Drawbar Question

[blackhorse]

OK, you guys who aren't conceptually challenged as I am can start laughing now...

Am I correct in assuming that if you use a drawbar on a drill chuck in the tailstock, then you cannot crank in the tailstock, so that drilling must be done with the chuck in the headstock?

BH

 

[Richard Baker]

DH,
A drawbar is typically used in the headstock to secure a collet or a Morse Taper mandrel (with chuck or whatever) in place. When using an MT mandrel with Jacobs drill chuck in the tailstock a drawbar is not required, as the force applied during drilling (cranking in the tailstock quill) is sufficient to hold it in place and prevent it from rotating. Hope this is helpful. Have never used a drawbar in the tailstock, so do not know the answer to your question.

 

[Ken Grunke]

Am I correct in assuming that if you use a drawbar on a drill chuck in the tailstock, then you cannot crank in the tailstock,

With a drawbar in the tailstock, the tailstock ram can't move out. But it CAN be cranked in, and the drawbar would move with it.

 

[Mark Wollschlager]

Generally, you hold the drill chuck with your hand when cranking the tailstock back to keep the drill bit from hanging up in the workpiece and pulling it from the taper.
You probably won't forget to do that the second time

Mark.

 

[Bob Hadley]

First, make sure the Morse taper is engaged securely. You don’t need to hammer it into place, but a swift and firm shove into the taper is necessary.

Morse tapers (1, 2, 3 etc.) are described as "self-locking" tapers inasmuch as they should not require a drawbar to reliably engage the male taper to the female spindle. In certain special cases, in particular Morse taper collets, a drawbar is necessary.

On my mini mill I use both a M3 taper boring head and a Jacobs drill chuck without a drawbar and have no trouble with self-extraction of the taper. Same for the drill chuck in the tail-stock of my Jet 1642 lathe… but I did experience that problem with my two earlier lathes, I suspect the issue was poor quality fit in the mating tapers. Count this among the many things that may or may not be up-to-spec with lower cost, discount lathes or cheaply made Morse taper accessories. The tell-tail is uneven burnishing of the (what should be) precision ground taper.


BH

 

[Joe Greiner]

Provided that both the taper and the socket are well-cleaned, MT engagement can be enhanced by "wringing" into place: give the MT a slight twist as it touches bottom in the socket. My drill chuck has an ordinary shank, i.e. no female thread for a drawbar. Very rarely tries to disengage when withdrawing the bit, and that usually because I didn't engage it well enough. My tailstock must be advanced to allow placement of the MT, so for removal I just unwind back from that location. I've used it only once or twice in the headstock with similar results, but obviously need the knockout bar for removal. I don't remember why I used it in the headstock.

Joe