Squaring up on the grinder

I have die parts that have been rough milled and hardened. I need to know what the proper procdure is for squaring parts on the surface grinder. After milling and heat treating the parts are out of square by .002" to .003" I need to get them to be .001" or better. The parts have about .005" excess all the way around.

Also, does any one know a good book on basic grinding procdures?

Thanks

Reply to
orionstarman
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Mr. Ted Giese recommended Grinding Technology 2nd Edition by Krar. He also recommended PRECISION GRINDING by Victor Repp.

also see:

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In addition to Moltrecht, there is a relatively new paperback out called "Machine Shop Trade Secrets" by Harvey, James, A.

If at all possible, after reading the books, try to work with an experenced grinder for a few hours. You will learn more in an hour looking over the shoulder of someone who knows what they are doing than hours of reading.

Unka' George [George McDuffee] ............................... On Theory: Delight at having understood a very abstract and obscure system leads most people to believe in the truth of what it demonstrates.

G. C. Lichtenberg (1742-99), German physicist, philosopher. Aphorisms "Notebook J," aph. 77 (written 1765-99; tr. by R. J. Hollingdale, 1990).

Reply to
F. George McDuffee

~~~~~~~~~~~~~~~~~~~~ Two great books on grinding are the 1951 "The Grinding Wheel" by Lewis and 1971 "Grinding Technology" by Krar & Oswald published by Delmar. "Grinding Technology" illustrates the set-up for squaring work such as yours using an accurate angle plate, a C-clamp and dial indicator on a surface grinder. Looks surprisingly simple on paper... (^: Health & Peace Al

Reply to
Honest A Babin

Grind one side just to cleanup. Then turn it over and grind the opposing side just to cleanup. Now you have a part with two faces parallel but not necessarily square to the bottom. Set the part on its bottom and use a dial indicator on a base to slide the base against the part solidly and get a reading from the ground side. Repeat on the other side. Most likely the readings won't match. Shim and regrind until both sides match. Now that reading can be used on any side to indicate squareness.

I did this and got a 4" angle plate square to within .0001" over 4", about as good as I could have hoped for.

Not my idea, it's Dan Caster's. See the original thread:

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Grant Erwin

Reply to
Grant Erwin

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Not really my idea. Just how I was shown to make an angle plate.

Dan

Reply to
dcaster

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If you dont like shimming it, you can grind a taper in the unground side that you put in contact with the surface plate, leaving a thin edge on the high side for the piece to set on. You can easily grind off the edge to get the piece to sit perpendicular on the surface plate. Grind the top and then grind off the edge and finish grinding the surface.

John

Reply to
John

Not sure I understand.

Ok.

So far so good.

base against the >part solidly and get a reading from the ground side.

Would the bottom be one of the sides not yet ground? Why do I need to slide the part against the base holding the dial indicator? I'm not sure what you mean. I just can't picture it in my head. I did find a copy of the book "The Grinding Wheel" on eBay. It should be here in a day or two.

Thanks

Wayne

Reply to
orionstarman

base against the >part solidly and get a reading from the ground side.

The bottom is one of the faces not yet ground. By the term "sides" I implied opposite each other, vertically oriented.

The idea of using a dial indicator on a base in this way is to get a reading at a definite height. Then you can just indicate the other side to see if you get the same reading. It doesn't matter what the reading(s) are, it only matters if they're the same or not.

The dial indicator in this case is mounted horizontally.

The idea of sliding the indicator base all the way against the workpiece is to get yourself a reference point to work from.

Hope this helps.

Grant

Reply to
Grant Erwin

base against the >part solidly and get a reading from the ground side.

What you are saying is to shim the part so that the ground faces are vertical so that when the top is ground, it will be at right angles to those vertical sides. Yes?

Mark Rand RTFM

Reply to
Mark Rand

base against the >part solidly and get a reading from the ground side.

No. The sides are parallel by virtue of the fact that they were ground that way, but they are very unlikely to be vertical. If they aren't vertical, then the part needs to be set down on one side but shimmed to bring the other side closer to horizontal (lying down) after grinding. Then the part is flipped and the other side ground, then the part is set back on its bottom and the sides checked again for being vertical. Only when the readings on the sides are identical, are the sides not only parallel but also vertical. Here's the key point: at that point, the reading on the indicator is the "magic number". Now the part can be flipped onto one of the just-ground sides, and the top can be indicated. If the reading isn't the magic number, then the part is shimmed and ground to correct this.

This is stretching my technical writing skills.

Grant

Reply to
Grant Erwin

base against the >part solidly and get a reading from the ground side.

As Grant mentioned in a reply, (a) yes, (b) to get a reference point.

The nearly-vertical sides (which were ground to be parallel in the first couple steps of the procedure) will be exactly vertical if they are perpendicular to the bottom surface. You will get the same reading from the DI on both sides if both sides are vertical; otherwise, the DI will read a little lower on the side leaning in and a little higher on the opposite side, that leans out.

For example, let p and q be parallel, opposite, 2x3 sides of a 123 block. Let w be a 1x2 side, with w against a surface plate. If the angle between p and w is 89.9 degrees, then the angle between q and w is 90.1 degrees. Your DI will measure B-3*sin(0.1) at the top of p, and B+3*sin(0.1) at the top of q, where B is related to the length of the DI base. So the difference would be 2*(3*sin(0.1)), or about .0105.

-jiw

Reply to
James Waldby

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