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  • Surface Grinder newbie questions

    I just aquired a Sanford 6x12 surface grinder like the one at the bottom of this website:

    http://www.speedwaydesigns.com/projects/shop/

    It doesn't have a spindle nut. The threads are 1 1/4 -16 right hand. I'll likely make a nut & washer for it.

    Should I run the spindle so the right hand nut will tend to tighten the wheel? I understand most surface grinders have LH nuts.
    How tight do you tighten the nut?

    Dressing:

    I plan to get a diamond nib dresser. How do you dress the wheel? Do you dress at the bottom of the wheel with the nib straight up or on the "back side" of the wheel (say at 4 o'clock) with the nib pointing toward the center of the wheel.

    If you don't have the nib directly below the wheel you would have to dress with the cross slide "Y" axis. If you go directly below you could use both axis. seems like below would be more accurate?

    wheel hardness.

    I need to buy wheels, but what hardness should I try for "general" purpose? My application? I have no idea at the moment!

    Thanks,
    Andy

  • #2
    Don't dress with the nib directly below the wheel, you want it to be slightly to the left of the wheel and then use the table crossfeed to dress the wheel. The reason you want it to the left of the wheel (when you're facing the wheel) is because if the nib is directly under or to the right, there is the chance of the nib being grabbed by the wheel and thrown or blowing up the wheel.

    Look around online for wheel type selection charts or tips. It's hard to pick a "general" purpose compound since it is all dependant on material being ground.

    Originally posted by hitnmiss View Post
    I just aquired a Sanford 6x12 surface grinder like the one at the bottom of this website:

    http://www.speedwaydesigns.com/projects/shop/

    It doesn't have a spindle nut. The threads are 1 1/4 -16 right hand. I'll likely make a nut & washer for it.

    Should I run the spindle so the right hand nut will tend to tighten the wheel? I understand most surface grinders have LH nuts.
    How tight do you tighten the nut?

    Dressing:

    I plan to get a diamond nib dresser. How do you dress the wheel? Do you dress at the bottom of the wheel with the nib straight up or on the "back side" of the wheel (say at 4 o'clock) with the nib pointing toward the center of the wheel.

    If you don't have the nib directly below the wheel you would have to dress with the cross slide "Y" axis. If you go directly below you could use both axis. seems like below would be more accurate?

    wheel hardness.

    I need to buy wheels, but what hardness should I try for "general" purpose? My application? I have no idea at the moment!

    Thanks,
    Andy

    Comment


    • #3
      I suspect that you are describing the wheel adapter nut, not the spindle nut. Don't buy or make anything until you find out the spindle thread.... either LH or RH.

      Gene

      Comment


      • #4
        Hi Gene, it's the nut that holds the wheel on the spindle. I measured it, 1 1/4 - 16 rh.

        Jimmer, makes perfect sense, glad I asked. As far as direction, I've found pictures on the web of my grinder with a wall on the left side to stop the grinding dust, so it must turn clockwise, even though it has rh threads.

        Comment


        • #5
          Sometimes there is a washer keyed to the shaft under the nut to keep rotational forces of the wheel from acting on the nut.

          Comment


          • #6
            Here is a grinding wheel guide from Norton that is helpful in wheel selection:
            http://www.nortonindustrial.com/uplo...art%207505.pdf

            From the Norton selection I would suggest a 32AA or 32A series for typical home shop use.

            >wheel hardness
            I find a hardness of either I or J works fairly well for most hardened steels and a little harder wheel of K for soft steels. Although I will often use a K wheel if its what I currently have on the spindle as it seems to work fairly well all around.

            A grit of 46 will give you a decent ground finish without loading-up too fast. A grit in the 80-100 range will allow you to achieve semi-mirror finishes, but the finer grit size wheels tend to load up much faster.

            If I'm just starting to grind on a piece that is rough machined or contains scale, I will start (and maybe finish) with 46K wheel. If I really need a semi-mirror finish I will switch to a 80I wheel to finish up only taking cuts of 0.0002" or so.

