As the title says, I've got two lathes. An old 17" Clausing and a 90's new to me Kingston HJ1700. Using an Iscar SGTBU side hung blade holder on a CA sized Quick Change tool post, the Clausing will smoothly part stuff off 10" away from the chuck. Take the same tool and material out of the Clausing, and put it in a CXA on the Kingston, and it chatters no matter how close to the chuck I get, or what speed I try. The only way I can get it to work is by running the tool .060 low from center. The Kingston appears to be in excellent shape, and the chuck jaws seem to grip well all the way to the nose. I put a dial indicator between the tool post and material, and I can get about .001 deflection by prying under the chuck and against the tool post, etc. I could really use some suggestions as to what else to check?
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One lathe will part off, the other won't. Help diagnose please.
- Thread starter Ksracer
- Start date
- Replies 18
- Views 2,143
eKretz
Diamond; Mod Squad
- Joined
- Mar 27, 2005
- Location
- Northwest Indiana, USA
What kind of workpiece are we talking? You might want to check headstock bearing preload.
Anything from 1.250 416r SS, too 4" aluminum. The Kinston chatters on everything, at any speed, any distance from the chuck.
Cole2534
Diamond
- Joined
- Sep 10, 2010
- Location
- Oklahoma City, OK
Check the cross-slide gib? Could be loose. Or the leadscrew's thrust bearings.
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Sent from my SM-G930R4 using Tapatalk
eKretz
Diamond; Mod Squad
- Joined
- Mar 27, 2005
- Location
- Northwest Indiana, USA
Check your headstock bearing preload. Many lathe manufacturers will give a minimum torque that it should take to get the spindle moving in neutral. The last shop I worked in had an 18" Sharp lathe that had very similar symptoms as what you're describing and after readjusting the headstock bearing preload I solved the problem on that one.
I would not necessarily expect to part off without chatter at that distance while unsupported at the tail end if using an indexable parting tool. HSS might be better, but on something like 1.25" diameter you are going to get chatter at 10" extension no matter what. Chattering at every extension you try says headstock preload to me.
Joe Gwinn
Stainless
- Joined
- Nov 22, 2009
- Location
- Boston, MA area
My new old Clausing 5914 also had that problem, in 2007-2008 or so.
I lost it when I was unable to make a 1/16" inch wide snap-ring groove in a bit of 1.5" diameter mild steel without the lathe bucking - this cannot be right.
Turned out that everything that could be loose was loose. Including the headstock bearing preload nut, as mentioned above. No periodic maintenance had ever been performed. Replaced most of the gibs as well. I used parting-off as the test case, fixing one thing after another until the lathe almost passed its original factory graduation tests.
I lost it when I was unable to make a 1/16" inch wide snap-ring groove in a bit of 1.5" diameter mild steel without the lathe bucking - this cannot be right.
Turned out that everything that could be loose was loose. Including the headstock bearing preload nut, as mentioned above. No periodic maintenance had ever been performed. Replaced most of the gibs as well. I used parting-off as the test case, fixing one thing after another until the lathe almost passed its original factory graduation tests.
Thanks guys, you've reinforced my suspicions that there has to be play somewhere, I'm just not sure where it could be or how to find it. I had the carriage, cross, and coumpound all off and apart to clean and readjust before I ever put power to it. Everything looks to be in excellent shape. I did not touch the spindle preload nut though. With the machine in nuetral, it takes a light tug on the 15" chuck and then you can keep it rolling with very little effort. Does that sound proper?
michiganbuck
Diamond
- Joined
- Jun 28, 2012
- Location
- Mt Clemens, Michigan 48035
Very good advice .. and perhaps see the compound is not far out extend..but backed up a bit so is not hanging overboard but a little more centered over the saddle and cross..
