collet chuck vs collet arbor used on lathe headstock spindle

[Y C LuiParticipant @yclui16187]

My Emco Compact 8 lathe is equipped with a ER25 collet chuck which can hold workpieces of diameter up to 16 mm. The spindle has a MT3 taper bore so it should be possible to put in a MT3 ER32 milling arbor to hold larger workpieces. I am wondering if this is a good idea because if this works Emco would not have made a collet chuck. Inquiring mind will appreciate some answers .

[Y C LuiParticipant @yclui16187]

[Paul LousickParticipant @paullousick59116]

The collet chuck will allow you to pass long pieces thru the spindle bore. A 3MT-ER32 will hold larger diameters but not pass anything thru the bore. Both have their advantages. An ER32 collet chuck is a better option

Edited By Paul Lousick on 14/07/2022 09:21:48

[Clive Brown 1Participant @clivebrown1]

Presumably your collet chuck allows long pieces of bar to pass through the spindle.A chuck which is mounted on an MT would prevent this

[EmgeeParticipant @emgee]

Sounds OK for short work pieces, but check the MT3 socket will take a full length MT3 taper because many of the 5 series spindles need a reduction for a small length of the taper diameter at the small end.

Emgee

[bernard towersParticipant @bernardtowers37738]

Make your own spindle mounted collet chuck or buy an er25 flange mount collet chuck and make a backplate , also get oversize collets to 20 mm.

[Paul LousickParticipant @paullousick59116]

Bernard. The first line of the post states " My Emco Compact 8 lathe is equipped with a ER25 collet chuck"

Edited By Paul Lousick on 14/07/2022 11:21:27

[bernard towersParticipant @bernardtowers37738]

SORRY MISREAD

[DC31kParticipant @dc31k]

If you go for a MT3-mounted chuck, you will need a drawbar if you are to subject it to anything but axial compression loads.

[old martParticipant @oldmart]

You might be able to get a MT3 er40 collet chuck if larger size is important.

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