Grizzly 4003G Lathe Chatter Problem

Couple other things to check...

Remove the dials from your crossfeed and compound -don't lose the little tensioning tab between the dial and the slip collar. Make sure the plate (behind the radial thrust bearings) that holds the ACME screws are tight. The acme screw for the x-feed has a split tab it threads into... adjust the set screw in the split tab to remove the backlash. You can remove the little tab by unscrewing the ACME screw then, unscrew the cap screw that's in front of the tool post. The tab will drop right out. Also make sure the screw that holds the tab through the top of the x-feed is tight when you put it back in (this can cause all kinds of weird problems if it's loose).

If that doesn't get rid of the chatter, I'd take the whole compound off, inspect and clean everything. It's not hard to take the compound off. Remove the x-feed plate first to reduce weight (BE CAREFUL... Wear heavy gloves. The dovetail edges are sharp).

I still think there are 2 issues. One is the compound or cross slide. Something is caught in the ways and it's not sitting flat or, there's excess clearance somewhere. Taking a test cut with the carriage lock partially engaged will help rule-out things.

The bearings just went bad for some reason. The dull finish on the race and visible lines in the rollers should not look like that.

Just out of curiosity, have you cut any other type of material? That piece in the picture looks like SS and if you're using raw carbide instead of TiN or TiALN you can get an ugly finish like that and it even gives a little chatter too. That could be what's setting up the vibration and other factors with the compound, carriage of crossfeed are resonating.


Ray
 
Gotta go sleep now. Maybe the lathe fairy will give me the answer in the morning...

- - - Updated - - -

kd4gij said:
Timken is one of the top bearings. What your bearind guy sold you is wheel bearings.http://www.summitracing.com/parts/tmk-30212m?seid=srese1&gclid=CPb-1OD2yr0CFeJF7AodGVcAPQ
Here is a spindle Bearing.http://www.ebay.com/itm/like/221316731899?lpid=82

Put a DTI on your spindle and check it for end play and runnout.
Click to expand...

I can't get a solid ID on the Timken types he purchased and they're rated under a different ISO spec that cost > 100 bucks to download. I'm curious but not at that expense... Most precision bearings in the 2.5" range are pretty darn expensive but, I'm not yet willing to cry foul on the ones he's got until all my facts are lined-up.

I'm arranging some replacement bearings for a little 11" swing lathe and they're $200 (wholesale price).

Ray
 
Ray C said:
Couple other things to check...

Remove the dials from your crossfeed and compound -don't lose the little tensioning tab between the dial and the slip collar. Make sure the plate (behind the radial thrust bearings) that holds the ACME screws are tight. The acme screw for the x-feed has a split tab it threads into... adjust the set screw in the split tab to remove the backlash. You can remove the little tab by unscrewing the ACME screw then, unscrew the cap screw that's in front of the tool post. The tab will drop right out. Also make sure the screw that holds the tab through the top of the x-feed is tight when you put it back in (this can cause all kinds of weird problems if it's loose).

If that doesn't get rid of the chatter, I'd take the whole compound off, inspect and clean everything. It's not hard to take the compound off. Remove the x-feed plate first to reduce weight (BE CAREFUL... Wear heavy gloves. The dovetail edges are sharp).

I still think there are 2 issues. One is the compound or cross slide. Something is caught in the ways and it's not sitting flat or, there's excess clearance somewhere. Taking a test cut with the carriage lock partially engaged will help rule-out things.

The bearings just went bad for some reason. The dull finish on the race and visible lines in the rollers should not look like that.

Just out of curiosity, have you cut any other type of material? That piece in the picture looks like SS and if you're using raw carbide instead of TiN or TiALN you can get an ugly finish like that and it even gives a little chatter too. That could be what's setting up the vibration and other factors with the compound, carriage of crossfeed are resonating.


Ray
Click to expand...


I completely disassembled the crossfeed and compound prior to replacing the bearings. There was nothing that appeared to be out of the norm. It was all cleaned deeply and reassemble. I'll follow your advice and adjust the backlash and everything else on the crossfeed and x-feed, then take everything apart again for deeper inspection if the problem remains.

For All SS my bits are TiN coated, and always have been. I also use the same bits on 1018 and every other steel that isn't aluminum, bronze, copper, or magnesium. What concerns me the most is my tooling has literally been the exact same since I was using my G0602 prior to buying my G4003G.

I did blow up a parting tool bit about a month and a half or so ago when I was parting some 1018. Turns out it had a HUGE air gap in it.

I had completely forgotten about that, It was a great exercise for the sphincter muscle and I think I unconsciously forced it to the back of my memory.

Perhaps I jammed something out of place or loose with that pop? I wouldn't think so, but every bit of info helps, right?

