Collets

[BallistolParticipant @ballistol]

Hi Guys,

A couple of questions on collets if I may please before I take the plunge.

What are the various pros v cons for 5C vs ER32 Collet systems and why do you prefer one to the other?

There are quite a few videos online highlighting the perils of the cheaper Collet sets accuracy/quality problems, is there an easy way to identify good from bad?

Thanks in advance.

[BallistolParticipant @ballistol]

[Steven CorstonParticipant @stevencorston14096]

5C collets may, might, could be more accurate but this depends on how good the holders are. the disadvantage to them is a very narrow clamping range of a couple of thou from the collet size. ER collets have a greater clamping range of up to 1mm. ie. a 10mm ER collet will hold matewrial between 10 and 9mm.

If you are always using accurately sized material then maybe 5C is best BUT if you have a variety of odd sizes then ER may be best. You can hold imperial stock in a metric ER (and visa versa) as the greater clamping range will allow this where as with 5C collets different sets of metric and imperial will be needed as well as accurate stock.

I prefer ER collets and have ER11, ER16 and ER25 sets all cheap Chinese from ebay. Maybe I have been lucky but they are all more accurate than my admittedly very old 5C set up.

Cheers

steve

[Neil WyattModerator @neilwyatt]

You'll find most, but by no means all, hobbyists use ER collets.

Neil

[PeteParticipant @pete41194]

Your asking about a fairly complex subject. And your not providing enough information to give the best answers to your question. Are you buying collets for tool or work holding, or a combination of both? Are these for use on manual machines or CNC?

While 5C CAN be used for driving tools, and Hardinge even produced some smaller vertical and horizontal mills that used 5C for tool holding. Today there pretty much a world wide industrial standard as work holding collets. The main deficit with 5C is they only have a few thou tolerance for the size there capable of gripping without permanent damage to the collet itself. So a multitude of collets are required. A major benefit of the 5C design is the shear amount of different work holding devices, indexers, dead length internal stops, hand, lever and even air operated collet closers, round, square and hex collets that are available. In my opinion it's a well thought out and highly versatile collet system. But all of that will add up to a multi thousand dollar price if your buying guaranteed accurate collets and accessories.

ER collets at least in the larger collet series, will generally have about 1 mm or roughly .040" of range they can reliably hold tool shanks or work when used in that capacity. And because of that size range they can hold, far fewer collets are required. ER collets are in industrial situations, really designed as a tool holding collet. And because of how slow they are to operate when changing tools, then with CNC they use multiple collet chucks to hold a variety of tools, the tool changers are then used until the tool requires replacing. On manual machines, then the extra time involved can usually be tolerated to switch out tools or parts. ER collets despite there simplicity, have a whole lot more complexity and subtle non intuitive logic behind how there designed and meant to be used to obtain the very best out of them. There's a YouTube channel titled REGO-FIX Group that has an extremely informative series of videos about ER collets that should be mandatory viewing for anyone using that design of collet. If you want an education about them, there's no other substitute than putting your own time into watching those videos until you grasp what there trying to teach.

No there's literally no way to properly judge what accuracy/quality you'll get with those cheaper collets. And I've also watched more than a few of those YouTube videos that demonstrate serious issues with those cheap collet sets and chucks. I use simple logic when shopping for tool or work holding items. Unless a tool manufacturer or supplier has written guarantees of the maximum allowable deviations in the product, I simply won't by it at any price. I already have decent lathe and drill chucks fully capable of repeatable run outs to .0015" or a bit less. Collets were invented as a method for gaining repeatable accuracy's well below that as well as having much better tool shank / part grip and support over those more standard lathe and drill chucks. If any collet can't be guaranteed to have a minimum of .0005" or less, I wouldn't buy it. As those REGO-FIX videos show, low run out numbers will directly affect tool life and part accuracy. For my own shop, I really can't afford those dirt cheap and poorly built examples. For my Bridgeport clone, I paid what it cost for a guaranteed accuracy set of ER-40 collets and a R8 collet chuck. I purposely chose that ER collet size even though it's a bit too large for what my mill is capable of even driving for tools since I wanted multi usage out of them on my lathe, rotary table and dividing head. So for either tool or part holding, my ER 40's allow holding any diameter between .188" – 1.024". Below that size I have a full set of Emco ESX 25. Above that size then a 4 jaw lathe chuck will get me whatever run out I want with enough time. Buying any collet type is in reality just about pointless if it can't produce the accuracy levels and performance collets are designed and meant to do.

