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Surface grinder runout question.

g90_zero

Plastic
Joined
Sep 27, 2019
Hello everyone,

After many hours of searching I have finally came to the experts to ask this question. I have a new to me Chevalier 2 FSG-2A20 Surface grinder. After getting it hooked up and leveled. We did a quick test grind on a block and noticed some wheel hop... pretty much the same hopping that is on the chuck from when the previous owner had "tried to grind in the chuck". So I did some further investigation. I put a .0001 indicator on the spindle nose and I'm getting .0008-.001" runout. How bad is this? And could it be due to loose preload on the spindle bearings or just bad bearings? The reason I'm asking this is because when rotating the spindle back and forth it feels like it takes the spindle a 1/4 revolution for the spindle play to catch up like having rotational play.( Best I can explain.) I've attached links to the videos of the runout as well as the spindle rotational play and a picture of the mag chuck in it's current condition. Any help is GREATLY APPRECIATED.


YouTube

YouTube


Thanks guys. J
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Has the wheel been dressed with a nice sharp diamond?
Yes sir, I'm just fairly new to surface grinding in general and am wondering if the runout and rotational play is alot?

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Perhaps that radial play, (when you rotate back and forth) might be loose wheel hub lock nut, or worn/broken/loose coupler between motor and spindle.
 
Perhaps that radial play, (when you rotate back and forth) might be loose wheel hub lock nut, or worn/broken/loose coupler between motor and spindle.
I think maybe the coupler like you said. Cause the play is still there with the wheel hub off. Could this cause the runout?

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Watching the video, getting .0008-.001 isn't right. Is the same amount present when you simply try to move the spindle up/down without rotating it? Do you get any indicated movement pushing/pulling the spindle parallel to the axis (in/out)? Make a dot with a sharpie magic marker on the spindle at the highest indicated value. Turn the spindle on/off a cycle or two. Does that same dot come up for high indicated location? I haven't rebuilt a spindle for a SG but I've never seen one that had more than .0001 or two play in any direction unless something was wrong. Does it make a lot of noise/heat/vibration when the spindle is on? There are other possibilities but one thing at a time for now. The rotational play would have me check the coupler too. Look for signs that it might have been worked on like disturbed paint. How old is this grinder?
 
Watching the video, getting .0008-.001 isn't right. Is the same amount present when you simply try to move the spindle up/down without rotating it? Do you get any indicated movement pushing/pulling the spindle parallel to the axis (in/out)? Make a dot with a sharpie magic marker on the spindle at the highest indicated value. Turn the spindle on/off a cycle or two. Does that same dot come up for high indicated location? I haven't rebuilt a spindle for a SG but I've never seen one that had more than .0001 or two play in any direction unless something was wrong. Does it make a lot of noise/heat/vibration when the spindle is on? There are other possibilities but one thing at a time for now. The rotational play would have me check the coupler too. Look for signs that it might have been worked on like disturbed paint. How old is this grinder?

Thank you for the help. So this morning I located the high and low points. Cycled the spindle a few times and the high point is always in the same location. I also pushed and pulled the nose in line with the axis and could not record any movement. I could while pushing up and down but that was probably in the column. The spindle doesnt seem to be getting hot either. It does have some odd noises when the spindle is on. Like a rattling noise like something is loose. I've include link to a video i took so maybe you could hear the noises. Also on the manufacturer's stamp the date was never recorded so I dont know which exact year the machine was made.

YouTube

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Ok, high point clocks the same and no excessive heat. How about vibrations? Was the hydraulic pump running (assuming it has one) while making the video? Sure is a bit noisy but that's compared to all the other makes of SG I've run. In testing for "up and down" movement you should be applying moderate pressure, your fingers are enough. Looking at an image of this grinder shows the motor in-line hanging out the back of the column. There's no way you could move that much mass just using your fingers unless you used two hands and a good grip. How much movement can you get using only your fingers and about 5-10 lbs. of pressure?

I'm hoping some other members here that are more knowledgeable will chime in here. I've done enough grinding to know when something is wrong but zero experience with rebuilding a SG spindle besides what I've read. Of all the SG's I've run (about 2 dozen or so) only one had bad bearings and it was an ancient Covel that still produced a better surface than what your chuck looks like (no offense intended). Can the rubber spider (coupling) be reached/inspected without disturbing the spindle or motor alignment? Photos will help.

I guess the next question is what you need this machine to do and to what level of precision? If that's the chuck I see in the photos it looks bad. John O asked if you used a sharp diamond to dress the wheel? How much grinding experience do you have? IF grinding requirements aren't high then try doing as John suggested and use a sharp diamond to dress the wheel, testing for full dress of the wheel, and take a light dress cut on something. Post photos of results.
 
It seems to me that your clunking is overlaid on typical spindle noise i.e. That the clunk is not coming from the spindle itself. You might be able to locate the source by using a stick to your ear, Eric The Car Guy has a vid on the Tube on this.

As others have said that mag chuck grinding is bad but don't try to fix it until you have got to the bottom of the apparent issues.
 
I had a beater Boyar Schultz years ago that came to us with the rubber spider in the Lovejoy coupling missing. It had that same 1/8th turn of slop and made a rattling clunking noise. When we pulled the motor we found the drive surfaces of the coupling had worn to about a 10 degree angle and had to replace the whole coupling.

The bearings were also shot. It's my theory that the worn coupling puts a lot of sharp impacts on the bearings really accelerating their wear. Fix the coupling first but be prepared to also do the bearings.

Dennis
 
All the above and also try brand new Wheel..at least a different one and with it fresh dressed..First. It's not uncommon for a wheel to to be coolant logged on one side so no amount of dressing can make it run right. The .001 is odd/a lot but I have seen a .001 run-out and still run a decent finish.

I once had a customer who thought he bought a bad spindle grinder at auction and was thinking about scrapping it. I pulled the new looking wheel and it ran smooth as silk. I Put on one of my wheels and it still ran smooth.
Yes good to break such a wheel and send to the dumpster..
 








 
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