04/2022 10:47:18:

The 0.005" error could be explained by the bullet points above. The only thing that can be said with confidence is that the collet run-out is less than 0.005", perhaps a lot less.

Run-out measured at the chuck-jaws would be much lower than run-out

Maybe not Dave. If the mill, ER32 and ER16 setup had 15thou runout and the collet a 10thou runout and was only tried in one position you could get a reading of 0.005".

A quick way to get an idea of the collets runout would be to measure the runout inside the ER16 holders taper and without removing it from the machine put in a collet and see what reading you get. If the combination of errors makes the ER16 holder run out by 4thou then there may only be 1 thou runout of the collet.

[Chris TriceParticipant @christrice43267]

Surely this all depends on the nominal size of the collet and the size of the tool being held. I can't see a 10mm tool held in a 10mm collet in a clean chuck needing a lot of torque to hold the tool concentrically? You'll need more torque the further the tool held goes away from the nominal size of the collet due to the amount of distortion that needs to occur.

[JasonBModerator @jasonb]

The quoted torque figures are generally for tool holding where you are likely to be using the collet at it's largest size eg a 10mm cutter in a 10-9mm collet.

The closing force to get the collet to close down less than max dia is quiet small compared to the tightening force.

[SillyOldDufferModerator @sillyoldduffer]

Posted by JasonB on 24/04/2022 16:52:31:

The quoted torque figures are generally for tool holding …

Maybe the tightening torque could effect run-out because the collet is a multi-fingered spring. I suppose a tool in a loose collet might be slightly skewed until all the fingers grip, but I'd expect the effect to be small.

I've always assumed the high-tightening torque is required because of the amount of power industrial machines can put on the tool. Hobby machines aren't in the same league as grown-up machines; it's not unusual for a medium sized Machine-Centre to have 15kW available at the spindle. The amount of force 15kW can put on a collet held tool-shank is enormous and bad things happen if the tool slips. Apart from spoiling the work, the tool will spin and ruin the collet. Even in normal operation, cutters and collets have a short life on busy production machines. In a production setting, ER collets are disposable and chucks are replaced regularly too.

I'm happy if my cutters don't slip in ER collets and the resulting cut is accurate within the limits of my workshop. Cutters only slip in my ER32 chucks when I forget to tighten the ball-bearing collar with a short spanner: seems my 1100W mill isn't powerful enough to overcome that level of friction, and I rarely push the motor to the limit.

Dave

[michael mParticipant @michaelm]

Needing some ER collets and not too happy about taking a chance quality wise I followed Old Mart's advice and went with APT. As he said they sell different run-out tolerance grades.

I'm totally pleased with them.They're all within the quoted spec. and were delivered very quickly. Their website gives a warning, of which I was unaware, that the very highest precision grade should be used with stock close to the collet's nominal size to ensure minimum run out.

The prices I thought quite reasonable.

Michael

[Neil LickfoldParticipant @neillickfold44316]

I just received these today. The short collets are from the oversized range . I got an ER20 Ø16, ER20 Ø12.7mm(1/2inch), ER20 Ø6.35mm(1/4inch), ER32 Ø24mm, ER32 Ø25mm.

They have the oversized collets in all from ER11 to ER40.

For me the over sized collets allow an overlap of the holders, so instead of using an ER32, I can still use the ER20, especially if I am using any of the Ø16 adaptors I made for the small ER11 collet chuck. The oversized ER32-24mm collet saves having to change out to the ER40 collet chuck. The two that I checked are very good, better than the bearing run out in my mill drill.

Cheers, Neil

[Nick WheelerParticipant @nickwheeler]

Thank you for that.

Oversize ER32 collets are now on my need to get list

[David Taylor 4Participant @davidtaylor4]

re ER 16 collets: – I bought a collet chuck and 8 collets for about CND $40. 00 from Ebay. The chuck is good and most of the collets. BUT the 0.125" size has a ,006" total run out. Checking it seems to indicate the bore is not concentric with the O/D.

I am not complaining because a pucka replacement 0.125" collet, (.0003" run out,) cost CND $25.00 plus $40.00 freight. The Chuck alone is good value despite the poor collet.

Has anybody tried correcting the errors and if so how?

