Looking for Sanford MG-612 Surface Grinder owners

Great score! Noticed your pic on first grind. Maybe I see wheel hopping and left over pass marks. I guess once you get her all tuned up that will all go away. I have the smaller Sanford 4“ surface grinder. Produces almost a mirror finish. It’s one of those toys for the shop that once you get one you wonder how you got along without. Enjoy…Dave
 
I just got back from a used equipment dealer. The owner wasn't there at the time, but I did find a hub for 1 1/4" surface grinder wheel. It didn't have the washer or retainer nut (left hand thread) so for the time being I passed on it. After I left I got to thinking it might have a non-standard taper. A rough measurement on the small taper was .656. The large end was .946. It was dirty so I'm sure those won't be the exact measurements once the crud is removed. I'll be going back tomorrow to talk to the owner and see if he has any more hubs.

I'm out of town right now, but I don't recall any holes on the sides of the cover. Having said that I have seen other grinders that had a rubber sheet covering the rear of the machine. In most cases the sheet overlapped the sides and was held in place by a few machine screws.

Looking at your test piece it appears you're moving over almost the width of the wheel with each pass. I was taught to generally use a "medium" grind which would be 25% to 50% of a wheel up to 1/2" in width per pass. When working the final pass I was also taught to grind until the piece "sparked out". The term "sparking out" essentially means to continue to move over the piece at the same height until sparks are no longer generated. You may be surprised at the amount of material that remains after one or two passes, and the difference in finish when grinding until the part "sparks out".

I'm not sure what grit wheel you're using, (couldn't find the specs in my Radiac catalog), but I believe something like an A36 wheel with a closed dress would give a better finish. Be aware that using a soft wheel will give a better finish, but the wheel won't last long. By closed dress I'm referring to passing the wheel over the diamond at a slow rate. The faster you move the wheel over the diamond the more open it leaves the grit. An open grit generally removes more material quicker, but it also leaves a rougher finish.
 
projectnut -

I'll be interested to hear what you find out about those wheel adapters.

The wheel I'm using is 46 grit, 1" width with a recess on one side. You can see the specs here. I think I had two problems on my first test grind - I was going a bit too fast and not sparking out. I was only doing about 20% of the wheel on each pass, but I think I did not dress it as well as I could have.

I flipped my test piece over and did a second test grind (picture below). I dressed the wheel again first and took a bit more time doing it. I made numerous passes over the test piece again, taking 5 tenths on each pass, and making sure to spark out. I think I got noticeably better results - not a mirror finish, but very respectable if I do say so myself.

sanford-mg-second-grind.jpg
 
Using deeper cuts along with a smaller step over and only working the part in one direction works better for a couple reasons. Almost all of the hard work of surface grinding is done by the leading corner of the wheel. As the corner wears, more cutting occurs at newly formed corners deeper into the wheel, leaving a tapered shape to the face of the wheel. This causes larger dimensional changes to the following end of the wheel, which hurts flatness, and also tends to load up the following end of the wheel, which increases heat in the work and hurts surface finish. Commercial grinder hands, using grinders with larger, wider, and more powerful wheels will often takes much deeper cuts, like .020 for roughing work, but with step over of only .050 or so. The leading corner is working hard, but as the wheel advances across the work the relatively pristine following surface cleans up and finishes the grind, leaving a nice surface finish. I do the same on my 1946 B&S 2L 6x18" grinder, but to a lesser degree. I might use .002 to .003 depth of cut with a .040 to .050 step over, sometimes up to .100, for metal removal, and this is with 1/2 x 7 x 1 1/4"wheels... A single, lighter depth finish pass with the same wheel, undressed, cleans it up nicely.

If the wheel is stepped over in both directions, then both corners get worn, leaving a slightly "U" shaped wheel that will not finish well in either direction. Try both approaches, experiment and see...
 
Kevin, If you're looking for more factory brochures I found 4 of them at this site:

http://digital.hagley.org/islandora/search/sanford surface grinder?type=dismax

There's a 1945, 1953, 1963, and 1965 brochure.

The 1953 brochure is quite interesting. The list price for the MG is $925.00, which is about 10% of the 1996 quote. It also lists 2 three phase motors for $18.00 and $30.00 and a DC motor for $35.00. The base sells for $75.00 rather than the $800.00 in the 1996 quote. The best part is the optional table stiops for $35.00 rather than $430.00

I didn't get back to the equipment dealer last Saturday, work around the cottage got in the way. We'll be going back the next 2 weekends to finish things up. Hopefully I'll get back and talk to the owner about the grinder hubs
 
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kevin said:
Andy - thanks for confirming the serial number; please let me know when you have a chance to measure the taper. Were you able to get info from your co-worker?
Click to expand...

Hi All,

Kevin,

I'm waiting on the second spanner wrench. The wrench is a Williams #424. It's identical to the Sopko wrench I have minus the hex socket. The back side of the adapter has the same hole pattern as the nut. It ought to be here in a couple of days. The nut is still frozen on the end of the spindle. I've been squirting a little Kroil in it each day.

