1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  2. ATTENTION FORUM MEMBERS!

    Guest, if you have not yet updated your forum bookmark to a secure log in connection, please delete your unsecure book and add the following secure bookmark: https://www.aawforum.org/community/index.php

    You can dismiss this notice by clicking the X in the upper right of the notice box.

    Dismiss Notice

Craftsman 8" variable speed grinder - problem

Discussion in 'Getting Started' started by Philip Ralph, Jul 17, 2018.

  1. Philip Ralph

    Philip Ralph

    Joined:
    Jul 11, 2018
    Messages:
    15
    Location (City & State):
    Marshfield, MO
    I have a Crafsman 8" variable speed grinder that I purchased on the cheap (60.00), when I first started using it, I set the dial to 1800 and started the grinder. It started up great and keep the speed for a couple seconds and then jumped up to full bore. I tried turning the dial on the grinder, but now it just runs at full speed no matter what I do. My question is, does anyone know what might have happened and/or how to fix it? I am thinking about getting a dimmer switch to plug the grinder into just so I can get it back to the lower speed. This is the grinder... https://www.sears.com/craftsman-professional-variable-speed-8inch-bench-grinder-21162/p-00921162000P
     
  2. Lamar Wright

    Lamar Wright

    Joined:
    Jun 29, 2017
    Messages:
    667
    Location (City & State):
    Jasper, Alabama
    Phil, sounds like the variable speed rheostat may have gone bad? You can probably order a rheostat from Craftsman. Shouldn't be hard to fix.
     
  3. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    11,356
    Location (City & State):
    Dalworthington Gardens, TX
    Home Page:
    A dimmer won't work and would ruin the dimmer if you hooked it to the motor. The problem is that one of the electronic parts has failed. It's probably not worth the cost of having it repaired and cost wise you might be better off getting a low speed grinder like the Rikon.

    The motor in your grinder is a hybrid between a two-pole and four-pole motor. The synchronous speed of a two-pole motor is 3600 RPM and 1800 RPM for a four-pole motor. In this hybrid design, the electronics switches between the two configurations to run at intermediate speeds.

    I think that the variable speed thing is more of a novelty than something of actual value as far as sharpening woodturning tools is concerned. Unless your grinder is vibrating it should be usable running at high speed.
     
    hockenbery likes this.
  4. Philip Ralph

    Philip Ralph

    Joined:
    Jul 11, 2018
    Messages:
    15
    Location (City & State):
    Marshfield, MO
    Thanks for the help guys, one more thing, do you think I will be alright putting a CBN wheel on my current grinder? I don't want to replace the grinder if I don't have to, especially since the CBN wheels can cost as much if not more than the grinder itself.
     
  5. Bill Boehme

    Bill Boehme Administrator Staff Member

    Joined:
    Jan 27, 2005
    Messages:
    11,356
    Location (City & State):
    Dalworthington Gardens, TX
    Home Page:
    Definitely, no. As a bare minimum you need 1/2 HP and 3/4 HP or more is preferable. That grinder motor is probably somewhere around 1/4 HP.
     
  6. Finn Posner

    Finn Posner

    Joined:
    Nov 1, 2008
    Messages:
    42
    Location (City & State):
    Turnwater, Washington
    Phil - Here's my 2 cents worth. I have the same grinder and while I've not had this problem, I rarely if ever turn up the speed. So based on that comment and Bill's suggestion you could get a new fixed slow speed grinder and be perfectly happy for a long time. The Rikon's from Woodcraft are on sale frequently and are 1/2 HP.
     
    Bill Boehme likes this.
  7. Philip Ralph

    Philip Ralph

    Joined:
    Jul 11, 2018
    Messages:
    15
    Location (City & State):
    Marshfield, MO
    Live and learn, sometimes you do get what you pay for. I guess I will try to get my money out the grinder and look for the Rikon to go on sale. Thanks again for all the help and advice.
     
  8. Perry Hilbert

    Perry Hilbert

    Joined:
    Sep 27, 2017
    Messages:
    301
    Location (City & State):
    Windsor, Pennsylvania
    I remember my uncle sharpening his lathe tools on an old foot peddle grindstone. We have it soooooooo bad.
     
    Bill Boehme likes this.
  9. John Torchick

    John Torchick

    Joined:
    Jan 24, 2010
    Messages:
    2,653
    Location (City & State):
    Cleveland, Tennessee
    What Finn said. I doubt if you could find the part as Sears has a habit of running out of parts after a few years, especially if it is something that is prone to go kapooey frequently.
     

Share This Page