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Are my spindle bearings fucked??

I

implmex

Diamond
Joined
Jun 23, 2002
Location
Vancouver BC Canada
Good afternoon All:
So my new to me Jones and Shipman is proving to be a disappointment; I have lots of small problems to fix.

I also have a really big problem to fix and I need the advice of other experienced eyes.

I can't grind a decent surface for shit.
Attached are two photos.
This is with a balanced wheel freshly dressed taking 0.0001" DOC and 0.100 WOC.
If you look at the surface of the mag chuck (ignore where the previous owner burned the shit out of it on the sinker EDM) you can see waves...the wheel is bouncing.
The first photo is right after the grind, the second is after stoning the surface to bring out the contrast.

If I take a bigger cut, say 0.0005" it's much better but still nothing to write home about and I get steps in the surface as if the wheel is dropping deeper on one side of the stroke than on the other.
The steps are maybe 0.0001" deep but they're definitely there.

I've tried everything I can think of:
The hubs blue onto the spindle taper properly
The wheel is tight on the hub and is dressed all over and balanced.
The hub is tight on the spindle taper.

I've got about 0.0003" of runout on the taper when I clock it, but it runs free and doesn't hump or grind.
I put a glass of liquid on the wheelhead while it's running and can't detect any vibration.

I think the spindle bearings are shot...what say ye all?

Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
Vancouver Wire EDM -- Wire EDM Machining
 

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These run solid ways on oil, right? I would almost think something to do with table travel because of the way the lines are perfectly aligned. If it was a spindle bearing issue I would not expect to see those lines forming a straight linear pattern across the surface like that. Out of curiosity, what speed are you running the table at? Have you tried it at a pretty high speed? Does changing the table speed affect the spacing or linearity of the lines?
 
Give Ekrets credit for the first call..see that your long ways are wet with oil. then post the hardness of the wheel, it looks like a 46 something from here, but if too hard and it may be loading up. A loaded wheel likes to bounce. Making big crossfeeds can load up a hard wheel, or make a wheel bounce. Climb grinding can also make a wheel bounce.

I would fresh dress and take a slow pass across a slug of mild steel with the long ways oil-wet. try that part at center chuck, then at the very end of the chuck/left.

Qt [I think the spindle bearings are shot...what say ye all?].. could be(?)

Might give the chuck a bang-bang with a whacker and see that the chuck is solid on the set pad, the wood handle but of a good size hammer would do, whacking straight down with using your other hand to feel. A slim possibility the burning of the chuck made the chuck warp and so a hollow under the chuck.

A push-pull of your wheel head to see it is not too free...and a push-pull of your spindle.

A spindle bump can more seat the bearings and so preload may need a little tightening..but check out everything before blaming the bearings,

Oh, and be sure your diamond is turned to a fresh facet.
 
I always had good luck grinding tables with a aluminum oxide wheel of about 46 grit as I recall. White wheel. Also use a very wide step over to avoid loading the wheel.

Edit to add: Make sure that you have a sharp diamond on your dresser. Diamonds do wear out and get rounded instead of pointed and that can cause your wheel to bounce.
 
Can you divide the ripple spacing by the traverse speed and see whether that equals the wheel rpm, with proper accounting for units? Thinking out loud, if the ripples are .25” apart and the traverse speed is 450 in/min (7.5 in/sec), then the ripples would happen every 33.3 ms, which would correspond to 1800 RPM if the ripples are due to once per rev of the wheel. Are those numbers anywhere near the ballpark?


Sent from my iPhone using Tapatalk
 
How fast are you traversing across the wheel when you dress it? Don't dally dressing it. Move along swiftly. The idea is to sharpen it, not glaze it over.
 
If you haven't used a surface grinder much or seen these videos ,they might be worth a look in case you find something that you are overlooking.
How to Dress and Balance a Surface Grinder Wheel - YouTube

How To Grind A Surface Grinder Chuck - YouTube

SuburbanTool Inc - YouTube


Links were posted to other videos on his channel on the Antique Machinery Forum a while back .

