Can I get an MT1 extension with a through hole?

I need to extend the shaft on my lathe. The shaft has an MT1 taper. I need to hold a milling tool in an MT1 collet, but if I just fit the collect into the end of the lathe shaft, it can't reach the work (the lathe has a gap bed, so the work can't be moved closer to the headstock). I can find MT1 to MT1 extensions, but I need one which has a through hole of at least 6mm dia for the M6 draw bar to tighten the collect. Does such a thing exist? From whom?

Thank you - Rowan

I have successfully hacksawed off the tangs of Morse taper drill chuck arbors and drilled them with hss bits. If you cannot find something ready made, you might be lucky and be able to get a 6mm hole through one. It all depends if the core is soft, though, I have drilled four MT2 ones easily.

The other way would be to hold the cutter in a lathe chuck and take small careful cuts. Not an ideal method as the chuck will not hold the cutter as securely as a proper collet.

Edited By old mart on 01/04/2023 14:22:24

I wonder if an MT1 fitting ER20 collet chuck would give you enough extension? As the small end of the collet is larger than the big end of the taper it would have to protrude at least 35mm from the spindle.

Brian G

If you have a look on Ketan's site you will find a few different adaptor sleeves, including an MT1 to parallel.
Yes it might need through drilling for a drawbar, but would provide a means to use your MT1 collet securely in a 3 or 4 jaw lathe chuck.
https://www.arceurotrade.co.uk/Catalogue/Adaptors-Sleeves

There are also R8 to morse adaptors , though only MT2/3

Alternatively, I wonder about any old length of round bar, with the end drilled/bored to accept your milling cutter, and held in a 3/4 jaw.
If the overhang/projection causes chatter, then run it through a fixed steady on the chuck side of the cross slide.

Bill

Thank you for those suggestions. I had not investigated ER collets, but will do so now. It seems to me that a Morse Taper collet chuck would work better than a faceplate mounting one, since it won't need to be centred. It looks as if an ER32 chuck would be most flexible since it seems to fit the largest range of collets, but I will see what gives me the amount of extension that I need in order to mill the parts that I'm working on.

Hi, I drilled a 10.5mm hole in a 3MT to 3MT extension from Arceurotrade, and didn't even bother to remove the tang, although I did do it on a big lathe at work. It was done for getting to mill a piece that I couldn't reach on my Chester milling machine, so was used to hold my collet chuck with a long piece of threaded rod, and it all went very well.

Regards Nick.

Edited By Nicholas Farr on 01/04/2023 17:52:30

.

With respect, Rowan … I fear that ‘flexible’ might be the unfortunate word there

I find it hard to visualise an ER32 chuck on a MT1 taper doing anything very useful.

[ Not sure what this milling job of yours involves, so I may be barking up the wrong tree ]

MichaelG.

I think Frances probably meant backplate mounting rather than faceplate mounting where the collet chuck is fixed to a backplate that screws straight onto your spindle nose. Main advantage of this type over a MT shank collet chuck is you can pass long stock right through as there is no drawbar in the way.

Are you saying that an MT1 mounted collet cuck will be too flexible to be of any use? And that a faceplate mounted one would be better? I don't have the experience to know this for myself, so if that really is the case, I will have to find a different solution. But then I ask myself, why would anyone sell MT1 collet chucks if they don't work satisfactorily?

Rowan

That sounds like a solution that might work for me. It needs to be an MT1 extension and I would need to drill a 6mm or 6.5mm hole for the M6 draw bar. I have ordered an extension and will have a go at drilling it when it arrives.

Rowan

Edited By Rowan Sylvester-Bradley on 01/04/2023 19:35:00

Rowan,

As you put it that way.

Do exactly what you want, buy an extra MT1 blank and drill it 6mm clearance.

.

I am simply observing that an ER32 collet chuck is a big heavy lump to put on the end of an MT1 … especially if that is an MT1 to MT1 extension [which is what you appear to be contemplating].

MichaelG.

.

Edit: __ yes, I see that such things exist

https://www.beaufortink.co.uk/pen-making-tools-drill-bits/collets-collet-chuck-sets/er32-18pc-metric-collet-set-and-chuck-1-morse-taper

Edit: __ There’s a nice sectional drawing of an ER32 on MT2 here: 

https://www.toolots.com/review/product/list/id/50939/

Try overlaying your MT1 dimensions on that …

it might be O.K. for what you want to do, but instinctively it just looks wrong.

Edited By Michael Gilligan on 01/04/2023 19:40:35

Hi Rowan what lathe do you have. I have a MT 1 ER16 collet set from RDG. If you can give us an idea for the job in hand it may help in suggesting other ideas.

David

As already mentioned, MT1 is a very small diameter to hold the larger sizes of er heads, even my little 7 x 12 lathe has MT3, so a plate type to fit on a chuck backplate would be much better. Getting one lined up should only take a couple of minutes with a lever indicator on a magnetic stand.

Yes, it has often been said that using an MT1 in the headstock was a design error on these Portass PD5 lathes. I will try with the MT1 extension that I have ordered, but if it seems problematic will move to an ER32 collect chuck on a backplate. Thank you for your advice.

Rowan

This is my MT1 ER16 collet holder with a fly cutter facing of s smsll casting.

David