Advice on Collets

I have managed up untill now without spending money on collets, but perhaps I may be missing out. My lathe and mill have MT3 spindle tapers, how much benefit would I get from acquiring a set of MT3 collets?

Hi Chris

Depends on how accurately you can hold work in the chuck or whatever you use now, if that holds material to very small run-out then you may not gain much.

With collets you can get better concentricity between turned diameters when each is turned by turning the work around to finish.

Emgee

In the first instance you could just get a couple of commonly used sizes for the work you do, don't forget though these collets only hold dedicated diameters.

Edited By Emgee on 15/10/2020 23:51:22

Hi Chris i have ER25 collet chuck MT2 taper which i use on the Mill. I would not be without them. I also have a Clarkson autolock chuck.

Maybe the Clarkson is more accurate. The ER collets are a great addition to the lathe or mill. You will not go far wrong buying a set. I believe they do Imperial & metric. Mine are metric, but do hold some imperial tooling & drill bits.

Steve.

It depends how often you need better accuracy than your three jaw, and on how fat your wallet is. What do you use to hold milling cutters, one wonders. If you need great concentricity only occasionally, the 4 jaw isn't too painful, and making a split bush is another option. If you have the money though, collets are great to have. I have 5Cs and ER 32s.

I have a set of ER16 collets for my Taig Lathe and ER32 for my Mill. I would not be without them.

Metric ER collets will squeeze down onto Imperial sizes so there’s no need for two sets.

I was able to buy secondhand collets for the mill from an EBay seller at a good price - so it pays to keep one’s eyes open. The Mill was supplied with an R8 collet Chuck.

But after a couple of days I invested in the Ball Bearing nut!

Good luck

Hi Chris,

If you have an accurate chuck the MT 3 collets may not give you much more accurate clamping. I occasionally use MT 3 finger collets in my milling machine to get as much headroom as possible. My SC 3-jaw lathe chucks are not the most accurate so I have an ER 32 chuck for my lathe and one for my milling machine. ER collets work well for holding milling cutters and can hold round work in the lathe accurately. I too wouldn't be without my ER collets/chucks.

Thor

As I see it, the main advantage of dedicated sized collets is the extra head space afforded on the mill.

One set of ER collets will cover the complete range - but accuracy is only guaranteed (if it is) at the nominal size if that is important.

I mostly use ER collets.

My lathe and mill both have MT3 spindles and I use an ER collet adaptor for most of my milling operations. Not so much on the lathe but they are much more accurate and smaller than my 3 jaw chuck. (use 4-jaw for precision jobs)

Also very handy to take the collet with job from the lathe and mount in my rotary table which also has a MT3 taper. (Had to purchase a second MT3-ER adaptor to hold the cutters)

I originally purchase the collet adaptor with a minimum set of collet sizes and buy extra sizes as needed.

Paul.

I seldom use finger collets though they do come in handy on the odd occasion when a bit more head room is needed. On the lathe I have 5C and on the manual mill ER32 is the norm, ER16 on the CNC.

You also have the conflict of wanting something for work holding on the lathe where a larger max diameter is desirable and cutter holding on your small mill where access to the work needs to be considered. You may well find that with small cutters on the mill held in finger collets that the spindle makes it hard to see what you are doing and can get in the way when working near clamps or a vertical rotary table so something like an ER16 set or Weldon type holders would be better than finger collets or a big ER32 chuck.

I have 4 imperial 3MT finger collets, bought for a specific reason. I find very little general use for them on either my mill or my Boxford lathe, neither do I use my ER collets to any extent on the lathe. I do have a set of Boxford / Crawford 3C collets, which can be useful for small work on the lathe. These require a 3MT adapter.

I find ER collets super useful for holding parts accurately on my mini-lathe. They are especially useful when a part is removed from the chuck to have other work performed on it before returning it to the chuck and being able to maintain concentricity. Or, as others have mentioned, if the part is to be turned round e.g. when you want to machine both ends of an axle.

Because collets grip a part more securely than a 3-jaw scroll chuck it will not spin in the chuck when doing things like using taps and dies. (Been there, done that, said some rude words...)

The thing with ER collets is they are designed to very accurately hold a part that is at least as long as the collet. So what do you do if what you are trying to hold is shorter than the collet? The best solution I have found, so far, is to first insert a bar of exactly the same diameter as what you are trying to grip. It doesn't need to be the same material as the part (just the same diameter), aluminium or even delrin/acetal will do.

