Collet Chuck or not ?

[Dave SpringateParticipant @davespringate]

[Dave SpringateParticipant @davespringate]

Hi all, as a novice is it ok to hold a milling cutter in a 3 jaw chuck for basic milling operations or should I get a collet chuck ? If I go for a collet chuck how do you choose a size ie : ER25, ER32, ER40 Or some other size ? I understand that the collet needed is the size of the item to be held but why buy An ER25 over say an ER32 or ER40 Thanks

[HopperParticipant @hopper]

I hold milling cutters up to 25mm diameter in the 80-year-old three-jaw chuck on my ancient Drummond M-Type (The Flagellator) without problem. Haven't had one slip on me yet, including milling 1" thick steel plate etc. A 16mm diameter end mill cutter seems to work best without too much "chunking" that you can get with the bigger cutters. Smaller cutters are a doddle.

So no need to buy ER collets for milling in the lathe. Give it a try with your 3-jaw first.

The 32 in ER32 refers to the nominal outside diameter of the removable tapered collet. The collets are available in a range of inside diameters to suit the size of bar/cutter you wish to hold. An ER32 collet set will hold up to about 20mm bar/cutter, whereas an ER20 collet set will hold up to 13mm bar/cutter. Sets are usually in increments of 1mm.

[Mike CrossfieldParticipant @mikecrossfield92481]

Aside from having superior grip, a decent collet chuck will have much lower run out than your average 3 jaw SC chuck. With a 3 jaw you will most likely be cutting on a single tooth.

[Howard LewisParticipant @howardlewis46836]

+1 for ER Collets, as Mike Crosfield advises. A good three jaw will probably have a run out of a bit less than 0.005", (A badly worn / abused one could be 0.030". An ER collet will have a run out of about a tenth of a really good 3 jaw )

If you go to the expense of having a collet chuck, and a collet holder, when you graduate being a mill owner, you can use one for work holding, and the other for cutter holding.

ER Collets have a range of 1 mm in all but the smaller sizes, so can be used to hold Metric or Imperial cutters or material.

Howard

[Clive Brown 1Participant @clivebrown1]

My experience of using a 4" 3-jaw chuck for end-mills was that it's OK if basically cutting with the end-teeth. However, if heavish cuts are taken using the side teeth, then the helical tooth shape can pull the cutter outward from the chuck. Trying to avoid this by over-tightening can be unkind to the chuck.

ER collets don't seem to suffer this and auto-lock chucks are immune of course.

Clive Brown

[not done it yetParticipant @notdoneityet]

Just thinking about days gone by might have given you some insight of past operations. ER collets did not exist in the early days of milling on the lathe. Did those hobbyists not make good models? Did they make inaccurate models?

ER collets are undoubtedly an improvement in tool holding over the standard lathe chuck … but our grandfathers did not have the benefit of the bits that were not invented back then.

It's all relative. Lots of things have changed over the decades. This is just one example.

Regarding size choice – obviously the larger the better, within reason. But most will likely consider other ER operations and buy the (first) set to also fit their (future?) milling machine – unless their first set was decided upon for other reasons (often size or cost).

[nigel jones 5Participant @nigeljones5]

A word of caution….I bought a cheap collet holder and set oft bay via china for my mill. Great at holding things rigid but a lot of runout…dont be tempted!

.

[IanTParticipant @iant]

NDIY – you can do just about anything with quite limited equipment and lot's of ingenuity, time and effort. The question is why would you do so, if a better (and quite affordable) alternative is available?

Dave – both my lathes have ER32 collet chucks – the type that mount on backplates – so that you can pass material through them. ER32 used to be the largest type that most dealers sold and is also available in collet block & spin indexer accessories – so it is versatile.

I use mine all the time where it makes sense, not only to hold cutters but also various useful mandrels and other devices where I want to remount them fairly accurately. I also directly hold 'work' with them, so the 20mm max of the ER32 collet is useful – but of course also larger than the material that either of my lathe headstocks can pass.

Before the Chinese made a lot of this stuff affordable to us mere mortals, clever people made all sorts of useful alternatives – including Master/Slave set-ups, MT cutter holders, 3-jaws that could be 'zeroed' (etc) but these days ER collets make many of these things somewhat redundant. Of course, if you already have them, they can still be useful – but much of the motivation to make these items has now gone.

Regards,

IanT

[thaiguzziParticipant @thaiguzzi]

Posted by Hopper on 26/03/2019 07:21:54:

I hold milling cutters up to 25mm diameter in the 80-year-old three-jaw chuck on my ancient Drummond M-Type (The Flagellator) without problem. Haven't had one slip on me yet, including milling 1" thick steel plate etc. A 16mm diameter end mill cutter seems to work best without too much "chunking" that you can get with the bigger cutters. Smaller cutters are a doddle.

So no need to buy ER collets for milling in the lathe. Give it a try with your 3-jaw first.

The 32 in ER32 refers to the nominal outside diameter of the removable tapered collet. The collets are available in a range of inside diameters to suit the size of bar/cutter you wish to hold. An ER32 collet set will hold up to about 20mm bar/cutter, whereas an ER20 collet set will hold up to 13mm bar/cutter. Sets are usually in increments of 1mm.

