dressing the wheel

What is the proper method for dressing a grinding wheel? I understand the part about moving across the wheel fast for a courser cut and slow for a finer cut but the rest I don't have a clue about.

It's good to see that you have questions but in these early days the expert with the answers might be a little harder to find.

At least with the specialised forum your question will stay on the front page longer to attract an answer.

steel- I read your question this morning and had to give it some consideration before replying. You already understand the most technical part, dressing speed. So that only leaves diamond placement and depth of dress. Is that what you are asking? -Mike

What is "fast" and what is "slow" for wheel dressing?

I'll repeat this question from just before the new forum.

When people say to dress the wheel "fast" to get a coarse cut, what is "fast"?

Would 1 second to span the wheel be fast or slow?

Some kind of numbers for where to start would really help.

bmw

Speaking only for myself, a 1 second pass would be fast on a 1/2" wide wheel. my normal speed would probably be 3-4 seconds. I have never thought about timing a dress before. Dressing a wheel is like seasoning your food. Everyone likes it different and uses speeds they are comfortable with.

Personally, I don't put too much stock in dressing speed as a useful tool for the reason mentioned above. I like controled variables like grit size and hardness to determine my finishes, not if I cranked fast enough.

Now let me stir the pot some more. I keep a small piece of seal peal (the plastic like stuff that new endmills have on their sharp edges) on my grinder to use to rub across the wheel after its dressed. This serves to knock the loose particles off of the periphery of the wheel and if pressed in hard enough could partially load the wheel. The guys at my first shop did this regularly to eliminate those nasty "pecker tracks" you get when there is one grain on the wheel that leaves a line that stands out on an otherwise pretty finish.

A couple of years ago there was a longish thread as the result of someone asking how many people checked their wheels smoothness with their fingers. Man that was a pot stirrer! The guys that grind for a living pretty much all said they did, and the rest said they'd pretty much nuke an unborn gay whale before they'd touch a spinning wheel. Can't wait! -Mike

Holescreek said:

A couple of years ago there was a longish thread as the result of someone asking how many people checked their wheels smoothness with their fingers. Man that was a pot stirrer! The guys that grind for a living pretty much all said they did, and the rest said they'd pretty much nuke an unborn gay whale before they'd touch a spinning wheel. Can't wait! -Mike

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It pretty much depends on HOW you touch that spinning wheel. You can check for "hangers" with no damage to the finger, or you can grind a pretty nasty chunk out of your finger.

Someone asked about a video of dressing. I'm gonna make one and put it on YouTube one of these days. I'll post a link here when I do.

You'll get a feel for dressing speed after you experiment with it. You'll learn to adjust the speed for the type of material, how much you have to take off, how much heat and stress you are willing to put in/on a part, and the finish required. For specifics look in the Machinery's Handbook. There is quite a bit of info in there.

If you make a video RJ, there should be a link kept at the top of the forum. You gonna demonstrate what happens when someone puts the dresser block behind center and forgets to turn the mag on?

Mike that's a good idea about the endmill stuff. I'll have to try it. I use a shot of compressed air or if it's really critical dust a couple thousands off a block of CRS. Another guy uses a scrap chunk of pine 2x4 and it works for him. Neither me or anyone I work with touches the wheel except for the occasional oops that sent one guy to the hospital twice in one year. It's not the face of the wheel it's the jagged edges.

Marc

MarcS said:

If you make a video RJ, there should be a link kept at the top of the forum. You gonna demonstrate what happens when someone puts the dresser block behind center and forgets to turn the mag on?

Marc

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Hmmmm.... I think I'll pass on that one...

Personally I do not notice too much difference as far as speed goes as long as you aren't going so fast you don't cover the entire cutting surface. We grind mainly all hardened steels and dress normally from a dedicated radius dresser although we have post dressers on the machines as well.

I find it amusing when people say your dresser MUST be at a certain angle to dress properly, kind of hard with ANY radius dresser. I don't use perfectly sharp diamonds either as they break down too fast and change your finish numbers that leads to messing something up. When dressing I just in a CONSTANT, even turn in AND out. When something is getting polished to 4 micro(mirror) the only thing I change is I go in and out twice. Over dressing on normal work(12 - 16 micro) will only cause the wheel to glaze over quicker and start burning or tiger striping. We try to give them at least a 10 micro and with practice you can get it with a normal porus 46 series wheel.