Compound not far extended outboard:
lathe far extended cross slide photos - Google Search
eKretz
Diamond; Mod Squad
- Joined
- Mar 27, 2005
- Location
- Northwest Indiana, USA
No. It should take a decent pull to get going and make right around one free rotation when given a good spin by hand. After you adjust run it for a while and make sure it's not getting too hot. It does NOT take much bearing play (i.e. lack of preload) to cause chatter when cutting over a wide surface area.
edwin dirnbeck
Hot Rolled
- Joined
- Oct 24, 2013
- Location
- st,louis mo
Put some pressure on your workpiece with a live center. This will load your bearing and take slack out. If you cant have a center hole,use a 1/2 nut from a bridgport clamp set between your center and up against your part.I run a lot of junk lathes and this useually works. Good luck Edwin Dirnbeck
PeteM
Diamond
- Joined
- Jan 15, 2002
- Location
- West Coast, USA
Curious about this. Way I was taught was to never part off using a tailstock center. Are you talking about using a center rest or ??
I'd start from spindle bearings as it is the most critical part for the operation.
You could have 1/10" play in the leadscrew or gibs and still successfully part with bit of luck but spindle bearing needs more than luck.
Good catch on your part to make my post clear.
I support the part where possible with a center in the tailstock, do most of the cutting and then slide the tailstock back out of the way. Obviously, if you leave the tailstock in position things will jam up and cause a disaster as the part breaks free.
The other thing I do when at the end of the parting cut is stick a wooden dowel into the part to catch. This for a pretty standard job of some kind of ring or flange that can be easily held in one hand. That is a pretty common job for me, like a thin aluminum ring with threads inside or out. On bigger parts or parts not given to the method, its best to let it drop free. I might even part a lot of the cut before I finish the part, so theres only a small amount left to finish the parting. If its big, heavy, long it might have been smarter to saw it off then put it back in the lathe. If it looks scary or even if not scary, think about whats likely to happen when the parts breaks free.
eKretz
Diamond; Mod Squad
- Joined
- Mar 27, 2005
- Location
- Northwest Indiana, USA
This is not a bad idea but the bearing issue should be taken care of first. It sounds like his preload is way too low.
I have a solution for the larger ring-shaped parts falling away. I made a bunch of "donuts" from 2"x X" blocks glued together. Used an old spade drill shank that had been crashed - about 2" diameter to set in the tailstock and stick inside the bore of the item being parted. The wooden rings had 2" holes in the I.D. and various O.D. sizes to suit different size rings being parted - one at every inch size or so. Stuck the wooden ring that would fit inside the I.D. on the spade shank then inserted into the bore of the ring before parting. After the part broke loose, the wood donut would catch the ring. Heavier solid items should be sawed, not parted. Not safe to part them.
Bill D
Diamond
- Joined
- Apr 1, 2004
- Location
- Modesto, CA USA
I figured out my lathe problem today. My compound is held on by two bolts that cannot be seen without unbolting the compound from the cross slide. these bolts hold the compound down to a round plate which in turn is bolted down to the cross slide.
Those hidden bolts had worked lose and the compound could rotate and tilt slightly under load. Tightening the visible hold down bolts did not help. I had wondered if the crosslide was the factory one or not. It seems to be a American made cross slide on a Metric English lathe. But that shifted the original handle and indicator dial to the American one.
Bil lD.
Those hidden bolts had worked lose and the compound could rotate and tilt slightly under load. Tightening the visible hold down bolts did not help. I had wondered if the crosslide was the factory one or not. It seems to be a American made cross slide on a Metric English lathe. But that shifted the original handle and indicator dial to the American one.
Bil lD.
Lead screw thrust bearings was a damn close guess. One of the gibs in the sliding taper attachment was.'t in place correctly, and would move out of position if the leadscrew pulled on it hard enough. I finally found it by mounting indicators at.various locations and firmly pushing an empty tool holder against a short piece of material in the chuck and watching for movement.
Head bearings aside. Assuming the saddle is locked and the compound isnt hanging out when you part off.
Clamp a foot long bar of something in the tool holder, itll be used as a lever.
Indicate from the tool holder to the bed. If you find a pile of movement indicate each connection. Ie bed to saddle - saddle to cross slide - cross slide to compound etc.
You can have the gibs super tight and still get significant movement, guided way surfaces generally wear so as they rock, like a rocking chair, especially the saddle.
Clamp a foot long bar of something in the tool holder, itll be used as a lever.
Indicate from the tool holder to the bed. If you find a pile of movement indicate each connection. Ie bed to saddle - saddle to cross slide - cross slide to compound etc.
You can have the gibs super tight and still get significant movement, guided way surfaces generally wear so as they rock, like a rocking chair, especially the saddle.