bgreenb Posted April 24, 2014 Report Share Posted April 24, 2014 Hi all, Wasn't sure whether to post this in the Turner's Corner or here, but it seemed like more of a tool question. Mods feel free to move it. I recently got an old Jet 1236 lathe from a neighbor. It was kind of beat up, but I cleaned it up a bunch, and the motor is in great shape. I haven't actually used it to turn anything, and I'm looking to build Marc's tilt top table in the next month or so. Anyway, I got a new drive center and tailstock center for it, and when I installed them I noticed that they are misaligned by about 1/16" in two dimensions (see pic). Both of them spin true (no wobble), but they're misaligned. How big of a problem is this? Part of me says that as long as I contact the center of each end of the blank, and they both spin true, and I put the tool rest parallel to the blank, everything should be fine, right? Maybe not. I'm new to turning. If it's a big problem, how do I fix it? I suppose I could shim the tailstock on the dovetail ways, but it's difficult because it's a moveable part - in other words, if the tailstock were stationary, you could shim it and just leave it, but it has to travel along the lathe bed. Any advice? Thanks! Quote Link to comment Share on other sites More sharing options...
TerryMcK Posted April 24, 2014 Report Share Posted April 24, 2014 You should be able to loosen the bolts holding the head stock on the bed and move it slightly from side to side to correct horizontal alignment. There is generally enough play in the holes to do that. Is it also out of alignment vertically? Quote Link to comment Share on other sites More sharing options...
bgreenb Posted April 24, 2014 Author Report Share Posted April 24, 2014 You should be able to loosen the bolts holding the head stock on the bed and move it slightly from side to side to correct horizontal alignment. There is generally enough play in the holes to do that. Is it also out of alignment vertically? Yes, it's out of alignment vertically as well (by the same amount). Essentially, if the drive center is in the center of a clock, the tailstock center is at about 4 o'clock (in other words, it's about 1/16" over to the side and down, relative to the drive center). I didn't think about removing the headstock. Maybe I could move it to the side and shim it up? Or just shim one side of it upward, which would take care of both directions. Does that make sense? Quote Link to comment Share on other sites More sharing options...
bgreenb Posted April 24, 2014 Author Report Share Posted April 24, 2014 As I take a look at the manual online (http://ec1.images-amazon.com/media/i3d/01/A/man-migrate/MANUAL000057398.pdf), it appears that the headstock comes attached to the lathe bed. It's not obvious from the exploded diagram how it is attached (I'm not in front of the machine right now so I can't look further). If the headstock comes attached to the bed, it might be difficult to shim. Quote Link to comment Share on other sites More sharing options...
skiback46 Posted April 24, 2014 Report Share Posted April 24, 2014 The possibility also exists that there's some rust or crud in the Morse taper housing. If you take both centers out, take a small brass brush to the insides, and make sure there's nothing that's causing the centers to not be centered. You could also try rotating the centers a little, to see if they sit differently at different angles. If you find an orientation that works mark both pieces so you can put them back in the same orientation. Although I just reread your post and since there's no wobble, that seems unlikely on the headstock, but double check the tail stock(which is static) since it may be just misaligned in the sleeve. Quote Link to comment Share on other sites More sharing options...
calblacksmith Posted April 24, 2014 Report Share Posted April 24, 2014 I can't say anything for the Jet, METAL lathes have adjustment in the tail stock for alignment as it is common to offset the tailstock front and back, for turning a taper when between centers. Do check the MT holes for being clean. I suspect that the headstock is held on by bolts from under or inside the head stock. That is the way that my el cheepo HF lathe and my Powermatic lathe are put together. If there is no vertical adjustment in the tailstock, and it is higher than the headstock it is easy to shim the headstock up for alignment. I would also try to place as long as possible of a rod into the headstock spindle. If you can get it aligned squarely into the spindle, you can then check to see if the spindle is square to the ways or if it is running at an angle but it may be close enough just by aligning the centers to each other. Quote Link to comment Share on other sites More sharing options...
bgreenb Posted April 25, 2014 Author Report Share Posted April 25, 2014 Thanks guys. I removed the cover on my headstock last night and found the mechanism for rotating/moving the headstock. I didn't have a ton of time to mess with it, but I think I can get it in the right position and lock it down there, probably with a couple of small shims. I will also clean out the morse taper housings to be sure there's no gunk in there. Quote Link to comment Share on other sites More sharing options...
dtrust Posted April 25, 2014 Report Share Posted April 25, 2014 All good answers. You are on the right track by adjusting the headstock first.. Being a machinist for many years, I can tell you there is a lot to consider when lining something up. Many variables, more than i will bore you with here. The quick answer is that for a wood lathe, considering the way it will most likely always be used, the alignment between the headstock and tailstock isn't as critical as turning metal. (only because you are doing most if not all dimensioning by hand.. As calblacksmith said, if you can get a long rod that is straight, and set it up true with the headstock then you can see if the tailstock is really out of alignment, and if the headstock is out of alignment with the bed. I'm at work now, and can't take long here, but there should be many internet sites that would help with understanding the alignment issues you aredescribing. sorry if this is too vague. :-) Don Quote Link to comment Share on other sites More sharing options...
Byrdie Posted April 27, 2014 Report Share Posted April 27, 2014 You don't want to shim the headstock because shimming it will interfere with the ability to rotate it should you ever want to use that feature in the future. Instead, the drive center is mounted to the inside of the headstock, usually with two or three bolts. There should be enough play in those to loosen them very slightly and shift the position of the drive center in relation to the tailstock so that they align. Quote Link to comment Share on other sites More sharing options...
mikem Posted April 28, 2014 Report Share Posted April 28, 2014 I would check the bearings in the head stock, make sure they aren't wobbling. Quote Link to comment Share on other sites More sharing options...
ScoFF Posted May 8, 2014 Report Share Posted May 8, 2014 How aligned is acceptable? At what amount of misalignment would you start seeing issues and what would they be? Quote Link to comment Share on other sites More sharing options...
skiback46 Posted May 8, 2014 Report Share Posted May 8, 2014 If the headstock does circles around the tailstock....there's really no amount of misalignment that is acceptable. After that it will depend on the length and diameter of the piece you are turning. If its something small and thin, the misalignment will be very problematic, but if its a bowl(which really just uses the tailstock for support) or a 15" spindle you could probably get away with 1/32" or so? But it will make things more difficult, like making peppermills where you need to bore from both sides. Since I haven't tested (and have no intention of screwing up my lathe to do so) I have no idea. Quote Link to comment Share on other sites More sharing options...
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