Play in headstock bearings

Been chasing chatter that has been getting worse lately. With a
crowbar under my chuck and a 1" bar in my chuck, I can measure
0.010-0.015" of vertical movement when I pick up on the chuck. Seems
like a lot to me. Lathe is an old Sheldon 11X56 circa 1942. Plain
bearings. What should I expect to see here? And what is the
recommended fix for what I have now? No money to buy a new lathe or
new bearings from the Sheldon rapists. Ideas? Comments?
Reply to
Gerry
Loading thread data ...
.01? Ten thousands?
Cringe....
Yah..you have a chatter problem.
Isnt there a bearing adjustment take up nut at the ass end of the front bearing?
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch
With plain bearings???
I think he needs to line bore the thing and convert it to tapered roller bearings so the take up nut option would exist.
Reply to
Pete C.
That's not an option. Not enough meat on the casting nor do I want to redesign the headstock. Then there's the money issur in this as well.
While I have not used Plastigauge on the bearings yet I am wondering is removing material from the mating surfaces of the bearing halves may be an option. Have no idea how to do this other than a piece of glass and some wet or dry and a lot of elbow grease. I don't know for sure but I suspect that new bearings from the Sheldon parts people would cost half of what a replacement lathe would cost me. Would it be possible to use poured babbitt here if channels were machined in the old bronze bearings?
Reply to
Gerry
In article , Gerry wrote:
Perhaps new bearings not from the Sheldon parts people? First you should at least find out what they really would cost from there. Plain bearings are cheap from MSC or McMaster-Carr. Buy oversize/undersize and machine to fit, if need be.
For a truly cringe-worthy attempt, you could try slipping some small shim stock between the bearing caps and the old bearing - cut the old bearing first (unless it's already in halves? Then just dress the ends if there's contact) so that it can be squeezed tighter without having to crush it - less likely to get badly binding ripples that way. Further fine adjustment could then be done with shims on the bearing caps mating surface as is standard for Babbitt.
Reply to
Ecnerwal
That wasn't exactly a serious suggestion. It was an oblique poke at Gunners suggestion to tighten a take up nut on the plain bearings.
Might be something useful on that lathes.co.uk site.
Reply to
Pete C.
Tapered plain bearings with a take-up are not unusual, though probably not as common as split and shimmed headstock bearings.
Reply to
Ned Simmons
Removing play by filing down [or removing shims] from the bearing caps is an old-old dodge as is rebabbiting the bearing.
IF the bearing surfaces on the spindle are in good shape, I suggest trying the easy/cheap fix first, using modern materials.
For the quickest/easiest possible fix, try applying 0.005 thick (assuming 0.010 shake/slop] teflon tape to the bearings, taking care that the oil holes are open. While not a permanent fix, it is easy and cheap, and may be adequate for your needs, with ocassional/light lathe usage. Even if you have to redo every year or so, this can be an adequate "repair." Note that materials such as UHMW-PE may also be suitable as a combination bearing material and shim as well as PTFE [teflon], and may be more resistant to "cold flow." click on
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For a more permanent fix Teflon impregnated epoxy liquids have been specifically developed for exactly this purpose. You will need to support the spindle in the correct [central] position while the epoxy sets, be sure to apply release agent to the spindle, calk the ends of the bearings so the liquid will not leak, and prepare the brass bearings so the epoxy will adhere. In many ways this is a "cold babbitt" with higher performance. This is a common machine rebuild technique for plain bearings. Moglice is a common brand, but there are others. It comes as liwuid and paste in several flavors.
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In both cases [tape and liquid] finding a supplier for small quantities you require will be the hardest part. Now if you can use a car load ....
Let the group know how you make out, and any small quantity suppliers you locate.
Reply to
F. George McDuffee
I see you have never been in the guts of a Swiss Screw machine. They generally have a tapered plain bearing with a matching spindle shank, that works like a collet. You tighten a ring nut at the back end of the bearing, which draws it in deeper, tightening the bearing, and then you draw in the spindle itself. Its quite a simple and elegant system and will last for many many years without replacing the plain bearings. In some cases of the machines I service..well over 50. under continous operation most of that time.
Id be surprised if a company as good as Sheldon didnt make some provision for tightening up plain bearings besides the old Southbend method of pulling out some shims and retightening.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch
Thank you.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
Reply to
Gunner Asch
I have heard of a "full shim pack" but have not found such an creature in my machine. Perhaps because I don't know where to look. Sheldon did make machines with Timkin roller bearing heads and ball bearing as well, I believe, but my machine is not one of these. My lathe was sold to the Navy in 43 so it possibly intended to go down with the ship. It survived the war and was surplussed and ended up in storage for some school system. I bought it three owners later. The Sheldon parts people wanted $400 for a compound feed nut several years ago. With that as a gauge I figure the price for a set of bearings would be outrageous. Besides, they have not answered two email inquires in the last two months.