If your hogging lots of stock up to .400 keep a coarse stone handy and rough it up when it starts glazing over. It all in the consistantcy and letting you mist cooler do it's job. Some have said you can't grind that much without changing the rockwell but trust me, you can. Our stuff is rechecked for rockwell before it's shipped and you WILL be noitified if it changes.

We touch our wheels on occasion but it's pretty uncommon to get spike marks. Might happen once evry six months but as you gain more experience it will happen less. The cause is normally operator error. Some guys touch it with a paint brush while others might touch it with the wood end to knock them off. Blowing with air is common as well but I don't do any of those anymore.

This may not fly as I don't have any book sources to point you to. Just 15 years of grinding shapes 8- 12 hours a day 5-7 days a week.

The point on the diamond is a factor, too. You don't want a big
radius (dull diamond). Also, when I mount a wheel I use an old cluster diamond to true it and my good single point to finish dress.
Old Bill

When you dress the wheel you are shaping the cutting face.

Slow shallow dressing is like feeding slow on a lathe. It leaves a very flat surface where all the possible grains are the same height. This gives fine finishes but since each grain is taking such a small load they don't want to fracture and break off so the wheel acts hard.

When you feed fast it's like you are threading on a lathe. Now fewer grains are at the highest point and they are doing all the work. Fewer grains in contact mean rougher finishes and since the individual grains are removing more material each they break off easier and the wheel acts softer.

This is why you need a pointed diamond. If your diamond is worn flat you get a flat surface on the wheel no mater how fast you feed. Again think about the finish on a lathe using a sharp insert point vs a tool with a large corner radius.
Bob

Fingers on the wheel

Yes, it was I that once mentioned about touching the wheel to see if the dress was correct. I first saw this method at a first class grinding shop. They also used a wood stick to knock off the stragglers. They also recommended dressing the sides of the wheel for better balance without actually balancing the wheel.

laminar-flow said:

Yes, it was I that once mentioned about touching the wheel to see if the dress was correct. I first saw this method at a first class grinding shop. They also used a wood stick to knock off the stragglers. They also recommended dressing the sides of the wheel for better balance without actually balancing the wheel.

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I routinely dress the sides of a new wheel to the paper. If I'm going to use the wheel for corners, I also cup the wheel about 1 to 1-1/2 degrees.

One thing I've not seen mentioned in here is the depth of cut when dressing. That controls the sharpness of the wheel more than having a sharp diamond. The coarser the wheel the more you need to remove per pass. On a 46 grit wheel, the minimum per pass is about .001".

My most used diamond is a large, well rounded single point diamond. I'll only use a sharp diamond for special operations.

The key is to make your depth enough to break the bonding agent, and knock out the old grit, presenting the sharp points of the underlying grit.
A rounded diamond will do that quite well, and act like a round lathe tool, leaving a smoother finish on the wheel. A sharp diamond tends to leave grooves like threading the wheel, unless you traverse quite slowly.

If your depth of dress is too shallow, it dulls the points of the grit instead of knocking them out. Thats fine if you are making a polishing grind as opposed to wanting to remove stock.

More later..

A "fast" dress to me is a traverse rate that almost "threads" the wheel. Say something near a 40-50 TPI type thing, or 2-3 seconds to traverse a 3" wide wheel. This will allow you to cut very freely and everything will stay cool even without coolant. However, if you have the proper wheel for the job, it will break down quickly to a smooth wheel anyways, so it will only be beneficial for a short while. It works better if you have a slightly harder wheel. For finish grinding I like to run a very slow dress, say about 6-8 seconds or more to traverse a 3" wide wheel. Usually I use a fast dress if I have a grind job that tends to load the wheel, then re-dress for finish grinding of .001"-.002" depth. The fast dress will not leave an acceptable finish so it is normally only used for fast/heavy roughing.

I believe the thread where touching the wheel was mentioned brought out quite a few people who were "wheel-touchers" myself among the group. I usually also touch a small block of flat steel to the wheel by hand after dressing to remove the straggler grits. I finger touch after that to make sure I got all the stragglers and also to check for rough spots or any bounce.