But if I was independently wealthy? I'd chose 5C for work holding, and for what I currently own, R8, Morse Taper and ER collets for tool holding. Since I'm not, then I consider ER collets over the 5C to be a workable alternative with some trade offs for what they can't easily do when compared to the 5C.

[JasonBModerator @jasonb]

5C vs ER also being discussed in this thread to save everyone duplivcating their posts but 5C for me.

Edited By JasonB on 03/05/2023 06:53:53

[NealebParticipant @nealeb]

As mentioned already, a lot depends on what you are holding and where. I have a lathe with 5C spindle nose and lever-operated closer (elderly British machine) which came with a set of metric collets. I have bought a set of imperial as well, and that works fine for a lot of workholding. Outside that range or for odd sizes, I have a Burnerd Multisize collet chuck, which is a bit like a giant ER collet holder but with its own unique collets (came with machine – would never have bought otherwise!) I like collets for various reasons on the lathe, not least being good for small work without chunky chuck jaws getting in the way. On my CNC mill, though, (no tool-changer, manual only) I use ER32 collets for tool holding. Specific imperial sizes to suit a small range of imperial cutter shanks plus full range of metric. Why imperial as well? As mentioned in another thread, while the metric set does cover a continuous range of sizes, close-fitting ER collets are a little easier to use. Manual mill uses ER32 collet chuck, plus selected R8 collets for most-used cutter shank sizes. ER32 are also used for work-holding in things like Stevenson blocks (useful little devices – see Arc Euro). CNC router uses ER20 for tool-holding – again, mostly metric but selected imperial.

ER32 set originally came from Warco; all other collets from Arc Euro – except metric 5C which came with lathe. Never measured any of them but never felt I needed to worry about them for my purposes.

So, horses for courses! If I did not have a native 5C lathe, I would probably be ER32/ER20 throughout.

Edited By Nealeb on 03/05/2023 07:08:13

[SillyOldDufferModerator @sillyoldduffer]

Posted by Steven Corston on 02/05/2023 23:31:30:

5C collets may, might, could be more accurate …

I think any differences in accuracy will be down to how well the collets are made and their condition rather than the system. A well-made 5C collet will outperform a too-cheap ER, and a well-made ER will outperform a cheap or worn out 5C.

ER is primarily a tool-holding collet system, whilst 5C is primarily a work-holding system. More about pros and cons in the thread identified by Jason.

I standardised on ER32, no regrets.

Ballistol asked 'There are quite a few videos online highlighting the perils of the cheaper Collet sets accuracy/quality problems, is there an easy way to identify good from bad? ' The answer is partly in the question 'perils of the cheaper Collet sets', and partly related to whom they are bought from. A £20 Rolex bought from a stranger in a pub car-park could be genuine, right? Buying cheap from abroad via the internet is often fine, but it's much riskier than buying expensive named brands from UK industrial suppliers. Throwing money at the problem isn't the answer: top-end ER collets balanced to run at 40,000rpm are seriously expensive and totally unnecessary on a mill that maxes out at 2500rpm. I manage the risk by steering a middle course, generally buying medium priced gear from hobby suppliers like Arc Euro and the others. So far it's worked, but the cost of buying mid-range from reputable suppliers, is I've certainly missed several bargains.

There is an easy way to identify good from bad collets, unfortunately it's by testing them after they arrive…

Dave

[not done it yetParticipant @notdoneityet]

Not even the suppliers of best quality ER collets will provide a guarantee, of specified parameters, for anything but the nominal size – certainly not the minimum achievable.

Hobbyists are not generally absolute perfectionists to absolute sizes – as may be required for series production of replacement parts for high precision machines. I use ER – and also a Clarkson occasionally.

[Martin ConnellyParticipant @martinconnelly55370]

5C collets have an internal thread so they can be fitted with a depth stop. ER do not and neither do any of my lathe specific collets or R8 collets. I'm sure if it was felt necessary someone could design a workaround for a depth stop but there are usually other alternatives for a one off requirement. The Clarkson collets (as mentioned by NDIY) go into a chuck with a centre that acts as a depth stop but they are not designed for work holding, only milling tooling with the necessary thread on them.

I usually use a Clarkson style Vertex chuck for milling tool holding but sometimes use R8 or ER. I also sometimes use ER in the lathe tailstock and lathe specific in the lathe spindle. I have a spin indexer that is 5C but has an ER adaptor but I do have a few 5C collets for it that are larger than ER32 sizes but rarely use them. I have square and hex collet blocks for the lathe collets.

