Accuracy of cheap ER collets

[Neil WyattModerator @neilwyatt]

I have a full metric set of ER25ss plus a few imperial ones for regularly used sizes like 1/4".

Neil

[AjohnwParticipant @ajohnw51620]

Posted by Arnljot Seem on 01/09/2016 10:20:14:

Posted by JasonB on 01/09/2016 09:58:09:

Out of interest have you tried a 12mm tool in the Regofix collet?

Yes, as stated in the OP, a 12 mm tool fits perfectly in the Regofix 12mm. Same holder and nut.

The fact that this is well used might have something to do with it. As Ajohnw says: "I suspect your problem is precise collets and the fact that they are ER32 – a lot more metal to bend ". Just like new shoes, they hurt in the beginning, but as you wear them in, they fit much better

 

Arnljot

I very nearly ordered a full set of ER40 collets and then thought hang on. Grip length seems to go up with size due to the design – not good. Compressing to small sizes may not be easy and to be honest a 10mm cutter doesn't slide into one of my ER16's that easily. Slightest pressure collet taper against chuck taper and it wont go in.

My reason for wanting ER40 was for lathe work but I now have a collet chuck, Jacobs, a cheaper option. I'm not inclined to think that it's worth going to ER32 for milling just for 20mm rather than 16. ER40 would take things up to 26mm but past 16 I feel a couple of sizes of shanked face mills would be a better idea. Maybe a shanked cutter.

I did have ER40 fever for a while though and some regrets not buying ER32 but now I feel ER25 is a better option and use ER16 for small stuff.

John

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Edited By Ajohnw on 01/09/2016 12:44:33

[Arnljot SeemParticipant @arnljotseem72268]

I very nearly ordered a full set of ER40 collets and then thought hang on. Grip length seems to go up with size due to the design – not good. Compressing to small sizes may not be easy and to be honest a 10mm cutter doesn't slide into one of my ER16's that easily. Slightest pressure collet taper against chuck taper and it wont go in.

My reason for wanting ER40 was for lathe work but I now have a collet chuck, Jacobs, a cheaper option. I'm not inclined to think that it's worth going to ER32 for milling just for 20mm rather than 16. ER40 would take things up to 26mm but past 16 I feel a couple of sizes of shanked face mills would be a better idea. Maybe a shanked cutter.

I did have ER40 fever for a while though and some regrets not buying ER32 but now I feel ER25 is a better option and use ER16 for small stuff.

John

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Edited By Ajohnw on 01/09/2016 12:44:33

Interesting points. I got ER32 for the 20mm span since I needed 20mm end mills. Maybe these are better held in a Weldon holder. I was also looking at OZ collets, they seem to be very popular in Switzerland.

Since I'm just starting out, it was hard to make the correct selection at first go, and this was also part of the reasoning behind buying a less expensive collet set. I just didn't know what would be the best choice for my needs. I also have a tool holder for ER16 collets, I might get some ER16 collets later

[AjohnwParticipant @ajohnw51620]

For a large size I am intending to use something like these

**LINK**

Along with a face mill for 1604 sized inserts. The face mill sizes set the size of the inserts and to save having to buy more than one type so the end mill needs to be 25mm. 10 inserts are about £40 so each end mill works out at £8. Can't sharpen them though.

I'll either modify a morse blank end arbour to hold it or machine the cutter to a size I can cope with. ArcEuro stock some morse shell mill arbors. I just got round to ordering that and a 50mm face mill. The end mill can wait until I need it. I'm hoping Arc's arbors are good. Never know might see some cheap hss shell mills, doubt it though.

John

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[Steve PaveyParticipant @stevepavey65865]

Posted by Bikepete on 01/09/2016 09:56:32:

Arnljot, I would just like to say I really enjoyed your videos about the Schaublin 22 on Youtube – I've just taken on a Schaublin 53N with some electrical damage and it was very interesting to see your work!

**LINK**

Me too, just watched all three of your videos – first class electrical work in rewiring the cabinet.

[mechman48Participant @mechman48]

Posted by Neil Wyatt on 01/09/2016 11:15:09:

I have a full metric set of ER25ss plus a few imperial ones for regularly used sizes like 1/4".

Neil

Ditto… my imperial ones go from 1/8" – 1/4"

George.

[Arnljot SeemParticipant @arnljotseem72268]

Thanks for the great response to my question. This really is a helpful community.

