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View Full Version : Adjustable tailstock quill bushing?



DICKEYBIRD
11-21-2009, 08:30 AM
I ran across these pics during my Sat morning coffee/web perusal and wondered if this adj. bushing setup from a horizontal mill might help snug up a worn tailstock quill. Pretty neat deal regardless.

http://i57.photobucket.com/albums/g227/DBAviation/TailstockAdjBush.jpg

http://i57.photobucket.com/albums/g227/DBAviation/TailstockAdjBush2.jpg

edit: Ahh, it just dawned on me; you'd have to rig up some way to push the bushing into it's tapered bore rather than pull like I 1st envisioned.

John Stevenson
11-21-2009, 09:07 AM
Something like a taperlock ?

.

J Tiers
11-21-2009, 10:09 AM
That sort of thing occurred to me also. Nobody has EVER done it on any commercial lathe, as far as I know, although it makes a lot of sense if you are going to use (and wear out) the tailstock. Not even the very best makers I know of.

That's a little odd, as it is the ONLY item which is both very hard to fix, and has no adjustment capability whatsoever.

Possibly that is because the most usual means would put the 'works" up front right where you do NOT want the barrel to be thick and clumsy. So it was just deemed impractical.

More likely, since it would be possible to reverse the system and have a narrow nose, it is because the makers figured that if you wore out the tailstock, you could just get another one from them , or alternately, that if you wore out the tailstock, the ways were probably down to a nubbin.

Leblond had replaceable ways on at least one model, but I wonder if anyone ever did that, or if they instead just surplused/scrapped the machine when worn too far. Probably the latter. Tailstock ram could at least be locked, and most likely got moved a whole lot less.

DICKEYBIRD
11-21-2009, 10:14 AM
Yup! I just Googled "Taperlock"...very interesting stuff. Geez, the more I think I've learned, the more I realize I have left to learn.

Should I copy/paste that into the one-liners thread?:)

Bguns
11-22-2009, 05:51 AM
Gee, I mentioned this many threads ago, using a 5C as an example

Lets reinvent the wheel....

I have run a few horizontals that use that system for outer end of arbor...

A tailstock with a wheel ( in center section of tailstock) to tighten up a pair of opposing collets, is just too simple of an idea to concentricly align a tailstock spindle/ram. Another wheel/ handle for tailstock feed....

Would involve grinding both collet seats in, and would allow precision = to concentricity of collets and tail stock ram collet tapers/seats...

Worn ram/spindle, just pop a new one in, let collets adjust for center... Test bar for scraping in, would just be simple OD ground round stock..

Would be perfect for CNC, release collets, use ballscrew for ram/spindle/quill feed, lock collets.....

Could even allow for larger than spindle hole diameter bar feed, from tailstock end...

oldtiffie
11-22-2009, 06:22 AM
Bguns,

you are on the right track so far as I can see.

Quite some time ago I was putting new quick-connectors on the garden hoses. Those connectors - which have been around for years - are split/sawn radially in several places and have an end taper like an ER collet.

The closing nut is similar to an ER collet nut as well. The nut it tightened to close the "collet" onto the hose. It grips pretty well.

It struck me that the radially-slit tapered-nosed "split collet" and the male screw for the "collet nut" could be machined onto the nose end of the tail-stock. The pseudo "ER nut" could be made of any material, that is to hand that suits.

Bguns
11-22-2009, 06:33 AM
Every one fixates on one end of tailstock.. Both ends need to be constrained.

Headstock side will wear more, but if both ends are centered by collets, end of problem...

Tiff
A set of bevel gears, and an opposing set of ER collets ( to turn ER collet nuts), could work also...

John Stevenson
11-22-2009, 07:08 AM
Only one end can be restrained as the back end is always moving.

Chances are though that if initial wear at the front, the most likely area, can be reduced the non rocking won't wear the rear.

Do other snug the barrel lock up when starting a hole to reduce any wobble ?
this is the way I was taught.

Timleech
11-22-2009, 07:25 AM
First big lathe I had , Polish (AFM?) had adjustable headstock bearing, similar idea but much longer, and with threads both ends so it could be loosened as well as tightened. Not sure now whether it was split all the way along, or just relied on compressing the bronze sleeve within the tapered housing to get the few tenths of adjustment needed. I'd thought that was a common way of adjusting headstocks? I suppose you could arrange a captive nut to enable adjustment both ways from one end.
Obviously more difficult to apply to a tailstock but it could be done. Certainly quite expensive to do properly, with two precision tapered parts to make as well as the other complications.

Tim

DICKEYBIRD
11-22-2009, 08:56 AM
Gee, I mentioned this many threads ago, using a 5C as an example

Lets reinvent the wheel....Oops, sorry Bguns, I musta missed your previous post and wasn't trying to steal your idea.:) It just occurred to me when I found those pics.

Speaking of collets though, wouldn't an ER style or full length split collet be better so that the diameter reduction would be full length rather than just one end like the 5C? Come to think of it, with the many slits of the ER style, it could be bathed in oil and would last forever, no adjustment needed. Catch 22

oldtiffie
11-22-2009, 09:13 AM
I think we are too constrained to thinking and staying within the square/box.

In my first year as an Apprentice I was put to work on a OZ-made flat-belt driven "Hercus" (SB licenced clone) lathe with a capstan attachment on it (the tail-stock was to be kept for centre-ing work). The idea was to show me that somethings taught at "Tech School" needed to be expanded upon or "unlearned".

It was a great time with some great teachers/Tradesmen. The main lesson was in stuff that otherwise might have been done with/on/by a tail-stock.

