Sqeeeeeeky Eclipse Permanent Magnet Surface Grinder Chuck

Hey Jim-

I think it was partially luck, but the whole table was not complete wavy. Maybe I didn't have to clean it up completely, but thought once I was grinding it, might as well get the whole surface. There was a whole inch on the back side and 1/2 inch up front that were ugly and worn away less than the center, which had a flat plateau.

We'll see if I did a good thing or bad pretty soon!

Bernie
 
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It should work fine. Is that just the picture or is the surface as rough as it looks? I've seen that effect before with that type of grinding wheel in softer materials, that looks like a 60 grit or so. I personally like an 80 grit pink wheel for most general grinding.
 
Hey Jim

You are a correct, it is a 60 wheel. I don't happen to have a more course wheel right now. I have quite a few wheels from 80 up to 220! Will I ever use those??
The surface feels perfectly smooth, but does have that wrinkly finish on everything I do. I wonder if it is the old belt, as I realized I forgot to replace it when I got the machine! I would think thank you belt quality would be pretty important at this stage, with some of the other things worked out at this point now?




Bernie
 
Surface grinding the top of the table is fine that you could accomplish it. But,what do the surfaces BENEATH the table look like? The table will still move in an arc unless the V ways,and the bottom of the table are flat and true.

Check the top surface of your table with a very straight straight edge to see if it is flat. It might have been ground,but ground convex if the surfaces beneath it are worn.
 
Thanks George

I am trying to test for that now. I guess I have to use that parallel test, chocking up each end of a parallel with Gage blocks and running the table, measuring with a dial indicator. I have a .0001 Brown and Sharpe on a magnetic base.
The ways look nice, which doesn't mean much. I don't know if it's factory, but there are oil retention troughs cut into the ways in both directions, which are still there. BUT the Z-screw (cross-table movement I understand?) has .100 backlash!!! Hah hah, that's pretty crazy and insinuates wear of course.
Last night I performed a pretty useless test, running the table while the indicator was touching the table directly. It read zero- no surprise hah hah.

I read that I need to put some Gage blocks at each side and a trusted parallel across them, and run the indicator along that to check for wear causing convex surfaces.
This is opposed to using the "multiple block method" which actually hides this issue.

I will try the Gage block method and check in here with my results!


Bernie
 
JimDawson said:
That is why the power feed was invented. :grin: I've done the same thing too many times. I'm getting ready to do a full CNC conversion on my DoAll, no more cranking!!
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Click to expand...
It is normal procedure to true up the top of the chuck as needed to flatten the surface as a result of wear that is inevitable with permanent magnetic chucks due to the residual magnetism and having to wrestle the part off, and also when for one reason or another the chuck is removed; they seem to never go back on and still be as accurate as before. I have had surface grinders with both permanent magnet and electro magnetic chucks, and vastly prefer the latter, especially, like my present B&S MicroMaster, which has the Neutrofier control that neutralizes the residual magnetism in the chuck and workpiece and makes it ever so easy to remove from the chuck.
 
benmychree said:
It is normal procedure to true up the top of the chuck as needed to flatten the surface as a result of wear that is inevitable
Click to expand...

Yes...... I've seen electro mag chucks that held more residual than permanent mag chucks. The timing/technic of throwing the switch being important.
I would always regrind if my chuck was removed from my surface grinder or if I mounted a new one.... but on my tool and cutter grinder I put them up and down and never worry about it...it probably doesn't have the accuracy to grind one anyway.
 
george wilson said:
Surface grinding the top of the table is fine that you could accomplish it. But,what do the surfaces BENEATH the table look like? The table will still move in an arc unless the V ways,and the bottom of the table are flat and true.

Check the top surface of your table with a very straight straight edge to see if it is flat. It might have been ground,but ground convex if the surfaces beneath it are worn.
Click to expand...

George, I'm having trouble getting my head around this one. If the ways are arc shaped and you grind the table, then the table will have a mating arc?

In that case, if you were grinding a plate flat, then the ends of the plate would be a different dimension than the center due to the arc?
 
Actually,the top of the table would be ground into the same arc that the underside would have.

Many years ago,my first DECENT milling machine,a #4 Burke,had gotten an arc in it from years of tightening things down in the single T slot. I took it to Basic Machining in Hampton to get the table machined flat. I was in my 20's. The owner,a macho acting guy in his 40's,wearing a silk shirt said they'd just mill the top of the table and it would be fine. I said,"no,it'll still travel in an arc. You'll have to mill the bottom and the dovetail underneath. He said he charged $25.00 an hour to tell people how he'd do a job. But,he promised my satisfaction. I was worried,but left it and came back in a week. The table had been machined EVERYWHERE,top,bottom,dovetail. When Mr. smart alec had taken it back into the shop,where the REAL machinists were,they had set him straight. The owner stayed back from me while I examined the table,turning it over while looking. I asked "How'd you do?" He said they did o.k.(meaning on money). Actually,he had screwed himself!! It was great. I got the job for 1/3 what it should have cost. Maybe next time he might not assume all his customers were idiots!!!:):):)

My only mistake was in not asking for the cutter,which I had had to pay $30.00 for. That would probably REALLY have aggravated him!
 
Go watch the suburban tools don bailey video on building a mag chuck, they advise that you do NOT attempt to open a mag chuck unless you know what you are doing, as they have enough power to take fingers off when the two poles come together, special fixtures are needed.

On a another note, I too used my harig a couple months before being brave enough to dust off the top of the chuck, it took 3 passes @.0003-.0005 to clean off the D shape that was caused from removing parts from the center of the chuck, tip, use the whole chuck, put work in all the area you have, don't just use the center, plus that will help wear the ways evenly instead of just the center.....
 
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