Clausing 5914 chatter -- solved at last

Well, I think I finally figured it out, although there is still a
mystery.
The problem has been that I could not cut a 1.25" diameter mild steel
bar off in the 3-jaw chuck without house-shaking chatter. This with a
HSS T-blade 1/8" wide in an Aloris BXA-7 holder.
I tried many things, mostly to rule out one possibility or another that
came to mind. The gibs are now all tight, and so on. The Aloris BXA
toolpost replaced the warped Dickson that came with the lathe
On the off chance that loose back hold-down plates on the carriage were
the issue, I used a C-clamp and a piece of aluminum (to protect the bed
way) to clamp carriage firmly to bedway. No effect.
Running fast and slow using the variable speed drive and/or the VFD had
some effect, but gross chatter happened even at very low speeds.
I recently bought a used slotting tool bit, consisting of a 1/16" wide
carbide blade brazed to a 3/8" square shank, the blade protruding about
1/4". Even this chattered.
Huh? How does that work? We are making a tiny groove using this 1000#
machine. This ought to be easy. Time for some reading or re-reading.
Marlow suggested cutting off (parting off) at one third the speed used
for turning, and pressing hard if it chattered. This worked for the
little slotting tool, although I did manage to break it by pressing too
hard. Well, the used bit cost me $0.75, so I happily shed 3/4 of a
tear. Clearly, we have progress here.
So, why then did the tiny slotting tool chatter no matter the speed?
Something must not be stiff enough. But what? I've tightened or
clamped or adjusted just about everything, to no avail.
I woke up the next day with the answer -- torque. I was going slow to
be sure, but was not using the back gear, and so the drive system was
not torsionally rigid enough. When I used the back gear, the chatter
went away, and I was able to part that 1.25" diameter bar off without
danger of shaking the house apart.
What also seemed to help was that I was using a mister to spray lots of
Rustlick WS-5050 emulsion right into the bottom of the deep groove.
Trying to keep the cut lubricated using a hand brush just was not
working, especially when the groove became deeper than it was wide.
However, coolant by itself did not abolish the chatter. The back gear
is essential.
But, I did notice the whole toolpost and holder tilting when I leaned
into the cut, so I'll have to track down if something is still loose and
needs to be adjusted. Or perhaps it's normal, given the forces invloved.
The other thing that happened is that the toolpost and/or compound
rotated perhaps 5 degrees under the stress of parting off, causing the
blade to drift out of perpendicular with the bar being parted. This
caused a lot of trouble until noticed and fixed.
One thing I noticed when I first got the lathe is that one of the two
5/16-18 swivel bolts (055-017) that lock the compound against rotation
had been stretched enough to visibly distort the threads, and I always
wondered why someone would apply that much force. Perhaps this creeping
is the reason. (The stretched bolt was replaced, and the newer bolts
are slightly beefier to the eye and may have been hardened.)
Joe Gwinn
Reply to
Joseph Gwinn
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========= As you have discovered "parting off" or cut-off is one of the more difficult lathe operations.
Many people use a cut-off tool upside down from the back of the machine with good results. These are generally home made.
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kits are available
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for a commercial version see
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also see
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we machined one as a class project.
Unka' George [George McDuffee] ------------------------------------------- He that will not apply new remedies, must expect new evils: for Time is the greatest innovator: and if Time, of course, alter things to the worse, and wisdom and counsel shall not alter them to the better, what shall be the end?
Francis Bacon (1561-1626), English philosopher, essayist, statesman. Essays, "Of Innovations" (1597-1625).
Reply to
F. George McDuffee
I found loose spinde bearings caused my lathe to chatter real bad while parting. I tightened up the bearings and the chatter went away. Something to look at.
Reply to
Dan
Thats very common with quick change tool holders. leverage with the tool hanging out to the left/right of cross slide centerling.
Tighten up the tool post, or put a bit of yellow legal pad paper under it.
And learn to sharpen/setup/line up your cutting tools better. A cut shouldnt take all that much pressure to accomplish unless they are dull, or you are feeding way too fast
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 to agree, I have had the same experience.
cheers T.Alan
Reply to
T.Alan Kraus
I did think of this possibility, based on other postings, so I went through the checkout procedure in the Clausing manual.
Basically, with a 9" drive plate (well, mine is 6") in place and the leadscrew not connected, let the lathe run for an hour to warm up, then stop the lathe, pull the pin so the spindle is disconnected from the drive, and give the spindle a spin by hand. It should spin to a stop in about one turn.
It spun down in about one turn when I followed the procedure, and made no odd noises, so loose spindle bearings do not appear to be a problem.
Joe Gwinn
Reply to
Joseph Gwinn
The chuck, while old and with cosmetic rust, appears to have had little use. I took it apart and gave it a cleaning and greasing, but the innards were pristine. It appears to be made by Pratt Burnerd, and appears to be original equipment supplied with the 5914.
The steel bar was rusty and irregular and was in fact loose in the chuck, so I did give the bar a skim cut. This allowed the bar to be held securely, but it still chattered badly until I used the backgear.
Joe Gwinn
Reply to
Joseph Gwinn
The problem with the 5914 is that the cross-slide won't go far enough back to allow for two toolposts, and has just one T-slot. Apparently, there is a two-slot cross-slide available for the Clausing 5900-series lathes, but I have not seen one. DoN may have one.