Reply to
Gerry
Given the age of your machine it is not unusual that there are no shims. In many solid bearing machines, the new machine had 0.010 or more shims in the split bearing when it was machined or fitted. These could easly be removed as the bearing wore to compensate for wear, thus all the shims could have been removed. I don't know if Clausing used such a system.
Some solid bearings had a taper at one or both ends and an axial nut could be tightened to adjust clearence. Again I don't know if Clausing used this system.
As you can always cut and install shims if you have a split bearing to restore the original fit, your though to use a flat plate and emory cloth to remove 0.010 seems like a good one. Actually you may want to take of a little more and provide a few shims to allow for future wear/fitting.
If you do this there will be a tendency for one end/side to be ground down faster than the other, so change your grip and check with a good midrometer FREQUENTLY. You can also add additional weight to the fat side/end such as a dial indicator magnetic base.
Lubrication will be critical on the tighter bearing, and oil cups can be a big help if you have room. Also I find that synthetic oil such as Mobil One is significently "slicker" in that the bearings runn cooler by hand check than the specified no detergent oil.
for oil cups examples click on
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any good mill suply will have in stock.
Good luck and let us know how you make out.
Reply to
F. George McDuffee
Maybe lucky it has plain bearings, the set of zero-clearance bearings on my Sheldon R15-6 will cost several thousand $. Is there any way to adjust the bearings, like caps with shims that can have a layer peeled off? That's how you do it on the Atlas lathes. Some others have a split in the bearing that can be adjusted with a bolt.
What type of bearing is it? If Babbit or similar material, it may be necessary to repour the babbit. If a bronze bushing, you may be able to order a replacement bushing through an auto parts store or machine shop supply. The lathe may be able to machine the bushing to size, with a little care.
Jon
Reply to
Jon Elson
Just pulled the caps and used plastigauge. I find 0.007in the inboard and 0.005 in the outboard. No shims between the bearing halves. Bearings are bronze. What would normal clearance be?
Now, if the top bearing was removed from it's cap and a piece of shim, say 0.005 was placed behind the bearing, then what was protruding from the cap was carefully worked down with 400 wet or dry on a piece of glass, would this be an exceptable repair? Is there a better way to accomplish the same thing?
Reply to
Gerry
================ The first thing I would try as it is cheap, easy and makes no permanent changes is to install PTFE or HDPE wear tape. [see other message on sources] in the top and bottom bearing halves to maintain spindle location in reference to the tailstock/bed.
Complete coverage is not required, but you should try for 90-95% on both the top and bottom, so you may want 0.0025 tape. Be sure the oil holes are open, and no laps. You may want to put a 0.002 shim in the inboard side to insure parallel, however be sure to check to see that the spindle is not [worn] tapered. Assuming this is not a porous/oillite brass bushing, be sure the surfaces are de greased for proper tape adhesion, using acetone or lacquer thinner.
Lubrication will be critical with a tighter bearing.
Good luck and let us know how you make out.
Reply to
F. George McDuffee
Shimming the bearing(s) or dressing the caps will work fine if carefully done and the surfaces are okay. It is best to leave a few thousandths of the bearing protruding from the split to ensure that the bearings are held tightly. Be sure that there is not more than very light drag on the bearings and that they are well oiled.
Don Young
Reply to
Don Young
The infamous Sears 109 AA bench lathe used a tapered plain bearing. Simple and elegant is right.
-Carl
Reply to
Carl Byrns
The wear in this bearing is probably not uniform. It will either be in the "up" or "back" direction, or likely both. If you shim it uniformly, it will probably bind. Are these just like auto engine main bearings? You might measure the journal OD and thickness, and go to an auto parts shop and see if they can find a bearing the same or slightly larger and the same thickness. If larger, you just shave a little off the ends of the bearing insert.
Jon
Reply to
Jon Elson
The manual for my South Bend says to remove or add shims to achieve 0.001" to 0.002" play in the spindle nose (not the chuck or test bar).
You could mount a dial indicator on a long boring bar and check for asymmetric wear by recording the readings on both bearing shells at the front and rear upper edges and the bottom.
I've fixed a worn brass bearing by simply piling on solder and scraping it until the shaft fit.
Jim Wilkins
Reply to
Jim Wilkins

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