Very soon after buying an ER32 chuck for the mill, I gave the Clarkson clone away. I rarely remove the ER one.

I quickly added a collet chuck to the lathe, that also fits the rotary table.

ER collet blocks quickly pay for themselves for milling flats, squares, hexes, cross holes and just holding small round parts.

Chris' question was specifically about getting MT3 collets, not ER. As someone above said, the great advantage if that you gain perhaps 50 mm more daylight under the mill head, as well as greater rigidity. Single collets are quite cheap and you only need a few for the main cutter shank sizes.

All depends on the type of work you regularly do. I make a lot of spindles/studs /bolts etc for my old motorcycles. 80% of my turned work is done in a 5C collet, I have a full set of imperial sizes and a good selection of metric plus some common hexagon sizes. On the mill mainly R8 collets plus Clarkson for the jobs where a cutter could pull down.

Not much benefit in MT collets if you're like me! They save headroom on a mill compared with holder-mounted systems like ER32, and may be a little more rigid, but I can't think of any other advantages.

More complicated on the lathe. Most of what I do is held in a 3-jaw chuck, which is quick and convenient. 4-jaw comes out when reset accuracy is important, as when a job needs work to be moved between machines. 4 jaw chucks are wonderful except setting them up takes time. Lathe collets beat 4-jaws when quick accurate resetting of round objects is frequently required, as in clockmaking. Not called for much in my workshop.

However, once in a blue-moon I make something that moves repeatedly between machines and collets provide the best answer. They allow the job to be accurately repositioned several times without fuss. All done with an ER Collet Chuck on the lathe, supplemented with Stevenson Blocks on the mill, and although the approach is good enough for my needs, someone doing a lot of this sort of work might go up-market.

I suspect if Chris hasn't hit a requirement for MT collets, then he doesn't need them. Yet! In the middle of a job one afternoon, I suddenly realised an ER collet chuck on my lathe would have saved a huge amount of time and a couple of rejects. That's when I ordered a collet chuck. Likewise, I bought a couple of MT collets for a particular job, but in the event they weren't needed - waste of money.

Dave

Like you, my Lathe and Mill are both 3 MT.

I have a few 2MT collets left over from when I had a smaller lathe, which I use with an open ended 2 - 3 sleeve.

These are handy if headroom becomes short (Usually me being too idle to move the head on the column for fear of losing the location. )

Most of the time I use ER25 collets, because they have a range of 1 mm which allows me to use /abuse them to hold Metric, Imperial or any "odd" size that I produce in between.

In the Mill they are used in holder, (blank ended, which allows cutters to be used.

I also have ER25 and ER32 collet blocks which are used for workholding.

In the Lathe the ER25 and ER32 collets are used in collet chucks on backpplates which allow long work to pass through into the Mandrel..

The ER collets see the most use.

HTH

Howard

Another throwback "must have" from industry. Must be one of the most abused items in the toy Ingineering hobby. "I can fit imperial items in my metric collets" ( or vicky verky ) and "it grips 15 - 14mm" Garbage, no, 15mm grips a 15mm shaft and NOT smaller or 9/16". What's difficult to understand that a bore of a specific diameter magically reduces? Bit like expecting an M6 die will cut M5 if you crush it down a bit. Extreme but you get the idea. If you're going to make dozens of studs of a specific diameter on a regular basis, fine buy a specific size collet, otherwise 3 or 4 jaw is ideal.

A few decades ago, school had two lathes in the Metalwork class. Big one was a Harrison (they were a couple of miles down the road at Cleckhuddersfax), and a Boxford (they also were not far away) Boxford had three collets, can't remember what the two bore sizes were but third was 1/2" square cos everyone made a centre punch from 1/2" square bar.

As previously mentioned, an Autolock clone and 6mm and 1/4" (one each) for Weldon cutters.

Regards Ian.

Edited By Circlip on 16/10/2020 11:10:36

Same here but without the Clarkson chuck & I have imperial collets in.. 1/8 - 3/16 - 1/4 - 3/8, commonly used sizes

George.

Forgot to mention, ONLY collet for multi size gripping is the "Rubberflex" type.

Regards Ian.

Hi Chris

Before deciding on MT3 collets for your lathe, I would suggest checking that the carriage will go far enough that a tool can reach the end of the spindle. If your motor is behind the headstock it may restrict movement of the carriage and either make this difficult or require excessive overhang of the compound.

Brian G