Man does Kennametal have a big catalog. What I didn't see was a comparison of the advantages and disadvantages of the various methods of holding inserts.
Joe Gwinn
Reply to
Joseph Gwinn
That sounds like the production cross slide, which was probably intended for use with a bed turret. They came in two versions I think, those being leadscrew and lever types. I've got the leadscrew type and never found the need to try it, mostly as it seems best suited to production work and I'm more into one-offs or very short runs.
Reply to
Mike Henry
They have them - Most big production shops use lots of air and have multiple 25-HP or larger screw type compressors to supply it. And they run the primary in continuous unloader mode and cut in the secondaries as needed, and they are usually on a sequencer to spread the run-time and wear around.
Or there's a manual switch so the plant maintenance person can swap the starting order weekly.
They might have a small 10-HP piston unit as the "Oh Shit" backup, and to supply any needed nights and weekends air use loads.
There are "Small" vortex tubes that only take 2 CFM to 8 CFM @100 PSI, and that's well within the range of a 5 'real' HP (Not "5 Sears HP") 2-stage compressor. One at a time of course, and realize that you are wasting a lot of energy compressing shop air just to get that little bit of cold air out the end.
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Reply to
Bruce L. Bergman
Hmm ... with a 6" plate instead of 9" you have less flywheel effect, so I would make the test time about 1/2 turn.
Enjoy, DoN.
Reply to
DoN. Nichols
[ ... ]
Don't I wish! I've only seen them in an old catalog which was scanned for me.
Typically, I think that you pick a system which matches what you already have. At least that is what I did -- starting with a couple of good holder from eBay auctions along with 100 matching inserts for each. :-)
Enjoy, DoN.
Reply to
DoN. Nichols
I have no problems with my Clausing 5418 -- pretty much the same except step pulley and manual belt changes. I always part of with the backgear.
Well ... for larger workpieces, I use the 4x6" horizontal/vertical cheap bandsaw. But I will certainly part off workpieces which I feed through the spindle -- both up to 1" in the 5C collets, and the hex 12L14 stock which is the maximum which will fit through the 1-3/8" ID spindle with the drawtube removed. (I think that is 1-1/8" hex, but until I have to buy more, it won't matter much.) The hex stock is held in the 3-jaw chuck.
If I ever do see chatter when parting off, I know that it is time to tighten the spindle draw-up ring again. (I swapped spindles to get an L-00 spindle nose in place of the 2-1/4x8 which came with the lathe.
Enjoy, DoN.
Reply to
DoN. Nichols
Hmm. Maybe someday.
I'm leaning towards buying new, not wanting to wait a year to get lucky. Now you know that the day after I order the new item, three fine used items will turn up on eBay, for a third the price.
Joe Gwinn
Reply to
Joseph Gwinn
Hmm. Rotational momentum will vary with the moment of rotational inertia, which will vary as the square of diameter: (6/9)^2= 0.444, call it one half.
Joe Gwinn
Reply to
Joseph Gwinn
I burned those nerves out long ago.
The cutoff has made sharp bang noises, to the point I thought something must have broken, but no damage ever found. I think it was passing a lump of chips, apparently because the tool was cutting on the side because the toolpost had rotated.
I also had it stall the workpiece in the 3-jaw chuck, which did not stop. Very dramatic. I backed off, then resumed cutting off. The workpiece now wobbled a bit, but the cutoff succeeded without further drama. I must have pushed too hard, but I'm getting the feel.
I buy used tool bits cheap, precisely so I don't need to cry when I break something. My objective is to not break the lathe, but all else is open season.
But I'm stubborn, and am using cutoffs as a way to uncover accumulated problems, so they can be fixed. If the lathe can part off, everything else will work.
This is an industrial lathe, and would have been laughed off the planet if it were unable to part off. So if it cannot now do cutoffs, something is wrong and ought to be fixed.
Joe Gwinn
Reply to
Joseph Gwinn
I thought the spindle was tight enough, but maybe not. The 6" drive playte should have stopped in a half turn, as discussed elsewhere. I think I'll revisit this.
Joe Gwinn
Reply to
Joseph Gwinn
Polar moment of inertia is proportional to the fourth power of the diameter.
Reply to
Ned Simmons
[snip]
I will see how it goes in my shop.
I was kind of pulling your leg. Good luck getting either solvent, although they would work well. And you would be *very* happy from the solvent fumes. Till you passed out.
What kind of oil do you use, by make and model?
Joe Gwinn
Reply to
Joseph Gwinn
That was my guess. The sidewalls of the groove are ragged and galled, which is a clue.
Need to find the optimum degree of push.
The top of the T is scooped, but gently. The blade is 1/8" wide by 11/16" deep. I'll have to try putting a narrow groove in the center, using a Dremel tool. Need to make sure the center can still cut, though, as there would otherwise be no place for the resulting disk to go.
Some of the carbide inserts used for cutting off also have this geometry. I recall that the Manchester ones do, from the photos in the J&L catalog.
It was right on. Think it still is. Will check, though this has not tended to drift.
I'll read it.
Joe Gwinn
Reply to
Joseph Gwinn

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