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Harvel Grinder Questions

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  • Harvel Grinder Questions

    I've got a Harvel 8x15 grinder model 815 and I need some help. Hopefully somewhere out there is another owner who can answer a few questions for me.

    I butchered the nut that holds the wheel on the spindle. The nut is left-hand thread. I measure it as 1/2-18, which is an oddball thread. I measured the threaded spindle myself. My cheapo digital calipers say it's .55" which is pretty close to 14mm - but the threads don't match anything on the metric thread gauge. It matches the 18 perfectly.
    So question 1: Am I right that 1/2-18 is the correct thread for that nut?

    The wheel that's on there is a 9.75" diamond wheel and the wheel adapter is frozen solid, kroil isn't doing a thing to budge it, nor is heat. The four grooves for the spanner are butchered too and there is really no hope of getting it apart. It looks like that standard 3:1 taper, no keyway or anything. But my experience with surface grinders is just from looking at them in the pages of HSM.
    So question 2: What is the correct replacement size for that adapter? The wheel I'll put on will probably have the standard 1-1/4" hole and be 1/2-3/4" wide.

    And if anyone knows any source of info on this grinder I would really appreciate knowing more before I restore it into the ground. Even the country of origin if it's not USA would help because then I could google it better.


  • #2
    Mine is a 1/2 - 13 left hand thread. Yours is probably a 9/16 - 18 left hand thread. The 3:1 taper is a the same as a Sopko adapter. If that's what yours is you're in luck. That's a common industry standard.
    These wheels are normally mounted and left on an adapter for the life of the wheel (ideally). That means you need a collection of adapters just like you have a set of collets for a mill or lathe.
    Normally you remove the wheel and adapter together. On Sopko adapters the area around the spindle nut has an ID thread that you screw a hollow nut onto. This hollow nut has an OD thread to match the ID thread on the adapter with the other end closed and tapped for a jack screw. The puller thread is 25mm x 1.5. You screw the nut into the wheel adapter, then tighten the jack screw against the end of the spindle and it easily pops the adapter free. It is very difficult to get the adapter off any other way.


    • #3
      Thanks Toolguy. I just got off the phone with Sopko - that guy knows his stuff. I've got a couple adapters, the proper wrench, and the puller coming in the mail now.
      You are correct on the 9/16-18 thread. And they had that nut too so I just bought it rather than trying to do LH female threads. I measured a bunch of times and even though the calipers said .5625, I was thinking of it as 1/2 because in my mind 9/16 was just way too big. (That's the same pigheadedness that got the adapter and nut butchered in the first place.) Then I plugged 9/16 into the calculator and got .5625.

      But at least I'm on track now. Thanks again.


      • #4
        You're welcome Joe! Glad I was able to help you.


        • #5
          Wheels come off easy with one tool -- a medium size hammer. :-)

          You are dong the right thing in buying a set of tools.