Best methods for getting a part set up on a surface grinder

[laminar-flow]

So you have a piece that is flat. At least you think it is flat, probably within .001 or so, and you need to get it on the mag chuck and start grinding.

What are some of the best methods to get the wheel down to the part without:

A: Taking forever by sneaking up on it in .00025 increments...

-or-

B: Sending the part into orbit, trashing the wheel, and messing up the surface of the chuck.

I have a few methods I use but I'm sure there are better ones.

 

[WILLEO6709]

depends on the part.... easier to take a few thousandths than a couple tenths sometimes. I have left the spindle off, downfeed turning the wheel by hand until it touches.... zero the dials, back it up, and touch under power. If you don't want to scratch the part use a piece of paper as a feeler., this can be done wheel running too, but put the paper on the side it will be pushed out from under the wheel. sometimes there is no substitute for easing in slowly.

 

[rj newbould]

I turn the wheel off and touch like willie. When it touches, I set the dial to zero before backing off. This will get you within .0002.

However.... I have a slow start spindle and the wheel does not shift on starting. A quick start spindle can shift the wheel losing your dress as well as the setting.

In that case, you can carefully hold a paper under the wheel until the wheel spits it out.

If your piece is not pretty parallel to begin with, you need to be careful to set position on a high spot, or ease onto the part from the side while cycling the table.

 

[easymike299]

Sight between the workpiece and the wheel from the right hand side. Hold a piece of white paper in your left hand or tape it to the Left hand wheel guard. Shine a lamp on it for even greater effect. Bring the wheel down and observe the gap between the wheel/workpiece. With practice you'll be able to gauge the size of the gap within a few tenths. Be sure to wear safety glasses.

 

[Old Bill]

If the part is big and not flat sometimes I use a brass base surface gage and my beater indicator
to find the high spot and touch there.
Old Bill

 

[Holescreek]

Thanks to my VFD settings I also have my spindle set to a 10 second start. I usually check and mark my part on a surface plate before it gets to the mag chuck. If I do try to grind without indicating first, I sight like easymike says looking at my bright yellow dust collector. -Mike

 

[rj newbould]

Obviously sighting is needed to get close. Don't know about you, but when it gets to be .001 or so above, I lose the light and need to touchdown.

 

[huntinguy]

I kinda follow WILLEO6709 suggestion.

IF I know the part is flat, I try to check it with a surface gauge or measure it in some fashion, I will bring the wheel down and slide a .03 shim between the part and the wheel. When that pick up I switch to a .015, then to a .003. I then make my first pass at a slow step. Then I have at it.

I also watch the coolant; it will react differently when the wheel gets into the .001 range.