Aligning Tailstock

[Bamban]

Easiest way is to turn a 60 degree dead center in your lathe chuck and without taking it out of the chuck, slap this in there. I much prefer to make my own but then again, I have the stuff to make it with. That ET bar will work just fine for you.

Here is an example of the dead center Mikey mentioned. The test bar is a 12 inch ground rod from Pacific Tool and Gauge, the reamer grinder operation.

Watch "PM1440TV HS to TS Alignment Chuck Side" on YouTube

 

[RJSakowski]

Capturing a rule between the two centers isn't accurate unless the centers come to a sharp point.

The Edge Technology Bar method works but only at that particular distance. If the tailstock is not truly parallel, when you set it up with work at a different distance, the tailstock won't be on center.

A modification of the two collar method where the bar is turned between centers works and has the advantage of selecting a bar length appropriate to the job, thereby removing any errors due to a non parallel condition in the tailstock.

A variation of Rollie's Dad's Method where the far end of the bar is center drilled and the tailstock center is used will also work. The chuck can be used as the method accounts for any runout. It is not even required that the center drill on the tailstock end have no runout for the same reason.

Another method that works involves using an adapter for the tailstock that had a cylindrical section. The adapter was fit to the tailstock and an indicator was zeroed on the cylindrical surface. The adapter was then moved to the headstock with the appropriate sleeve, the carriage move to the headstock without changing the cross feed, compound and indicator and the indicator positioned on the cylindrical surface and read. I haven't found a source for the adapter yet so most likely one would have ti be made. Boring a dead cente and press fittin a short rod and turning true is probably the easiest way to make the tool.

 

[mikey]

So, let me ask you guys; if you align the tailstock at a foot from the chuck and it is dead on center, how off will it be at 6" or 18"? Is this something you tested or just heard somewhere? if you tested it, how off are we talking about?

Please enlighten us.

 

[Bamban]

Here is another way I did to make sure the TS is centered where I normally turn down barrels. Took a shot out barrel, chucked it up in the set tru 6J, dialed the bore, single point cut the center, then skim cut the od for no run out cylinder, flipped the barrel. Single point cut the center.

To test, chucked up a bar stock and single point cut the dead center. Put the barrel between centers. Indicate the cylinder skim cut on the HS side. Without changing the indicator setting and TS location, run the carriage to the other side, and flip the test barrel. Indicate the same cylinder that is now on the TS side.

As mentioned, TS center adjustment is specific to the location it was adjusted, all things being the same, like the gotchas mentioned by winegrower in his post.

 

[RJSakowski]

So, let me ask you guys; if you align the tailstock at a foot from the chuck and it is dead on center, how off will it be at 6" or 18"? Is this something you tested or just heard somewhere? if you tested it, how off are we talking about?

Please enlighten us.

If the tailstock isn't sitting square to the ways, advancing the quill will shift the center alignment. If there is a twist in the bed, moving the tailstock along the ways will shift the center alignment.

This shouldn't be a problem with good iron but Chinese iron???

 

[Bamban]

So, let me ask you guys; if you align the tailstock at a foot from the chuck and it is dead on center, how off will it be at 6" or 18"? Is this something you tested or just heard somewhere? if you tested it, how off are we talking about?

Please enlighten us.

Mikey,

My worn out ACER1236 is off by 0.004 between 2 locations I use the TS, judging by the barrel OD

Nez

 

[RJSakowski]

I first noticed the discrepancy when I was drilling .009" holes some years ago with my Atlas/Craftsman 6 x 18. I cherck tonight and it looks like I vary by around .5 to 1 thou horizontally over 1" of quill travel. My G0602 is good horizontally but drops about 1 thou at 2.5" of quill extension. I didn't check a different positions on the ways.

 

[mikey]

The reason I asked is not to be difficult or insulting in any way, I hope you believe me.

I asked because I tested for the impact of moving the tailstock to different places on the bed but I did not test for alignment with quill extension; that is a whole other can of worms. I don't recall the exact length of the pieces I used but I used three test bars, all cut on the same lathe with the same dead centers using the same lathe tool to the same depths of cut. This was done on an Emco Super 11 CD lathe with under 200 hours on it at the time so it was in pretty pristine condition.

What I found is that there was almost no difference in tailstock alignment when moving it up and down the bed but there was a difference in the indicator readings with how hard I locked the tailstock down and how hard I applied pressure to the ram when placing the test bar into position. The harder I tightened the ram or the tailstock locking mechanism, the more variance I got.

This sort of makes sense. The tailstock rides on the rear rail that takes almost no wear over time. If the ways are hardened and ground accurately then alignment should not vary all that much as you move the tailstock. It will vary with how hard you tighten the tailstock down because the locking plate under the tailstock is locking down at different places and who knows what the condition under the rail is at those places. It also makes sense that pressure from the ram will vary readings due to deflection of a bar. My personal practice based on these tests is to try to be consistent in how I apply pressure when locking the tailstock down and when applying pressure into the end of a work piece. Subjective, I admit, but I like to think I'm pretty consistent.

In practical terms, I submit that using a test bar between centers is an acceptably accurate way to align the tailstock. This is especially true if the bar is cut on that lathe and tested with the centers used to make the bar without moving the centers. This is just my opinion that is admittedly biased by my tests so I could certainly be wrong.

 

[projectnut]

Easiest way is to turn a 60 degree dead center in your lathe chuck and without taking it out of the chuck, slap this in there. I much prefer to make my own but then again, I have the stuff to make it with. That ET bar will work just fine for you.

I use the same method. I could insert a piece of round stock and do the 2 cut method, but I like the simplicity of the test bar. Since I don't have a taper attachment on either of my lathes I regularly offset the tailstock to make a taper. For years I did the 2 cut method, then got tired of all the extra steps. For the last 5 years I'ved use the Edge Technology Alignment Bar. I notice they've gone up in price. When they were "Made In The USA" they cost $49.95. Now that they're made in China they cost $79.99.

 

[epanzella]

I use a test bar as well for alignment. It plugs right into my MT5 headstck taper and is center drilled on the other end. I also use it as a quick check periodically because it's so convenient. Mine was made in England and cost $100.