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Sherline Tailstock Misaligment
- Thread starter tomw
- Start date
- Joined
- Aug 5, 2015
- Messages
- 276
I, like previous posters on the subject of tailstock alignment, have had my frustrations with my first Sherline lathe bought in 2012. The headstock on that lathe is out of alignment with the tailstock. When the headstock is in very good alignment with the ways, the tailstock is out by 0.005". That's 0.010" TIR! Back then Sherline even exchanged my headstock when I complained. The replacement was no better. I thought of ways to correct the alignment, but gave up. I had thoughts of making an offset key that would move the headstock over 0.005" but Mikey talked me out of it. I then realized that the hold down arrangement did not have enough slack in it to allow such an offset in the headstock anyway. I lived with it.
I had to choose whether to align the headstock to the bed ways or to align it to the tailstock, depending on the job.. Never both.
I bought the adapter for the tailstock with the small chuck that can be used to compensate for the misalignment, but don't really like it. And the thought of having to use that and an offset center....well...not so good.
Then....
I came across a lightly used Sherline lathe on Craigslist last year at a good price and bought it. My intention in buying the Craigslist lathe was to set it up just for threading. It was made around 2017. To my joyful surprise it does not have such tailstock alignment problems. Because it turned out to be the better lathe all around, I set up my older lathe for threading instead. Most threads I cut are very fine and pretty short.
My point in this rambling discussion is that not all Sherlines are created equal. I think Mikey must have gotten a good one to start with. I got one with lousy alignment and one that aligns pretty well.
Now I am happy with my setup. Of course the good thing about the Sherline headstock is being able to take the key out and turn the headstock to cut tapers. I have used it to cut odd tapers like the ones on on watchmaker lathes. Very easy to dial in.
However, I WISH that the Sherline tailstock was designed so that the misalignment could easily be corrected. If some entrepreneur offered up a good modification to the tailstock that would allow the user to align it both vertically and horizontally, I am sure I would be their happy customer.
I had to choose whether to align the headstock to the bed ways or to align it to the tailstock, depending on the job.. Never both.
I bought the adapter for the tailstock with the small chuck that can be used to compensate for the misalignment, but don't really like it. And the thought of having to use that and an offset center....well...not so good.
Then....
I came across a lightly used Sherline lathe on Craigslist last year at a good price and bought it. My intention in buying the Craigslist lathe was to set it up just for threading. It was made around 2017. To my joyful surprise it does not have such tailstock alignment problems. Because it turned out to be the better lathe all around, I set up my older lathe for threading instead. Most threads I cut are very fine and pretty short.
My point in this rambling discussion is that not all Sherlines are created equal. I think Mikey must have gotten a good one to start with. I got one with lousy alignment and one that aligns pretty well.
Now I am happy with my setup. Of course the good thing about the Sherline headstock is being able to take the key out and turn the headstock to cut tapers. I have used it to cut odd tapers like the ones on on watchmaker lathes. Very easy to dial in.
However, I WISH that the Sherline tailstock was designed so that the misalignment could easily be corrected. If some entrepreneur offered up a good modification to the tailstock that would allow the user to align it both vertically and horizontally, I am sure I would be their happy customer.
- Joined
- Dec 20, 2012
- Messages
- 9,422
It can be done. I don't think there is enough meat in a Sherline tailstock to be strong enough so you would need to make a custom tailstock but that wouldn't be all that hard to do, either. I thought about it once and decided I rather just make a more accurate live center and that worked out okay for me.
- Joined
- Jan 28, 2020
- Messages
- 197
I didn't know about it. I found a 2"x48" RadiusMaster Series II belt grinding machine at www.trick-tools.com. From the description and photos, I'd say that is quite a tool. I see that it's made in Australia.
- Joined
- Feb 24, 2018
- Messages
- 1,044
Yep, a combination vertical and horizontal belt grinding machine, with the radius wheel cartridge, that has 3 different rollers, that can be changed almost effortlessly. I have no idea where it’s actually made, but it is an Australian design. I found it’s incredibly versatile.
RM48, Radius Master Series II Belt Grinder, 2x48 belt sander
The Radius Master grinder offers greater versatility than any other belt grinder. 7 grinding surfaces include 5 radius wheels with no tools required.
Damn!! That’s gotten expensive, when I got mine I paid about $1600, and I felt somewhat violated, but after using it, as long as I live, it will not be leaving the shop. I also have a 2” x 72” Burr-King, the RadiusMaster is my go to machine.