I just wanted to share a picture of the direct-collets for the ISO30 taper that came with the mill. The great advantage with these is the ease of use, rigidity, and extra headroom. Sometimes however, it is an advantage with some distance between the spindle and the work piece, so that is when the ER holder comes in handy.

These direct collets go on ebay for close to €50 a piece, so rather expensive. Fortunately, I have 6,10, 12 and 16mm, so I really only need an 8 and a 20 to cover my immediate needs.

 

Thanks for all the help. I'll let you know how things work with the new collet holder next week.

 

Edited By Arnljot Seem on 01/09/2016 20:30:45

[Neil LickfoldParticipant @neillickfold44316]

There was a chinese made sets of ER32 collets about 2-3 years ago and they were just terribly made. The front 30 deg taper was not concentric to the 8 deg taper. The other issue was the groove was cut too shallow for the collet retract. It may be possible that you got one of these collets or one with similar problems.

I have learnt that cheap is just wasting time and money if you are expecting any level of precision.

Neil

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Arnljot Seem on 01/09/2016 20:29:51:

I just wanted to share a picture of the direct-collets for the ISO30 taper that came with the mill.

.

Thanks … I like the look of those.

[too big for my machines, but a very logical solution]

MichaelG.

[Ian PParticipant @ianp]

Posted by Arnljot Seem on 01/09/2016 20:29:51:

Thanks for the great response to my question. This really is a helpful community.

I just wanted to share a picture of the direct-collets for the ISO30 taper that came with the mill. The great advantage with these is the ease of use, rigidity, and extra headroom. Sometimes however, it is an advantage with some distance between the spindle and the work piece, so that is when the ER holder comes in handy.

These direct collets go on ebay for close to €50 a piece, so rather expensive. Fortunately, I have 6,10, 12 and 16mm, so I really only need an 8 and a 20 to cover my immediate needs.

Thanks for all the help. I'll let you know how things work with the new collet holder next week.

Edited By Arnljot Seem on 01/09/2016 20:30:45

I have not seen that type of collet before but I can see its eminently suitable it is for toolholding close to the spindle bearings etc.

I'm curious though about the design reasoning why it has only three slits. I thought two cuts across the diameter would be simpler/cheaper from the manufacturing point of view, but would it grip any better with four tines?

Because there is so much metal in each tine the slit has to be extended to the thinner part of the collet so it has a chance of flexing. As the curved bore of each tine is not going to flex or conform in any meaningful way to the cutter shank, the cutter diameter has to be spot on. Cutter shanks are usually very accurate so its not a problem but it seems to me that one sawcut and two tines would work just as well.

I have no real reason for asking this question other than idle curiosity.

Ian P (Love the Schaublin mill!)

[Roger HeadParticipant @rogerhead16992]

Posted by Ian Phillips on 02/09/2016 21:00:13:

Posted by Arnljot Seem on 01/09/2016 20:29:51:

 

I'm curious though about the design reasoning why it has only three slits. I thought two cuts across the diameter would be simpler/cheaper from the manufacturing point of view, but would it grip any better with four tines?

Because there is so much metal in each tine the slit has to be extended to the thinner part of the collet so it has a chance of flexing. As the curved bore of each tine is not going to flex or conform in any meaningful way to the cutter shank, the cutter diameter has to be spot on. Cutter shanks are usually very accurate so its not a problem but it seems to me that one sawcut and two tines would work just as well.

I have no real reason for asking this question other than idle curiosity.

Ian P (Love the Schaublin mill!)

 

I'm sure someone will write a full-page response to this, but the answer(s) are simple.

1. A simple diametrical slit will only provide a two-point grip of the cutter, hence no positive location of the cutter axis. (An infinite number of circles can pass through two points, only one can pass through three.)

2. This type of collet is only intended to grip one specific diameter cutter. Trying to hold something that is even just a few thou larger or smaller is exceeding the design parameters. As you will have observed, the design of wide-range collets (e.g. ER-series) is dramatically different.

{edit} Just re-read your post Ian, sorry, point (2) isn't relevant to your question. However, point (1) is, especially when chasing accuracies at the tenth-of-a-thou level.

Roger

Edited By Roger Head on 03/09/2016 02:08:05

[AjohnwParticipant @ajohnw51620]

It's interesting to compare the cost with R8's and ask just what do these offer over them.

