# Buying A Surface Grinder ?s



## AGCB97 (Sep 23, 2016)

I'm looking to buy a surface grinder but would like to know what I should look for.

I have a small home shop (not inside house) so would like to get something not too big.

Are there things I should look for when looking at used machines?

how to test for spindle bearing wear
are there different types of spindle bearings  one guy said he paid $500 for new bearings
are some stone sizes easier to come by
are there different types of table support (I think one is ball bearing ways, what else is there)
I know that it must include a magnetic chuck, is one type better than another
I would like it to be single phase but is it easy to change the motor if it's not or nor recomended
is cooling a must, ditto exhaust venting
what other things should I look for, I'd rather not have to start a complete rebuild

I looked at the other posts in this forum section but did not see one with buying guidelines like this so am hoping this might be a popular post for others in the same boat. If there is one I missed, please let me know.

Thanks
Aaron


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## countryguy (Sep 23, 2016)

Excellent post and question.  I an a but further along as I have a used unit but really know little here.  Looking forward to learning from folks here and online.  I ended up getting into bundle deal and came home w/ a Bridgeport 815 dirt cheap.   Hard to say no when it looked in great shape but I had no clue if it was in good operating shape or not.     It's a small unit and that's what I wanted.  
I'm sure someone here will post us some help.   I have developed a keen likeness for these manual grinders. Fun to just make sparks I guess. 

I just put scales and a DRO on my unit from Ditron.  I have started learning on a large steel plate that I had.   I need to make a large sine-plate for something my kids working on.   It needs to be pretty flat and I have a lot of wiggle room to mess up and learn 

My first question is related to wet grinding.  I have the unit running.  It has a nozzle,  when should I use a coolant setup?   Is that a flood or mist?  and is that just for dust control more than anything else? 

Anyway-  I think I've seen some manuals on the web that I'll post back if I can locate them. ( I think they are in a post here someplace...) 

http://www.americanmachinetools.com/how_to_use_a_surface_grinder.htm
http://www.abrasiveengineering.com/speeds.htm
http://americanmachinist.com/machin...ol-applications-grinding-methods-and-machines


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## countryguy (Sep 23, 2016)

Got one of my answers... 
*COOLANTS:*

Most surface grinding machines are equipped with coolant systems. The coolant is directed over the point of contact between the grinding wheel and the work. This prevents distortion of the workpiece due to uneven temperatures caused by the cutting action. In addition, coolant keeps the chips washed away from the grinding wheel and point of contact, thus permitting free cutting.

Clear water may be used as a coolant, but various compounds containing alkali are usually added to improve its lubricating quality and prevent rusting of the machine and workpiece. An inexpensive coolant often used for all metals, except aluminum, consists of a solution of approximately 1/4 pound of sodium carbonate (sal soda) dissolved in 1 gallon of water. Another good coolant is made by dissolving soluble cutting oil in water. For grinding aluminum and its alloys, a clear water coolant will produce fairly good results.


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## AGCB97 (Sep 25, 2016)

Thanks countryguy

Those are good links

I wrote a reply yesterday but must have forgotten to hit the submit button.

To make it somewhat easier for others the reply, how about just telling about what you wish you had known before your purchase of a surface grinder.

Thanks
Aaron


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## Bob Korves (Sep 30, 2016)

I am a newbie at this, too, but this is how I see things.  If someone more experienced disagrees with any of this, listen to them and not me...

If you are looking at a surface grinder that has been sitting for years, do not just start the spindle.  Turn it by hand and check for smoothness.  Keep trying that for a while to see if it smooths out.  If it is crunchy, walk away as fast as you can unless you want to rebuild the spindle, which can cost as much as the used machine or likely more.  If it turns freely and smoothly by hand, turn it on and pay very close attention to how is sounds and if there is any vibration.  Vibration might be from an out of balance wheel, but might be a bad spindle.  ($$$$)  Remove the wheel and try again.

A manual surface grinder is a pretty simple machine.  It needs to have a good spindle, smooth and with very little runout.  The lead screws should have little backlash or wear and operate smoothly.  The table commonly just lifts off the machine, so do it and look at the ways and get a feel for what kind of care or abuse it has seen.  If it is loaded up with grit and grime under the table, and the scraping and/or flaking on the ways is worn out, take notice.  Look for things that have not been properly lubricated and for missing dust guards.  Grit and lack of oil kills surface grinders.  If it has ball or roller ways, rub the oil off the balls or rollers and the table and see if there are dings in them from transporting it with the table still mounted, bouncing up and down.  One road trip like that can ruin a grinder or require major repair$.

The most common stone size for home shop and tool room use is 7" diameter with a 1-1/4" center hole, in various widths.  They are the easiest to come by, new or used, have the most options, and cost the least.

