Lathe set-up

My clausing lathe cuts tapers instead of straight cylinders.
I am trying to set up my Clausing lathe in a way that eliminates the
possibility that these tapers are caused by anything other than wear
on the lathe (ie, improper leveling, etc)
To that end, I leveled this lathe with a Starrett 98 level.
However, despite that, it still cuts tapers, such as 8/1000 inch per
4 inch of carriage travel. It also produces an uneven finish, which I
would expect to be better. I took some pictures of the finish, which
did not turn out to be good, but I think that you can tell that it is
uneven.

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The surface finish alone could account for quite a bit of diameter
variation.
In short, I want to do everything to align the lathe properly and
produce the best surface possible so that I would only be dealing with
late wear and not any other mistake in turning.
So.
How can I improve the surface finish. This piece that you see in the
chuck is 12L14 steel.
Reply to
Ignoramus3975
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So you should test the bearings and the ways for runout and play. Then test the alignment. Connelly is your friend.
Reply to
Richard J Kinch
Did I see the tailstock supporting the other end of your stock? I don't think so.
Your stock is deflecting. You needed to have a live center in a properly adjusted tailstock. The LtoD ratio is way wrong. Put a test indicator on the far end, press down on the stock and see the deflection.
Wes
-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller
Reply to
Wes
Also google follow rest.
Wes
Reply to
Wes
OK. All good points.
My plan is as follows;
1. Replace the three jaw chuck with welded on jaws (something weird) with a four jaw chuck, which I also have.
2. Somehow, align the tailstock so that it is on center (not yet sure how).
3. Make one more cut with the four jaw and tailstock.
Reply to
Ignoramus3975
Iggy, you want to be turning between centers. A drive plate will have a taper for a center. Drive the workpiece using a lathe dog.
A quick and dirty check of tailstock alignment is to pinch a flat piece of metal between the lathe centers. Assuming the centers are properly ground, the metal should be perpedicular to the ways. If it is not, the tailstock is misaligned.
Kevin Gallimore
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Reply to
axolotl
I've got a link somewhere on how to check alignment , when I find it I'll post . But Wes is right , too much sticking out in relation to the diameter . Rule of thumb I learned is no more than two diameters protruding from the chuck .
Reply to
Terry Coombs
If that material is truly 12L14, and that's the surface finish you are getting close to the chuck, there's a problem.
What DOC, feed and speed were you using? How did you set the tool height?
I agree with others, you have too much part sticking out, for a Carbide insert. Would be fine with a high rake, small radius HSS tool honed sharp for very light cuts.
Google "rollie's dad's method" for an alignment procedure.
I've seen lathes with so much wear near the headstock, it could be seen with a wood yardstick. Some American Iron is not worth the trouble. Dave J.
Reply to
Mechanical Magic
Here's that alignment link .
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's_Dad's_Method.pdf
Reply to
Terry Coombs
The way you did that, any lathe would cut a crappy-finished taper. Try a test with 2" CRS round sticking out 3". Then cut it with HSS with a rake. Your set-up might just as well be a rubber rod sticking out 15 diameters and cutting with a butter knife.
Reply to
Buerste
Iggy, There is no half ass way of doing this. Right now you haven't got a clue what is going on. All of those factors the responders suggested could be the fault, but you have no way of knowing anything for certain without a test bar. At the moment, you are chasing your nose. An experienced lathe operator can out guess the problem, but you do not own those skills. Get a test bar. Watching you do this is painful to me. I will make you a deal, I think your spindle nose is a MT 5 taper. Please confirm. If it is, you may borrow my test bar. I will mail it to you. You use it according to my direction, then mail it back to me. Contact me off-line to confirm. Just eliminate nospam in my address. Steve
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Reply to
Steve Lusardi
Iggy,
A good place to start might be
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I found it and many others by googling "lathe alignment" without the quotes, but it may be better WITH the quotes.
Hope it helps.
