diamond dressers

[Tony]

no one tell the wife I'm shopping for diamonds, deal?

single point, multipoint, re-settable and non -- does it really make a difference? (home shop).

From what I gather re-settable dressers have tips.. I assume you unscrew the tip, flip it over,
new diamond? They're only ~$10 more (from McMaster). Seems like its worth it. Any down
sides to re-settables?

Also McMaster recommends 1/3 carat for 7-8" wheels. Why would wheel diameter have
any impact? Couldn't I just very well use a 2 carat diamond to dress a 4" wheel?

Granted, I'd rather shoot a 1/3 carat diamond ($30) across the room than a 2 carat ($300)

Then there are indexables. Assumption #465: I could just rotate a single point diamond in
its holder and not worry about even indexing?

Lastly, I see batches of these on ebay. 5- 10- 20 pcs diamonds in all shapes and sizes for
what seem like a great price. Worth it? Or is it likely they've dulled and best stick with fresh
ones?

Chock full'o'questions,
Tony

[dalee100]

Hi,

I prefer single point diamonds for dressing. I find them inexpensive and versitile. I was also taught to rototate the nib as it wears. That way you keep wearing it sharp and they will last for years even with heavy use.

I currently possess a multi-diamond dresser. I don't really care for it. And it doesn't seem to "sharpen" the face much, if at all. I don't think it's any better than an alox dressing stick. I haven't had the opertunity to try re-settable dresser.

Dalee

[MichaelP]

I too prefer single point diamonds for my pedestal, tool post and surface grinders.

[macona]

Unless you plan on a massive amount of grinding a single single point diamond will last forever.

[projectnut]

I also use the single point diamond for my surface grinder. I learned with a dressing tool that approaches the surface grinder wheel at an angle. The tool was placed in the 7:00 position and the wheel passed over it. The reason for the angled position is so if the operator makes a mistake, like not engaging the magnetic chuck, or lowering the wheel too close, the dresser will be pushed out of the machine rather than catch it and shatter the wheel.

Having said that when I bought my grinder it came with 2 dressers. Both are vertical and need to be placed at the 6:00 position for the diamond to touch the wheel properly. I've used them many times but I still get a little nervous. The thought of lowering the wheel directly onto the dresser is still something foreign to me.

Here's a link to an angle type dresser: http://www.shars.com/files/products/...12/page119.pdf

The one labeled "Adjustable Dresser" is one similar to the type I learned to use.

[Jpfalt]

I made and reset diamond dressers for several years under the trade name of Beaver Tool Engineering.

A diamond crystal is an octohedron with six points. When purchased, the diamonds are graded by the quality of the stone and the number of points. A resettable dresser is one where the diamond has multiple points available. The diamond is set with one point exposed. When worn, the dresser is machined to release the diamond. The diamond is positioned in a new shank with one of the remaining points exposed.

The shank was cold rolled steel. A hole is drilled to form the pocket for the diamond and the hole is filled with setting media. The diamond is positioned in the media and a carbon punch with a machined pocket to hold the diamond in alignment is used to press the diamond and media. The typical medias are either a wurtz metal powder or silicon carbide mixed with nickel brazing powder. The shank, diamond, media and punch are heated and pressed. Then the shank steel is machined to expose the diamond and the media.

In use, the diamond is on the wheel centerline with the shank is oriented so that the shank runs downhill relative to the wheel rotation. This is mainly to prevent the dresser from chattering, which can shatter the diamond. As soon as a perceptible wear flat appears on the diamond, the dresser is rotated 10 to 20 degrees. The edge of the worn flat then starts dressing. When the point is worn all the way around, the dresser is ready for resetting.

Once all the points have been used, I used to crush the diamond and mix with the silicon carbide and nickel brazing compound to make a cluster diamon dresser.

Diamond dressers have a tendency to dull the grinding wheel by crushing wheel abrasive into the face of the wheel. This is wildly different depending on the breaking characteristics of the individual grinding wheel grains, the wheel bond material and the porosity of the grinding wheel. One method to minimize this was to dress the wheel with the diamond point moving slowly, setting the dresser in about .0005 and doing a high speed pass across thee wheel face to put in a spiral groove that makes the wheel a little more free cutting. Another approach is to shape with the diamond dresser and then open up the wheel with a crush dresser.

