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04-30-2007, 07:56 AM #1
We have found that the stops on our Schaublin 150 do not repeat very well. Typically we set the stops for screw cutting up to a shoulder. It will be fine for a few cuts then over shoot by 1mm or so. We have learned to make the run out groove extra wide when threading on the 150! This is never a problem on our Schaublin 125 which always stops within 0.1mm. (125 is definately a nicer machine to use all round in my opinion)
150 uses limit switches which contact with ramps to stop the machine.
125 uses a collar clamp which you position on one of the shafts, it gets pushed by a ground steel dog. This is a very positive and reliable method compared to the ramp method on the 150.
Has anyone had this problem on their Schaublin 150? I would really like to fix this problem.
Oh, just a quick warning about the 150. One of my guys threw a job out of the chuck, the job hit the rapid lever and whammo! Carbide tool plunged into hard jaws!
04-30-2007, 11:21 AM #2
What is the condition of your spindle brake ? I have a Schaublin 135 where I thought the brake was working fine but I did some adjustments* on it recently and was amazed at how much better it works now. Just wondering if spindle "coasting" is your problem.
Re your job hitting rapid lever....due to the location of that lever, this seems like one of those one in a million events that would be unlikely to happen again in anyone's lifetime. Did you see this happen or retelling the story from the operator ? Seems more likely he panicked and hit the lever by mistake himself.
*actually I replaced the plastic bushings that serve as bearings between brake armature and hub... due to irritating faint knocking noise and vibration coming from the motor. In the process fitted the armature closer to the magnet. Now it's smooth as silk, quiet as a church mouse and brakes the spindle instantly. Before, there was a slight delay in the braking.
05-02-2007, 08:28 AM #3
Thanks for that, I will check the spindle brake more closely. If the bushings are ok is there something else to look for?
By the way does the 135 have the same stop arrangement as the 150?
No I didn't see the accident happen.
05-02-2007, 10:59 AM #4By the way does the 135 have the same stop arrangement as the 150?
At say 1000 RPM, when I turn the rotation off, even with a 160mm chuck in place, the spindle brakes instantly...no perception of "coasting" at all.
Still, at the much slower RPM's used in threading, even an out of adjustment brake would probably stop the works pretty quick, so perhaps that is not the issue in your case...but just thought that is one possiblity. Another possiblity would be the limit switches themselves needing adjustment or replacement.
05-02-2007, 06:19 PM #5
As I understand it the problem is not the stopping of the spindle, but when threading the lathe don't stop each time at the same position.
This can be caused by the shoulder on the rails is moving a little.(happend to me, that is why I don't use the stops any more.)To fix that problem you have to make new shoulders or modify them so they fit properly on the rails without play.
And Metric, when I am reading your story it seems like you are not quit happy with your 150.
No problem, I can sell you a brand new Takang lathe (made in Taiwan) and get you free from that old and outdated Schaublin!Your shop will be up to date again!
05-06-2007, 01:53 AM #6
Yeah mate, while we're at it, got any cheap mills that I can swap my Deckels for?!
Yes, my problem is, when threading the lathe tool does not stop in the same position each time. Or to be exact it usually stops fine but occasionlly (less than 1% of the time) overshoots by about 1mm.
Actually I agree with Milacron that the stopping of the spindle could be the problem here since this will cause an overshoot of the tool when threading. (Yet to check this out). Thanks also for the suggestion about the limit switches, definately worth a check.
Kees, I,m suprised about the blocks moving, they shouldn't come under any load. Should be just the spring pressure of the limit switch against them. I,ll put a clock on the blocks and see if they are moving.
Thanks for the replies, will do some checks and post any findings.
05-06-2007, 12:35 PM #7
Kees, stopping the spindle doesn't stop just the spindle, but the entire drive train (that is driven from the same motor in the end) as well...hence my spindle motor brake theory.
05-07-2007, 12:40 PM #8
Don, I don't fully understand your last post.I know when the brake doesn't deliver the same resistance each stop, the carridge moves in another position.
I just suggested another possible cause for the problem.I did not want to "break" your theory
05-07-2007, 12:53 PM #9
Kees, ok, we'll take a "break" while Metric roots around in his 150 ... coffee or tea ?
05-07-2007, 01:34 PM #10