Al
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Ignoramus3975 wrote:
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Reply to
Al Patrick
Recheck this every few days at first. It will take a while for the iron to relax into its new configuration.
As others have noted, that bar is far too long and skinny, and deflection alone would cause a taper cut.
What is the sound as it cuts?
Carbide inserts intended for roughing don't necessarily cut smooth.
It didn't look that way in the photo. Deflection is more likely.
I think that you are trying to do too much at once, so there are too many variables.
I would start with a 1" bar held firmly in a 5C collet, and figure out how to machine a smooth surface. At that time, you will also be able to verify that the machine is tight enough.
You remember my 5914 saga - it turned out that multiple things were wrong, and it required simplification of the setup before I could figure out what to do. I ended up tightening everything that it was possible to tighten.
Joe Gwinn
Reply to
Joseph Gwinn
Hi Iggy
Looks by the picture that you're using a CNMG332 or 432 tool to cut with (and the proper insert clamp is missing...). Some notions,
(1) Negative rake tooling requires more horsepower and rigidity than positive tooling, (use the tailstock and center even if your "soft jaws" are bored correctly).
(2) The "2" at the end of an insert designation denotes the radius of the point in 1/64s". Your .032" tool nose wants to be "at least" .032" depth of cut for the negative rake design of the tool to work properly.
(3) In practicality the best finish for a given radius would be 1/4radius = feedrate, (for a 432 insert that's .032"/4 or .008" per revolution).
(4) Surface footage is also important and depends on insert design and composition, machine horsepower, and lastly machine/part rigidity, (most job shoppers will just determine surface footage by "feel and experience", use a calculator and do it right, a good start is 300SFPM if you can).
(5) 12L14 is soft as butter, negative rake tooling actually wants to shear the material off a slight bit above the business edge (nose) of the insert (on 1/8" depth of cut the shear starts 1/8" back from the nose). Any leaded material tends to deform easily and often finishes poorly with neg rake. Try 1144 (a resulpherized steel) and you'll see a big difference in finish. *NOTE* it's not wise to weld any leaded or 11XX materials....
You can set the tailstock by turning 2 places on a bar between centers. I would take a bar some 12" or longer and make a small cut at the tailstock and 4" to 6" in, measure and adjust, most folks indicate against the tailstock spindle for reference. Some notions,
(1) a test bar (inserted in the headstock taper) is usefull to align the headstock with the ways, IE: if you "know" the bed is level and the bar shows your headstock and saddle are not parallel, then you have to re-align the headstock. I don't know (can't tell by pics) if your headstock sits on the flat ways or the "v" ways. Anyway if you re-align by twisting the bed (for chuck work) you'll have issues with long work.
(2) If you shim on a "v" way for horizontal parallel you can introduce permenant errors that will show up later, again, with longer work, (almost everyone shims and lives with it, very few scrape the ways anymore).
(3) The test bar will also help you determine way/saddle wear close to the headstock, (very common on used lathes, live with it or re-grind or scrape).
(4) The "98" type levels (at least 10 arc/sec or better) are plenty good for engine lathe or grinder leveling (they are iffy for turret lathes which are always aligned with bed twist).
Lastly (I think... too much typing), looks like you have 2 piece soft jaws which are great but need to be bored for each diameter chucked and the grip must be as close as possible to the scroll plate as there is more deflection of the chuck body when you move the grip out (promoting chuck wear and permanent deformation). Also the "American taper mount" type chucks move your business farther from the spindle bearings and are less robust for chuck work.
Matt
Reply to
matthew maguire
Chuck that piece with about an inch protruding. Turn the end square with a fairly coarse feed which will mark the center of rotation. Move the tailstock up to it and check that the point is centered on the bullseye pattern. If it's way out it could break the drill bit. The insert's cutting edge has to be at center height for this. File off any tit it may leave.
