Ah ok ,
these are the ones I saw from a supplyer I have used before.
Stu
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Tailstock Alignment?
- Thread starter Kroll
- Start date
Ah ok ,
these are the ones I saw from a supplyer I have used before.
Stu
Yes, that is it. I do not use two indicators, I just do the top and side separately. You have nice zero run out on your indicators, so the bar is accurate. The lathe is accurate, too, if the indicators read the same value at both ends. I used that for setting up my tail stock, which was way farther off than it should have been. The tail stock required quite a bit of work to get it right again, scraping the bottom of the tail stock where there was rock and poor spindle readings. Got them all back correct again. The goal when reconditioning these items is not to get them dead nuts, but to leave them set up to be correct when working against the tool pressure and wear of the parts over time. The tail stock spindle for a 13x40" lathe like mine should read about .0005 to .001" higher at the left end than the right end with the quill extended all the way and locked, and the same values when measuring on the side of the tail stock spindle, .0005 to .001" closer to the tool out near the end, compared with close to the tail stock housing, again with the spindle locked. That helps to correct for movement from the weight of the part and the pressure of the tool, along with wear over time.
Yeah, mine is nothing like that, looks like a much better thought out design. The one I have is the typical ones that were sold on ebay from India. I paid something like $40-$50 shipped for my MT5 at the time.
To make protected centers, first drill the center, and then use a cutting tool with a larger included angle, like a countersink, to add a shallow cut at a wider secondary angle at the surface of the work. Then, minor dings in the end of the part will not disturb the 60 degree center cone.
Never occurred to me to use it unsupported - that would certainly make it unreliable.
Ultimately, what you're doing is taking one center out of the equation. The MT end acts as a center and test bar, the other end is held in a center. It doesn't provide any more accuracy than using two centers and a standard test bar. In theory, it could be less accurate, because the bar taper might be off, but then so could the tapers on the centers, or the points on the centers for that matter. So in my thinking, it's one fewer potential point of failure, and it was cheaper than the non-tapered Edge product
Never occurred to me to use it unsupported - that would certainly make it unreliable.
Ultimately, what you're doing is taking one center out of the equation. The MT end acts as a center and test bar, the other end is held in a center. It doesn't provide any more accuracy than using two centers and a standard test bar. In theory, it could be less accurate, because the bar taper might be off, but then so could the tapers on the centers, or the points on the centers for that matter. So in my thinking, it's one fewer potential point of failure, and it was cheaper than the non-tapered Edge product
I was curious how much runout & sag it had so I did some quick measurements. With just a dial indicator, pretty much no needle movement close to the head stock just like the spindle taper. Just barely over a thou runout at the unsupported end. Supported it with a center, about .0002". I didn't bother to grab a tenths indicator or run my carriage along it. Back into the drawer it goes.
I bought it in case I ever need to align the headstock. Luckily I haven't needed to yet. I'll worry about it when that time comes. For testing bed twist/cutting a taper & TS alignment I'll keep using the other methods I have been using.
Thanks but I won't bother. I'll just use the oak dowel I bought a couple of weeks ago for knocking out centers (thanks again to whoever suggested it). I was just using a piece of alumn stock before, never got around to making a knock out bar, kind of glad I didn't.
When I bought my test bar I wanted something to verify readings that I had from my made devices. I had already done the donut test bars and a ground rod but I wanted something that took “me”out of the equation.
Luckily my bar a mt3 fits the spindle on my jet lathe the tailstock on my 14x40 and with the mt5-3 reducer it works for the spindle. So for the couple bucks I was able to check both lathes and have something for aligning fixtures with the popular mt mount. And yes it sits in the box for the most part but at least once a year I go around and make sure everything is reading correctly. Which is coming soon once these temps stay consistent.
Luckily my bar a mt3 fits the spindle on my jet lathe the tailstock on my 14x40 and with the mt5-3 reducer it works for the spindle. So for the couple bucks I was able to check both lathes and have something for aligning fixtures with the popular mt mount. And yes it sits in the box for the most part but at least once a year I go around and make sure everything is reading correctly. Which is coming soon once these temps stay consistent.
To check the alignment between the chuck and the tailstock at further distance than a 12 inch test bar, I made a test bar from a shot out barrel.
First after cutting off the complete chamber I dial the bore using 0.0001 increment Deltronic pins. Once satisfied with the near zero runout, I single point the 60 degree center cut. Then I turn down a register to indicate on. With the bore dialed to near zero runout, the register cut is coaxial with the bore.
Flip the barrel, dial it in and single point the 60 degree center cut.
To test the alignment I chuck a grade 8 halt inch bolt and single point cut the dead center point. With the repurposed barrel test bar between dead centers, I indicate the register at the chuck end, then flip the test bar and indicate the register at the tailstock end.
On my 1236 there is 0.002 difference front to back with tailstock near chuck and further out. So, when turning I know which way to adjust. I suppose the difference is due to wear.
First after cutting off the complete chamber I dial the bore using 0.0001 increment Deltronic pins. Once satisfied with the near zero runout, I single point the 60 degree center cut. Then I turn down a register to indicate on. With the bore dialed to near zero runout, the register cut is coaxial with the bore.
Flip the barrel, dial it in and single point the 60 degree center cut.
To test the alignment I chuck a grade 8 halt inch bolt and single point cut the dead center point. With the repurposed barrel test bar between dead centers, I indicate the register at the chuck end, then flip the test bar and indicate the register at the tailstock end.
On my 1236 there is 0.002 difference front to back with tailstock near chuck and further out. So, when turning I know which way to adjust. I suppose the difference is due to wear.
Here’s the setup for checking horizontal alignment of the tailstock:
Run the carriage left to right and adjust the tailstock until there’s no variation in the dti reading.
Positioning the clock on the top will check the vertical alignment though there’s rarely adjustment for this:
You can also do a quick check with a ruler gently gripped between centres. Ruler vertical checks vertical alignment, ruler horizontal checks horizontal alignment:
Hope this helps,
Mal