[not done it yetParticipant @notdoneityet]

If it is one collet that is faulty, just get another. I cannot understand how one Er16 collet can cost $65 even if they are Ca $!

[Michael GilliganParticipant @michaelgilligan61133]

Posted by not done it yet on 09/05/2022 06:33:51:

If it is one collet that is faulty, just get another. I cannot understand how one Er16 collet can cost $65 even if they are Ca $!

.

The $40 cost of freight seems a good explanation.

… It makes what you get for the other $25 look pretty fair.

MichaelG.

[David Taylor 4Participant @davidtaylor4]

The cost of freight is now close to or more than the small articles I buy on line. Many suppliers don't give options on carriers and a flat rate is charged but no indication of max weight for the money. Progress?

[Bill PhinnParticipant @billphinn90025]

Posted by michael m on 26/04/2022 17:13:17:

Needing some ER collets and not too happy about taking a chance quality wise I followed Old Mart's advice and went with APT. As he said they sell different run-out tolerance grades.

I'm totally pleased with them.They're all within the quoted spec.

I'm afraid my experience of APT collets is less positive.

My current ER20 collet chuck isn't an APT offering but a fourth-time-lucky chuck bought elsewhere. There is, happily, negligible runout with it when using most of the very cheap ER20 collets that I originally bought with my first, very untrue, ER20 collet chuck (off eBay) and subsequently returned. I still have these original collets.

Recently, thinking I could improve on the runout on the most often used sizes (6, 10, 12mm) I bought "superprecision" collets in these sizes from APT.

The runout on these is unfailingly between one-and-a-half to three times as bad as on the bargain-bucket collets that came with my first ER20 chuck. No amount of rechucking makes any appreciable difference to the initially observed discrepancy.

 

Edited By Bill Phinn on 09/05/2022 17:39:22

[Tony Pratt 1Participant @tonypratt1]

So Bill what did you do with these out of spec collets from APT?

Tony

[JasonBModerator @jasonb]

I did not see mention that they were out of spec, just not as good as the Cheapies. Bill may have got lucky and had some very good cheapies.

[Neil LickfoldParticipant @neillickfold44316]

Posted by David Taylor 4 on 08/05/2022 18:58:45:

re ER 16 collets: – I bought a collet chuck and 8 collets for about CND $40. 00 from Ebay. The chuck is good and most of the collets. BUT the 0.125" size has a ,006" total run out. Checking it seems to indicate the bore is not concentric with the O/D.

I am not complaining because a pucka replacement 0.125" collet, (.0003" run out,) cost CND $25.00 plus $40.00 freight. The Chuck alone is good value despite the poor collet.

Has anybody tried correcting the errors and if so how?

 

I have , by making a mandrel that is the upper size of the collet range. With a centre support and then super glue the collet in place. Re grind the outside 8 deg per side and then regrind the 30 deg per side for the front taper. Really a lot more time than it is worth. For a little extra time, a new one could be made. When they are less than 3mm diameter for ER16, it just becomes too flexible to easily get it right. On a 6mm or a 1/4 inch one the mandrel really is very substantial by comparison. I was not going to waste a piece of turnable tungsten to save a collet. Quite often the bore the and the main 8 deg taper are ok, and it's the front 30 deg taper that is out of whack. On a larger ER40 collet, I super glued the collet into the holder, and then very lightly put the front nut on. I just turned it out with light cuts and a sharp positive rake boring bar. Made a specific sized collet for a job.

Edited By Neil Lickfold on 09/05/2022 20:49:03

[David Taylor 4Participant @davidtaylor4]

Thanks for the reply Neil. I shall not go down that route.

I have wondered how they are made.I suspect a powered metal blank including the slots, then heat treated and then ground. To do the machining I think they lock the collet slots using a plastic compound because I have found traces of such in some collets.

[Bill PhinnParticipant @billphinn90025]

Posted by Tony Pratt 1 on 09/05/2022 19:50:33:

So Bill what did you do with these out of spec collets from APT?

Tony

I unwrapped them for the first time three months after buying them, and after repeated testing just put them back in the drawer they're kept in.

I didn't say they're out of spec – I have no way of testing that infallibly – I just found them to be worse, on my chuck with my set-up, than the eBay ones.

If you want to PM me your contact details I'll send you one of them and you can test it for yourself.

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