# Inspiration for a 3rpm motor



## stragenmitsuko (Nov 3, 2016)

I've got this nice 3rpm electrical motor wich I salvaged from some 
medical machine I had to dismantle and send to the metal recycling . 
The motor itself is 900rpm , there's a gearbox attached to it 
wich reduces to 3 rpm with a torque of 8 Nm . 
The motor also has an electromagnetic brake . 
It's a 110Volt , but luckily it came with a matching 220/110 Volt transformer . 
We don't have 110V in europe . 

I'm trying to find something usefull to do with this one . 
I won't trash it , but sitting on a shelf gathering dust isn't gonna do much good either . 

Pat


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## stragenmitsuko (Nov 3, 2016)

Here are some other projects I did with electrical motors 

1 A table saw / box jointing machine , motor salvaged from an electrical lawn mower . 
The unusal arrangement of the drive belt next to the blades is because the motor  turned 
wrong way . And altough it could be reversed electricly , the cooling fan had curved fins  so it was 
was a one direction only . 

2 Toolpost grinder . Motor came from an industrial sewing machine , 8000 rpm series wound motor
Offcourse , as a law of nature it also  turned wrong way . Luckily it could be reversed by desoldering the stator winding .  

3 Cilindrical grinder attatchement for my clarkson 
Salvaged from a machine that separeted computer listing paper . 

4) 60Watt 2800 rpm 3 fase motor , with a matching vfd . 
Destined to become a blower for a foundry waste oil burner . 


As you can see , I like to make a tool to make a tool to create a fixture to grind someting to hold something to finally just maybe do something usefull ....


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## Blogwitch (Nov 3, 2016)

M,

Don't take the motor label to heart. Check to see whether it is 50Hz or 60Hz

I used to work for an American company and fell for the age old problem when trying to run their 60Hz single phase motors from our 50Hz mains (even with a 110volt transformer). The motors ran just fine, just about 1/6th slower. So you can't really use them for critical uses unless that problem is taken into account and allowed for.
When I first started to work for them, it had me tearing my hair out. They had brought over all their equipment from the US. 
Try setting up factory clocks which ran at 60Hz when all I could feed them was 50Hz. Eventually I just bought all new UK equipment and the problems were solved.

John


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## stragenmitsuko (Nov 3, 2016)

I can imagine calibrating 60hz cloks on 50hz lines  being a real pita . 

This little motor has the specs for both 50and 60 Hz on its label . 
It's 3.2Rpm @ 60Hz ;  2.7Rpm at 50Hz . 

So what  could a 2.7Rpm 8 Nm motor be used for ? 


Suggestions , ideas .... fire away


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## bb218 (Nov 3, 2016)

Can masher ?


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## vederstein (Nov 3, 2016)

Brian Rupnow's walking conveyor?


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## Barnbikes (Nov 3, 2016)

Rotisserie for your charcoal grill.


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## chucketn (Nov 3, 2016)

Know anyone that builds fishing rods? That motor would make a good rod wrapper, used for wrapping the thread that holds the guides and decorates the rod.

Chuck


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## Blogwitch (Nov 3, 2016)

You could make a superfine diamond plate lap with it, using say an 8" diameter plate.

Perfect for resharpening tungsten tooling and replacement tips.

The one I have designed works a little faster, at 20 rpm dipping into a water trough. The slow speed makes sure water doesn't go everywhere. Mine is through the prototyping stage, and works great, just awaiting time to turn it into a safe working machine, if I can find all the bits I have to do it somewhere in my shop.

I buy my diamond plates from here, and the 8" backing plates is the next link down, mine is only 6". As far as I know, they only do the backing plates for 6" & 8", but the diamond plates themselves go up to over 20". I bought a few plates ranging from 1200 grit to 2000 grit, and they can be changed in seconds.

http://richontools.com/index.php?main_page=index&cPath=1_9&sort=20a&page=3

http://richontools.com/index.php?main_page=product_info&cPath=45&products_id=798

I turned the face of the support plate to leave a small close tolerance spigot in the middle that the diamond plate sat over and mounted 3 rare earth magnets around the backing plate to hold the diamond plate in position.