Blimey Hopper!

First time i have had to disagree with you…

[Neil WyattModerator @neilwyatt]

Posted by not done it yet on 26/03/2019 09:09:41:

Just thinking about days gone by might have given you some insight of past operations. ER collets did not exist in the early days of milling on the lathe. Did those hobbyists not make good models? Did they make inaccurate models?

But they often used a 4-jaw chuck for holding end mills, or used home-made slot drills that were usually only cutting on one edge at a time.

Neil

[SillyOldDufferModerator @sillyoldduffer]

Posted by Dave Springate on 26/03/2019 07:07:24:

Hi all, as a novice is it ok to hold a milling cutter in a 3 jaw chuck for basic milling operations or should I get a collet chuck ? If I go for a collet chuck how do you choose a size ie : ER25, ER32, ER40 Or some other size ? I understand that the collet needed is the size of the item to be held but why buy An ER25 over say an ER32 or ER40 Thanks

Holding the cutter in a slightly unsuitable 3-jaw will be the least of your problems! Big machines do better than small ones, but at root lathes aren't designed for milling. The workspace is very limited and the slide likely to move due to the unusual for a lathe forces caused by milling. Clamping the job can be awkward. Lathe milling works, but only within narrow limits – small parts, and gentle cuts. Quite often I would file by hand rather than go to the trouble of setting-up.

Combination machines (ie with a milling head permanently bolted to the headstock or ways) are a better bet, but they are still low capability compared with real milling machines.

Back in the day milling on lathes was common due to lack of affordable mills. Not because lathes are any good at milling! Great work has been done – ingenuity and patience can move mountains. However, at best I found milling on a lathe deeply frustrating. Even worse the machine simply wasn't big enough to hold rather ordinarily sized milling jobs. If you have the space buy a real milling machine. If budget is a temporary problem, save up for one – money spent on vertical slides & collets etc for milling on a lathe is likely to be wasted.

Dave

[SillyOldDufferModerator @sillyoldduffer]

ER Collet Chucks each cover a range of collet sizes, for example:

ER16 0.5 to 10mm
ER20 1.0 to 13mm
ER25 1.5 to 16mm
ER32 2 to 20mm
ER40 3 to 40mm
ER50 12 to 34mm

ER32 is most common in hobby use because it suits 'our' size machines. ER16 is for watchmakers and ER50 for hefty work. The step size between collets varies, for example an individual ER32 collet will grip over a 1mm range, so you need 18 collets to cover the full 2-20mm range. Quite expensive.

ER collets are mainly for tool-holding on milling machines but they also do a good job holding work on a lathe. Collets hold lathe work accurately and repeatably but they're Over The Top compared with a 3-jaw for most work. A 4-jaw can achieve collet-like accuracy and hold odd shapes but take more setting up. Which type of chuck is best depends on the job in hand. I rarely use collets in my lathe (rarely chasing high precision), others use nothing else.

Dave

[Dave SpringateParticipant @davespringate]

Wow, how quick was that. Thank you all very much that has shed some light on the subject. Now if I wanted to true up the edge of a piece of 20mm steel would a cutter slightly wider than 20mm be the preffered way to go so that a full width cut is taken in a single pass?

Also would a two or 4 flute cutter be used for this operation.

[JasonBModerator @jasonb]

The Minnie in my avitar was done on the lathe and any milling cutters held in the 3-jaw, seemed to work OK for me back then.

I'm sure MT collets were used a lot in the past to hold tooling.

How big is your 20mm steel? can it not me held in the 4-jaw to true it up.

[Russell EberhardtParticipant @russelleberhardt48058]

If you're going to hold a milling cutter in a three jaw chuck it's a good idea to interpose some brass shim between the chuck jaws and the end mill. The cutter will be much less likely to slip. I did this for many years, milling in the lathe before I bought a mill.

Russell

[Former MemberParticipant @formermember32069]

[This posting has been removed]

[HollowpointParticipant @hollowpoint]

Posted by Dave Springate on 26/03/2019 10:22:51:

Wow, how quick was that. Thank you all very much that has shed some light on the subject. Now if I wanted to true up the edge of a piece of 20mm steel would a cutter slightly wider than 20mm be the preffered way to go so that a full width cut is taken in a single pass?

Also would a two or 4 flute cutter be used for this operation.

That sounds like a job for a fly cutter. Personally I use the biggest cutter I can get away with for rigidity.

[SillyOldDufferModerator @sillyoldduffer]

Posted by Barrie Lever on 26/03/2019 10:47:33:

Posted by SillyOldDuffer on 26/03/2019 10:20:03:

" ER16 is for watchmakers "

Dave

That must be a Neanderthal watchmaker that you know using ER16 collets !!

Regards Barrie

I plead guilty to the charge of Gross Exaggeration and ask for 477 other offences to be taken into consideration!

[Dave SpringateParticipant @davespringate]

Posted by JasonB on 26/03/2019 10:30:19:

The Minnie in my avitar was done on the lathe and any milling cutters held in the 3-jaw, seemed to work OK for me back then.

