Thursday , December 14 2017
Home > Miscellaneous > Rewiring (Replacing the Power Cord) on a Dumore Tool Post Grinder for the Lathe.

Rewiring (Replacing the Power Cord) on a Dumore Tool Post Grinder for the Lathe.

My friend Barry had two Dumore tool post grinders so he sold me one that needed a new power cord. So first things first, I needed to take the thing apart. I remember watching my grandfather take an electric motor apart when I was a kid (probably about 8 years old) and he told me that if I ever took a motor apart I should make sure and mark the housing with a line so that I knew how to put it back together. This is especially important if the motor has a symmetrical housing – which would allow you to put it back together incorrectly. So before unbolting anything I drew a reference line on both halves of the housing.

Next I removed the two nuts that held the housing together and removed the end of the motor housing and the rotor. I needed to remove the stator as well to get access to the wires, but I was stumped on how to get it out without damaging it. It’s a tight press-fit in the housing.

After a bit if pondering I thought I might be able to slip c-clamps under the lip of the stator and use them to extract the stator. It worked like a charm.

I turned each c-clamp a 1/2 turn alternating back and fourth so that the stator pulled out straight without binding. After a few minutes it was out.

With the stator out I had access to the wiring. I noticed that both wires going to the stator had black cloth shielding so there was no visual indicator of which was hot and which was neutral. However, the power cord did have a white (neutral) and black (hot) wire so I made a note of which stator wire went to the white and which went to the black, and then I removed the old power cord. Note, there was no green (ground) wire.

Next I slipped a piece of black heat shrink tubing over the hot wire going to the stator and a piece of white heat shrink tubing over the neutral wire going to the stator. That way I wouldn’t mix them up.

Then I needed to replace the rubber grommet, slip the new power cord through and wire it up. Here you can see the old power cord vs the new power cord. I was able to salvage the on/off switch on the old power cord and wire it up on the new cord.

It was time to give the grinder a test run, but right away I discovered that the guard hit my cross slide. I had to raise the grinder above centerline to get it to fit. I’ll eventually replace the guard (which isn’t the original anyway) with a smaller one that doesn’t interfere. Here’s the grinder being used for the first time.

And here’s what the ground surface looked like. It’s a bit rough, but I haven’t dressed the grinding wheel yet so it’s only hitting in one spot. Once properly dressed I think the grinder will produce a wonderful finish. Which brings me to a request, if anyone has an extra diamond dresser that they don’t need please let me know (you can contact me via the “Contact Us” tab at the top of the page or through the Forum). In the meantime I’ll keep an eye out for one on eBay.

So, the lesson here is if you see an old Dumore tool post grinder on eBay that’s selling for cheap because the power cord is 50 years old, cracking, and falling apart – BUY IT! Replacing the power cord is easy and having a tool post grinder in your shop is worth it!



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About Tyler

Tyler is a hobby machinist and 3D printing aficionado. He teaches computer programming and web development at Highline College near Seattle. Tyler founded Projects In Metal in 2008 because he was frustrated by the lack of free plans available for hobby machinists.

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