John

PS, thinking about it now, when I come to the build, I will offset the centre spigot by about 1/4", that will save having to make a wobble table, the offset plate will give that effect.


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## Nick Hulme (Nov 4, 2016)

You could use it to turn a Mirror Ball, if you're into DISCO! ;-) 
Or a really huge nursery mobile if you have relatives with little 'uns 

 - Nick


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## stragenmitsuko (Nov 4, 2016)

Lol , some great ideas .... 

John I really like the diamond lap plate idea . 
Any pictures of what you have sofar maybe ? 

Big thanks for all the replys guys 


Pat


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## Blogwitch (Nov 4, 2016)

Pat,

Have a look at this. They run at 350 RPM, but I used to have a horizontal water cooled version in my shop that I used for grinding the edge of glass and found that it was way way too fast for the sorts of finishes I required. As slowly as possible gives razor sharp polished surfaces.

http://www.gadgetbuilder.com/GrindRLap.html

For my project, I jury rigged it up in a bench vice with bits of wood about 4 or 5 years ago, and it was stripped down and put into a box soon after it was proven.

The reason I wanted to make one was that I used to use one very similar at work and it allowed you to sharpen almost anything to a razor sharp edge with perfectly formed faces, basically, although not au fait, you can turn a CCMT into a CCGT as long as you don't use them for heavy work, plus because of the very low speed, you can lap up all your HSS as well, a thing you can't do with an offhand grinder as one bit of pressure in the wrong place and the edge would be ruined or not flat.

I then started to use my surface grinder for doing all my HSS stuff, and it is only now that I realise the small machine needs to be got up and running sooner rather than later.

Here is a rough sketch, and the machine I will be assembling, it will be nothing fancy, just making sure it works and is safe. I will be making everything out of 10mm thick UPVC or Makrolon bolted together with silicone as a jointing compound.






John


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## goldstar31 (Nov 5, 2016)

John, Congratulations   on reducing some of the supposed difficulties often expressed into what can be done with  'bits of wood' and common sense.

Oddly, I've just come in with a heap of 2"x2" but PAR to 44mm. When I got my dear old Clarkson T&C it had no tooling and I used wood and bits of studding and nuts and washers as its initial tooling. 

Hoorah for just real honest to goodness sense.

Cheers

Norman


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## purpleknif (Nov 5, 2016)

Turntable for a model railroad ?


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## Blogwitch (Nov 5, 2016)

Norman,

Common sense can overcome lots of problems as long as logical thinking runs in parallel with it.

For almost anything I want to do that is more than just following plans or easy builds, it was always a requirement to make a basic prototype to prove the concept before making the real thing, whether it be out of folded paper, wood, plastic, cardboard etc. It can save many hours of anguish in the long run.

Pat,

Having had a little more thought about it, your motor should have plenty of torque, so allowing you one of the rare occasions where you can actually speed things up a little by the use of gears, belts (preferable) or chains. Just taking the speed up by a factor of 5 or 6 should give you almost the same speed that I have done trials on, in which case you could go down to a 6" disc. 
For the offset pin in the backing plate, it would only need around 1/4" offset to give you a sweep of 1/2" every 3 seconds or so, which is plenty wide enough for any tooling face, and at such a slow speed, vibration shouldn't come into the equation, so taking the place of the 'wobbulator wheel' in the article I sent you to.

BTW, I don't have a large motor to drive it. It is a small 240 volt geared motor  down to the required revs as I won't be digging or forcing the tool into the face of the lap, just wiping it gently across the face for only a few seconds.

With tungsten, there is a little more to it than just putting the tool face to the lap, as if done incorrectly, and get the 'grinding marks' going in the wrong direction, the tips can very easily crack and delaminate, but with HSS, it can be got away with.

I hope this explains things a little better.

John


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## stragenmitsuko (Nov 5, 2016)

Yes  indeed , I also thought I'de gear up a little bit to get into the 25 - 30 rpm area. 

I'm gonna give it some thought to soo what's the best approach , but it sure is a great idea todo something with this little motor . 

Come to think of it my dad is a carpenter and he has a bench grinder with a water stone at one end . It also runs very slow and it passes trough a water bath . 
Migh find some inspiration on the construction there to . 


Pat


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