PM 1440 GT spindel delfection

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BCwoods

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HI if anybody out there has a 1440 GT, Im getting about .0004 deflection at the spindle if I grab it and push and pull, I trying to see if this is somewhat the same for others. If not, possible that the spindel bearings need a little more preload, has anybody ever attempted this?
 
Are you sure of your measurement? Which part of the machine is your reference surface?
-Mark
 
You also want to measure after the bearings have been run and warmed up. Spindle bearings are adjusted warm. Dave
 
Thanks , here's how I measured movement
 

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On my lathe that would be in spec. There has to be movement for lubrication. As previously said, check after you run the spindle for 30 minutes or so. IMHO
 
Janderso said:
There has to be movement for lubrication.
Click to expand...

Just to be clear, rolling-element bearings do not require clearance for lubrication; they nearly always operate under preload, and rely on that for stiffness.
 
I stand corrected.
The last time I measured my spindle taper for movement, there was .0002-.0003. I found a spec somewhere and this was within.
My uneducated assumption was space for lubrication.
 
All good information, thanks to all, in fact I have been in touch with Matt at Precision Matthews who assured me all is good. I even asked he he could check a similar machine to compare which he did, so Im leaning more to the operator (me). However I was getting inaccurate measurements after a cut and I noticed a little play in the spindle which would translate to the chuck to the work etc... and I had no real reference other then google. So thanks again to all for the info
 
BCwoods said:
All good information, thanks to all, in fact I have been in touch with Matt at Precision Matthews who assured me all is good. I even asked he he could check a similar machine to compare which he did, so Im leaning more to the operator (me). However I was getting inaccurate measurements after a cut and I noticed a little play in the spindle which would translate to the chuck to the work etc... and I had no real reference other then google. So thanks again to all for the info
Click to expand...

It seems like 4 tenths is rather small. Another area of potential error would be the tool post. It could be the tool post setup itself, cross slide, or the compound. On my previous lathe, I had issues with the cross slide being loose enough to slide but tight enough to eliminate deflection.
 
.0004 seems as high as I'd like for a spindle pushed by hand but I have little reference. With warm bearings my old 1024 has less than that. A good chuck, even a collet chuck will have additional runout of tenths. My cross slide screw has some play. When I lock the slide, the DRO moves .0006 and my tailstock quill moves .001 when locked. I compensate but I would expect a newer machine to be better. I'd be interested in what those with new machines get for readings. Dave
 
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