# PMR Dynamo.



## Tony Bird (Nov 12, 2014)

Hi,

I recently finished making a PMR Dynamo which is fairly simple to make and a good project for someone new to machining castings.  In the UK the PMR Dynamo kit consists of two sheets of drawings, two aluminium castings, two magnets, one cast iron casting, an armature and a bag containing screws, brushes and the rest of the materials to complete the model.  The cost was £42.

Box of bits.





The cast iron body was machined first.





Bored for magnets.





Not on the drawings but part of the cast iron body's base was machined away.





The mating faces of the aluminium end caps were first finished by hand.  Then drilled and mounted in the lathe.








A register was turned on the end cap and the bearing fitted.





On the end cap that holds the brush gear the screw holes for the bushes needed to be spot faced inside the casting.  This looked a little awkward to do so to give clearance the inside of the casting was machined away.








Trial assembly.





PMR's castings are very good but the screws supplied aren't!  Being in the UK and not having American size taps I had to change the screws anyway.





Instead of using screws studs and nuts were used.





Because I didn't like the vertical orientation of the terminals the magnets were moved 90 degrees and held in place with a screw instead of the lifting ring, this allowed the terminals to be horizontal.





The dynamo works well as a motor so I hope it will generate well.  I intend it to be coupled to a Stuart 10H that I have.





Regards Tony.


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## ShopShoe (Nov 12, 2014)

Tony,

Great build on the dynamo. I like the way you matched paint to the engine. I think it was a good decision to use the nuts and studs. The screws you show seem to be pretty rough and typical of the inferior quality we are seeing for slotted screws.

I always enjoy your projects.

--ShopShoe


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## mcostello (Nov 12, 2014)

Like the studs, paint color, and the lifting ring.


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## Tony Bird (Nov 15, 2014)

Hi,

I have mounted the Stuart 10H and PMR dynamo on a board and bought some Mamod spring drives.













Regards Tony.


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## Swifty (Nov 15, 2014)

I like the multi belt drive, looks great.

Paul.


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## Tony Bird (Nov 16, 2014)

Hi,

I have tried the Stuart 10H in steam driving the PMR dynamo.  First I tried it with a small boiler that  would power the 10H continuously but would only run it for about a minute when the dynamo was connected.  Then my test boiler was tried which would power the engine continuously but might not when the dynamo is under load.  








Video.

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Regards Tony.


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## Tony Bird (Nov 16, 2014)

,

Sorry wrong video code I hope!





Regards Tony.


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## Brian Rupnow (Nov 16, 2014)

Tony--Very well done so far!!! Of course the true "test" will come when the dynamo has something to power up. I am following your thread because it is interesting, and because I may endevour to make something similar based on an old bicycle dynamo and my latest i.c. engine. I may even have to make a "fake" housing to run it in so it looks a bit more "authentic" like yours.---Brian


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## Tony Bird (Nov 17, 2014)

Hi Brian,

*Of course the true "test" will come when the dynamo has something to power up. *

Yes, the PMR spec's for the dynamo at 5300rpm are Voltage 10V DC @ 10 Watts,
No Load voltage 12V DC and a Maximum current of 2.4AMPS.

I think if the boiler used can produce enough steam the Stuart 10H has enough power.  The five belts together seem to be OK  for transmitting a reasonable amount of power but we will have to see.  The ratio between the engines flywheel and the dynamo's pulley is just over 4.5:1.

A friend of mine used a Dyno-hub from the front wheel of a bicycle built into the flywheel of a stationary engine that he had made.  This worked very well as a generator as it was designed to work at quite low revs. It also looked quite well with all its coils inside a body that he had made for it.

Regards Tony.


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## Tony Bird (Feb 14, 2015)

Hi,

Did get to try the PMR dynamo out.  It lit these Christmas lights, but for only the 4.5v required the Stuart 10H had to be run very slowly.

Regards Tony.


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