In every case, the drill, centre drill, reamer, taps, dies ("Coventry" and "button") etc. were held solid in its adaptor in the capstan head.
http://en.wikipedia.org/wiki/Die_head
http://www.namco-tooling.com/coventry-dieheads-chasers.html

http://www.mechanicalindetail.info/turret-capstan-automatic-lathes/differene-between-turret-lathes-and-capstan-lathes.htm

http://www.google.com.au/search?hl=en&source=hp&q=turret+lathe+and+capstan+lathe&meta=&aq=5&oq=turret+lathe

They were fed in and out by the capstan. All forces absorbed or applied otherwise to a tail-stock were absorbed by the sliding capstan bed and then to the lathe bed to which it was bolted/clamped.

Over time I moved onto bigger and better turret and capstan lathes ("Herbert", "Ward" etc.) and quite enjoyed them as they really made hard work easy once they were set up.

They were great engine lathes as well - including thread-cutting and centre-work (the live/dead centre was held in the capstan/turret too).

A centre drill and a spade drill are pretty good at self-centre-ing as well. They are often better on a longer flexible "stalk" in the tail-stock drill chuck than they are with the quill with-drawn and the tool as close to the chuck as possible.

The drill chuck ("Jacob's", "key-less" etc.) are "rubbished" as regards use in a drill press but then the same people will use them in the quills in their lathe tail-stocks and mill quills - seems a bit inconsistent to me.

I see a lot of comment about laterally aligning a tail-stock centre for one position of the quill but never for vertical alignment. I never see any mention or questioning as to whether the tail-stock quill axis is in fact parallel to the lathe bed and/or head-stock spindle axis - but it should be.

Is there any good reason why the quill should not be locked/clamped in the tail-stock and the tail-stock move/d along the lathe bed instead of being clamped to it?

Is there any reason why the turret/capstan tool-holder/adaptor cannot or should not be emulated on the cross-slide or in a tool-holder in the tool-post?

J Tiers
11-22-2009, 10:47 AM
Every one fixates on one end of tailstock.. Both ends need to be constrained.

Nah, it is just easier to focus primarily on the end which receives the direct wear, including particulates carried in , as few/no small lathes have ram wipers.

if the ram is long enough, the far end has any errors reduced by the "lever arm' between it and the distance of extension.

And there is a decent chance of installing an adjustment on the nose end as a retrofit.



I think we are too constrained to thinking and staying within the square/box.

The drill chuck ("Jacob's", "key-less" etc.) are "rubbished" as regards use in a drill press but then the same people will use them in the quills in their lathe tail-stocks and mill quills - seems a bit inconsistent to me.


Nope, different situation. Spinning the work automatically tends to keep the drill centered. If you need better precision, don't use a drill. I don't "rubbish" the drill chuck..........it works well for what it does, at least as good as the average drill, which would need to be ground to a precision exceeding the usual "hold it up and gage it with a gage calibrated in 64ths" procedure. making a 120" C-C lathe, and turning it into an 85" C-C at extra cost would cause the purchasing agents to dustbin your literature.



Is there any good reason why the quill should not be locked/clamped in the tail-stock and the tail-stock move/d along the lathe bed instead of being clamped to it?

Is there any reason why the turret/capstan tool-holder/adaptor cannot or should not be emulated on the cross-slide or in a tool-holder in the tool-post?

The first ones probably WERE moved along the bed. Then it was noticed that it was both easier and more effective to clamp the casting and just move a ram.

The turret is good, but obviously adds expense and takes up a lot of space, so teh lathe would then have less distance between centers for the same length (and cost) of bed.

if you suppose that large production lathes were not purchased in part on a relative cost basis, you have a few more "thinks" coming. They were highly competitive, and extra cost wasn't an option unless it had a compelling benefit. making a 120" C-C lathe, and turning it into an 85" C-C lathe at extra cost would cause purchasing agents to simply dustbin your literature.

Bguns
11-22-2009, 03:45 PM
Back to my idea again :)

As I said before, 2 opposing Collets would allow:

Different tailstock ram/spindles to be easily changed. Morse, ER collet nose, threaded OD or ID, etc...

Larger than headstock spindle bore work to be fed in from tailstock end

Wipers easily fitted to both ends (Simple lip seal)

Length of ram/spindle can be almost infinite. Travel probably to 2/3 or so of length between collets.

A large beefy key can be used in both collets to prevent ram/spindle rotation.

Aside from clamping wheel in middle of tailstock to draw collets up, and a hollow tailstock feed handle, would not look too unusual..

Rear OD of ram/spindle could be Acme or Buttress threaded for ram/spindle feed. With major OD of thread same as OD of ram/spindle.

Rear feed wheel would only push pull on ram/spindle, and would still allow collets to center ram/spindle

Tailstock would have 2 slots, one for wheel clamping collets midway, and one for ram/spindle feed wheel near outboard end .

A grinding spindle could be made to fit in also, instead of a normal ram/spindle.

A solid cross dovetail, or box way type crossslide on tailstock base with graduated dial for adjusting tailstock setover, would be a nice touch with a grinder spindle...

motorcyclemac
11-22-2009, 03:56 PM
Do others snug the barrel lock up when starting a hole to reduce any wobble ?This is the way I was taught.


I do that. It is also the way I was taught. I was also instructed back in the day that you should treat the tailstock well and clean / lube it frequently. I disassemble mine occasionally for a complete cleaning and re-lube. I suspect that if you treat it correctly it will last for a lifetime. Mine uses a cam locking mechanism so often when drilling holes I will release the cam and back the tail stock out to clear chips. I then reinsert the bit..and relock...continue cranking. This saves some of the wear on the tailstock as opposed to cranking in..and out so much. Not to mention it is much faster.

Cheers
Mac.