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  • Surface Grinder Questions

    Hello All,
    I am not a machinist. I have used a surface grinder for about a year now to surface barstock for making my folding knives. I first owned a Rockwell Delta grinder, which worked great! For some odd reason, I sold the Rockwell and purchased a Boyer Schultz 612. I am using the same wheels. Radiac Abrasive 32A's. I could cut .001 passes very easily with my Rockwell. I cannot figure it out with the BS612! It tends to burn metal very easily and quickly. I can't even think about a 001. pass most of the time. The steel I am grinding hasn't changed any between grinders. Now, I have been wondering about the dresser that I am using for the wheel. It is just a regular diamond that sits, I believe, on a 15Degree angle. I have been using this diamond for about a year. It seems to dress the wheel okay, but I am not experienced enough to know. Can anyone help? The Boyer Schultz grinder table is in fine condition with hardly, if at all, any deviation from one side to the other. About how many wheel dressings can one expect from a diamond? Thanks for any help!
    Chris S.

    [This message has been edited by cds (edited 04-27-2004).]

  • #2
    I own a Rockwell surface grinder with the cutting tool attatchments, in pieces though. Next project. I an not an expert on grinding. I do very little of it. What my experience has taught me is the most likely causes are using a wheel that is too fine or hard, or trying to remove too much material in one pass. .0005" MAX. per pass is a pretty good rule of thumb. Unless you have a very rigid machine, and set up, trying to remove more than .0005" may cause problems. Other thing to consider are: Are you using coolant? Is there a difference in spindle RPM's between the Rockwell and the Boyer Schultz? Hand or power feeds? Wheel speeds/table feeds? As far as dressing, that operation trues and cleans the wheel, I do not think the angle of the dresser has anything to do with it, though as I am no expert, I may be wrong. If someone proves me so I will not be offended.
    Paying Attention Is Not That Expensive.

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    • #3
      My 2 cents worth. I have had very little experience with a surface grinder, only in class. For Cast Iron we used a very slow feed rate and got a mirror like finish. Also groung some hardened 4140 with a very high feed rate, again a perfect finish. On the 4140 with a low feed rate I was getting a burnt finish. Down feed on either job was only .0005". As for the diamond dresser I think it will last a long long time.

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      • #4
        Get a new dresser. A worn dresser can make a grinding wheel do funny things. I have chased taper on an O.D. grinder for hours and changed dressing tool as last resort. The taper was caused by premature wheel breakdown and the problem was a worn out dressing tool. Could be the issue here. As a matter of fact the Norton rep once told me to make a ceramic media wheel act harder you dress it slower.

        Good Luck
        C. Tate

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        • #5
          Who ever made your dresser was smart but you are not using it properly and it may be to late to save the diamond in the holder, when a diamond holder is made it should always hold the diamond on an angle (preferablly about 30*), the reason behind this is so you can periodically rotate the diamond in the holder and the wheel will always wear the diamond into a point thus you have a sharp diamond all the time until the diamond is actually wore out, I have used Boyer Schultz grinders for years and unless you have an obvious problem with the machine this should not be a factor at all.

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          • #6
            I am definately not an expert either on grinding matters, but some things have been learnt the hard way. As stated if the wheel and stock are the same for both machines, as mentioned by someon else, are the spindle speeds the same or is one running faster?. While the table maybe flat has the (I assume) mag chuck been trued on the new machine, way wear can see the table rise several tenth's of a thou or more towards the ends of its travel. If the burning all tends to be towards one end this again would tend to indiate table rise, non trued chuck. Oiling of the ways (auto or one shot) during the grinding cycle can also upset the system. Burning tends to create very localised heating and consequently material expansion at the source until the heat is absorbed by the surrounding material. Coolant is very adventageous if your machine is set up for it, if not lighter cuts and moderate feed rates. Facing of a wheel, I was taught 1 thou each way accross the the face followed by 2 half thou passes. As for diamond dresser, yes they do wear out ultimately and this in indicated by a flat surface, it no longer cuts (it bulldozers). A half carrat diamond for wheels 1/2 inch wide or 3/4 inch at the outside then 1 carrat or more for the wider wheels. Orientation, I was also told lay the dresser back at around 15 degrees and place the point slightly behind (relative to rotation)the vertical centre line, however overwheel dressers are at right angles and seem to work well. The quality (ie faces, points etc) of diamonds in generic dressers seems to vary greatly and I now look closely at the points when buying a new one, pick the best of a bad bunch. Balancing of wheels, mount on arbour, dress until concentric running, remove and balance, remount and dress / face. Sometines it is necessary (with caution) to dress the side of a wheel to get a good balance. As you are finding grinding can be a mysterious undertaking at times with outcomes changing for no readily apparent reason. Good luck.

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            • #7
              One thing I have noticed about surface grinders,not all a graduated the same.We have at work a BS6x12 also,it is graduated in .001" increments,but we also have a Brown and Sharp model that is graduated in .0001".

              Big diffrence on a surface grinder.
              I just need one more tool,just one!

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