An ER32 chuck and full set of collets would be ideal offering maximum flexibility but of course can be a bet expensive to get a decent set all in one go. Some suppliers will sell the chuck alone and then you can add individual sizes of collet as needed. On my smaller mill I use ER 25 and leave the chuck pretty well permanently in situ. I use the collet chuck for drilling as well as milling.

Advantage of the MT3 collets is that they don't use any headroom but you will be limited to size choice. That said you can get away with just four for the common shank size cutters 4,6,8 & 10mm. More restrictive if you need larger sizes. Same applies you don't have to buy them all in one go.

MT collets have a very limited range of opening basically just the nominal size. ER collets have a wider opening range .5mm for the smaller sizes and 1mm for the larger this range enables holding tooling with odd size shanks and indeed drills as necessary.

John

Some thoughts.

I have not used morse taper collets but they have a bad press regarding removing them from some types of machine. Ideally if you use morse taper tooling you would want either a slot to allow use of a taper drift or a drawbar that was able to eject the morse taper from the spindle. The bad press is that without the mechanisms for easy removal they can be overtightened in the socket by too much drawbar tension and then they require a lot of effort to remove.

They do allow for more space under the spindle than an ER chuck and may be cheaper if you only use a small number of cutter shank diameters.

If you get a morse taper ER collet chuck it would be easy to put it in the spindle and leave it there then some point in the future find it is very hard to remove as it has not been disturbed for some time.

There is nothing to stop you from using ER32 for most work and having a few morse taper collets in common sizes for when you want a bit move space under the spindle.

Large diameter cutters or fly cutters can have a lot of reaction force on them. The shorter stick out when used with a morse taper collet would probably be better than the longer stick out that would result from using an ER collet. The more rigid a set up the better when making swarf. So if sweeping a large surface with a fly cutter is likely use a morse taper collet, using a Ø5 milling cutter in a morse collet may be hard to see if the spindle nose is over the workpiece.

Martin C

I bought an ER32 chuck for my lathe. I then bought a chuck for the mill as well. I’ve also got ER32 collet blocks and a Spin indexer so it’s all proved very useful. I did start with a few finger collets for my first mill though as I was short of cash at the time.

It's worth noting that the mill is also available with an R8 taper – some searching here would have suggested that this is a better choice than MT3.

Sorry, I missed that the OP has a mill, not a lathe.