Drill a 60 degree center hole in the end and then turn the OD until the tool cuts all the way around. The accuracy of the chuck doesn't matter, the cut makes the hole and OD concentric. Zero the crossfeed dial with the tool holding an old credit card lightly against the turned OD, like a feeler gauge. The plastic shouldn't chip the insert.
Extend the piece way out, lightly tighten the chuck and run the tailstock point into the (clean!) center hole. Move the bit to the turned area and run it in against the credit card again. The crossfeed dial will show you the tailstock offset, which you can now adjust nearly to zero.
A dial indicator is better for this if you have one and a way to hold it. On a worn lathe, watch for increasing play as you crank the tailstock out and a shift when you tighten the clamp.
Now the lathe should turn a smooth cylinder, at least near the well- supported ends.
HSS honed to a sharp edge puts less pressure on the work and holds size better on long flexible shafts like that one. I can shave off half a thousandth with it.
I save all unembossed dummy credit cards for this, and for padding rough work in the mill vise.
Good Luck Jim Wilkins
Reply to
Jim Wilkins
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Try this link to Making a Lathe Test Bar.
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I think it will answer any questions you may have. Roger
Reply to
Roger Paskell
Wes offered excellent advice, but not for the circumstance at hand. The use of a center will not disclose the condition of the machine, due to the influence of the location of the tailstock as it relates to the spindle. If it has any offset, be it by wear or by having been moved for the purpose of cutting a taper, you introduce error that may have nothing to do with the condition of the machine.
In order to determine if your lathe is cutting straight, or not, after it has been leveled properly, the material you use for the test should be such that the amount sticking out of the chuck is greater in diameter than 1/3 of the length of extension from the jaws. That will keep deflection out of the equation.
You mentioned that the finish you're achieving is uneven. That's a dead giveaway that your tool is wrong. Leaded steel will cut without skipping or tearing when you have the geometry right----a statement that can't be made when machining mild steel. Do not use carbide for this test. Use HSS with a honed edge, one that has a slight chip breaker ground, which will increase rake angle. Carbide tends to cut with greater tool pressure, so it isn't conclusive.
What I'd suggest for the test is a piece of aluminum. 6061-T6 or 7075 T-6 is good, as is 2024-T3 or greater. I strongly suggest the diameter be fairly large, no less than 1-1/4", to minimize bending of the material under tool pressure.
Check your jaws to see if the chuck is sprung, which allows the material to deflect easily. When you chuck a known straight pin, there should be full contact of the jaws, front to rear. If you find clearance at the outside edge of the jaws, you can expect material deflection, even with large diameter material.
Small chucks are often sprung, a function of having been over tightened on short pieces of material.
How about a report once you've changed a few things?
Harold
Reply to
Harold and Susan Vordos
perly adjusted
far end, press down
Wes, I'm not sure that his tailstock is deflecting, but if his lathe consistently cuts the same tapers, the tailstock is definitely set off center. Thats how some of us intentionally cut tapers.
A quick and simple test is to put a dead center in both the headstock and tailstock, bring them point to point, and using a strong magnifier, see how closely the points meet. I'm not sure about other brands, but the tailstocks on Clousing and Atlas lathes have a tailstock adjustment to do just this.
The key here is that the OP says the tapers are consistent. This strongly suggests tailstock offset, although there may obviously be other problems. Still. for consistently tapered cuts, I'd first eliminate issues that generally trace back to tailstock mis-alignment.
Harry C.
Reply to
hhc314
Iggy also said nothing about using the tailstock . I was definitely left with the impression that the far end was unsupported .
Reply to
Terry Coombs
I didn't see a tailstock in use. When I was repairing a hub for my Clausing I intentionally deflected a tailstock to get a tapered spud to further process the hub.
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I had a thought, most beds are worn near the chuck. Mount an indicator in tail stock on a long rod held in drill chuck, indicate carriage along the first 10 inches moving tail stock a corresponding distance as staying over a pickup point. I have a feeling the tailstock ways are in fair shape at the far end. It should give an idea of how the carrage is tracking.
Wes
Reply to
Wes

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