Thread: Buying surface grinder question

Guys,

I am buying a used Abrasive Tool Co. Surface Grinder.
Can anyone tell me what should I check for when I see it for inspection?

Thanks,
Alex

Just use the search option, there's plenty of good info from previous threads.

The purpose of a surface grinder is to get perfectly flat parts with parallel faces, accurate in thickness to a tenth.

A $550 beatup grinder off Craigslist probably won't fulfill that.

I've got an Abrasive 3b, 8 X 24 grinder. Obviously the magnet's strength will be a concern for you as replacement magnets are not cheap. You can't just lay a plate on the magnet to test it either as magnets will develop dead spots in random places. Take a small metal part with you to test the magnet in a wide variety of positions. The Abrasive grinders that I've seen all have mechanical automatic feeds, (as opposed to hydraulic) both longitudinal and cross. It can be kind of finicky, make sure the feeds work consistently. After running for a minute or so, you can actually lift up slightly on one end of the table and see with a flashlight if the ways are getting adequate lube. They are not bad little grinders. We run ours for production jobs a few shifts a month. Has been fairly reliable outside of oil leaks and the aforementioned feeds.

Greg

Zumba,
Don't be so quick to think everything is junk just because of price. I bought a Reid 618H of Ebay for $155.00. Even had the spindle with it! I DID go and inspect it Before bidding though. Look dirty from the one pic they had on the listing. ALL the factory scrapeings are mint with NO grooves. I tore it all apart and had a buddy who scrapes for living look at it and said there was no need. Ground the chuck and it's out less than a .0001 over the chuck. And that is measuring 8 inches of the bottom of the spindle head to the left OR right so the saddle has no wear. Good equipment is out there but DO inspect before buying, Kevin

Here is the picture of it.

Guys,

will I need to buy a balancing device to balance a new wheel or I can just mount a new wheel as is?

Thanks,
Alex

If it doesn't have automatic table and crossfeed, don't buy it. A surface grinder without auto feeds will cost someone a good portion of their life. WWQ

Did the seller include any tools? There should be a threaded tool to help you remove the wheel hub (with the wheel attached to the hub).

After removal, the hub is placed on a balancer, and you position three small weights around the wheel hub (secured by set screws) until the wheel is balanced.

Typical procedure is mount new wheel, dress wheel, remove hub+wheel, balance hub+wheel, and repeat once.

only way to truly inspect a grinder is to grind something and inspect the workpiece....you can look at the ways, listen to the spindle, if it does not grind flat its worth $0.06/ lb.

AlexKu,
Why is the stop/fence thing on the right side of the chuck?
Old Bill

Just inspected the grinder and tried to grind on it.
It was able to hold 0.0003" over 5" length. It might be even better since the wheel is about 40 grit and leaves rough scratches.
All cranks move very smooth with very little backlash.
Machine runs very quiet and smooth. I took the wheel off then put it back. The hole in the wheel is slightly bigger than arbor - 3" so the wheel was somewhat off center. Even with the wheel off center machine still runs smooth without any vibration.

Unfortunately no tools included. Looks like a good deal to me.

Guys,

what kind of wheel dressing device do you recommend?

Describe your inspection procedure to determine .0003 over 5". (Which is not very good, assuming that is near the center of the travels) More interesting is what happens near the ends of the X travel.

Also, was that at both sides & in the middle of a piece as wide as the grinder will grind? Z axis ways (Table in-out direction, often confused as Y) Generally wear the worst on older small grinders since they are harder to keep lubed.

put a good parallel across the magnet, shimmed stable, and indicate that going in-out, and see what happens.

As far as a dresser, you don't need anything fancy, just a block with a hole in it at a 15deg angle & a set screw to hold a single point diamond nib. The wheel is dressed by putting the nib on the magnet beyond the wheel axis, (off center in the direction of wheel travel) and the 15deg leaning away as well; and running the table in and out under the wheel with the diamond removing about .001" per pass.

You're going to hate that thing the first time you have to manually surface grind anything bigger than a playing card. OTOH, if you are going to tool it up for tool making & sharpening, it will be fine. At least it has coolant. Good luck with it.

smt

Stephen, I just put a piece of steel on a table and ground it. Magnetic chuck is only 8" long so I can't check anything longer than that.

BTW This grinder is using 10" wheel. Do I need to balance it when I replace it?

"Just inspected the grinder and tried to grind on it.
It was able to hold 0.0003" over 5" length. It might be even better...."

"Describe your inspection procedure to determine .0003 over 5". "

"I just put a piece of steel on a table and ground it."

Yeah, you said that. But what is your inspection procedure. Also, how wide is the piece?

"Magnetic chuck is only 8" long so I can't check anything longer than that."

Say what???? You can inpect it without a chuck at all. What procedure are you using?

If the arbor has provision for balancing, then it is good to do it, and you can't get much better succinct description than Zumba gave.
OTOH, I run 10" wheels on a DoALL, Mostly Norton, and have never had a need to balance them for general work. You do need to dress them round, and then dress them as needed to keep sharp.

If you balance a wheel, it should not come off the arbor, as others have mentioned. Pull the whole arbor to change the wheel, not the wheel itself. That way neither concentricity nor balance is lost between wheel changes. However, this does require a set of arbors, one for each wheel commonly changed.

Another note on balancing: it is good you got coolant. To keep a wheel from getting unbalanced from coolant settling to the bottom between uses, always shut the coolant off first, let the wheel run for few minutes to wring it out, before hitting the off button for the spindle.
smt

I put a 1"x5" piece of 3/16" thick steel on magnet chuck and ground it on both sides. (Can't remember if I flipped on the side or "over the top")I used no coolant, just ground slowly making many passes till I could not see any sparks from under the wheel. I took about 0.001 on each side. The steel piece wasn't hot when I was done. Then I measured thickness with a micrometers at different points.
This is my first time with a surface grinder. [img]smile.gif[/img] Please bare with me.

it has a stop fence on the right side so splah gards can be put on the front and back of the table. you can see the hooks in the picture.

don't throw rocks at a manual machine. i used one for years. not all grinding is put a pice on and grind it flat. you can grind angles, threading tool bits. make round punches for dies. and more.
by the pic it looks like a 6x18. so you will need another chuck to get the full use out of the grinder. i would get a fine pole chuck if you buy a new one. enco has them.

.0003 in 5" is not bad for that thin of a pice of metal with no coolant.

It might sound stupid, but what is the chuck in a surface grinder?

The magnetic table with the lever.