Newbie question MT3 collet chuck

[fatoftheland]

Hello, I have a Warco 918 and want to fit a collet chuck to it. I know how to fit and remove my standard 3 and 4 jaw chucks but MT3 collet chucks have a taper with a drawbar thread. Do I need a drawbar on my lathe or is it just an interference fit? Confused!
Thanks


Jon

[John Rudd]

Jon,
IIRC, the 918 has a thread nose on the spindle....
There are 2 ways to do this, you could use the method you suggest and use a draw bar, else the 2nd is to buy an  ER chuck that mount on a backplate....like this...

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Lathe-Collet-Chucks...
If you already have the MT3 ER chuck, then the cheapest option is to use a drawbar..

[fatoftheland]

Thanks for the speedy answer and the welcome.
My first project will be a drawbar with some sort of centring plate for the spindle hole.

[John Rudd]

Tbh, it doesn't need to have a shoulder , a flat washer big enough to go over the spindle bore....
I use a piece of M12 studding with a nut and the washer is made from aluminium....
The ally is soft enough not to deform the end of the spindle, not that the nut needs to be tight....
I just screw the stud into the thread in the taper, fit washer add nut and just nip it up....over tightening just causes aggro when you come to remove it...

HTH....

[chipenter]

A washer with a shoulder is quicker to set up , I have made a short converter 3\8 whit to 12mm that fits imperial collets and only need one drawbar , morse and clarkson go to 3\4" ER32 go to 20mm , if you go for ER you wont need a drawbar as the collets dont have a pocket and long stuff can go up the spindle .

[John Rudd]

Oops, yeah I forgot to mention, if you go the backplate mounted collet holder route, as I linked to, as Chipenter says, long stock can go through into the spindle and beyond  if needed....but obviously if you go the MT route you can't do that....

[Manxmodder]

Thanks for the speedy answer and the welcome.
My first project will be a drawbar with some sort of centring plate for the spindle hole.

Jon,
Just to second what John Rudd has said,if you go for the draw bar setup don't over tighten it,a light nip is sufficient.

 Morse tapers are very shallow angled creating a high degree of wedging action with a comparatively large surface area and over tightening is a common error made by beginners to lathe practice.....OZ.

[sparky961]

I see some talk of "if you use a drawbar" - would you really trust the taper to hold while turning a part in the collet without one?

A drill chuck I get because almost all of the force is locking the taper even tighter.  But when turning, especially if you are applying force away from the chuck, I don't think I'd feel comfortable without something positively keeping the taper in place.

Having MT3 as the main taper in my combo-mill spindle, I know first hand that those buggers really lock up tight with too much force.

[DMIOM]

Sparky,

The original query was how to mount a collet chuck, possibly MT3.

In John's message (post no. 2) he suggested (a) Morse Taper plus drawbar, or (b) mount a collet chuck on a backplate on the spindle, which wouldn't need a drawbar and would leave the spindle bore free for longer stock.

[vtsteam]

They don't always stay in a drill press quill, either....... 

[chipenter]

Also iff you go for ER collets they are self extracting and don't have to bash seven shades out of the drawbar .

[Jonny]

MT3 just tap it and unwrap it, easy after grollying up just got to have the knack. I am usually on 4 changes an hour daily.
Unlike ER need three pairs of hands, take up extended length stressing bearings and reducing space available.

5C much better wish I hadn't given mine away.