Norton used to have more about the dressing tools on their site
Optimize Grinding Processes with Proper Truing and Dressing Tools | Norton Abrasives

If the bearings are not obviously loose or noisy , wheel dressing and table travel speed can affect the finish also.
Cross feeding only when the table is traveling into or against the wheel and sparking out on the way back can sometimes help too rather than cross feeding both ways so no tendency to climb as in climb milling .
Just a few things I might look at before writing off the bearings.
Jim
 
Coarse grit,loose bond,sharp diamond,open dress......I much prefer to grind with coolant,most problems disappear as soon as the fluid cools and washes the grind clean.
 
If you stop the spindle it should come to a quick stop Ecspecialy the last bit If not the bearings are too loose Also make sure you use the right oil for the spindle Thin as water
Peter
 
Were you using the hand feed instead of the hydraulic feed? They should be interlocked so the hand feed pinion can't be engaged at the same time as the hydraulic feed is engaged.
 
Another way to check if the problem comes from the ways is to put a parallel on blocks over the chuck (or table) and indicate with a tenth indicator while moving the table: it doesn't matter if the parallel is not perfectly leveled. What you're looking for are small bumps in the movement of the needle.

Paolo
 
Paolo_MD said:
Another way to check if the problem comes from the ways is to put a parallel on blocks over the chuck (or table) and indicate with a tenth indicator while moving the table: it doesn't matter if the parallel is not perfectly leveled. What you're looking for are small bumps in the movement of the needle.

Paolo
Click to expand...

I was just coming back this morning to read replies and say that same thing. I was also curious to know how high the "bumps" were. The picture makes them look huge, but pictures aren't always very telling.
 
Pretty sure that surface has nothing, or at least not primarily, to do with bearings. It's too regular.

46I fast, sharp wheel dress with sharp diamond facet.
If that does not fix it, try setting auto at about .005" step with perhaps .003 down and let it run for a few inches width on a scrap work piece.
If the head is bouncing, floating, the slow cross feed should smooth out.

Rack could be exasperating the condition - say if table ways are worn enough that the gear/rack clearance has closed up a bit.

smt
 
I agree that the lines are too regular to be a spindle bearing problem. There's no way the spindle would stay clocked to the table like that to make straight lines all the way across.

I don't think this machine has a rack though. I believe it's like my Micromaster in that it uses a hydraulic cylinder to move the table back and forth.
 
Well, all of the above. I'd never grind a chuck until I knew the grinder was working perfectly. And you don't want to grind out damage as that would mean grinding way too deep, just get the surface touched up. The bearings are likely fine, but when I got my ancient B-S, the grease was hard, contaminated and I don't think the preload Bellevilles were doing their job. Cleaning everything, especially the bearing bore, and reassembling resulted in a much better running spindle. Even though my bearings aren't perfect, having the right preload works wonders and the surface finish is fine. I did have some contact with the screws holding my rack, which was an easy fix. As for balance, you should hear only the hiss of air around the wheel, with no lower frequency hum. If you hear any lower tones, it's probably not as well balanced as you think. Run it with no wheel. I had to rebalance my motor before I was completely happy.
 
We need Bruce Ballen to chime in on this as he tore down a Shipman and likely could throw in some light.

A fresh dress *(with a tuned diamond) and a full wheel grind with only down feeding(no Cross), to only down feed .0001 to .0002 per grind side-direction long traveling only, very slow across. No down feed on the climb-side but just Passover should prove the spindle bearings good or not so good...yes spray bottle coolant is good for this.

Yes, on a piece of mild steel (CRS ok)

slow long travel might be 1 1/2 feet per second...perhaps 3" long piece of steel (?).
 
eKretz said:
I agree that the lines are too regular to be a spindle bearing problem. There's no way the spindle would stay clocked to the table like that to make straight lines all the way across.

I don't think this machine has a rack though. I believe it's like my Micromaster in that it uses a hydraulic cylinder to move the table back and forth.
Click to expand...


It has a rack and pinion drive on the hand feed wheel. Tha automatic feed is hydraulic. That was the reason for my question about whether Marcus had been using the hand feed or not.



PS:- 0.0003" runout is a bent spindle. But that shouldn't be the cause of the observed pattern.
 
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