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- Joined
- Feb 24, 2018
- Messages
- 1,044
No, the speed is constant, at roughly 3800 fpm, the Burr-King is variable speed, I guess some people find it to be an asset. I just turn it on and use it. I’ve never felt the need for more speed, even at 3800 fpm and a 50 grit ceramic belt, I can remove some serious metal, but still have enough control to do light touch ups. Would variable speed be a bonus, maybe, but so far I have not needed it.
- Joined
- Jan 28, 2020
- Messages
- 197
Mike,
I checked headstock alignment, following your instructions in your 2020-June-18 post. Doing this took three tries. Here is what I did the third time:
I cut a 3/4" OD 6061 aluminum rod 5" long on a bandsaw. With the rod held in the three-jaw chuck, I turned down four-inch-length-of-it with 0.010", 0.003", and 0.001" cuts. I achieved a decently smooth finish using a HSS tool bit that was custom-ground for aluminum by Jeff. I cut with 500 rpm at the spindle, 25 rpm at the z-axis handwheel, which works out to 0.0025" feed/spindle revolution). Using a micrometer, I measured the OD of the rod at 3.5" and 7" to the right of the pivot point of the headstock (where the locking screw is located). These locations on the rod corresponded to roughly 3.75" and 0.25" to the left of the right end. The OD at 7" to the pivot point of the headstock measured 0.0075" greater than the OD at 3.5" from the pivot point. The headstock was definitely misaligned (not square with the ways).
To align the headstock, I preloaded a dial indicator against the rod at 7" from the pivot point of the headstock. I loosened the locking screw, and tapped the headstock until the dial indicator showed that the rod had moved 0.0075" toward the front. I tightened the locking screw. To check the new alignment, I covered the 4" turned length of the rod with black permanent-marker ink. Removing the ink from the entire 4" turned length required two 0.003" cuts. After the second 0.003" cut, the point at 7.5" from the headstock pivot point was 0.0010" greater in diameter than the point at 3.5" from the headstock pivot point. I made a final 0.001" cut, and the difference in diameter went to zero (not measureable).
Comment: When I measured the misalignment, I wondered whether there was enough play between the headstock and the alignment key to move the rod 0.0075" and achieve alignment. Based on my observations during tapping and watching the dial indicator, approximately 0.009" was the maximum amount that the rod moved.
Karl
I checked headstock alignment, following your instructions in your 2020-June-18 post. Doing this took three tries. Here is what I did the third time:
I cut a 3/4" OD 6061 aluminum rod 5" long on a bandsaw. With the rod held in the three-jaw chuck, I turned down four-inch-length-of-it with 0.010", 0.003", and 0.001" cuts. I achieved a decently smooth finish using a HSS tool bit that was custom-ground for aluminum by Jeff. I cut with 500 rpm at the spindle, 25 rpm at the z-axis handwheel, which works out to 0.0025" feed/spindle revolution). Using a micrometer, I measured the OD of the rod at 3.5" and 7" to the right of the pivot point of the headstock (where the locking screw is located). These locations on the rod corresponded to roughly 3.75" and 0.25" to the left of the right end. The OD at 7" to the pivot point of the headstock measured 0.0075" greater than the OD at 3.5" from the pivot point. The headstock was definitely misaligned (not square with the ways).
To align the headstock, I preloaded a dial indicator against the rod at 7" from the pivot point of the headstock. I loosened the locking screw, and tapped the headstock until the dial indicator showed that the rod had moved 0.0075" toward the front. I tightened the locking screw. To check the new alignment, I covered the 4" turned length of the rod with black permanent-marker ink. Removing the ink from the entire 4" turned length required two 0.003" cuts. After the second 0.003" cut, the point at 7.5" from the headstock pivot point was 0.0010" greater in diameter than the point at 3.5" from the headstock pivot point. I made a final 0.001" cut, and the difference in diameter went to zero (not measureable).
Comment: When I measured the misalignment, I wondered whether there was enough play between the headstock and the alignment key to move the rod 0.0075" and achieve alignment. Based on my observations during tapping and watching the dial indicator, approximately 0.009" was the maximum amount that the rod moved.
Karl
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- Joined
- Dec 20, 2012
- Messages
- 9,422
Very good, Karl. If you can cut all the way down a 4" rod and have zero difference in the diameters at any point on that rod then the headstock has to be aligned with the ways. Get used to this procedure because if you ever have to cut a Morse taper, or any taper, then the way you do it is to offset the headstock. Then you have to put it back. Now you know exactly how to do it!
- Joined
- Jan 28, 2020
- Messages
- 197
Mike,
Aligning the headstock was the prelude to making a test bar and measuring the tailstock misalignment. I followed your instructions in your June 17 and June 18 posts, except that I made the test bar six inches long instead of twelve inches long. I didn't expect to succeed with the first one, and my projects so far have been on pieces less than six inches long.
