Surface Grinding

I would mount a magnetic base and a .0001" indicator on the column and practice lowering it down .0001" at a time with nothing on the chuck...say 2" above the chuck. Also grind a practice piece before doing the real thing. I suspect you will burn the part and it won't work. but you may get lucky. If I were you I would try to buy a shim the right size. Also dress the wheel fast and course, meaning take .002" and dress the wheel and then stop. don't dress the stone back and forth as this will dull the wheel and help to burn it. Also if you can run the mister wide open as the shim will get hot super fast. On the wheel, use the courses one. finish may not be the best, but the wheel and shim will stay cooler. Did you say how thick the shim was before your going to grind it?

PS. Bob and John, coming to say hi when I come out there in April? DH said he was going to come over on the 24th I think.
 
Well I actually have the grey wheel installed and made a few practice passes on a large washer I had lying around. It seems to work very well. Haven't measured anything yet just wanted to get it flat so I can start practicing getting down to a target depth. Funny thing about the wheel colors. I purchased the pink wheel based on a recommendation from someone for surfacing the chuck. It is an Aluminum Oxide J46 open pours type wheel. I have since saw a Youtube video on surfacing chucks and the guy was recommending an Aluminum Oxide H46 with the same open architecture but the one he was using was white. I went to MSC to look up these wheels and found that Aluminum Oxide J46 open architecture wheels are available in all colors of the rainbow with no description of what the difference is besides the color??? I really like the grey ceramic wheel with the closed architecture as my general purpose wheel. Its twice the price of the pink but really cuts steel nicely.

On my machine trying to take off 0.001" will stall the machine, at least if I try it on a full 1/2" width cut. Maybe that's a good thing. I was wondering if maybe I should be using 1/4" wheels.
 
Richard King 2 said:
I would mount a magnetic base and a .0001" indicator on the column and practice lowering it down .0001" at a time with nothing on the chuck...say 2" above the chuck. Also grind a practice piece before doing the real thing. I suspect you will burn the part and it won't work. but you may get lucky. If I were you I would try to buy a shim the right size. Also dress the wheel fast and course, meaning take .002" and dress the wheel and then stop. don't dress the stone back and forth as this will dull the wheel and help to burn it. Also if you can run the mister wide open as the shim will get hot super fast. On the wheel, use the courses one. finish may not be the best, but the wheel and shim will stay cooler. Did you say how thick the shim was before your going to grind it?

PS. Bob and John, coming to say hi when I come out there in April? DH said he was going to come over on the 24th I think.
Click to expand...

Already started with a practice washer. Buying a shim the right size is no longer an option. Tried to buy one but Mercedes has consolidated there inventory for these 30+ year old cars making grinding a requirement. What is considered a course wheel. Currently I'm at 46. +1 on the indicator practice. I have an indicator that reads to 0.00005".
 
You plan on measuring with a depth mic ? If not ,

Little trick is to grind another object next to your good piece at the same time that can be removed . You can mic that part and not disturb your good part on the mag chuck . ;)
 
Tom lipton has a good trick for this... He uses a surface plate sample in granite, bonds a steel top to it and puts a mag base/indicator on top of that. he can move the indicator around (granite non magnetic, etc), and takes direct readings of thin parts...
 
We seldom take 1/2" width move-overs when you have change of throwing the part off. Who told you to do that? Move over 1/2 turn on the hand wheel or 1/8 turn and see how that goes. On most hand crank lightweight grinders I would say 1/16 to 1/8 " move over. and .0001 to .0002 down feed. A fast trick when grinding a lot off is to plunge straight down to .001or .002" to where you want to be. Mark your vertical location with a magic marker on the crank. Move up away from the part. crank over the full width of the wheel and crank it straight down again, etc. Once your done plunge move over, then dress your wheel and grind it the regular way taking 1/2 turn on the cross crank. Do a lot of experimenting before grinding the real McCoy. Oh before hand spray the washer with Dykem, so you can easily see what your doing. I found these for you: http://vintagemachinery.org/pubs/10678/18132.pdf
 
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mmcmdl said:
You plan on measuring with a depth mic ? If not ,

Little trick is to grind another object next to your good piece at the same time that can be removed . You can mic that part and not disturb your good part on the mag chuck . ;)
Click to expand...

Good advice. I did find that removing the part after each pass to measure did not work out too well.
 
Richard King 2 said:
We seldom take 1/2" width move-overs when you have change of throwing the part off. Who told you to do that? Move over 1/2 turn on the hand wheel or 1/8 turn and see how that goes. On most hand crank lightweight grinders I would say 1/16 to 1/8 " move over. and .0001 to .0002 down feed. A fast trick when grinding a lot off is to plunge straight down to .001or .002" to where you want to be. Mark your vertical location with a magic marker on the crank. Move up away from the part. crank over the full width of the wheel and crank it straight down again, etc. Once your done plunge move over, then dress your wheel and grind it the regular way taking 1/2 turn on the cross crank. Do a lot of experimenting before grinding the real McCoy. Oh before hand spray the washer with Dykem, so you can easily see what your doing. I found these for you: http://vintagemachinery.org/pubs/10678/18132.pdf
Click to expand...

Well no one actually told me to move over 1/2". The machine itself told me not to move over 1/2" and not to take off 0.020" the first day I put it together and a turned it on. It also told me hard wheels are not for hard material. I have been using 1 turn of the wheel to move over which is 0.1". that seems to work well and easy to keep track of. The 0.0001 to 0.0002 down seems to be a challenge on this machine with the wheel having 0.001" resolution. I would love to put a ball screw on the "VERTICAL" of this machine with a different gear ratio using a zero backlash harmonic drive.

PS if you ever run a scraping course on the east coast, keep me posted. My next project may be scraping the Bridgeport.
 
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