Thread: Collets for lathe work

Hi

I am looking at buying collets for lathe use

I see that it is possible to buy MT taper collets ( drawbar type ) , say for a Spindle with a #2 MT . But some people seem to prefer the ER chuck as you can hold longer work pieces .

There seems to be many types out there ,some the older collet designs only fit certain brands of lathes .

So is there anything against using the MT type collets in a lathe spindle ?

Mike

Whats the grip range? i.e. can you get them so grip every size from 2mm to 20mm without gaps? or do they just come in "standard" sizes?

Stuart

Originally Posted by Stustoys

Whats the grip range? i.e. can you get them so grip every size from 2mm to 20mm without gaps? or do they just come in "standard" sizes?

Stuart

Hi Stuart

I have seen a few sets like this on EBAY



Milling Lathe MT2 Collet SET 5 PCE Morse Taper | eBay

Also I have seen individual collets in MT #1 and #3 up to 16mm and as small as 1.6mm ..all on EBAY

A UK seller has a MT#1 set ( six collets ) for about $50 .

Mike

Originally Posted by morrisman

........So is there anything against using the MT type collets in a lathe spindle ? ..............Mike

Mike,

- MT collets need a drawbar. This means that you cannot feed stock through the hollow lathe spindle and the collet. You will soon find that feeding stock through the collet is a highly desirable feature.
- MT collets are not self releasing. To remove the workpiece or collet, you need to hammer onto the drawbar. Not something you like doing regularly if you value your lathe bearings and headsock alignments.
- Mt collets do not have a very large clamping range. You either need lots of collets, or you can only clamp certain stock sizes. Compare this to ER collets, each collet has a 1mm clamping range, with a set of around a dozen collets you can clamp gaplessly from say 1mm to 20mm (in the case of ER32 size).

The above issues do not make MT collets very popular for lathes, and I would not recommend. They have one small advantage though, and that is the least possible overhang from the spindle nose.

In the past 20 years or so, ER collets have become popular for lathe workholding in home shops. Especially if your mill uses the same size of ER collets, one set will fit both lathe and mill. Not so in the US though, over there ER collets are still new, and another problem is that most ER collets are metric and need to be closed quite a bit to clamp imperial stock. There are imperial ER collets too, but much more expensive. Another thing to be aware of is that true lathe workholding collets are hardened, whilst ER collets are softer as originally intended to clamp hardened tool shafts. Also note that ER collets do clamp over a short length only, for smaller diameters the clamping length is a lot shorter than the collet length. That said, ER collets are a double taper design and clamp parallel, whilst MT collets and many lathe collets are only single taper and can not clamp parallel except at their exact nominal diameter. If you go ER collets, make sure you do not use a milling collet chuck, but a real lathe collet chuck that lets you feed stock through the spindle. Chris

But will the 12mm collect grip 10.1mm?

Stuart

Originally Posted by Stustoys

But will the 12mm collect grip 10.1mm?

Stuart

Of course not. But I think you wanted to ask if the 10mm collet will clamp 10.1mm. The answer is no again. An ER collet can never grip larger than its nominal diameter - if you try you ruin the collet. To clamp 10.1mm you use the 11mm collet. ER collets have a 1mm clamping range thanks to their "double slit" and "double taper" design. By the way, they were invented by RegoFix of Switzerland. Chris

Are you able to get a dedicated Collet chuck for your lathe.
What type of spindle end has your lathe got.

Hi Chris,
No thats not what I meant. I somehow missed your reply(lots going on atm).
Mike linked to an MT collect set with 4mm, 6mm, 8mm, 10mm, 12mm collets. I was attempting to point out that as you've said the 10mm cant grip 10.1mm so that leaves you with the 12mm and it cant do it either.

Stuart

I have an ER32 set and it only has the nominally even sizes.

My experience is that the compression range (diametric) is 2 mm for all ER collets inclusive of 6 mm and above.

Collets below 6 mm only have 1 mm compression.

That's why they sell the nominally even sets.

Also the ER series supposedly has a 20% longer grip axis than any other system, for potentially less run out.

Rob

From my experience the ER are only good for 1mm and thats a stretch.
2mm I think it would distort the collet for good, but have never tried it as I have a full 1mm increment set.

Dave

I've never felt comfortable screwing my 20mm collet down to 19.05 to suit the 3/4" shank cutters I have. Rego-Fix offer their ER32 collets in half millimeter increments up to 20mm, 39 collets in total. REGO-FIX® - ER Collets ER 32 / ER 32-UP The seventeen that I had covered most of my needs for cutter holding and when I found a 19.5mm collet, all of my needs within the 32's clamping range. I use a ER40 for inch and 25mmm shank cutters.

I don't have a spindle nose mounted ER chuck, the optimum setup for ER usage on the lathe but I do have a less convenient 20mm parallel arbored ER32 chuck that I can mount in a 4 jaw. That chuck has an adjustable depth stop, a handy feature that compensates for its other shortcomings.

Hercus 9s accommodate 3C collets in the spindle bore, I have a scant 3C collection. With the hollow draw bar long workpieces can be supported but the collets are nominal size only. Good quality 3C collets such as those offered by Hardinge and Crawford are fairly expensive. Bruce "Abratool" Smith uses Chinese 3Cs in his 260 Hercus and reckons they are fine. Bruce hasn't embraced the newer, 40 year old, ER technology yet.

I have a few Chinese 3 Morse collets that I'd bought to use in my Hercus mill to maximise Z clearance. Their nominal sizing offers no advantage over the 3Cs if used in the lathe spindle and they make work piece positioning difficult. The collet must be loosened, moved slightly forward in the bore for any readjustment, then pulled back again when tightened. Tricky. Chris has mentioned the other Morse collet deficiencies.

Mike, buy the biggest ER Morse arbored chuck that will suit your lathe along with a set of collets as a starter then make your own nose mounted chuck to suit, at your leisure. CTC chucks and collets are about the best value you'll find.

Bob.

Have a look at CTC Tools items - Get great deals on items on eBay Stores!

ER collet chucks are not hard to make. Buy the nut, but the bore is just an 8 degree taper and the outside is a metric thread. You can then make the back end to suit your lathe (A point of fact - I do the lathe attachment first so that I can then mount it on the spindle and get the bore concentric).

Michael

I've never found the basic even sized set to be a restriction. They definitely will pull down to the next even size without an issue.

The main advantage of having the odd sizes as well is that it would make it a lot easier to fit say a 16 mm end mill into a 16 mm collet. Instead using a 17 mm collet and pulling it down to 16 m would save the risk of cutting your fingers pressing it in (or wear gloves)..

The only odd sized collet I have had to buy was 3 mm because a 4 mm won't pull down to 2.5 mm.

My collet set is from CTC.

Rob

If you can't afford to lash out on a whole set of ER collets, buy the ones you need now and add to the set as needs be. An ER40 collet can be had for $13 with free postage on eBay. I have a couple from this seller and they are nice:

1 4" Super Precision ER40 Collet CNC Chuck MILL | eBay

I haven't found the imperial collets to be much (if any) more expensive, so buy sizes that cover a standard imperial & metric size. A 1/4" collet also does 6mm. A 1/2" collet comfortably clamps 12mm stock, whereas a 13mm collet would be at the limit of its clamping range (I also reckon 1mm is the comfortable limit of their clamping range). I only have five ER40 collets and they do everything I need (so far). I will probably get a 1" collet to take a milling cutter with a 1" shank.

Edit: Looks like CTC are cheaper than the seller I linked.