I cut my 6" piece of drill rod from a 3'-long 3/8"-diameter tight-tolerance W1 tool steel rod (McMaster-Carr #8890K247). I made the machined section 1" long instead of your "maybe 1/2" long". I initially made the section 1/2" long, but that length required large tailstock ram extension to be able measure the diameter with my dial test indicator mounted in a Sherline insert holder tool post (#7600). For facing the ends and machining the section, I used a Sherline 55° RH carbide insert 3/8" tool holder (#2256) with carbide insert (#7605), as I don't yet have an adjustable tool post for mounting the custom "square" HSS tool bit that Jeff ground. (Cutting conditions for the section: 340 rpm spindle, 12.5 rpm z-axis leadscrew handwheel (0.0018" feed per spindle revolution); 0.010", 0.003", and 0.001" depth of cuts; and Boelube 70104-L machining lubricant.) The section came out adequately smooth.
I measured horizontal and vertical misalignment values across 4.4" of the 6"-long test bar. The values were 0.0032" and 0.0006", respectively. Here is a photo of my measuring set up, using a dial indicator mounted in the Sherline insert holder tool post (#7600) for horizontal, and dial-test indicator mounted in Sherline riser rocker tool post (#1288) for vertical.
Question: Are the horizontal and vertical misalignment values of the tailstock closer to 6"/4.4" times greater than what I measured? (multiplied by the ratio of the test bar length and the length that I measured across)
In doing this exercise, I came to realize that a dead center from Sherline can have significant runout. I measured 0.0008" TIR at the dead center in the headstock. The TIR varied between 0.0006" and 0.0010" as I loosened, turned, and reinstalled the dead center through 360° relative to the headstock spindle. (On July 16, I measured 0.0002" TIR at ID of the headstock Morse taper, near the mouth.) The misalignment values I reported above were measured with the spindle turned midway between the high and low points on the dial indicator (when the machined section of the test bar was at the headstock).
I didn't measure the runout of the tailstock dead center. I measured 0.0010" TIR on my Sherline adjustable live center (#1201), and 0.0002"-0.0003" TIR on my Sherline adjustable bullnose live center (#1205).
Karl
Aligning the headstock was the prelude to making a test bar and measuring the tailstock misalignment. I followed your instructions in your June 17 and June 18 posts, except that I made the test bar six inches long instead of twelve inches long. I didn't expect to succeed with the first one, and my projects so far have been on pieces less than six inches long.
I cut my 6" piece of drill rod from a 3'-long 3/8"-diameter tight-tolerance W1 tool steel rod (McMaster-Carr #8890K247). I made the machined section 1" long instead of your "maybe 1/2" long". I initially made the section 1/2" long, but that length required large tailstock ram extension to be able measure the diameter with my dial test indicator mounted in a Sherline insert holder tool post (#7600). For facing the ends and machining the section, I used a Sherline 55° RH carbide insert 3/8" tool holder (#2256) with carbide insert (#7605), as I don't yet have an adjustable tool post for mounting the custom "square" HSS tool bit that Jeff ground. (Cutting conditions for the section: 340 rpm spindle, 12.5 rpm z-axis leadscrew handwheel (0.0018" feed per spindle revolution); 0.010", 0.003", and 0.001" depth of cuts; and Boelube 70104-L machining lubricant.) The section came out adequately smooth.
I measured horizontal and vertical misalignment values across 4.4" of the 6"-long test bar. The values were 0.0032" and 0.0006", respectively. Here is a photo of my measuring set up, using a dial indicator mounted in the Sherline insert holder tool post (#7600) for horizontal, and dial-test indicator mounted in Sherline riser rocker tool post (#1288) for vertical.
Question: Are the horizontal and vertical misalignment values of the tailstock closer to 6"/4.4" times greater than what I measured? (multiplied by the ratio of the test bar length and the length that I measured across)
In doing this exercise, I came to realize that a dead center from Sherline can have significant runout. I measured 0.0008" TIR at the dead center in the headstock. The TIR varied between 0.0006" and 0.0010" as I loosened, turned, and reinstalled the dead center through 360° relative to the headstock spindle. (On July 16, I measured 0.0002" TIR at ID of the headstock Morse taper, near the mouth.) The misalignment values I reported above were measured with the spindle turned midway between the high and low points on the dial indicator (when the machined section of the test bar was at the headstock).
I didn't measure the runout of the tailstock dead center. I measured 0.0010" TIR on my Sherline adjustable live center (#1201), and 0.0002"-0.0003" TIR on my Sherline adjustable bullnose live center (#1205).
Karl
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