Coolant produces better finishes, more accurate work, and helps to keep the dust down.  It is also a PITA, makes a mess, corrodes machine and tooling, and needs to be cleaned up after every use.  I watch shadonHKW on YouTube.  Stan uses mist coolant almost all the time, and seems to do well with it.  Still needs cleanup after use, makes less of a mess, does a pretty good job at helping to keep the work cool.  Dry grinding leaves a dusty mess, a shop vac hooked up to the wheel guard helps to keep the dust down, but does not keep the work cool or the wheel clean.

There are surface grinders with plain ways, with roller ways, and with ball bearing ways.  Ball and roller ways take less muscle to traverse the table.  If you have power feeds that work, plain ways are less of a disadvantage.

Surface grinders with power feeds are much more complicated than manual machines.  Generally hydraulically driven, they can leak and/or fail.  When the hydraulics are not working, it is usually a bear to operate the table manually.

Magnetic chucks are not needed for certain classes of work.  There are other ways of holding things, like vises and various fixtures.  Most people use a magnetic chuck.  Closely spaced poles are better for smaller work.  The lines of flux from the poles are closer together and do not extend as far above the surface of the chuck.  For large work, wide pole spacing is more effective.  That is the simple story, but it gets more complicated.  Some people like permanent magnet chucks and others like electromagnetic chucks.  In good condition, both work.  There is lots more to mag chucks than I really know about.  Be careful, there is a lot of used junk out there at high prices.

Surface grinders need to run smoothly, and three phase motors run more smoothly than single phase.  A VFD gives you the best of both worlds, plus control of the spindle speed.

If you cannot run the spindle of a candidate machine, or take the table off and look at things, or test grind a chunk of metal, you have an unknown, and should not pay more than scrap metal price for it, and expect to have to do a lot of work to it to make it correct.

Just my opinions, and I am a newbie, but I am just finishing bringing an old power feed surface grinder back to life.  I did not necessarily follow all of my own advice.  It helps to also be a good judge of people, and I judged correctly.   8^).


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## 4GSR (Sep 30, 2016)

Along with what Bob said above, don't buy one sight unseen like I did.  
But if you have to buy one sight unseen do your homework first.  Get lots of pictures from the buyer.  If they won't provide addition pictures, walk away.  Do some research on the brand/model.  Lots of information out there on most of them out there on the internet.  Think about the things that may require fixing like the bed ways or if on linear bearings.  And as Bob mentioned above, the spindle, will it need to be rebuilt?  Not a easy task for most of us to encounter and get it right when it goes back together.  A spindle rebuild on most SG could require rebalancing the spindle besides spending upward toward $800-1000 just for bearings.  Not saying every used SG has bad bearings.  I got lucky on mine, good bearings! But I had to replace the motor and electrics on mine.  It was wired for 575 volts! No changing out motor leads!  And last, be prepared to tear it down and do a thorough cleaning, they get clogged up with the nastiest crud you will ever see! Ken


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## Holescreek (Sep 30, 2016)

While you are considering the purchase of a grinder you should also factor dust collection into your purchase. 

The one thing that budding machinists forget is their health.  Dressing a wheel and  grinding is very dangerous to your lungs (look up silicosis) and requires a dust collection system.  A manual dry grinder should have at least 650 cfm at the intake chute. Wet grinders pose a health risk as well since mist is also generated.  

If you don't care about yourself (but love your other machines) dust collection is needed to keep the fine silica off the ways of the other machines.


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## AGCB97 (Oct 1, 2016)

Thanks for all the good info!

1 question. What makes the spindle bearings soooo expensive. I guess very close tolerance but wow.


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## rgray (Oct 1, 2016)

I've never had a manual one. Very quickly these are extremely boring machines to run. I can't imagine running a manual machine.
So my advise is look for a hydraulic or cnc driven machine.


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## Holescreek (Oct 1, 2016)

If all you ever use a grinder for is flattening stuff it would get boring. Unless you do a lot of it and have plenty of extra room for coolant tanks and/or hydraulic components I wouldn't put an automatic in my shop.  I use mine as much for rotary (punch type) grinding as flattening. If I had both types of grinders in my shop the auto machine would sit idle 99% of the year and the coolant would go rancid.