            When dressing the wheel be sure to not doddle or you will close the grain behind the diamond. Move fast across the wheel and don't transverse back across unless you down feed to take more off the wheel. Make sure the wheel is completely dressed with no gray spots on the surface or the wheel is prone to not cut well and will load up faster. You only need to take about 0.001 or 0.0005" per pass of the dresser, so dressing the wheel a bunch of times for practice does not reduce its size much. So practice until you get a good dress on the wheel. When the wheel is stopped you can feel a well dressed wheel; it will have crisp edges and course feeling across the face. Once you get the hang of dressing a wheel, don't shut the machine down after dressing (if possible) as the wheel may shift slightly upon re-starting the spindle.

            If you have a manual transverse machine, be sure to keep the table moving at a good clip under the wheel when grinding. This is probably one of the biggest problems on a manual machine with a new operator moving too slow and burning the part or leaving ripple in the finish. I think someone on this board mentioned previously that the table should transverse at a rate that would match a car windshield wiper on high; that's about right. Keep the wheel dressed correctly and the work moving fast and you will be fine.

            Be sure to experiment and gauge your results. Surface grinding is a little bit of an art to get good finishes and precise dimensions. Lots of tricks to be learned if you are looking for dimensionally precise parts especially on slender pieces that are prone to warp under the magnet.
            Last edited by jungle_geo; 11-29-2012, 02:50 PM.

            Comment


            • #7
              Originally posted by Jimmer12 View Post
              Don't dress with the nib directly below the wheel, you want it to be slightly to the left of the wheel and then use the table crossfeed to dress the wheel. The reason you want it to the left of the wheel (when you're facing the wheel) is because if the nib is directly under or to the right, there is the chance of the nib being grabbed by the wheel and thrown or blowing up the wheel.
              If the nut that holds the wheel on has RH threads dressing on the left side could be very interesting at least once if the wheel rotates CCW. In any case if you have a lock for the X axis do use that when dressing the wheel.

              John
              My Web Site

              Comment


              • #8
                Originally posted by jungle_geo View Post
                If you have a manual transverse machine, be sure to keep the table moving at a good clip under the wheel when grinding. This is probably one of the biggest problems on a manual machine with a new operator moving too slow and burning the part or leaving ripple in the finish. I think someone on this board mentioned previously that the table should transverse at a rate that would match a car windshield wiper on high; that's about right.
                Dang good info there, any idea of the IPM the table should move at?

                John
                My Web Site

                Comment


                • #9
                  Good stuff guys. Thanks alot, it's appreciated.

                  Comment


                  • #10
                    Originally posted by hitnmiss View Post
                    I just aquired a Sanford 6x12 surface grinder like the one at the bottom of this website:

                    http://www.speedwaydesigns.com/projects/shop/

                    It doesn't have a spindle nut. The threads are 1 1/4 -16 right hand. I'll likely make a nut & washer for it.

                    Should I run the spindle so the right hand nut will tend to tighten the wheel? I understand most surface grinders have LH nuts.
                    How tight do you tighten the nut?

                    Dressing:

                    I plan to get a diamond nib dresser. How do you dress the wheel? Do you dress at the bottom of the wheel with the nib straight up or on the "back side" of the wheel (say at 4 o'clock) with the nib pointing toward the center of the wheel.

                    If you don't have the nib directly below the wheel you would have to dress with the cross slide "Y" axis. If you go directly below you could use both axis. seems like below would be more accurate?

                    wheel hardness.

                    I need to buy wheels, but what hardness should I try for "general" purpose? My application? I have no idea at the moment!

                    Thanks,
                    Andy
                    The crossfeed is "Z". The downfeed is "Y".

                    Comment


                    • #11
                      About the nut tightening:

                      Originally posted by jungle_geo View Post
                      Once you get the hang of dressing a wheel, don't shut the machine down after dressing (if possible) as the wheel may shift slightly upon re-starting the spindle.
                      That above quote shows a condition of not tightening enough. The wheel doesn't shift anywhere, if it is tightened enough/properly. At work we have a 400 x 50 mm wheel spinning at 1700 rpm and it doesn't have any "soft starter", it just swings in to action once you switch it on and it hasn't moved once in the years I've been using it.
                      Amount of experience is in direct proportion to the value of broken equipment.

                      Comment

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