Surface Grinding Problems

S

sculver

Joined
Jun 28, 2007
Messages
196
I bought a surface grinder about 9 months ago (Harbor Freight) and have been having problems getting a good finish on the parts that I grind. It seems that the stone is loading up and burning the material. I always dress the stone before using, but can’t even get through grinding a small part before I start getting burn marks in the metal. I’ve tried different feed rates. I’ve tried grinding dry and with a water soluble lubricant. I’ve tried different hardness stones.

Am I expecting too much from this machine? I’m about to convert it to run belts…..

I’ve asked a few guys who have surface grinders for help, but have received conflicting advice. Any surface grinding experts out there with some answers?

Thanks,
 
Many of the steels we use for knives (D2, CPM 154, etc) can a problem to grind. However, I think you should be able to get good results if you:

1. Take light cuts. (try .001 per pass)

2. Dress the wheel frequently (you'll get a feel for when it needs dressing)

3. Get a good wheel. I switched to a norton 5SG 46 grit seeded gel (5SG46-IVS) wheel and have gotten great results ginding D2 and CPM 154. I used to have problems with burning some of the more difficult steels; this wheel solved the problem.

4. Follow proper safety prcatices.

Jim
 
please let me know your grinding proceedure and I may be able to help.
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I only take .001” or .002” at a time. I usually index the table over .050” to .100” per pass. I have varied the feed rate. I’ve tried going both slow and faster. It seems that I have fewer problems with loading the stone with a faster feed rate, but the quality of the finish is not as smooth. I’ve tried all of this with, and without lubricant.

Thanks,
 
norton 5SG 46 grit seeded gel (5SG46-IVS) wheel
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I was using a Norton 32A46-KVBE wheel today. I've got several grits of KVBE wheels, as well as a Norton 38A46-GVBE wheel, plus a stack of ToolMaster wheels in different grits and hardnesses.
 
try feeding by hand and see what it feels like. when i had to grind some 1075 i used the power feed and had problems. i went to hand feed and didnt have the same problem. try taking even less. does the steel have dark streaks in it where it was ground?
 
What are you grinding? If it is something simple like O1 or A2 the 32A wheel should work fine. For more abrasion resistant steels, you would do better with the SG wheel.

Jim
 
A couple of things to remember. For soft(unhardend) steel you want to use a hard wheel.(j,k) for hard(or hardend) steel use a soft wheel( g,h). I use the 32a white wheels for almost everything. How fast are you feeding the steel into the wheel? it sounds like you are feeding too slow to me. what I do is to feed at maximum rate 50fpm. I set over ai a maximum of 1/4 the width of my wheel /4 inch wheel = 1/16 set over and I take .003 off at a time for rough cuts then .0005 twice then .0002 twice and spaerk out for a finish. using this method I get almost a mirror finish. I dress the wheel before starting to grind and then again too finish. there is a good thread in the abrasive section on the practical machinists forums I recomend that you read it and everything else thatpertains to surface grinding there. good luck
 
What are you grinding? If it is something simple like O1 or A2 the 32A wheel should work fine. For more abrasion resistant steels, you would do better with the SG wheel.
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I am usually grinding O-1 or damascus.

How fast are you feeding the steel into the wheel? it sounds like you are feeding too slow to me. what I do is to feed at maximum rate 50fpm.
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I've been told that I may be feeding too slow and burning the metal. It seems to do better when I feed faster, but the wheels still load up faster than I would expect them to. I can't get through the rough grind before the wheel is loaded and has to be dressed. I've seen in the Machinery's Handbook that the crossfeed rate should be 1/10 to 1/5 of the wheel width, but I thought that was a lot.

try feeding by hand and see what it feels like
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My machine is hand feed only........

I guess I should just crank 'er up and jam the steel in there faster and see what happens. I'll check out the machinist's forum.

None of you guys are using a lubricant?
 
1/10 of a quarter inch wheel is .025 and 1/5 is .050 so part of your problem may be the amount of cross feed that you are using. Try using the 32a-46-kvbe wheel. use a cross feed of .025 and a down feed of .003 and infeed at about two to three turns of the wheel per second or pretty fast if you are still burning the steel then try the 38a wheel at the same feeds and speeds. I am no expert but i have ground up a ggod share of steel
 
The cross feed that I am using may be part of the problem. The Machinery’s Handbook gives cross feed as a portion of the wheel width. I use mostly ½” wheels. That makes the feed rate twice that of a ¼” wheel. I don’t see how the wheel width is relative to the amount of feed and what is happening on the surface of the work piece. I have been using a .050” cross feed, with a .001” to .002” down feed.

There was a thread on the Practical Machinist’s forum about wheel dressing. They where discussing the rate of feed of the dresser across the wheel and saying that a slow feed can glaze the wheel. This could also be part of the problem that I am having, as I usually make a slow cut with the diamond.
 
One more thing that I didn't mention is the diameter of the wheel. If your wheel is too small in diameter then the surface feet per minute is too slow and it will load up or break down too fast. also watch the corner of the wheel when your lead in sparks reach the center of the wheel it is time to dress the wheel i.e. with a freshly dressed wheel the sparks will come from the corner of the wheel. As the wheel wears the spark ring on the wheel will start to move towards the center of the wheel.
 
Most of my wheels are still close to the original 7" diameter, but I will keep this in mind for the future. I am considering getting a coolant mister for the grinder.

Thanks for all of the advice guys!!
 
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