I would make the spanner, but I have too much other work going on in my shop at the moment. $12.95 including shipping isn't bad....I can't make one for that.

My co-worker is also busy. He's setting up his shop at the moment. I'll keep after him.

I did speak with a tool and die maker friend of mine about wheel selection. He recommended Norton wheels and said that the 60H grit is a good starting point. He also said to have an assortment of wheels available for different jobs.

I never did much grinding in my 38 years. A little here, a little there. Most of the grinding that I've done is on automatic machines. Using the wheels that were already on the machine. We have a big Gallmeyer and Livingston machine at work. 8" x 24". It's a sweetheart of a machine. The biggest one I ever ran was a 36" Blanchard. That thing was a little intimidating. The lights would dim when you turned on the spindle motor on that beast.

Andy
 
Andy -

I'm a total novice when it comes to surface grinding, but I'm pretty sure the only good answer to "What grinding wheel do I need?" is "It depends." I started researching grinding wheels after I got my machine, and the variety is mind boggling. One thing I'm sure of is that buying a surface grinder is just like buying a mill or lathe in that once you have the machine, you have to invest in tooling up for it.

I'm starting out with some 46 grit wheels, but I have no doubt I will be buying more eventually. Ultimately I would like to do some wet grinding with diamond wheels, but that is far in the future for now.

Here's a good video on wheel selection:

By the way, I've started a second web page with info for people new to surface grinding. IF any has suggestions for additions, I welcome them; I'm looking for good text or video on surface grinding at all levels - novice to expert. Here a link to the web page:

https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/my-surface-grinder---2
 
I finished cleaning up the spindle and hub a couple days ago, so I thought I'd try it out. I dressed a slightly used 46H wheel to do a test grind on this piece of A2 tool steel. I used the method Bob suggested of always working from the same side. Each pass was .00041" deep, and I moved over .045" per pass I moved the table relatively slowly left to right at what I would guess to be about 50" per minute.

I mentioned in an earlier post I didn't think the spindle bearings were precision in that they were marked 205SZZ. When I went to look them up I found that there is a 205 series made by MRC that is considered precision. I can't remember the full number, but new from most bearing suppliers they cost around $150.00 each. I'm not planning on changing them out at this point, but I did see they are available from Locate Ball Bearings for $108.00, and free shipping.

IMG_0672.JPGIMG_0671.JPGIMG_0672.JPG

The finish is about the same as it has been since I got the machine. I did check the balance of the hub and wheel using a balancer like this:

https://www.stens.com/750-087-blade-balancer-mag-1000

According to the documentation that came with it (I bought it in the 1960's) it's supposed to be accurate within "less than1/10 oz. I'm thinking the accuracy is around 1 gram, but in the 1960's we didn't dare think (let alone mention) metric in this country. I tried looking up the specs of the current models, but couldn't find anything.

The wheel and hub were both heavy in one spot, but since I don't have weights on the hub and wasn't willing to remove material from the wheel, the best I could do was mark the spots and rotate the wheel on the hub to the point where it would show the least imbalance.
 
projectnut -

Great information on the bearings, I have added it to my web page.

That finish looks pretty good to me. Very creative use of a blade balancer. I do not have a balancer yet, and looking at the prices on them I'll probably end up making one; right now I'm just winging it.

So far I am happy with the results I am getting. I checked my test piece (surfaced on two sides) on my surface plate, and the sides were parallel all over to within a two tenths. Not bad, I think, for a machine that has not yet been tuned up, and with a very used wheel.

I finally got around to removing my mag chuck from the table, so I could get them both cleaned up. I did a lot of online research on mag chucks, and I have saved the best links here:

https://sites.google.com/site/lagadoacademy/machining---lathes-mills-etc/my-surface-grinder---2

Once I had the chuck cleaned up, I found a serial number on it:
sanford-mg--mag-chuck-serial.jpg

From my research I found the following "facts" which may or may not be correct:
  1. Older Walker chucks (and maybe all older mag chucks) are oil filled.
  2. Newer ceramic magnet chucks are not oil filled (typically a specific grease is recommended by the manufacturer)
  3. Oil filled chucks can "stiffen up" if they are kept upright for a long time; flip them over to allow the oil to lubricate the magnets - this may help the mechanism work more easily
  4. Chucks may lose oil if the seals around the on/off handle are worn. Some chucks have an oil fill hole. For oil, 90W (non-detergent) or way oil is recommended.
  5. Weak magnetic chucks: This may be due to wear in the internal cam mechanism or related parts. Opening up the chuck and repairing this may rescue the chuck.
My chuck has an oil fill hole (I think). There is an open threaded hole on one end; I didn't think it would hurt to squirt a little Vactra-2 into the hole. I also flipped the chuck upside down and worked the on/off handle a few times; it seemed to help. I closed up the oil (?) hole with a screw to keep crud out.

An alternate explanation for the "oil hole": Some chucks have an adjustment screw to stop the internal mechanism from sliding past the optimal position. There could have been an adjustment screw in the hole at one time.

Finally got some new wheels in. Next step is to grind in the table and mag chuck.
 
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