Surface Grinder Wheel - Diamond Dresser question?

[widgitmaster]

Does anyone know the angle from perpendicular at which the diamond should be to dress the side of a 7" wheel?

I need to make a dual diamond dresser to true up some cheap wheels from Mexico, and will be using two 1/2-Carat diamonds.

The chepo wheels are not balanced, and my regular diamond block will not reach the entire exposed side of the wheels!

usually I just eyeball the angle, but sense I'm making this fancy double block, I figured I'd do it right!

Eric

[Mcgyver]

Eric, I don't think it matters on the side of the wheel, if anything slightly angled away from the direction of rotation, but unlike the periphery, you don't have to worry so much about placement of the dresser and whether it can jam. maybe angle upwards to reach past the housing? for expediency, you could clamp your regular diamond tool holder to an angle plate and then just turn it around to do the other side. I'd be thinking of knocking together a balancer before this fancy double sided dresser, if the wheels are that far out - it can be differences in density not just dimensions that put them out, so dressing may not fix it.

I think there is a place for balancing these wheels in the home shop. I've been scoffed at by pros for this, who believe there's no need except on larger dia wheels. I maintain this is crap, that to the extent that a wheel being out shows up in the work is at least partially a function of how robust the machine is, and since in the home shop we're using lighter machines than most of industry, we need to balance the smaller wheels. i notice it more on my t&c grinder which is really light than the surface grinder which is the same size as yours, but still, balancing will correct for density differences and may improve surface finish on those less than perfect cheapo wheels (and whether we should using those at all is probably a whole new topic )

[widgitmaster]

Originally Posted by Mcgyver Eric, I don't think it matters on the side of the wheel, if anything slightly angled away from the direction of rotation, but unlike the periphery, you don't have to worry so much about placement of the dresser and whether it can jam. maybe angle upwards to reach past the housing? for expediency, you could clamp your regular diamond tool holder to an angle plate and then just turn it around to do the other side. I'd be thinking of knocking together a balancer before this fancy double sided dresser, if the wheels are that far out - it can be differences in density not just dimensions that put them out, so dressing may not fix it. I think there is a place for balancing these wheels in the home shop. I've been scoffed at by pros for this, who believe there's no need except on larger dia wheels. I maintain this is crap, that to the extent that a wheel being out shows up in the work is at least partially a function of how robust the machine is, and since in the home shop we're using lighter machines than most of industry, we need to balance the smaller wheels. i notice it more on my t&c grinder which is really light than the surface grinder which is the same size as yours, but still, balancing will correct for density differences and may improve surface finish on those less than perfect cheapo wheels (and whether we should using those at all is probably a whole new topic )

Mcgyver
I was under the notion that the angle was for the prolonged use of the diamond, that it had something to do with the grain and the facets!

I had dressed one of the wheels using the clamped block method, and it was a nusance, but the surface finish was worth the effort! These wheels are so uneven, that I can feel the vibration in the spindle in my 2000 lb machine!
I'm retired, and have all day to make neet usless stuff, and have no boss to bite me for wasting time! A faint memory tells me it was around 15°, but have been unable to locate proof!

I know the number of Carats is based on the thickness of the wheel, and increases as the wheel width increases due to the heat generated during dressing. The wheels I need to dress are 1/4" to 3/4", and the 1/4" wheels are the worst! They even have "BAL" stamped in the sides in black ink!

Eric

[lakeside]

this site may help answer some of your question as they do make the best wheels on the market
http://www.grindwellnorton.co.in/Bro...htm#Care&Usage

[widgitmaster]

Originally Posted by lakeside this site may help answer some of your question as they do make the best wheels on the market http://www.grindwellnorton.co.in/Bro...htm#Care&Usage

Cool!
The gray matter is still functional! I found that I was right, it is 15°

http://www.grindwellnorton.co.in/Gri...elDressing.pdf

Thanks for the link!
Eric

[Mcgyver]

Eric, I continue to believe (although it’s just based on observation, not teachings) that the angle is to prevent the dressing from being drawn into the wheel, something that matters on the periphery, but not the side - so long as its not angled into the direction of rotation, in other words the exact angle doesn't matter that much. In my observation, the diamond is irregular looking - the angles/facets bear no relationship to the setting. Furthermore, I've read that you can re-seat the diamond (i think it just sits in brazing material) to expose a new surface. This, to me, cements the idea that the angle of the diamond relative to the holder is pretty random.

If it’s a balancing problem, it won't necessarily go away with dressing, Here's where i got started with some ideas for a home shop balancer

http://www.homemetalshopclub.org/news/sep04/sep04.html

and here's what i did with it

http://www.homeshopmachinist.net/bbs...ncing+grinding

In hindsight I probably made it more work than it needed to be, you can get by without the weights and just carefully use a dressing stick to balance it.

As I think about it more, it strikes me that given the safety concerns of poorly made wheels, and the incredibly long life of a wheel in a light duty, home shop environment, it may be a false economy not buying the better wheels, which will require little or no balancing. Then again I have a (perhaps irrational but healthy) fear of a grinding wheel letting go.

[lakeside]

when using a diamond dresser the angle only need to be offset if diamond has a flat from wear on top. (it more imporant to be behind center of wheel when dressing face) you could put the diamond on any angle and the side of the wheel will be true to machine axis this is only and issue if you are grindind a grove to a wall. In this case you should use a side on table and put a 2deg. dish in wheel to prevent dragging of the wheel on the side of part

[all around]

15 degrees will give you perfect wear, then spin 10 degrees radially every so often to keep the geometry fresh.