Tailstock Handle

[Canuck75]

For some time I have wanted to change the tailstock locking system on my 10” SB.

Except for threading, and without a DRO, my compound rest is often at the 90 degree position to get those small accurate distances for turning, parting, etc. Add a situation where you want tailstock in close for support it becomes difficult to get the wrench in to tighten or loosen the locking nut, and you can’t use the compound handle with the wrench in place. Maybe others have noticed this same issue.

I thought a solution was possible so made the parts necessary for a lever and cam operated locking system. The original lock used a 1/2”-13 centre bolt and needed 1/4 of a turn to operate (.019” tightening movement). I turned a .032” offset on the cross pin which through the lifting yoke, gives the same effect. I also kept the locking handle in close to the tailstock which gives good compound dial/handle clearance at max cross-slide where the base of the compound hits the tailstock casting. Everything fit nicely into the tailstock cavity and the only modification necessary was to drill two 1/4” holes up from the bottom at the rear of the boss to hold the device in place.

Already feels normal.

Hope some of you find this interesting.

 

[4ssss]

Nice job. Very impressive idea.

 

[T Bredehoft]

I applaud your inventiveness. That lack was one of the deciding factors that convinced me I needed a new (PM10-30) lathe.

Edit: correct typo

 

[SLK001]

That looks very good.

But... I question the need for it. With the compound at 90º, you get a 1:1 ratio of feed to input. If you change the compound to 30º, then you get a 0.5:1 ratio of feed to input, so it basically doubles your resolution on the compound dial. With the compound at 30º, you will have the clearance you need for the tailstock wrench. The only time that you should ever need the compound at 90º is possibly when you are trying to bore an accurate depth hole, but even then, there are better ways to do it. If I needed an accurate depth, I would use a micrometer carriage stop and dial in the depth I needed and just turn to the stop.

That said, your mod would be VERY useful when drilling DEEP holes (those deeper than the tailstock ram travel), where you have to unlock the TS and move it out to clear the chips. I recently had to drill multiple 8" deep 1/2" hole (in steps) in steel on my Heavy 10. A levered TS clamp would have come in very handy!

 

[Canuck75]

Thanks for the interest. For SLK001 you bring up some good points, in particular the additional accuracy that an angled compound can give you, however, at 90 degrees I find it easier to not have to compensate for the change in cross slide position to maintain a diameter. Yes, instant lock/unlock definitely helps with deep drilling.

Thanks again.

 

[markba633csi]

Now I see why some lathes have the locking handle at the rear of the tailstock- makes sense now. I always preferred the front handle, but I can see
the advantage of having it in back or like you did with a cam device.
Nice job on your mod; how did you drill the two 1/4" holes by the way?
Mark

 

[Canuck75]

Mark,-

Good question and part of the planning of whether it would work or not. Removed the bottom plate, anchored the casting upside down against an angle plate, dialed the bottom surface in flat, located on the bolt hole with a DI, knew where I needed the holes relative to the centre hole and the original boss above, spot faced with a 3/8" EM (head size), then drilled thru 1/4". The best part is the heads are accessable through the casting hole in the base plate with it installed.