Belt Vs Rock on surface grinder

[Jerry Shorter]

I recently purchased a nice Norton surface grinder. So can some of you guys that have made the conversion to belt enumerate the advantages and disadvantages of doing so. One disadvantage I can think of is I don't think you can use coolant with the belt setup. (all coolant I have had any experience with really messes with rubber and neoprene.) I really can't think of any advantages. so help me out here :confused:

Jerry

[polarbearforge]

All the surface grinders I've ever used had stones. The advantages I can see to having a belt, is ease of changing grits and not worrying about truing and dressing the wheel.

Disadvantages I see, is the stress it puts on the spindle bearings. I also wonder about the accuracy of the belt versus the stone. If the grinder is in good shape, it's not that difficult to keep whatever is being ground accurate within .0002 inches or less. The coolant issue is also a disadvantage.

For those with belts, have you ever seen how accurate it will hold dimensions?

Jamie

[Ed Caffrey]

I personally would not have my surface grinder set up any other way than with a belt. I tried using the stones when I first got the machine, and found it to be frustrating at best. Truing the stones was a real pain, and it took forever to get anything flat due to the TINY "bites" you had to take with the stone wheels. The other thing I noticed was I could not gauge the depth of cuts using a stone wheel. It seemed that the stone would wear away as I made passes, causing one end of the work piece to be over thickness, when I tried to compensate I would wind up with the other end of the work piece being too thin.

Converting to belts has the advantage of using the same abrasives I use on my KMG and Square Wheel machines, plus, I can take 2-3 thousands at a pass with 50 grit belts and get the job done in a hurry, without any of the aforementioned problems. Once I am close, I just switch to a finer grit belt until I'm where I need to be.

Accuracy is dependent on how dense the contact wheel is, and how you true it up when you first install it. If you use anything less than 100 durometer contact wheel, and apply down pressure your going to get "cupping" on your work piece. My contact wheel is 100 duometer solid urethane. The way I trued it up was to place a file on the mag chuck and then ran several passes across the wheel until it was trued up with the mag chuck. Mine has been running for about 5 years now, and maintains 1/2 thousandth accuracy.

[polarbearforge]

I guess it's what you're used to. It would bug me not to have a stone.

I was thinking about it today, and talked about it a bit with one of the guys in surface grinding. We decided that for the tolerances that knifemakers need, a belt system is probably sufficient. For some of the tolerances we need though, half a thousandth would be way out of tolerance.

The grinders I've worked on easily take 4-5 thou off at a pass with a stone wheel. It all depends on alot of factors. The machine rigidity and power, grade of the wheel, structure of the wheel, etc... Books have been written on the subject. Needless to say, it could end up being a REAL long post if I summarized everything...

Our grinders at work are usually left on all day long unless the wheel needs to be changed, so truing the wheel isn't needed that often. Dressing it ocassionally is needed if the wheel gets loaded up, dull, or glazed.

Jamie

[Jerry Shorter]

Thanks for the replies guys. ED; where did you get your wheel? and what diameter?

Thanks, Jerry,

Ps. I'll probably see you at the Reno Show

[fitzo]

Check out Bertie Rietveld's contact wheels and conversion diagram:

http://www.batavia.co.za/

One can also order high-durometer wheels stateside from Contact Rubber:

http://www.contactrubber.com/

[Ed Caffrey]

I got my contact and idler wheels from the first link that fitz listed. Very high quality stuff, at a fraction of the price you'll pay for rubber wheels sold in the US.

[Jeff Higgins]

I use mine with a stone and NO coolant. For me, coolant is a hassle at best. I'm no production worker. Most of my stuff is one-off anyway. The stone and no coolant assures complete flatness to my work. That said, I'd love to have a cheap used SG with a belt setup for taking off scale and general truing. What a timesaver that would be!

[Donald Bell]

I have the 2x72 belt setup on my old B&S model 2. Not only is it easier to change grits, but with the use of 2-sided carpet tape and a thin stop plate you can quickly grind wood , ivory, or pearl to uniform thickness. I am using a serrated 8" contact wheel and rarely need to true it. accuracy is about 1/2 thou with a 400 grit finish.