dressing surface grinder wheel

why does nobody dress (open up) the wheel after the diamond has cut through the grit on a surface grinder? to much work? no benefit? chances of ruining the geometry? or does anybody do it and how?

The diamond tends to tear the grit out, rather then cleanly shearing it off.

It's worth holding a bit of wood or similar to the wheel before the first cut, just to knock off any loosly held particles that might otherwise cause scratches.

Mark Rand said:

The diamond tends to tear the grit out, rather then cleanly shearing it off.

It's worth holding a bit of wood or similar to the wheel before the first cut, just to knock off any loosly held particles that might otherwise cause scratches.

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That procedure is a must for grinding graphite EDM electrodes.. Otherwise you get deep scratches. I usually use a piece of .005 or .007 shim stock to lightly touch the wheel

I kept a 2" wooden handled paint brush on the surface grinder table to brush grit from my chuck, either after dressing or before removing parts from the chuck. Use the wooden handle to GENTLY touch the wheel to remove loose grit, especially when setting up to grind graphite.

I use a chunk of plastic cutting stick out of a paper shear, then its something i always have on hand.

A sharp dimond will knock some grit lose, but most it should be shearing off.

A well dressed grinding wheel should more or less be acting as a multi thousand tooth milling cutter with all the teeth very much at the same height. Its why used correctly a 46 grit wheel gives you a finish you would expect of several hundred grit sandpaper. not the road rash a piece of 46 grit paper would give you!

well, the ratio of fractured particles will depend on grit size to dressing deph, hardness of wheel and other parmeters. if you slowly dress a 46 wheel going 0.01 mm deep, you fracture most of the grains and the wheel woud benefit from opening up. as far as i can tell, nobody does it, though.

dian said:

well, the ratio of fractured particles will depend on grit size to dressing deph, hardness of wheel and other parmeters. if you slowly dress a 46 wheel going 0.01 mm deep, you fracture most of the grains and the wheel woud benefit from opening up. as far as i can tell, nobody does it, though.

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Many people do this.
It results in a very "closed dress". The wheel acts very hard and dulls or loads quickly but produces finer finishes.
In an open dress the wheel itself is more like a threaded rod on a microscopic scale. Less grains are doing the work but the much higher unit grain pressure allows the dull ones to pull out easier leaving new fresh grains to do the work.
One can move the hardness of a wheel all over the place with differing dressing methods.

Also depends on the type of grinding.
A 46 will leave a nice finish while conventional surface grinding or if you have some amount of in-out motion.
Not so nice in pure plunge grind with no sideways movement where you need the slow dress and are generally forced into finer grits to hold the surface Ra. You run into this in plunge centerless or complex form grinding where any in-out is a disaster.

Outside of the wood/plastic blowing out of loose grains that are free anyways I'm very against the "hand sticking" of a steel grinding wheel to try to open it. (you can also do this get rid of the loose guys with an air hose or medium pressure coolant)
In steel, sticks are great for the bench grinder, on the precision grinding machine and there should not be a need for such.
Resin bond diamond and cbn wheels ..... a whole different deal but having to stick them kills part production rates so you move bonds and cons around to tune a process.

Dressing a wheel and sticking a wheel are different things to me so maybe I'm not understanding your post.
Bob

no, you are understandidg quite well. im trying to find out if anybody is using any technique to open up the wheel, because "sticking" is obviously not ideal. like maybe touching the wheel to a hss or carbide edge, a stone or similar. 46 grit is around 350 micron (out of memory) so youd have to go at least 200 micron deep to not fracture most particles and get a coarse dress. poor wheel would be disappearing before your eyes. (unless you have a "H" bond, where the grain comes out just by looking at it.)

Dress the wheel, pull it, get out your 60x stereo scopes and 300x microscopes and have a look see at the grains and bond tails supporting them in the wheel.
Try your other methods, do the same, see how they all cut in use.
I think you are missing how to "open" a wheel.
Everything you describe leads to lower grain force (IE: more grains in contact) which closes a wheel making it act harder.
Bob

I do sometimes plunge a few grooves in a wide flat wheel, using a diamond or Norbide stick. I makes the wheel grind cooler, and allows coolant into the cut.

2 things.

