Thread: Grinding a Hardened Tailstock Bore

Ha ha, good story, I always wondered why they were just a teensy bit different.

If that's the case, at the rate I screw up I'm going to be REALLY famous one day!!!

Pete

If the sine bar and the DTI (existing taper) disagree, which do I favour?

If the alignment of the workpiece is laterally out - say I didn't have the TS centred when I did my setup - will the DTI still give me correct alignment of the compound with the taper? Pretty sure the Sine bar won't.

BTW Bryan, sing out if you need an MT4 reamer. I have a genuine USSR Soviet ditto. When you open the package you can hear strains of the Red Army Choir and the Americans go to Defcon Three.

Greg

Originally Posted by Bryan

If the sine bar and the DTI (existing taper) disagree, which do I favour?

If the alignment of the workpiece is laterally out - say I didn't have the TS centred when I did my setup - will the DTI still give me correct alignment of the compound with the taper? Pretty sure the Sine bar won't.

The Sine bar should give you an absolute value for the compound. As you suspect, any tailstock offset at set-up will render an error in the workpiece. I would have thpught that centres would be required to ge the TS ram colinear with the spindle axis. The TS chuck allows you to zero the runout, but only to some random, unmeasured offset.

Plus you used a Falcon part, thereby negating the whole enterprise. Couldn't you get a Masserati or Alfa Guilieta unit?

Guido Q

Originally Posted by greg q

btw bryan, sing out if you need an mt4 reamer. I have a genuine ussr soviet ditto. When you open the package you can hear strains of the red army choir and the americans go to defcon three.

Greg

Грегори Всегда комик :u

Originally Posted by Bryan

If the alignment of the workpiece is laterally out - say I didn't have the TS centred when I did my setup - will the DTI still give me correct alignment of the compound with the taper? Pretty sure the Sine bar won't.

Hi Bryan,
I was liking your idea a lot until you said this, now I'm not so sure. I've read stories about the work piece "walking" out of the chuck if the steady isn't "close enough"*. I wonder if you need to check the alignment vertical and horizontal with a DTI? But that beings in any errors in your bed.

* How close is "close enough"? no idea. I've havent done much work with steadys and the work I have done was much longer and pipe. (of course if your tailstock was to far out the work wouldnt turn between two four jaws..........)

Am I worring about nothing?

Stuart

Originally Posted by Anorak Bob

Грегори Всегда комик :u

да товарищ, особенно когда подпитывается лучшая водка Родины!

Grigor

Originally Posted by Bryan

Ok here is my cunning plan. The 4 jaw in the tailstock is live. This allows me to true both ends of the quill.



Which allows me to set up a steady.



Which allows access to the bore.



The 6" chuck is bolted to a modified Falcon front hub, which is mounted on a dummy quill.

No turnips were harmed in the making of this film.

Outstanding Bryan, outstanding.

Phil

Originally Posted by greg q

да товарищ, особенно когда подпитывается лучшая водка Родины!

Grigor

подпитывается ?????

Bryan,

When you have the time is there any chance that you could post some additional photos of the live tailstock chuck assembly? Nifty idea .

Bob.

Originally Posted by Greg Q

Plus you used a Falcon part, thereby negating the whole enterprise. Couldn't you get a Masserati or Alfa Guilieta unit?

Guido Q

I'm pretty sure Bryan wanted it to last longer than to "get it out of the mechanics and round the corner"

Was it an iconic falcon, or just some new plastic trash? My drop hammer has a h...something 6cyld front spring as the main coil, and red motor main bearings and diff (as clutch) from the same car. Old car parts are real useful and pretty cheap and easy to get, not to mention add a good story.

I'm watching with interest as i am still undecided whether to remake blondies quill, i swear i can see machining marks on it, but it seems to be too small to lock in the tailstock

Ewan

The night owls have left many deposits. Too hard to do multiple quotes but I'll take questions in order.

Greg, thanks a lot for the offer of the reamer. But I think that score line would read Mussolini one, Stalin nil.

Stuart, of course I will do my best to get the two axes aligned, that is, I don't think I'll have a walking problem. The question came from my experience of painstakingly setting the compound to a theoretical taper and having the part not quite fit. That was for a spindle adaptor and I was working to a drawing. Admittedly I didn't use a sine bar but indicators to show deflection over a known distance. Plenty of possibilities for error in that method. But it made me reflect that if you can read the mating part directly, there's less to go wrong. Which I then did, and it fitted.

Phil, thanks but I can't take credit for the idea of the live chuck. I read about it somewhere - possibly PM.

Bob, I will get some pics for you later.

Ewan, thank you for fielding Greg's cheek. Do you consider an AU plastic trash? That's what I'm driving so that's what I had on hand. I like that it has beefy angular contact bearings that are preloaded and idiot-proof. And the sizing is just right. Your TS it sounds like a candidate for a new quill, and boring the body in situ. Of course you have to think about the ways first. The hardest part of making a quill I think would be getting the fit with the body just right, along with a nice finish. On mine that fit is still very good so I'm leaving it be.

Today I hope to play with alignment then try and true the quill and see how the steady runs. Last night I finished the chuck mount and just slapped it together for the snaps.

Bryan

What brand of lathe is that ?

The steady is not sitting on the bed ? Looks like you have a spacer or bed protector there ?

In the words of the ultra right wing ( I didnt want to say fascist ) red headed QLD ex politician "please explain"

MIKE

edit ..its an illusion of the pic .. the steady rest is OK

Originally Posted by Bryan

The question came from my experience of painstakingly setting the compound to a theoretical taper and having the part not quite fit.

Yes I understand what you were thinking about.(the problem I see is that however you set the angle there is no way of easly tweaking it once you have the work piece setup. Maybe you need to make a test piece so you can be sure the angle is correct?)

But wasn't your tail stock low?
The only way I can think of to check the alignment is to set it up as you have and then loosen the steady. If the work still runs true then you are good to go. If not, you'll have to make some adjustments. Then careful tighten the steady(maybe with a couple of DTI on it to make sure you don't deflect it).

Stuart