Monarch 10ee

Michael--I do believe you nailed it. Checked out the undercarriage bearings, sure enough the bearing on the headstock side was not touching, and the one on the tailstock side just barely. I adjusted the headstock bearing as much as I could . It is just barely touching (maybe I need a new bearing?).

Bottom line: GREAT improvement. Down to about a thou over 11" on a now greatly thinned test piece. I suspect when I put the collet chuck on and turn a 1"x 12" piece it will be t--- on. Thank you, Michael. If you are ever in our territory stop by. I have some wine waiting for you.

I'd like to get back in the shop tomorrow but The Wife and I are going away for a few days .---Matt
 
Glad to hear you are making progress, I cant tell if you adjusted the bearings front and back, but there are two on back side of lathe too. I don't know how those bearings could ever wear out, they turn very slow. On a well used lathe its not likely you will get them perfect but you should be able to dial it in to a happy compromise, no binding is the goal, but least amount of slop possible. I think the spec is a few thou clearance between bearing on lathe. Now to get down to tenths. On my very worn machine, I get 3 tenths taper on 3/8" diameter work piece, no measurable taper on 3/4" work. Factory spec was half a tenth over 6 or 10".

good work
michael
 
I'll check the backside bearings before we leave today. Thanks again.
 
Put the collet chuck back on, adjusted the backside bearings, chucked a 3/4 ground and polished rod sticking out 8.5", no tailstock support.

Dead on at tailstock end, dead on at headstock end (or as close as I can read from the Mitutoyo indicator) , about .002 off in the middle.
 
Took the bar out and placed it in a large vee block on the surface plate. Ran over it with the .0005 indicator, no runout.
 
Chucked a 14" length of 1.25" axel metal turned it front to back and back to front taking .005 cuts. Beautiful finish. That's the good news. Still off .006 end to end.

Chucked an eight inch (stick out) piece of 1" aluminum and got .006 runout over the eight inches. The problem seems to be close to the chuck. About 3-4 inches from the chuck things go to hell.

I got thirty collets with the machine. Most of them have "pecker" marks on the nose. This indicates to me that most work was done close to the chuck.

Comments?
 
I assume the axle was supported by the tailstock center which might indicate the tailstock needs adjustment.

As far as the aluminum goes, are you sure the bar is straight to begin with? I would check it in V-blocks before I ever used it for a test bar. Not just one V-block, a V-block on each end.
 
Yes, it was supported by a live center. I did check and the tailstock is lined up.

Did not check the aluminum bar beforehand. I'll check it on the V- block, I have a large one.

I've been chasing this since I got the machine a few weeks ago. I'm thinking the ways are off near the headstock because it appears most work was done there. Guess I'll just have to live with it. I'm not about to have the ways reground, that would cost more than I paid for the machine.

So, what's the downside? I'll still be able to thread, cut tapers, face, but what about chambering? I'll use my Clausing if I have to do any long turning.
 
No expert in this area, but a few things to consider.
1. If you had excessive wear near the headstock on the bed, this would drop the cutter head relative to the center line of the chuck. Assuming the cutter is cutting on center line this would increase the diameter of the work at that end, as oppose to decrease it, but decrease the diameter toward the tailstock end assuming that on the center line (cutter would move up or down relative to the center line). You might double check the cutter height, and take a few passes with slight height adjustments. You should also be able to check tailstock height, if it is just a touch high or low relative to the chuck, the diameter will increase at the tailstock end assuming the cutter is at center at the chuck.

2. Check the TIR of chucked stock at the headstock, if it is out 2-3 thousandth, then that will give you the profile you describe.

3. If you have a 0.0001" dial gauge with a flat tip, mount it to the carriage first run it the horizontal plane, then the vertical plane, use something like a 12-18" ground precision rod and run it up and down the X axis slowly turning the chuck by hand wo/w support at the tailstock. Note the +/- TIR swing around 0 along the rod. Wider swing at one end would suggest a centering issues, wider swing in one direction, would suggest an alignment issue. If in the vertical plane the tailstock is high or low, it may need to shimmed or ground.

4. I would try to take a few passes with a very sharp cutter on Al bar stock with the stock held at different lengths w/wo the tailstock, like 6, 8 and 12". This will give you some idea of the affect where the problem is occurring and the influence of the tailstock on the cut.
 
I do not suspect this is your problem, but its best to rule out the easy stuff first, have you trammed your tailstock bore to your spindle yet. You can have tailstock centered front to back just perfect but if your tailstock is high or low by more than a thou or so you can have problems, Usually what happens is people move the tailstock incorrectly. They loosen tailstock clamp and push it or pull it by top of tailstock at the spindle or handwheel. This tilts that tailstock and the soft cast iron base starts wearing on the hard ways, so tailstock drops, the factory knows this and most good lathes come 3 thou high but with spindle tilted down, so over time the wear get about 10 thou or so and rube decides to shim tailstock, so he puts a big ass shim in, and gets it kind of good, but now tailstock is tilted up and high. 10ee tailstocks are not the easiest to shim, but its doable, you will likely have to stack small shims in combination to get front and back more or less equal in height.

If its bed / carriage wear it can show as larger diameter near headstock or smaller, depending on which way wore, or more likely the back side oil line got clogged, so no oil to back way, back side of carriage wears against the hard bed and wears lower tilting whole carriage top, causing bearing adjustment issues on the 4 bearings you adjusted last week. To check for the important to me last 2 inches up near headstock, I like to chuck a piece of 3/4" brass, nibble east a quarter inch, down to 3/8" diameter now do the next quarter inch moving west, repeat till you have taken off a inch and half or two inches and see what your change in diameter is, this method should limit tool push off if you take light cuts with a wicked sharp positive rake tool. On a machine with as accurate a leadscrew as you have in cross slide, you should be able to repeat your place with a few tenths, so after taking your several cuts it should be good with in a few tenths of variations due to cuts. I hope this makes sense. This is how I was taught to check out a lathe, it is pretty certain to show if ways or carriage are badly worn up near headstock. If this test works out, then I leave about an inch or maybe a bit more of 3/8" stock sticking out of chuck and do it again down to a 1/4" diameter, if that is half decent I am good to go. This test takes about 10 minutes including set up, I did it repeatedly on the road when I checked out machines before purchase. If you think you have a real bad area farther away from headstock do same type of test using much longer rod and steady rest. In my experience you want to use as small a diameter rod as possible when chasing bed wear issues.


michael
 
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