When I need the coarseness of a 46 wheel I screw the diamond across fast enough for the grit to spray off, more or less creating a screw thread, like the others have said.

That can be used 2 ways. 1.) conventional grinding where the downfeed is shallow (.001 - .0015 on a 1/2 x 7 wheel)but the cross feed is some large proportion of wheel width, say 3/4 of wheel. 2. About as deep as you want to go, say .030" down, but less than .005 infeed, on auto.

1st method cuts with the rim of the wheel, and will need dressed more or less frequently. But it cuts freely, leave more or less nice "ribbon" stripes, and does not load too fast initially. good for "dusting" a surface. Then dress a little more slowly and finish if you want more polished surface and no stripes.

2nd method cuts with side of wheel and cuts "forever" before it needs dressed. Leaves a very polished, stripe free surface, subject to a little tweaking for a given material/part/etc. Once the wear step in the wheel progresses about 1/2 to 2/3 of the way across the wheel, the whole thing needs dressed off to start again. If the wear causes a wear ramp, it will need dressed off to reduce wheel pressure on the work, and the table speed or other factors modified so the wheel acts a little harder and wears a step, rather than a long taper.

I am aware of what Dian mentions because I use worn down wheels or sometimes shaped surface grinder wheels on the pedestal grinder for profile grinding wood working tools (shaper knives). Recently dress wheels off the surface grinder act hard and dull on the pedestal, and as Carbide mentions, need opened with a hand stick to be effective. So it is a real factor. But screwing that dresser across fast, as appropriate to the work, is about the only effective way to change things and maintain the geometry of the wheel, on a surface grinder.

Dian, perhaps your thoughts could lead to a here-to-for un-recognized invention? Would dropping the wheel straight down on a cluster be effective if the cluster was made or dressed "perfectly? (I don't know)

smt

QT: [why does nobody....) likely many and most do just about every thing and anything, they don't talk about.

Most often I just diamond dress AO wheels with a sharp facet of the turned diamond..grinding a high finish I may rub with a stick or swipe with my sash brush. . Have plunged the diamond straight down-feed to make a circular notches around the wheel..Have dressed off part of the wheel for narrow wheel needed so not dressing the whole wheel narrow.. Have dressed .020 under cut at lead and follow edge. Have taken a wheel to the abrasive chop saw and put notches across the wheel OD. Have under cut the face with diamond and/or dressing stick to make a facing edge wheel( rule is don't grind with the face so this for grinder hands only). Have ground a mild steel stub with a diamond wheel to make a little better true. Likely more than I just cant think of now... and even some things they/we wish they/we had not.

Norbide stick, carundrum stick, piece of a broken diamond wheel, diamond set at perhaps 15* angle off the table, A diamond on a tilt arm so it becomes the dress-set height gauge, a crackerjack minie, and old carbide lathe tool, diamonds save for a certain plunge radius dresss,bought and home made Rolls for crush able wheels tilt angle for angle dress ..and more i just cant think of offhand..

Qt Stephen: [the wheel straight down on a cluster] we had some cluster diamonds with large diamonds at the big shop that would be good for your idea.. also had some diamond roller dressers .. about 3"dia x 4"long with diamonds set all around.. yes we sent the back for re manufacture..so diamonds could be reset.

I am looking for another diamond dresser for my Taft Peirce surface grinder My current diamond came with my Eagle Rock holder and is a BCSG2M6 and is quite rounded over. Norton brochure has so many options and I'm looking for advice. 7" wheels x .5" to .25 wide.

Cluster or Single? Carat Weight? etc. My holder uses 3/8 diameter shanks.

I use general shop wheels to grind soft and hard steel.

Good to look close at your diamond to find a facet to point to face the wheel. 1/4 carat single point is good for that dresser. You might get a loop to look at your diamond to find a facet edge.
Good to position the diamond under the wheel looking facet up top the wheel. Yes you angle the diamond a bit rather than always pointing straight up.
Dresser bottom can become out of flat in a convex way and so try to rock. good to check that so it is dead flat or having a little hollow at bottom.

Eagle Rock, A1-213-, EAGLE ROCK Diamond Holder - Model : AIN-37 : Tools & Home Improvement
This photo has diamond sticking too far out IMHO.