ISO30 really is a chuck taper. A rather small one. If I had a machine that used them I would be switching to an ISO30 chuck.

Up early – my wife likes doing car boots all though she tells me this one is a table top.

John

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[JasonBModerator @jasonb]

Posted by Ajohnw on 03/09/2016 07:48:49:

It's interesting to compare the cost with R8's and ask just what do these offer over them.

They fit machines with int 30 spindles

Appart from that they offer all the afvantages of any other finger collet

– more likely to be concentric as there are less surfaces between spindle taper and tool

– Less protrusion so more rigid and allows larger work/longer tooling to fit in the space available.

Ian I was surprised you were curious about 3 slots when all other finget type collets like R8 and MT have 3 slots as well as 5C etc, I would have been more curious if they differed from the norm and only had two slots

[John HaineParticipant @johnhaine32865]

Ian said 2 cuts across the diameter, which will make 4 tines.  (Oops, no, just re-read, sorry)

I have made an Int30 taper on my CNC'd Super 7 to fit my Novamill (though not made into a collet). If you have access to a CNC lathe I'd be happy to supply the Gcode. I must say I'd like some of those direct collets so may have a go at making some!  I'd make 2 saw cuts at 90 degrees to get 4 fingers.

Edited By John Haine on 03/09/2016 08:49:28

[Michael GilliganParticipant @michaelgilligan61133]

Posted by John Haine on 03/09/2016 08:43:58:

… I'd make 2 saw cuts at 90 degrees to get 4 fingers.

.

John,

May I suggest that you read-up on 'Kinematics' before making your final decision.

There is always a tendency for things to settle at three-point contact; so it's often better to just accept the fact, and design your device accordingly.

MichaelG.

[AjohnwParticipant @ajohnw51620]

I was thinking about the need Jason compared with other options. Seems that the cost aspect can be circumvented

**LINK**

but I would be tempted to buy a very high quality chuck instead rather than paying £50 a piece of them.

John

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[JasonBModerator @jasonb]

I think most of us would use a chuck of some sort but they are nice to have in the cupboard for that odd occasion wher you need all the Z height you can get, thats why I have a few sizes of MT ones for my mill but teh ER32 gets used 99% of the time..

[Nick HulmeParticipant @nickhulme30114]

Posted by colin hawes on 01/09/2016 10:20:34:

I would only expect precision if the collet is a slide fit on the cutter shank; too much ( ie more than 1/2 mm) looseness is likely to reduce parallel gripping accuracy. Although ER collets have a greater gripping range than this it is not wise to make full use of this if it can be avoided. I have many cheap ER collets from ArcEuro and have found the accuracy to always be good Colin

ER11 are 1/2mm intervals as 1mm intervals would push flex beyond elastic limits in small collets.

I don't have issues with ER40 collets close to lower size limit,

– Nick

[Arnljot SeemParticipant @arnljotseem72268]

I measured the diameter of the top surface, where the end-mill is inserted, and compared the Regofix to the Chinese collets. The surface of the cheap collet was a full 0.5mm larger in diameter than on the Regofix collet. This means that he taper will be "engaged" sooner and the collet compressed more when snapped into the nut. Since the end-mill will fit before the collet is snapped into the nut, the extra compression explains why I can not fit the mill while in the nut.

However, I received another collet chuck and nut yesterday, an this nut is obviously different. Using this chuck, I am able to fit the end-mills in the collets. I do think the collets sits a bit sloppy in there, and they tend to fall out when chaken. Buying collets and chucks from different vendors is obviously not a good idea.

I realize i did some stupid choices; first buying cheap unnamed collets and then buying a chuck from a different place. (The first vendor did not have the correct chuck.) The new chuck is from Vertex, and seem to be of reasonable quality. I have since discovered that a Regofix chuck come at the same price as Vertex. The collets are more expensive though.

The Vertex chuck seems to be of decent quality though. I'd like to hear if others have experience with them.

I think I will resolve this by returning the Vertex chuck, and order a Regofix and a smaller selection of Regofix collets. They are about €23-24 (£20 ish) a piece before sales tax.

Lesson learned: stay away from cheap Chinese junk, better to buy less tools of high named quality.

Thanks for all the feedback.

