I just got a new 13x40 precision? lathe. After leveling and mounting on concret floor with ancors I get a finish that looks like a phono record. I used a .0005 level so it is verry close. After turning SS,Alu. & some 4140 with toolsteel for Alu. and carbide & inserts on the others all have the same finish. I changed the belts to cog type Gates checked all bolts and put a rubber spacer on the adj. for the belt.The lathe is a Taiwan w/3HP. S/phase motor if you put your hand on the carrige while running, you can feel a light shimmy.I do not want to bad mouth the seller ,they said that it would be taken care of, but have not heard from them yet. I called my credit card service and they put a hold on payment.They are sending me a form to fill out.Could this be a cause of the single phase or just a bad part in the lathe . Thanks for any help you can give. Glenn
New Lathe Shakes
Collapse
X
-
if you take a piece of 1.25 dia stock let it hang out from the chuck about 6 inches and make a light cut say .03 with out the tailstock; dose it measure straight? if not maybe the machine is racked.
if everything is ok ;are the gibs adjusted right?
good luck
Comment
-
-
Glenn,
I Don't think single phase would have anything to do with it. There shouldn't be a shimmy in the carriage though. Try a cut while pushing the carriage down towards the bed. Then let up on it, then push down on it again. If the carriage is out whack you'll probably notice a change, however small, in the finish of the cut. (Just BE CAREFULL, DON'T SLIP!) You should be able to adjust any play out.
Also check the spindle bearings. They may not be adjusted properly from the factory. See if any info is available from the manufacturer on how to adjust them. I'm surprised, the Taiwanese stuff is usually pretty good.
Best of luck,
EdEd Pacenka
Comment
-
-
Hi Glen,
Loose spindle bearings can cause a poor finish, as the piece you are cutting will not be held solid. Chuck a piece of 1" dia. or larger, let it extend out a foot or so. Set your dial indicator against chuck 90 deg to the ways. Gently pull and push the chucked material so that the pressure is across the ways. If the spindle bearings are set too loose you will easily get movement on your indicator.
Yours, Jim
Comment
-
-
Glenn,
Maybe I read your post wrong but I understood that they are going to make it right but you haven’t heard back from them yet. If that’s the case, apparently they have a good idea of what’s wrong. Perhaps they just need to be pressured a little more! Maybe you could mention here the company that is selling it and then refer them to the post. If they fix it they will have some good free publicity, if not, then they deserve to be run down.
But…in the meantime you might test if the motor is the problem. If you have another single-phase motor that you know works well (doesn’t have to be 3 hp, a آ½ hp will work) temporally connect it to the lathe and see if the problem stops. You might not be able to test all the gearing if the hp is small, but at least if it clears up or improves, you will know it’s the motor.
Another thing that might be a problem is if it has two v-belts side by side on the pulley from the motor to the gear head. Sometimes if the belts are not the exact same length they will start to compete with one another and start to grab. This will set up a vibration that will transmit to the work. To eliminate this possibility, just remove one of the belts and machine another piece of stock.
Another thing…do the inserts have a negative rake? If so, negative rake inserts sure can make chatter if everything on the lathe is not tight – especially with light cuts. Maybe you could experiment with some very positive rake HSS tool bits (grind them yourself) and see what happens.
Just some thoughts….
________________________________________
[This message has been edited by Mike Burdick (edited 01-18-2005).]
Comment
-
-
Glenn,
How are you holding the tools? Quick change post, or the 4 sided post that seems to come with most of those lathes (as seen here http://images.grizzly.com/grizzlycom...88/G/G4016.jpg )? If it's the post that came with the lathe, you might want to switch to a wedge style QC tool post and see if it helps.
Comment
-
-
I ran the lathe with the belts off the motor was ok I could not feel anything shaking. The belts I took off were Elephant brand ,import I would guess. I did not try with one belt yet,but will. I do not think it is anything that can be fixed it seems to be in the headstock. I really want them to take it back. It is sold as a toolroom lathe for $6,500.00 it does seem to be worth that much. Maybe I just got a bad one. Someone at the warehouse went over a lot of things with me looking for problems.HE is the one that sold me on this model and does the repair on most ot the machines that they sell and is a machinist. I was told by him that the person that has final say was out of the country for 10 days . Well will see. The tool post is a Phase II wedge, inserts are Sumitomo TNMG331EUP Glenn
[This message has been edited by Glenn L (edited 01-18-2005).]
Comment
-
-
Do the feed marks in the finish look like the wavery grooves in a old analog phonograph record?
Dollars to doughnuts (even bet these days) it's the tortional vibration of the single phase motor. Single phase motors act like one cylinder engines in the way power is transmitted from the magnetic field to the armature - at each cycle flip the armature is snatched around, sometime over accellerating; sometimes not.
I suggest you conduct an experiment. It will be a PITA to do so but it will give you ammo for arguning with Grizzly. Mechanically decouple the motor from the machine as much as possible by slacking the motor on its bracket bracket and inserting pieces of rubber hose between lathe structure and the motor. You want to motor to drive the belt just enough to take a light cut but otherwise the motor just hangs there suspended in compliant rubber. Then take a light trial cut. If your raggedy finish smoothes out you've found the problem.
Comment
-
-
Forrest I never said Grizzly. This is the next thing I was going to try. If you put your hand on the carriage with it running and not cutting you can feel the shimmy. I put a test indicator on a stand and the tip on the carriage it shook about .001.-.0015. What you describe is what it looks like. You can run a fingernail over it and feel the ridges. Glenn
[This message has been edited by Glenn L (edited 01-19-2005).]
Comment
-
-
<font face="Verdana, Arial" size="2">Originally posted by Glenn L:
I just got a new 13x40 precision? lathe. After leveling and mounting on concret floor with ancors I get a finish that looks like a phono record. I used a .0005 level so it is verry close. After turning SS,Alu. & some 4140 with toolsteel for Alu. </font>
-3Ph
Comment
-
Comment