If you get ER collets and a square collet block you can hold something tightly then put the collet block in a 4 jaw lathe chuck and dial it in to an acceptable runout regardless of the collet's quality. Then transfer to another machine if required with it still in the collet block. So don't worry too much about such things as runout with ER collets until you have a real problem that can only be solved with super accurate collets and collet chucks.

Martin C

[JasonBModerator @jasonb]

5C collet blocks are available too so what you can do with ER blocks you can do with 5C with the added quick release option on the 5C if you need it.

One advantage I did miss out on the other thread was that having two collet systems you are less likely to run into trouble when wanting to hold say a 6mm dia part in your collet and use a 6mm shank tool to machine it with.

[PeteParticipant @pete41194]

Posted by not done it yet on 03/05/2023 10:33:58:

Not even the suppliers of best quality ER collets will provide a guarantee, of specified parameters, for anything but the nominal size – certainly not the minimum achievable.

Hobbyists are not generally absolute perfectionists to absolute sizes – as may be required for series production of replacement parts for high precision machines. I use ER – and also a Clarkson occasionally.

Maybe viewing some of those REGO-FIX videos first would have turned up the information that less than nominal sized tool shanks, or in our case when there being used as a work holding collet, they show no increased run out, and they will in fact guarantee those same guaranteed run out numbers over the holding range of the collet. At least REGO-FIX does. If an ER collet and it's chuck are correctly and accurately made, the collets segments will close down evenly against the tool shank, in fact there designed to do exactly that and provide the high grip strength ER collets are known for. So why would smaller than optimal diameters be any different than on size diameters since the collet has to close at least a bit even with on size tool shanks? My Bison ER 40's show no increase in run out over the various sizes I've checked. When I want holes with a high degree of location accuracy, or I'm using large diameter reduced shank drills, I'll use them instead of a drill chuck, so I can also use mine as a tool holder with a variety of sizes within each collets closing range. That ability is simply due to the radial and axial precision the collets and chucks are being made to, and what I think can be assumed adds a high percentage to the actual cost for those better collets and chucks. There's also more than a few YouTube videos that show cheap off shore ER collets having visually noticeable differences in segment widths, differences in slot widths, burrs etc. Since the collet isn't and can't close evenly around it's full circumference, then of course it will produce higher run out numbers even "if" it was bored and ground true to it's tapers. And if there being made that poorly, then it's highly doubtful anything else is correct other than by pure luck. There's also videos showing collet chuck thread deviations and nuts with internal tapers that are out of square enough to force the collet sideways or physically tilt the collet axially as the nut is tightened. So it's not only the concentricity of the collets themselves, it also has a lot to do with just how accurate the collet blocks or chucks are as well.

5C is completely different because of how there designed to work. That design of collet isn't meant to accept anything over sized, and even a bit too far under size will or can crack or break collet segments if the collet is closed on any smaller than optimal diameters. Since a 5C collet is a single taper and closed by drawing the collet inwards against the collet holders taper, that forces the collet segments to exert the most holding power towards the front of the collet. For that reason, special soft 5C over sized collets can be machined and used even for very short parts. If 5C was being used for driving tools, then yes nominal sized collets to fit the tool shanks diameter would be logical to obtain the highest grip. Possibly there still being made somewhere, or at least were at one time. But other than those now fairly rare machine tools that were designed to use 5C, I can't recall seeing any actual 5C milling chucks. About the only option left would be to build your own if that's what you really wanted to use. As a tool holder, I think 5C is a rather poor second choice.

ER collets are a dual taper, and the segments at each end are forced in and closed by both the chuck and closing nut tapers as it's tightened to the correct torque. For that reason it's highly recommended that at least 80% (or more) of tool shank, or work piece fills the collet length. If that's not done, then the collet's grip is seriously decreased and a collet can be permanently damaged because the tool or part is then only being gripped by the front of the collet. Run out numbers will then increase, but that's the fault of the user because there being used improperly and outside there intended design application.

It's also not about being a perfectionist, and as I already said, those REGO-FIX videos clearly explain just how detrimental any excess run out is to maximum tool life no matter what collet type or tool holding method is used. And since the ER collet design has a decent amount of closing range when holding work pieces, you can be quite sloppy about those exact sizes as long as the part length is inserted deep enough into the collet. 5C collets would require much more attention to those nominal diameters than ER's ever would. Like anything else, there's no perfect one size fits all when it comes to tool and work holding collets. 5C is logically the clear winner as a work holder just due to it's versatility. ER is a much better and far more secure tool holding method because of it's grip ability over the length of a tool shank.

