# Reversing Dumore TPG



## Inflight (Nov 18, 2011)

I have an older Dumore tool post grinder (model no: 11-011) I picked up from ebay a few years back.  I rarely use this because it spins the "wrong way". My lathe turns CCW (looking at it from the tailstock) and has a threaded spindle so I never bothered to make it reversible.  

The TPG, which spins CW (looking at it from the tailstock), has been running on 110VAC since I acquired it, but today I noticed the motor plate indicated it can run on 90V DC as well as AC. So, as a test, I connected the TPG to an MC-60 "Treadmill" motor speed controller. This worked well, as I could easily control the motor's speed from almost zero to full speed.  But when I swapped the two motor leads back and forth a couple time and the TPG always spun the same direction. Bummer!:banghead:

I then opened the motor and tried to swap the leads going to the brushes, but the cables were too short so I put everything back together.  Any advise?


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## Starlight Tools (Nov 19, 2011)

Bring the brush wires out to a DPDT switch that was the motor can be run in either direction


BUT why as it soulds like it is running in the correct direction now, wheel and work feed into each other.

Walter


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## Inflight (Nov 19, 2011)

Thanks Walter.  I'll add a DPDT switch to the brush wires tomorrow.


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## Inflight (Nov 19, 2011)

Walter, I added a DPDT switch to the brush wires and the grinder is now working in both directions. Thank you very much!!!Because the switch I had on hand was kind of bulky, I added a machined spacer block to the switch cover. Looks almost original.


BTW- For external grinding, the grinder wheel and work must rotate the SAME direction (both CCW or both CW). For internal grinding, they turn opposite directions.




-= Matt =-


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## Starlight Tools (Nov 20, 2011)

Matt

Glad it worked out for you reversing your TGP, playing with motors is what I do regularly.

I will admit that I am not up on TPGs as much as I should be.

I have a Dumore #44, but it does not get used that often.

I also have a B&S #13 T&C grinder and so far it has been used more as a 2900 lb bench grinder than anything else.

In all the books that I have picked up on Grinding, there is one detail they do not really address properly, the correct rotation of the wheel and the work.

One of these years I will actually figure it out.  LOL  I even plan to set the TPG up on the B&S #13 for internal grinding, well just maybe if I ever get "a round tuit" or need it.

Walter


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## Starlight Tools (Nov 20, 2011)

Ah so little cricket, with the power of you tube lights turn on.

[video=youtube;pD8xBsHNJ9M] http://www.youtube.com/watch?v=pD8xBsHNJ9M [/video]

[video=youtube;CRsVTkRNPQM] http://www.youtube.com/watch?v=CRsVTkRNPQM [/video]

[video=youtube;BJKm_3HLL7Y] http://www.youtube.com/watch?v=BJKm_3HLL7Y&feature=related [/video]

[video=youtube;SmHQ2KWIHQA] http://www.youtube.com/watch?v=SmHQ2KWIHQA&feature=related [/video]

But then they be lots that do it wrong too!

[video=youtube;RngF__yc7KM] http://www.youtube.com/watch?v=RngF__yc7KM&feature=results_video&playnext=1&list=PLAE9ADF2A4140F551 [/video]

Walter


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## churchjw (Nov 21, 2011)

I have a Dumore grinder I picked up at a yard sale a few years ago.  Runs like a top and have all the mounts to put it on my lathe.  My big question is where do you get grinding wheels for it?  :headscratch:

Jeff


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## Inflight (Nov 21, 2011)

Jeff,

I have been lucky to find a few nice wheels at a surplus dealer in town. But for a special project, I have ordered a couple wheels from Enco.
http://www.use-enco.com/CGI/INLMK3?PMK0NO=1273254




I dress the wheel with a diamond point before each new operation. Only takes a couple minues but makes a big difference in surface finish.


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## churchjw (Nov 21, 2011)

Inflight said:


> Jeff,
> 
> I have been lucky to find a few nice wheels at a surplus dealer in town. But for a special project, I have ordered a couple wheels from Enco.
> http://www.use-enco.com/CGI/INLMK3?PMK0NO=1273254
> ...



Perfect.  I order from them all the time.  Will get a few next time I order.  Was just never sure which ones to get.  My grinder came with the factory diamond point.

Jeff


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