[Ron of Va]

I made my own diamond wheel dresser. It was pretty easy to make and works fine.

I ordered a 3/8 x 2” diamond dresser from Enco and mounted it in a piece of flat bar. I milled a rib on the bottom to act as a guide, and used a ¼ x 28 SHCS as a pusher. I drilled a through hole for the ¼ x 28 cap screw, and then from the other side I enlarged the hole to 3/8. Threaded for the cap screw and installed a set screw to keep it from falling out.

[J Tiers]

What's the advantage of the diamond over a spur wheel dresser or abrasive wheel type dresser? I mean in how it works on the wheel.

My reading seems to show that the diamond shears and partly glazes the surface, while the spur wheel opens it up. But the diamond can be used to contour it, and the spur type obviously doesn't do that.

And the diamond works on narrow wheels that the spur won't work on. Cup wheels, TPG wheels, etc.

I have both, I have a drawer of diamond points that came to me in toolboxes etc, but have only ever used the spur wheel on the standard bench grinder wheels.

[Jpfalt]

The diamond dresser is used to shape the wheel and the spur dresser is used to open up the face of the wheel. Abrasive dressers usually don't do a good job of leaving an open wheel face, except for a type called a cutsforth dresser. It has a free rotating abrasive wheel on a shaft with ball handles on both ends of the bar. The abrasive wheel rotates with the grinding wheel and crushes the surface, so it both shapes the wheel and opens the wheel surface.

In really special applications, there is a type of dresser with a rotating wheel with diamonds set in the outer surface and ground to a precise profile. This is driven with an air motor and pressed into the grinding wheel. It is also a crush dresser and shapes the grinding wheel to the dresser wheel profile, butr also leaves an open, free-cutting surface on the grinding wheel.

[J Tiers]

The diamond dresser is used to shape the wheel and the spur dresser is used to open up the face of the wheel.

That's my understanding also.... But folks also use a diamond on a straight ordinary wheel with no fancy profile. Given that it shears and doesn't open the wheel as well, what's the advantage?

All I can see is that it is fairly convenient to use, by setting up the diamond in a holder and just traversing the wheel over it, for grinders with a moving wheel. But for a regular bench grinder, you would move either a spur dresser or a diamond, seems all same-same except for the "opening" effect which should make the spur-dressed wheel cut freer.

[Tony]

excellent info here folks, thank you.

Just saw the Enco deal, too.. picking up a 1/2 carat single point for just under $25.

[Jpfalt]

That's my understanding also.... But folks also use a diamond on a straight ordinary wheel with no fancy profile. Given that it shears and doesn't open the wheel as well, what's the advantage?

All I can see is that it is fairly convenient to use, by setting up the diamond in a holder and just traversing the wheel over it, for grinders with a moving wheel. But for a regular bench grinder, you would move either a spur dresser or a diamond, seems all same-same except for the "opening" effect which should make the spur-dressed wheel cut freer.

I had said once before that the abrasive grain type, bond and porosity of the wheel all affect how the dresser works. The wheels that can be successfully diamond dressed only have a couple of features. Either the grains fracture and produce new sharp edges, called a friable grain, or the bond material is brittle and the porosity is high, so that old grains fall off intact and totally new grains are exposed. Most often, the diamond dressed wheels are aluminum oxide or silicon carbide with a vitreous (glass or ceramic) bond. In the wheel grading, one main feature is the wheel hardness. The softer the wheel, the more delicate the bond is and the easier to fracture off complete grains. The other main class of wheels is resin bonded. Resin bonded wheels depend on heat from dull grains to soften the resin and let the dull grains fall out.

The last thing is that the diamond dresser needs to come to a point or sharp edge. That's why the comment about rotating the dresser whenever a flat appears on the point. The sharp edge or point is more likely to fracture or tear out a grain. A flat tends to skate over the surface and dull the grain further.