# Grizzly lathe grinder.



## big o (Sep 2, 2020)

Having time on my hands, and an old vacuum cleaner motor. Here are the results. Motor
    leads swapped around to give a counter clockwise direction. Switch from a pistol grip drill,
    ( changes a/c to d/c ) .Slot in housing limits rpm.This is a lightweight unit used to trim the 
     jaws on my lathe chucks.


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## Papa Charlie (Sep 2, 2020)

That is some cool engineering there.

Not to be a wise Azz but why would you want to grind on your lathe. Couldn't you accomplish the same end result by using the lathe tooling?


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## Reddinr (Sep 3, 2020)

Nice work!   You may want to guard that motor from directly inhaling grinding dust somehow.  Maybe a small duct or guard?


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## MrCrankyface (Sep 4, 2020)

Papa Charlie said:


> That is some cool engineering there.
> 
> Not to be a wise Azz but why would you want to grind on your lathe. Couldn't you accomplish the same end result by using the lathe tooling?


If you want to take away small amounts of material or need to apply a minimal cutting load then grinding will be better than any lathe tool, especially if you're working hardened material.

I'd be really worried about the ways wearing down from the grinding dust though, cool contraption none the less!


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## Papa Charlie (Sep 4, 2020)

MrCrankyface said:


> If you want to take away small amounts of material or need to apply a minimal cutting load then grinding will be better than any lathe tool, especially if you're working hardened material.
> 
> I'd be really worried about the ways wearing down from the grinding dust though, cool contraption none the less!



Interesting,  I have used Emery to do the same thing. I find it very easy to control  material removed for the last 10ths.
I can see the advantage  on hardened material with the right stone, control  would be my biggest concern,  need to try it and see. Thanks for sharing.


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## tweinke (Sep 4, 2020)

Tool post grinder from materials at hand , looks to work well for the job its designed for. I consider it a win!


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## NC Rick (Sep 5, 2020)

What type of bearings for your spindle build?  They need to be quite precise I assume?


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## big o (Sep 6, 2020)

NC Rick said:


> What type of bearings for your spindle build?  They need to be quite precise I assume?


    These bearings are marked Fafnir, Timken owns the company. They are metric. Bought 6 with a box of parts at a garage sale, including a air hose
     reel (20 bucks ).


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## big o (Sep 6, 2020)

Reddinr said:


> Nice work!   You may want to guard that motor from directly inhaling grinding dust somehow.  Maybe a small duct or guard?


    I hook up my Shop Vac when using the grinder.


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## big o (Sep 6, 2020)

big o said:


> These bearings are marked Fafnir, Timken owns the company. They are metric. Bought 6 with a box of parts at a garage sale, including a air hose
> reel (20 bucks ). They are very smooth running.


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## Flyinfool (Sep 6, 2020)

That sure looks a LOT more elegant than my tool post grinder.

Out of curiosity, why convert to DC?
Yes a universal motor will run on DC, but the Positive carbon brush will wear extremely fast, and it is also very hard on the commutator. The motor also will not run as efficiently, not just amp draw, but it will run hotter and slower and make less power.
You would be much better off running a plain old switch and feeding the motor the AC it was designed for.

The drill motor was designed to run on DC so it was fine.

To help save the carbon brushes, add a DPDT reversing switch so that every time you use the grinder the polarity of the power gets reversed, this only helps with the positive brush wear issue all of the rest of the issues will still be there.


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## big o (Sep 7, 2020)

Flyinfool said:


> That sure looks a LOT more elegant than my tool post grinder.
> 
> Out of curiosity, why convert to DC?
> Yes a universal motor will run on DC, but the Positive carbon brush will wear extremely fast, and it is also very hard on the commutator. The motor also will not run as efficiently, not just amp draw, but it will run hotter and slower and make less power.
> ...


 
   Converted to DC since I had a pistol grip drill switch, which controls speed thru a bridge rectifier, changing AC to DC. 
Didn't use the reverse part of the switch, not enough room in box.


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## big o (Sep 7, 2020)

big o said:


> Converted to DC since I had a pistol grip drill switch, which controls speed thru a bridge rectifier, changing AC to DC. Didn't use the
> reverse part of the switch, not enough room in box.


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