Thread: What size collet set to buy?

Hi all,

With the Pacific mill looking like it's going to be fully operational in the near future, my attention is slowly turning to acquisition of a collet system. My current mill (45 size gear head mill) has a collection of ER32 collets and the appropriate arbor, being a MT4 to match the spindle. Given I made the purchase of tooling for this mill with zero milling experience, the ER32 size was a very good and sensible choice. My up and coming mill has an INT40 taper and so requires new tooling. So once again I am faced with a similar choice. Do I stick with ER32 collet system or take advantage of the larger range and go for an ER40 system? I could just keep the ER32 collets and buy a new arbor but I plan on selling those collets with the mill when the time comes.

Are there any disadvantages of an er40 collet system over the er32? I realise there is an increase in size and so I guess bulkiness of the collet arbor itself for smaller jobs. TBH I'm leaning towards keeping the ER32 system as I have not found their sizing to be of any limitation with any work I have done so far but I just thought I would ask peoples opinions.

Edit: Oh I guess if all else is pretty much equal then one thing to consider is cost. 32 collet set is considerably cheaper than a 40.

Cheers,

Simon

You've pretty much answered your own question

But, remember ER40 only goes down to 3 mm. The extra size to 30 mm is handy though.

Yes ER40 is a lot more bulky and expensive, but it's a long term investment. However clearance can be an issue when gear cutting etc.

Comes down to personal choice.

Maybe it's a flip a coin decision.

I have ER32. Whatever you buy, make sure to get the full set.

Do you expect to be using larger diameter tooling than you have now?

If not I would suggest to just get an Int or Bt collet Chuck to suit the Er 32.

If you wished to go above 20 mm just by an Er 40 Chuck and the collets from 20 to 30.

If and when you sell your other mill the addition of Er 32 collets may gain you a few dollars but not an amount to cover the repurchase of another set in my opinion.

I would go the opposite route: I would buy a couple of ER-16 collet chucks, a set of collets, and duplicates in common sizes (3/4/6/8/10mm). Sometimes you really need that extra clearance around the chuck that you can't get with a bigger option.

For your main chucking solution, I'd stick with ER-32. Buy a couple of the chucks (I'd go at least 4), and again, buy extra duplicates in your common endmill shank sizes. I can't emphasize how much you'll wish you had extras when you have to swap tools multiple times in a job, and I always find I need more collets in the sizes I'm already using (for example, 8mm rougher in one chuck, 8mm finisher in another, two collets and chucks for the same job).

Thanks for the replies. Yes the er32 have served me well and have never felt the need for larger cutters. However i was pretty much limited by lacj of rigidity anyway. Thats nog as much of an issue but i cant really see my patterns of usd changing much i guess. Purchasing several of the same chucks will not be happening. I have more time than money, being a hobby. In any case i cant see the cost benefit in the time saving of swapping an entire chuck over an individual er collet.

As for having both er32 and 16, well i can see merit in that if a particular job limits the room of the cutter. As for use of smaller cutters, ive never used smaller sizes as i have not had a mill that achieved the required speeds. worth a look.

Cheers.

Simon

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A 40 taper ER chuck costs $50-60, and you will save so much time it's not even funny. Changing an ER collet and tool out is an order of magnitude slower than just slacking off the drawbar and swapping in a new chuck. Even if you have two chucks, it will save you hours and hours in short order, especially if you end up with any repeated cuts - a dovetail for example - that require roughing and finishing steps. If you swap the tools out of one chuck, you'll need to reset your Z zero, in addition to the pain of having to do the tool change.

Your time may be free, but the frustration saved is easily worth the cost of buying another collet chuck.

Having a smaller collet chuck isn't about the size of the cutter, it's about getting any cutter to where you need to cut; for example, if you need to cut a slot 25mm from a shoulder 50-75mm high, you won't be able to get the collet chuck close enough to the shoulder to allow the cutter to reach the part. Having an ER-16 chuck about half the diameter of the ER-32 chuck will get you into all sorts of tight spots like that.

Ultimately mill tooling isn't something you can cheap out on. If you're doing enough milling to justify moving up from an RF-45 machine to a knee mill, then you can justify just a few little expenses that will save you hours per year and dramatically increase your flexibility.

I did run ER32 collets in my lathe and mill but when the new mill came along, switched to ER40 - for the simple reason that ER32 stopped at 25mm from memory and as I use them in the lathe for holding stock as well, the ER40 with extended range going to 30mm was a plus. I found the extra bulk of the chuck to be minimal (they both are a big lump of metal; one is just slightly larger)
I rarely get into a situation where the collet chuck gets in the way but I made up an extended nose ER25 chuck for those occasions. You can buy straight shanked ER collet holders, so a simple solution may be to go for the ER40 and also buy a straight shanked holder with the appropriate collets for the cutters you are likely to use - if for milling cutters there is likely to only be a handful that you do need.
I do have a spare ER40/NT40 chuck in Adelaide - never been used - bought I think when I got confused about whether I had one on order or not

Michael

Originally Posted by Precious Mettle

A 40 taper ER chuck costs $50-60, and you will save so much time it's not even funny. Changing an ER collet and tool out is an order of magnitude slower than just slacking off the drawbar and swapping in a new chuck.

Not on my mill. You have to loosen the bolt. They are always stuck even though it is supposed to be non stick taper, so you have to hit the drawbar (good for the spindle bearings) to loosen it. Then as the mill is so high you have to stretch up and unscrew the drawbar while you hold the tool otherwise it will fall down when it unthreads.

Might be quicker with a power drawbar, but certainly not when it is all manual. I use the ER spanners like this
ER40 Collet Nut Wrench

Transitioning from a 45 size geared head mill to a knee mill im finding myself to be a little clumbsy in my use and operation. Although i felt this way when i first starting using the 45 mill so no doubt will get used to a bigger machine however i think i would change out an er collet quicker than a chuck for similar reasons to RC. The ability to maintain Z datum is however a compelling argument for multiple chucks.

Simon

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