[Neil LickfoldParticipant @neillickfold44316]

The most accurate form of the ER type collet I have used, comes from the Japanese company BIG. They have the highest of any specs I have ever seen in a collet , and used one for the First time on Monday to hold a part with an 8mm shank. But the price for the BIG collets and the holder , costs about the same as buying a cheap range Myford sized lathe.

Just to add to the ER situation, What is missing in alot of cases with the collet nut, is the concentricity of the thread to the inner taper on the mandrel or body of the collet system, and then the concentricity of the collet nut to the inner nose taper. When I made my ER spindle nose, having made the thread concentric to the inner 8 deg taper per side, I got all the Regofix nose nuts that I was going to use, and checked them all for the thread fit. It works really well. Another point in my set up, is a slotted pin, that keeps the collet in the same radial orientation. It does limit the closing of the collet to slightly less than the max closing.

There is now a fine thread format nose , where they use a 1mm pitch thread instead of the 1.5mm thread pitch for the collets in the ER20 and up. It makes a significant difference to the amount needed to tighten down or to hold a part or cutter on the system.

Most of the ER systems I see available today, do not hold a part dead true from the initial clamping, and require a small tap or adjustment to hold the part or cutter true. In short you get what you pay for and at some point a most hobbyist just get by and make do with what they have. Most hobbyist are not making a part that has to fit another part made by somewhere else in another part of the country or world.

Something that I make alot is what I call a distortion bush . I make a bush nearly finished size. Part it off the bar. Then hold it in the lathe chuck I am going to use, normally a 3 jay chuck, or even in an ER collet. Bore the inner over sized when it is lightly held in the chuck. Then tighten to close to the holding amount on the chuck, or collet, and finish the inner bore to being a close fit to the part and the end face. When released on tension, but not loose, the part can be inserted, clamped and the operations completed. This works very well for a few items that need a precision second operation.

5C and the ER systems have been mentioned alot, but with the ER systems, I have found that the cheap collets are not worth the time or money spent. I have some cheap collets that are just junk and should never have bought them. Others have got cheap collets and most seem to be fine for them. It all depends on what you are making, and the level of precision that is required. The AA graded collets seem to be just as accurate as the RegoFix High precision collets, is what I have found, when all else is correct.

Neil

[Anonymous]

Posted by Pete on 03/05/2023 19:48:50:

…they will in fact guarantee those same guaranteed run out numbers over the holding range of the collet. At least REGO-FIX does.

That may be the case for Rego-Fix but not necessarily for other professional suppliers. Cutwel for instance only gaurantee the specified runout at nominal diameter; at least for their precision and super-precision ER collets.

Andrew

[BallistolParticipant @ballistol]

Thank you for the information guys, it’s much appreciated.

I think all things considered, an ER32 solution would be the best fit for my needs.

[IanTParticipant @iant]

Posted by Ballistol on 05/05/2023 09:55:05:

I think all things considered, an ER32 solution would be the best fit for my needs.

Good decision – I use mine all the time, both for tool and work holding.

I've got ER32 'Chucks' for both my lathes, they screw-on and allow longer parts pass through the headstock. I also have an MT2 (ER32) collet holder for the mills and sometimes also use this on the Myford for smaller parts. I can then turn smaller parts before doing some other milling or drilling operation. A useful addition to this holder is an MT adaptor (MT2 to Straight) which allows the collet holder to be held either in a vice or simple jigs. Of course, I also have collet blocks and a spin indexer (I use the collet blocks a lot more than the indexer btw..)

I have a full set of metric collets but have also purchased a few imperial ones. If I need to hold a 1/4" part (or tooling) then I prefer to use a 1/4" collet rather than really compress a 7mm one. Bit less of a problem with 13mm going down to 1/2" but I still use a 1/2" one. You may not have the same need of course…

I do have four or five 5C collets, most were purchased for use with 5C collets blocks before I had the ER system (I migrated to ER from a 'Chinese' MT2 collet set) but one was purchased later to hold a specific 1" item that was over the 20mm limit of my ER32 set.

Anyway, I think you will find the ER32's a very useful addition to your tooling.

Regards,

IanT

[Author]

Posts