MarcS said:

If you make a video RJ, there should be a link kept at the top of the forum. You gonna demonstrate what happens when someone puts the dresser block behind center and forgets to turn the mag on?
Marc

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It is more entertaining if they forget to remove the dresser before engaging the feed (don't ask )

The reason for tipping the diamond at an angle (11deg) if my mind is working, is to not break off the tip of the diamond and it also allows you to rotate the diamond to a new sharp edge (or so I am told).

We use cluster diamonds on our auto dressers. Seven second to cross a 2" wheel with a 1" wide cluster, give or take. Keep in mind that is written in smoke.

I was told .001 DOC for roughing and .0005 for fine work. It seems to matter as to the material. Fine dressing on steels are okay (for the most part) for finish work but on aluminum I don't think you can dress to rough for that.

IMO, grinding is an art, as such there is a lot of feel and experience that can not be written. I would suggest getting different types of materials, different diamonds, and a note pad... (it works for me)

The touch the wheel thing... I have done it... don't like to do it. (It is the edge of the wheel that will cut you.) Tongue depressors work but you can't feel vibration.

Dressing sides of wheel.

Can someone enlighten me as to the correct technique for dressing/truing the sides of the wheel.

It seems to me that there would always be some runout on the side of the wheel because of the method of mounting (would you mount a face mill in a milling machine with card board washers????) so side dressing does make sense.

How do you indicate the face and/or side of the wheel without destroying your DTI stylus?

Thanks,

Mike.

Elliott 921 surface grinder;10inch wheel.

MikeJB said:

Can someone enlighten me as to the correct technique for dressing/truing the sides of the wheel.

It seems to me that there would always be some runout on the side of the wheel because of the method of mounting (would you mount a face mill in a milling machine with card board washers????) so side dressing does make sense.

How do you indicate the face and/or side of the wheel without destroying your DTI stylus?

Thanks,

Mike.

Elliott 921 surface grinder;10inch wheel.

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OMG.... Not with a DTI.... Why would you indicate the wheel?

I use one of my angle dressers to do the sides of the wheel.. All you need is a method of holding the diamond block and traversing the length required. Some guys even use an angle plate with a guide clamped to it and slide the block on it.

rj newbould said:

OMG.... Not with a DTI.... Why would you indicate the wheel?

I use one of my angle dressers to do the sides of the wheel.. All you need is a method of holding the diamond block and traversing the length required. Some guys even use an angle plate with a guide clamped to it and slide the block on it.

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An angle dresser is one of those expensive thingys with a curved arm holding a diamond dressing stick which can be moved in and out to change the radius imparted to the wheel?

RJ, are you saying that you can reverse the diamond, in other words, clamp the point on the outside of the arced arm and dress a shallow cup (dish) into the side of the wheel?

Damien W said:

An angle dresser is one of those expensive thingys with a curved arm holding a diamond dressing stick which can be moved in and out to change the radius imparted to the wheel?

RJ, are you saying that you can reverse the diamond, in other words, clamp the point on the outside of the arced arm and dress a shallow cup (dish) into the side of the wheel?

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Nope... you do not dress an arc if that's what you mean. You dress a straight line. You can do it with a radius/tangent dresser as you describe, but depending on the configuration of the dresser, that could be awkward, especially on the back side of the wheel.

I guess I'm overdue to take some pics and put them in here. (save me a thousand words eh?)

One thing that hasn't been mentioned is to check how straight your spindle is to your table. This comes into play when doing straight walls, slots and such. If it isn't straight you'll fight it harder and be dressing a lot more.

Place your diamond in the in the center of the wheel and dress the side of the wheel by moving the spindle up and down with the table LOCKED into postion. Once that is done, move the spindle down to as close to the center of the wheel as possible. Then move your table across the wheel in BOTH directions. If you start taking up more wheel your spindle is NOT straight to the table. I've always drilled the spindle holding tube with 4 larger set screws when you have a removeable spindle. Just adjust till it's straight. If it's more that you can move you may have to loosen the whole head assembly.

You can also check it by placing a dial indicator and base on your chuck and indicating the flat where the grinding wheel touches. It's just with the first method you have a bigger, easier to see, variance. Kevin