Boyar Schultz 612

[qwhit]

I just bought a Boyar Schultz 612 surface grinder and was having trouble grinding smooth. As I am prone to do I took the cover off the head tower and found a belt drive ( that was loose) from the motor to the spindle. My manual list it as direct drive, wrong manual or has someone changed the motor at some point?

If this was a design change when did it happen?

[Downwindtracker2]

There are guys who have used SGs, who know much more than me but just bought an '68 6x12 Delta Toolmaker when our mill shut down. The Delta is a '30s design and is good maybe to 1/2 a thou. I read up on the little dear, the motor and pulley are balanced together, the spindle is balanced and the arbor and wheel get balanced. One of the old millwrights warned me if I wanted a good finish, it would only do a 1/2 thou cut.

[GlennW]

They made 612's in different vintages. Some belt drive, some direct drive.

Did you tighten the belt? If so, did it grind better?

If not, did you true/dress the wheel after starting the spindle before using it?

Is the wheel adapter tight on the wheel?

Is the wheel adapter seated properly on the shaft?

How much down feed are you using, and how much step-over per pass?

What are you grinding, cold rolled 1018?

What is the wheel designation?

Lots of variables to grinding!

[qwhit]

It ground much better after the belt wasn't slipping.
Any thoughts on how tight to tighten the belt? I just used the motor weight to tension the belt.

[GlennW]

That's probably about right.

Good to hear it got better!

[walsheng]

Back in the 70's (that's 1970's, I'm old but not that old) we upgraded from Harvey Butterfly 6-12's to Boyar Schultz 6-12's and they were really nice (compared to the Butterflys anyway) I am pretty sure they were direct drive and I am pretty sure the newer one had Teflon coated ways. We used them for quite a few years and they turned out to be nice machines.
If the machine sat for any length of time you might want to consider changing the belt because it probably took a set and will cause vibration.

John

[John Evans]

I have a 6-18 with power x-y and it is direct drive . Found a manual online and it shows both style drives were available. 3 way styles were available ,plain,hardened steel inserts,and Turcite as options

[Harold_V]

One thing that can be an issue is the motor itself. If it isn't the original motor, it may not run balanced well enough to not transmit vibrations to the grind. Makes no difference if it's belt or direct drive, it can still be an issue. A bad belt can contribute to the problem, too. If it's old and lumpy, you might consider a new one, assuming the problem is ongoing.

Don't overlook the possibility that the power source is the problem, either. If you're running a single phase motor, it, alone, can be the problem. They simply don't perform as smoothly as three phase motors do. In any case, the motor should be precision balanced.

Harold

[earlgo]

All of what the above knowledgeable people said is true about what affects finish in a grinder.

One of the companies that I worked for bought a BS for the model shop and the older Russian toolmaker could play it like a violin. After 40 years I don't remember if it was direct drive or not.

The Delta Toolmaker I use originally had a 3Phase motor and I changed it to a single phase. It will leave a ripple finish if the wheel is not dressed, the cut is too deep, etc. Sparking out relieves most of the problems, but that takes some time at the end of the cut especially on a large surface. For what it is worth, I prefer the Norton 5SG60-KVS wheels because they are 'self sharpening' and don't load up very fast. At $43 to $65 a pop they are a bit pricey but they last a long time (YMMV). General Tool and Supply Company in Attleboro, MA had the best price ($43) at the last time wheels were needed (Jan 2012).
Eventually you are going to want to spring for a diamond wheel to sharpen all those carbide cutters.

Enjoy your new grinder but expect a steep learning curve with all the things that it can do.

--earlgo

[qwhit]

The grinder performed like it should after the belt was tightened.
I have used surface grinder for 40 years and ran into most problems.
This is the first one I have used with a belt drive. Most industrial grinder are direct drive to lessen vibrations.

[Conrad_R_Hoffman]

Mine's a Frankengrinder, a belt drive that was converted to direct drive, I assume with parts from another machine. I have't set it up yet, so can't comments on much else other than direct drive came later.