parts for an old time genny.

[Kermit]

Any way in which I can avoid having to seperate and insulate those copper rings is better than one in which I don't. ;D

Yeah I'll have to cut a keyway under the outside two rings and epoxy the wires into it.

My plan is to "hide" six high power silicon diodes on the generator and rectify the three phase AC directly. The binding posts I'll put on it will give pulsing DC just like a commutator, but no sparks!

I've inspected my share of motor/generator sets and I'm positive when I say making a commutator of any simplexity is more difficult than any number of pick up rings. Not that I don't want to try it eventually, but I don't want it stopping me right now, while I'm learning my tools and machine.

Hope that clears up any questions on the output of the genny.

Kermit

 

[Kermit]

I discovered that not just any old 1.5 inch piece of metal will work as a spacer for my field poles. So, I'm making up some aluminium dummy magnets to use during assembly and alignment.

Next, I'm gonna tackle the filling of the rotor with iron powder epoxy, and get it closed up on a short garolite axle. I'll have to join the garolite with the brass rod, or perhaps with a steel rod. I'm not sure yet. I have a feeling the brass rod would wear down too fast where it contacts the roller bearings. Perhaps just an outer race of hardened steel to fit on the garolite axle would be easier. It's going slow without a 'plan' to follow.

Hopin for more suggestions,
Kermit





View attachment Genny_Dummy Magnet Assy.pdf

 

[Kermit]

I created a dimensioned drawing showing all the major parts and mounting positions.
Nothing else accomplished so far.

The raw material for the rotor build up is here, but I'm not ready yet... :-[ Whole family has had the flu and seems it is my turn to experience the joy of viral invasion.

It's making my joints hurt more than they ever have up till now. Ouch!
Kermit

View attachment Genny_prototype 2.pdf

 

[Kermit]

The iron powder/paste is actually more of a dry sand mortar consistency. Wet enough to form a ball when closed in your hand, but it would break up if poked with a finger.
mix ratio.
1.5 liq. oz. of epoxy + 10 oz. of powdered iron fillings.

Whatever

 

[Krown Kustoms]

Where do you get iron filings that fine?
Did you make them?
-B-

 

[Kermit]

Purchased at an educational toy store.

Check google for iron filings for sale.


I clipped the first returns shown, out of about 50,000.

 

[Krown Kustoms]

I didnt think they would be that popular.
-B-

 

[mu38&Bg#]

Iron filings of this type are really not much better than a solid iron core. The epoxy does not insulate the particles so it's just one lump of iron. The proper material is a fine iron powder, but each particle is coated with an insulator of some sort. google "SMC powder".

 

[Kermit]

Iron filings of this type are really not much better than a solid iron core. The epoxy does not insulate the particles so it's just one lump of iron.

I went to the shop and retrieved my meter "just to be sure".

Wrong, my friend. Not a single lump of 1018 or 304 would read above 100 ohms on my meter. VERY LOW resistance.

Upon place the meter leads into pure iron powder as I have pictured above, the reistance reading was over 20 Meg Ohms, same with the dried lumps of epoxied iron powder material. The epoxy does nothing more than bind it all together, and is not an the sole source of high resistance. The iron powder is highly oxidized. Compacted under pressure I doubt I could lower the resistance any lower than several 10's of kilo Ohms, and adding in the epoxies resistance when cured, current flow through the two types of cores-iron filings vs. solid metal would be at least 3 orders of magnitude difference and probably more than that.

Break down- solid core -wasteful
iron filing core - very efficient.

I'd be glad to post pics or video of my meter and its readings on the above mentioned materials, if that is what it would take to have you believe me.

If I have to do anything more than that to prove it. You'll just have to go though life thinking I have got it all wrong. ;D


Won't bother me if won't bother you.

 

[arnoldb]

Kermit, I agree with you, though I would say the epoxy does have an insulating role in combination with the iron filings' oxidized layer. There is less surface area amongst the particles to conduct, as the epoxy inhibits that, and with oxidization on the parts of the particles that actually do make contact, resistance increases.

 

[mu38&Bg#]

Won't bother you my friend. Carry on.

 

[Kermit]

Carrying on then.

I glued up the four pieces last night and will square up the side faces and slot it. Hopefully I'll be glueing on the top and bottom pieces by dinner time. Will drill a small pass through at the back of the slots for the braided cable connection of the brush to exit by.

Still a long way to go,
Kermit

 

[RobWilson]

Hi Kermit

Looking good Thm:

this may/probably is a dumb question , is the iron powder core , the same sort of principle as a laminated core ? :hDe:


Regards Rob.

 

[Kermit]

exactly. any conductor moving in a magnetic field will have electric currents induced in it. Breaking up the metal, breaks up the circulating electricity by isolating it and reduces it tendency to heat up the core. The core is still mostly iron though so the magnetic circuit is almost as happy with laminated, or powder cores as it is with solid iron cores. Just the wasteful heating of the electric currents are reduced.

 

[RobWilson]

Cheers Kermit

so am i correct in thinking ,,,,,,,,,, if it was a solid core it would turn into an electric fire ?


Regards Rob

 

[Kermit]

Not quite. But it would heat up considerably more than the motors and generators we are familiar with. 200-250 C would be quickly attained with constant use if there was a solid core and at that point the insulation on the copper wire would burn away and the working parts would short circuit. Cooling holes through the core and fanblade like attachments on the shaft were common in the days before laminated cores were used.

 

[zeeprogrammer]

Another fascinating thread that I've commented very little on. I just don't know what to say. I'm enjoying it a lot. And the amount of detail is great.

 

[Kermit]

Found something this morning under a pile of iron scrap. Seems to be dry and nothing twisted too far out of position. A few minutes with a belt sander and I should have a useable part.

 

[Kermit]

I can't seem to find the third brush anywhere.... ???

 

[bearcar1]

Maybe it decided to hide under that pile of iron scrap you started with this morning Rof}

BC1
Jim