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Westline
02-14-2011, 06:38 AM
I recently had to setup my tailstock on the lathe, after I had to remove it for a job.
My problem was I don't have a testbar to make sure my chuck and tailstock is lined up.
I have a ground bar from a printing press that is ground to 0.005 mm.
Used that to dial in my chuck to total TIR of 0.015 mm more than good enough for the general work I do (and not to bad for a 3 jaw chuck on a cheap asian import)
Now how to setup the tailstock?
I'm not sure if anybody has done this or even if this is correct but it seemed right to me. ( If there is some problems please let me know.)
http://i1094.photobucket.com/albums/i460/KobusWestline/IMG_0176.jpg
I dial indicated the inside of my MT3 tailstock. I know it runs at a taper but if I use the same height on both side the taper should be the same right.
To make sure it's level front and back I used a cheap (but light level) not to bend my dial indicator or deflect it down to much.
The level is only accurate to 0.5mm over a meter but it's all I had to make it work.http://i1094.photobucket.com/albums/i460/KobusWestline/IMG_0177.jpg
I hope this helps someone or at least supply a bit of humour to their lives:D

Ron of Va
02-14-2011, 08:46 AM
Here is a similar method.
http://www.youtube.com/watch?v=1EZh8SUoA4o

Westline
02-14-2011, 09:18 AM
Ron of Va
thanks I'll check it out.
Only discoverd Tubal Cain's channel after a post from Tony Ennis on ACME thread.
His channel is a gold mine for a new guy like me.

Forrest Addy
02-14-2011, 11:50 AM
Tramming in the tailtock bore from the quill is exactly the wrong method for vertical alignment but right on for horizontal. Perfect alignment in the horizontal plane will not endure zero taper in a long turned piece. You still have to contenf with tool wear and work deflection. .

Westline
02-14-2011, 12:05 PM
Tramming in the tailtock bore from the quill is exactly the wrong method for vertical alignment but right on for horizontal. Perfect alignment in the horizontal plane will not endure zero taper in a long turned piece. You still have to contenf with tool wear and work deflection. .
It was one of my worries. If I misunderstand this please correct me.
Are you saying the tailstock would be aligned for center drilling and short shafts or anything that is centered close to the chuck.
The tailstock is lined up with the chuck and not the path the tool travels on the ways.
So if I mount a long shaft it will not be paralllel with the ways cuasing me to cut it tapered.

tdmidget
02-14-2011, 12:08 PM
What's up with that level? 2 things here:
If you just removed the tailstock and replaced it, there should be no change if everything is clean and intact.
Indicationg the quill taper or a center in the quill will get you lined up. No level needed.

tdmidget
02-14-2011, 12:16 PM
The tailstock will always be aligned with the ways, both for tailstock and carriage. The quill may offset but it is still parallel. Indicating the quill to the spindle means that your quill , or what ever is in it should be centered on the workpiece in the chuck, collet, whatever. If you have a long piece in the spindle and it is not parallel with ways, the you headstock would be out of alignment and that VERY unlikely. Indicating the quill will not change the headstock.

edit: the quill will be centered on the spindle's axis of rotation.

Westline
02-14-2011, 12:44 PM
What's up with that level? 2 things here:
If you just removed the tailstock and replaced it, there should be no change if everything is clean and intact.
Indicationg the quill taper or a center in the quill will get you lined up. No level needed.
My tailstock has bit of a droop so I just made sure the dial indicator is on 0 and 180 deg not somewhere in between that will affect my reading.

chipmaker4130
02-14-2011, 12:45 PM
I think Forrest was saying that even if the tailstock is perfectly aligned, cutting a long and therefore more flexible piece will likely result in 1) Tool wear, and 2) Mechanical deflection; both of which will interfere with a straight cut.

Toolwear may not be much of an issue, depending on tool material vs. workpiece material but deflection is always something that must be mitigated.

Westline
02-14-2011, 12:50 PM
I think Forrest was saying that even if the tailstock is perfectly aligned, cutting a long and therefore more flexible piece will likely result in 1) Tool wear, and 2) Mechanical deflection; both of which will interfere with a straight cut.

Toolwear may not be much of an issue, depending on tool material vs. workpiece material but deflection is always something that must be mitigated.
This is pretty much a given isn't it. No matter if the tailstock is aligned or not material especially long thin material deflect thats why there is follower and steady rests
Or am I missing something?

tdmidget
02-14-2011, 01:09 PM
My tailstock has bit of a droop so I just made sure the dial indicator is on 0 and 180 deg not somewhere in between that will affect my reading.

throw the level away. You put your indicator in the chuck, collet whatever, and set it in contact with the quill taper. rotate it . Your are looking for the readings at 3 and 9 o'clock. It does not have to be exact. The level is undoing everything you might have done. Don't let any thing touch or influence the indicator. Do this with the quill retracted so that it is supported.When you have the same reading at 3 and 9 o'clock the it is time to put a piece between centers and take a cut. This the real proof in the pudding. Measure the taper and adjust half that distance in the appropriate direction. the indicator will get you centered. Centered may not do the job if there is any twist in the bed. The absolute last word here is "how does it cut?". This overcomes twist, clearance in the quill, or any other variable that may be present.

moe1942
02-14-2011, 04:19 PM
I think there is some confusion on test bars. Any piece of CRS round stock is all you need. It should be at least 2/3 the length of the bed. Machine two raised shoulders. One at the headstock another at the tail stock end. That is the only true way I know of to check for misalignment and bed twist.

rws
02-15-2011, 07:26 AM
So why wouldn't using the indicator as shown work for vertical alignment? You are measuring the same thing, just at 12 and 6.

Westline
02-15-2011, 07:37 AM
So why wouldn't using the indicator as shown work for vertical alignment? You are measuring the same thing, just at 12 and 6.
:) You got me ....I still has to get around to it I tried to get some Tailstock viagra to sort out my droop but seems I'll have to shim it up abit.
I'll get there don't worry.

Westline
02-15-2011, 07:41 AM
The absolute last word here is "how does it cut?".
You know you just hit the nail right on the head... I have to do it and Gitrr done:)

aboard_epsilon
02-15-2011, 09:01 AM
dont forget your tailstock has a lock on it ..that will push the barrel to one side.

and the barrel will be worn to some extent ..

best way is trail and error ..chucking a 1 inch or more diameter bar in it..say 14 inches long ..with dead centres ..and taking cuts ..and adjusting tailstock untill cuts are as equal as you can get .

all the best.markj