I'm sure MT collets were used a lot in the past to hold tooling.

How big is your 20mm steel? can it not me held in the 4-jaw to true it up.

Hi Jason, I don't yet have a 4 jaw chuck but it's on the list when funds allow. The piece of steel is 60mm x80mmx 20mm.

Edited By Dave Springate on 26/03/2019 11:21:29

[MalcBParticipant @malcb52554]

If you cant run to an immediate collet setup then use a 4 jaw and set true.

Unfortunately shelling out on a new half decent collet setup goes against the grain when the cost could be on the way to financing a used milling machine package.

As others have said, once true in a chuck you have the lesser rigidity in a lathe to deal with. Make sure all slideway jib strips have any unwanted play taken up. If you can, lock any slideways up that are not being used. If your compound slide is still fitted, minimise any overhang.

Small cutters also demand much higher speeds than many lathes can achieve, so watch your max chuck rpm and take it easy.

[Rik ShawParticipant @rikshaw]

The thing about ER collets in particular is their versatility. Yes they are very handy for holding milling cutters both imperial and metric but they are also indispensable for holding finished machined surfaces on materials like PB, gunmetal, brass etc. without leaving marks.

In my case I originally bought ER25 but since then I have upsized my lathe. So in order take advantage of its larger capacity I had to choose between ER40 and 5C. I decided on 5C simply because a cheap job lot of new collets became available. I still use the ER25's on my WM16 mill and very accurate they are – am I allowed to say they came from RDG?

Rik

[not done it yetParticipant @notdoneityet]

IanT,

Did I not comment that ER collets were undoubtedly superior? ER collets are still rather more expensive than the current chuck (already in situ). It may (initially) depend on the user's depth of pocket – I don't know.

All I was pointing out was the obvious fact that lathe chucks were probably used, for this duty, long before ER collets were invented.

NW,

Would it really make any difference if they used one cutting edge, or more? Same holds true for present day, too, with ER collets? The oldies likely used a 4 jaw chuck (independent jaws) to ensure concentricity at times? Very clever, some of those 'oldies'! Might even include fly cutters as larger diameter versions – as those cutters with a single edge could be arranged as a fly cutter by offsetting the cutter from the centre line. There were,and still are, alternatives to the ER collet long before the ER was invented. There is nothing stopping a novice using old techniques.

Poster asked if he SHOULD buy an ER. I demonstrated that he did, in fact, still have a choice. Same with the size – it is down to the user to decide. There is no universally correct answer – we all might have different needs.

[Clive FosterParticipant @clivefoster55965]

If you are going to hold an end mill in an older chuck consider a crude alloy sleeve master slave system. Drill or bore the sleeve to fit the cutter in situ, mark where No 1 jaw goes and slit the wall pretty much opposite so the bore closes up to grip the cutter shank when tightened. If being sophisticated put a flat on where No 1 jaw goes to help it go back in the right place. Wall thickness or 3 or 4 mm sounds about right. Needs to be thin enough to flex but stiff enough to pull round cutter rather than just dimpling in where the jaws go.

Steel chuck jaws don't have the most wonderful grip on the hardened steel shank of a milling cutter (drill shanks are made softer than the business end so a chuck holds better). Softer alloy gives a much better grip on the hard steel shank.

Being soft alloy doesn't last that well so you will need to make new ones fairly regularly. Probably last for 20 – 30 or so uses. But making is hardly difficult. Last longer if you make one for each cutter and leave it on the the shank. Threading the end to stop pull out, clarkson style, if you have a bunch of suitable cutters is possible but probably stretching the idea too far.

One advantage of holding the cutter in a chuck on a smaller machine is flywheel effect from the heavy chuck which helps keep things spinning smooth as the cutter tooth engages the work.

Clive

[SillyOldDufferModerator @sillyoldduffer]

Posted by Dave Springate on 26/03/2019 10:22:51:

Now if I wanted to true up the edge of a piece of 20mm steel would a cutter slightly wider than 20mm be the preffered way to go so that a full width cut is taken in a single pass?

Also would a two or 4 flute cutter be used for this operation.

I happen to be about to true up the edge of a 12mm aluminium strip:

Unlike a twist drill, all the edges of a milling cutter are sharp. It's good to spread the wear over the full cutting edge available rather than always using one part, especially as most jobs require use of the precious bottom face and corner end causing these to wear quickly. In this example I'm aiming to use most of the sideways edge of the cutter, which happens to be the smallest with enough side length to do the job. Only a light cut in Aluminium is needed, so a small diameter cutter run fast will do a "better" job than a big cutter turning slowly.

As there's plenty of room for swarf to escape, it's advantageous to use a 4-flute cutter – more metal removed per revolution. Two flute cutters are generally reserved for cutting slots because the extra space between flutes is less likely to choke with swarf. Though they make poor drills, you can start a slot by plunging a 2-flute cutter into a plate.

In practice, truing an edge could be done more-or-less well with either 2 or 4 flutes in various diameters, or – if there's space to hold the strip vertically – with a fly cutter. The advantage of fly cutting is their easily resharpened cheapness and the large diameters that can be smoothed, especially when flattening a plate.

Dave

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