Using a drive center or live center to turn stummels?

[FrJacob]

I’m using one of Trent’s pipemaking chucks and they can pivot while being turned. Any one use a drive center or live center top when turning a stummel? An MT2 extension could get a drive center to the stummel. I’ve been exchanging emails with a machinist whose freaked out by the extending jaws of this classic and elegant chuck and it’s capacity to pivot. He says there’s no way to tighten the chuck enough to eliminate the possibility of this happening while turning, especially when chamfering the top of the bowl for a bulldog. This did happen to me. It tore out a chunk of cast iron out of the side of the compound channel where the t-bolts hold the tool post.The shank hit the ways and the end exploded into fragments. Pretty exciting. I just figured I’d not tightened enough or too too big a cut at one time. Maybe both. But maybe additional support is a good idea?

[LatakiaLover]

This might give you some thought food:

https://www.youtube.com/watch?v=YxVodOHo1Nw

[DocAitch]

(I edited this after watching the Former video)
Seems to me that sufficient contact between the jaws and block should prevent rotation. Lathe guys go to a lot of trouble to square their blocks to achieve that. I note that Former in the above video seems to have done that.
The chamfer of the top of the bulldog bowl can be turned before cutting the chamber and you could use a center there
I foresee some problems trying to use a center after you bore the chamber- there is no center there, same with the shank after boring the mortis.
Addendum- after watching Former do this on a lathe, it appears that you can use a center for the outside of the bowl and for the outside of the shank, then bore, but again, I do note that Former doesn’t use a center.
DocAitch

[seamonster]

There is a trick that goblet turners use: punching a hole in a tennis ball and poking the live center into that hole. This might allow a live center
to be applied to a pipe that has the chamber already drilled. Perhaps a smaller diameter rubber ball, to help with tool clearance.

That being said, I've turned about 20 bulldogs lately, and not engaged the tailstock for support ever. Small gentle cuts. The only time I use a live center to support a stummel is during the last few passes on a long, thin shank....

[wdteipen]

Turn your bowl round first then cut your chamfer for the bulldog bowl. I use Trent's chuck and have no issues turning bulldogs and don't get catches. I also don't typically square my blocks unless they are way off. Everything is easier to turn when it's rounded and doesn't have an irregular surface.

[caskwith]

Yep, I use a live centre on shanks and quite often on bowls. I don't think it's essential but it allows me to remove material faster and with more confidence and safety. I use a standard live centre for the shanks and I have an homemade large/pipe centre for the bowls.

[n80]

I use a live center on the shank and rarely on the bowl. Wood lathe though.

[FrJacob]

Great and very helpful responses! Thanks to all of you. I need to develop safe procedures so I can make them habitual and focus on the pipe!