[mechman48Participant @mechman48]

Posted by mechman48 on 01/09/2016 09:42:13:

Nice to see that I'm not the only one having this problem. My original collet chuck has a run out of .004", which is a phenomenal amount, so I bit the bullet & ordered a new chuck from my usual supplier. this new chuck when fitted has the same problem, I have fitted various size cutters into it & still have same run out. I did some tests to check where the fault could lie…

The run out of my mill spindle is .0005" ( 1/2 thou' ), with the new collet chuck, with the same dti set up, it showed the internal taper run out of .004-5 thou', when fitted with either a 3/8 tool steel or 12 mm cutter the same run out shows up. To me this indicated that the internal taper didn't run co-axially true with the MT2 taper.

I have raised the question with the supplier via an e mail plus a couple of video clips, they requested I sent the chuck back for investigation, the response from them was that their investigations revealed no run out greater than .001"… ( their video clips showed no discrepancy ), so I am at a loss at the moment. I have requested could they provide any further suggestions, also possibly an exchange / replacement chuck, I await their reply

George.

… I have now received a reply…

“Hi George,

Thanks for your reply.

We really don’t know what to suggest. On receipt, we cleaned every component with meths, took out a 3/8” collet and round bar for the second test from our stock, cleaned them and tested as you can see from our video.

We have seen your video. You have seen ours. We are unable to replicate the fault, and feel that the problem could lie elsewhere. Inaccuracy could be in a collet or spindle or elsewhere too. We really don’t know. These products don’t come with a test certificate, and it is extremely rare that we come across a problem such as this. When we do, we check and replace if found to be faulty. This is a product which is consistent in quality, which we buy from a specific manufacturer, who makes for well established ‘world brands’.

As we are unable to replicate the fault, we are unable to consider a replacement for this product. We are happy to return it to you. On return, it will be coated with metal guard – protective oil (as meths would have taken off any original oil/dirt), so before use you will need to clean it.

Alternatively, we are happy to give you a refund for the item – excluding return carriage, once we receive the C spanner back from you which was originally supplied with the product.

We are happy to consider either of the above options.

Kind Regards

Your Enquiries Team at

Arc Euro Trade Ltd.

… I rejected their offer of a refund as I wanted to have the chuck to look at other avenues to resolve the run out. I cleaned all my collets, the chuck & nut, & the MT on the mill with surgical spirit, no improvement, I have looked up other forums & t’internet & applied a couple of suggested tips without any improvement. I am at a loss now as to which direction to go, having rejected Arc Euro’s refund offer initially, I feel that option will no longer be available. Is there anyone in the Teesside area that has a mill with MT2 taper that I /they could check my chuck for comparison please pm me.

George.

[Tony Pratt 1Participant @tonypratt1]

You say your spindle run out is .0005" can you get a DTI on the MT2 chuck taper when it is in the spindle?

Tony

[AjohnwParticipant @ajohnw51620]

It's far better to grip something in the collet and rotate that in a V block and check the run out of the fixing. Needs some care but can be done as the collet face can be kept in contact with the side of the V block.

That may indicate the error in the V block so best check that as well with some straight bar.

If some one must check in the mill lower the quill and use a magnetic based stand with a V block aspect to it to clamped to the quill.

Actually checking tapers is a little more tricky and can be a little misleading. The only sure way is test mandrels but our main interest is how accurately it all runs including the collet and tapers.

John

–

[John Stevenson 1Participant @johnstevenson1]

George,

A coincidence that your first chuck had the same run out ? ?

I know you say the spindle only his 0.0005 run out measured on the internal taper but this is only in one position and plane. If the taper isn’t true further up then there will be run out.

Full marks for posting all of the saga as many just bitch and moan about ” not fit for purpose “

Edited By John Stevenson on 07/09/2016 13:13:34

[JasonBModerator @jasonb]

Could also be that the taper in the spindle if off. This would clock true at the wide end where you are getting 0.0005 but if it runs at and agle to teh axis of rotation the top ind of teh taper may be eccentric. Can you get a lever type dti up into the MT2 as far as possible and test that. Ot use a MT2 testbar and see if that gets worse the further from the spindle nose you are.

[mechman48Participant @mechman48]

Thanks for the replies guys;

… 'the taper may be eccentric. Can you get a lever type dti up into the MT2 as far as possible and test that'…

Will give that a try, just assumed that taper would be co-axial to the quill shaft as it is usually part 'n' parcel of the shaft & ground as such . Hmm assumptions.

p.s. must give credit to ArcEuro team for their assistance

[Author]

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