end mill holder

[John galloParticipant @johngallo38006]

I have a Palmgren milling attachment for my South Bend 9A. I am trying to find the best way to hold an end mill in my headstock. My question is, does a 3mt, drawbar end mill holder work the same as a 3mt collet, and is one way better than the other? Might there be an even better way to do the job? Thanks in advance, John.

[John galloParticipant @johngallo38006]

[EmgeeParticipant @emgee]

Hi John

The end mill holder will most likely retain the cutter by a screw locating on the flat ground on the cutter, this type are called 'throwaway' cutters and are usually much lower cost.

The collet will of course grip the complete shank diameter for the collet length.

In both cases you will only be able to grip the 1 size of shank, however some cutters are available on a std shank size with different cutting diameters.

Emgee

[Martin ConnellyParticipant @martinconnelly55370]

You could consider a 3mt to ER32 collet holder. ER32 collets hold with a parallel action and so grip parallel shanks well. They are also more likely to have lower runout than an end mill holder that must push the cutter to one side of the hole to secure it. You also have the option to vary the stick out of the cutter within the limits of the shank. You can buy additional collets as required to keep initial costs down.

There is a thread on this subject called "ER Collet chuck or normal Morse Taper Collets", not sure how to link to it.

Martin

[Jon GibbsParticipant @jongibbs59756]

+1 for ER collets.

You could also make your own ER32 (or ER40 which has same collet internal angle of 8 degrees but larger thread & nut) collet chuck to fit your headstock thread. This will be a cheaper alternative than an MT3 chuck and would also give you another workholding method for stock up to 20mm diameter since you can pass it through the headstock bore without obstruction.

If you make the body then all you need are the collets, nut and spanner.

I can vouch for Harold Hall's instructions here… **LINK**

HH also gives instructions for the closing nut but at around £7 each for a bearing version which is superior then I'm not sure it's justified.

HTH

Jon

[MWParticipant @mw27036]

I would say that they are two different things, a collet being just a fixture for a tool of your choosing and a morse taper end mill being exactly that, a morse taper shank with a carbide tip fixed in place with a hold down screw.

You could argue that the collets are better because you can choose different sizes and tools to fit in it but with the morse taper end mill you are stuck with whatever diameter it is. Then again, if you buy it knowing you want to do alot of work with 1 particular size then maybe you would favor the cost saved by using a tipped tool at the set size, because you dont need to re sharpen it and just replace the tip. So its a matter of what you want it for.

I'm gonna go against the grain with this, but would argue theoretically, that for cylindricity run-out then a morse taper tool should work better in the headstock because, if its been made well, then theres fewer parts to run out if that makes sense, the more variables involved, obviously its going to be much harder to keep all of them moving centrally to each other.

I use ER 20, ER 32 and ER40 collets and i would say it still relies on a good setup to perform well and isnt necessarily a magic bullet.

Michael W

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