- - - Updated - - -

Ray C said:
Gotta go sleep now. Maybe the lathe fairy will give me the answer in the morning...

Ray
Click to expand...


Enjoy your slumber, perhaps an epiphany awaits you on the other side...
 
kd4gij said:
Timken is one of the top bearings. What your bearind guy sold you is wheel bearings.http://www.summitracing.com/parts/tmk-30212m?seid=srese1&gclid=CPb-1OD2yr0CFeJF7AodGVcAPQ
Here is a spindle Bearing.http://www.ebay.com/itm/like/221316731899?lpid=82

Put a DTI on your spindle and check it for end play and runnout.
Click to expand...

I agree, check runout. If it is within 5 tenths put the bearings aside for now and examine the carriage. If the runout is more, check into better bearings but you may still have a carriage issue.

In your bearing number X = ISO part number, M means through hardened. I couldn't make out the other symbols in the picture (is one of them a D?) but they may provide a clue. Did you measure the old bearings, each race separate and then combined? The 30212 bearing you have is wider at 23.75mm than the spindle bearing above 22mm claims to be and the high precision ones I can find in the Timken catalog are narrower as well. Could be different measuring methods.

In Timken they list high precision metric bearings as classes C, B, A and AA where C = ABEC 5 = P5, B = ABEC 7 = P4, A = ABEC 9 = P2 and AA = probably cheaper to buy the space shuttle.

Dave
 
James after you blew up the parting tool did you notice any increased backlash (slop) in the cross feed or carriage dials? For example the cross feed should be .002 as you turn the dial back and forth within the backlash zone, did this increase?
 
Nope... No visit from the lathe fairy -just a dopey feeling all over and the usual sore joints and sore hands...

EDIT: The coffee is working. Judge Wapner is clear enough to render a decision (or a theory anyhow):

If the carriage x-feed and compound are removed, inspected and re-adjusted -and if the problem persists, my guess is that your spindle is bent. The parting blade event is probably the catalyst. It's good to know there was an unusual event but sadly it doesn't directly point to what may have been damaged -only helps develop theories...

If the spindle is being driven and the chuck suddenly stops, the spindle gets a good twist/torque put on it (this by the way is why I always run my lathe with just one drive belt and I don't tighten the daylights out of it to allow it to slip in the event of an issue). When you're parting, you're in low gear that has the highest torque potential... If the spindle is bent, it will wobble when rotated. The inner race of the bearings are seated flat to the spindle and the outer races are firmly planted in the gearbox. This means that the bearings are forced to spin with a wobble inside their races -and that will kill a bearing in no time at all. A wobbling spindle may (but not always) interrupt the forces of a cut so the bit is constantly, partially disengaging and re-engaging the material. -That might be the cause of the chatter. It may or may-not be measurable at the rotation point of the spindle face -just the same way a cock-eyed piece in a chuck can read zero at one location and show a big +/- an inch away.

Try measuring spindle RO at the outside then, remove the cover and measure the RO at several places along the length of the spindle. That will tell you if it's wobbling.

I'm fresh out of theories (and coffee) for now...


Ray
 
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Sorry to see your having so much trouble with this, I know it can be frustrating.
Do you happen to have a test indicator that measures .0001 or if possible maybe you can borrow one, chuck a piece of some nice ground stock and slap the indicator on it, spin it slow and watch for any quick bouncing in the indicator needle, I know you might see run out but if it's a smooth transition on the indicator keep going and see if you can detect any point where the needle takes sharp jumps, spin it quit a few times and watch close, this problem your having sound so much like a bearing problem and there's some kind of resonance building up, you'd not be the first person to purchase a bearing that's not quit right.
There's been a lot of good input here, this is just a thought and something you could try.
Good Luck..!
 
When he first adjusted the preload on the stock bearing he said the chatter wen't away for a couple of days.At this point I would pull the spindle and set it up on V blocks or better yet make up a quick bench center and check it for runout at the taper if on V blocks or center if on bench centers. If the spindle is with in a few tenths than bearings would be the suspect. The number on the timpkin bearings come up as for power transmission and wheel bearings when I googled the numpers. A standerd class bearing.
 
kd4gij said:
When he first adjusted the preload on the stock bearing he said the chatter wen't away for a couple of days.At this point I would pull the spindle and set it up on V blocks or better yet make up a quick bench center and check it for runout at the taper if on V blocks or center if on bench centers. If the spindle is with in a few tenths than bearings would be the suspect. The number on the timpkin bearings come up as for power transmission and wheel bearings when I googled the numpers. A standerd class bearing.
Click to expand...

Very good point, and seems to suggest the bearings didn't take long to demonstrate why there standard class, I'm curious why an experienced bearing retailer would sell a standard class bearing for this application..?
 
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