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## Cheeseking (Oct 1, 2016)

4gsr said:


> Along with what Bob said above, don't buy one sight unseen like I did.
> But if you have to buy one sight unseen do your homework first.  Get lots of pictures from the buyer.  If they won't provide addition pictures, walk away.  Do some research on the brand/model.  Lots of information out there on most of them out there on the internet.  Think about the things that may require fixing like the bed ways or if on linear bearings.  And as Bob mentioned above, the spindle, will it need to be rebuilt?  Not a easy task for most of us to encounter and get it right when it goes back together.  A spindle rebuild on most SG could require rebalancing the spindle besides spending upward toward $800-1000 just for bearings.  Not saying every used SG has bad bearings.  I got lucky on mine, good bearings! But I had to replace the motor and electrics on mine.  It was wired for 575 volts! No changing out motor leads!  And last, be prepared to tear it down and do a thorough cleaning, they get clogged up with the nastiest crud you will ever see! Ken



Ha!   Went thru the 575v fiasco with a press brake bought at auction.   It was in Canada and when we got it back discovered our "little" oversight.   $$ fixes most everything


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## AGCB97 (Oct 2, 2016)

Holescreek said:


> rotary (punch type) grinding



I'm unfamiliar with that operation. Just a little explanation please.


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## Holescreek (Oct 2, 2016)

Most people think of a "surface grinder" in a world is flat sense and forget that  surfaces can also have shapes.   With the right accessories a surface grinder is actually a very versatile and very precise machine capable of grinding contours, diameters etc.   Wheel shaping is accomplished through different styles of dressers. I use a Yuasa style import model capable of grinding angles and radii.







Punch grinding is a catch all term that includes rotary or "spin grinding" and actual punch shaping with dressed wheels.  I use spin grinding to grind OD's on various projects using a home made motorized attachment that takes 5C collets.  I used the spindle from a 5C indexer, added bearings and a motor.


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## Holescreek (Oct 2, 2016)

Set the 5C fixture on top of a sine plate and you can grind your own tapers. Making B&S #7 holders from straight shank Ebay end mill holders here:











I had to dig pretty deep for some photos. 
















Recently I needed to make a hinge. It's a lot cheaper to dress a wheel for the radius than purchase a custom cutter.


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## Cheeseking (Oct 2, 2016)

Nice work on that motorized collet fixture.  One thing that always amazed me about grinding forms is how they hold precise dimensions considering the shape must change as the wheel breaks down.


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## AGCB97 (Oct 4, 2016)

I notice a few have plain bearings. I assume this is journals and shells like a car engine. Anything to stay away from or old technology? They must run in oil or be somehow fed with oil. I used to shim auto engine bearings to get precise clearance with tapered shim stock and checked with Plastigage.


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## rgray (Oct 5, 2016)

AGCB97 said:


> I notice a few have plain bearings.



Not a disadvantage .... probably an advantage as long as they aren't worn out. Plain bearing spindles have a certain amount of oil in them just like ball bearing spindles do. They will have their ideal clearance when up to temperature. So many of these machines are left running to keep their spindle temp up during the day if they were going to be used on that day. And the reason many of these machines carry a warning sign. My one machine has two stickers one on the column and one on the wheel guard. On the column "CAUTION wheel may be in motion" on the guard " Grinding wheel may be unmanned and in motion approach with caution"

If you found two old machines that had been sitting around and had not had a huge amount of use the plain spindle machine could be the better choice it's bearings would probably survive non use for much longer. 
One of mine is air bearing, like plain bearing on steroids, but that's another story.


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## AGCB97 (Oct 6, 2016)

Holescreek
From what I can see, your  "home made  motorized attachment that takes 5C collets" has a divider plate (are you limited to number of dividing holes?) A speed control (What is the speed range as shown Also what type of motor and HP did you use?)

I'd like to make one similar to use my ER40 collets. I already made a collet chuck for my lathe and a collet block (hex) for the mill.

Thanks for whatever info you can share.
Aaron


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## Holescreek (Oct 6, 2016)

I used an AC motor, probably around 1/6hp but don't remember.  If I had it to do all over again I'd use a DC motor with a PWM control board.  I only run it at it's slowest setting as is. I've never measured the rpm of the spindle. The disc on the spindle plate has the typical 36 holes that all the import dividing heads come with which are further broken down with the 10 hole positions on the face of the bearing block, they're visible in the 2nd photo.


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## AGCB97 (Oct 6, 2016)

Thanks.
I was thinking even a gear reduced motor w/ speed control. Can't figure it needs to go very fast


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## Holescreek (Oct 6, 2016)

I'm sure there are different kinds of gear motor configurations out there but all the ones I've come into contact with  had some vibration at the output shaft from the gear backlash. I'd hesitate to use anything that didn't run smooth even if you were using a rubber belt from the motor to the spindle pulley.  I think a good range for speed would be in the 20 to 100 RPM range.


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## AGCB97 (Oct 19, 2016)

I'm looking at a Gardner 1  1/2. I believe this has a 3" spindle size I.E. uses 3" ID wheels. Can someone confirm that? I've searched for info but not found any yet.  Thanks


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