SP&S E7 #750 Completed Kitbash

[rrjim1]

I got all my Atlas Slow Speed motors out of Atlas locos. The few Life likes locos I own run very well and will keep there motors.

[victor miranda]

I went back and re-read
and assembled this:

black end bell - Fast Speed motor, higher starting speed, 30,000 +/- rpms at 12 volts dc.
sliver frame, black end bell - Slow Speed Motor, lower starting speed, 29,000 +/- rpms at 12 volts dc.
gray end bell - Scale Speed Motor, real low starting speed, 13,000 +/- rpms at 12 volts dc.

black end bell - new motor?

are the motors skewed? ... that may be another identification point.

[peteski]

Fast Speed motor, higher starting speed, 30,000 +/- rpms at 12 volts dc.
Slow Speed Motor, lower starting speed, 29,000 +/- rpms at 12 volts dc.
Scale Speed Motor, real low starting speed, 13,000 +/- rpms at 12 volts dc.

Jim W.

So you actually measured the unloaded rpms @12V DC? If you have all 3 handy could you measure their static resistance across the brushes?  There might be some variations depending on the position of the commutator, but there but that might still be a good way to tell them apart.

[mmagliaro]

Yes I reread all the old posts and I also came to the conclusion that there were 3 variations of motors.

I like the speeds... thank you Victor.  Based on that "Scale Speed" 13,000 rpm, that is more like a Mashima's performance.

[victor miranda]

Hi Max,

I appreciate the nod, however, I think you may want to thank rrjim.
he made the post about the three past Atlas motors, and he says there is a fourth version.

I was trying to understand his post and make sure I understood him.

[rrjim1]

So you actually measured the unloaded rpms @12V DC? If you have all 3 handy could you measure their static resistance across the brushes?  There might be some variations depending on the position of the commutator, but there but that might still be a good way to tell them apart.

Yes, I own a laser tach. to measure the RPMs, and a lathe/milling machine to make the plastic disk to hold the reflective tape.
 
It is impossible to measure across the brushes, the only way is to remove the armature and measure pole to pole. The only one I had disassembled to measure was a Kato and it measured 6.2, 6.1, 6.3, on the three poles that I measured. That about what a good stock HO slot car armature measuree, of course there only 3 poles.

[rodsup9000]

 Max,
 How wide is your tool you using to make the groove for the traction tire??  I might have to make one and try this.
Thanks
Rodney

[rrjim1]

How wide is your tool you using to make the groove for the traction tire??  I might have to make one and try this.
Thanks
Rodney

I would use a carbide cutoff tool, narrower than the tire, so I could cut the groove to fit the tire.

[rodsup9000]

I would use a carbide cutoff tool, narrower than the tire, so I could cut the groove to fit the tire.

Don't have any carbide cut off. Have a lot of HSS though. So I'll have to grind one.
Thanks anyway Jim

[victor miranda]

use a fairly narrow point.
the axle half is not a stout enough mount to cut a groove in a single crank move.

I hope that made sense.

think TT as 1.2mm wide  and the cutting tool as 1.2mm wide means you advance the tool straight in.
I got chatter and a slipping wheel on the axle and I bent an axle...

I certainly was not thinking about what I was doing...
I trimmed it to .4mm and all went well.

victor

[peteski]

Yes, I own a laser tach. to measure the RPMs, and a lathe/milling machine to make the plastic disk to hold the reflective tape.
 
It is impossible to measure across the brushes, the only way is to remove the armature and measure pole to pole. The only one I had disassembled to measure was a Kato and it measured 6.2, 6.1, 6.3, on the three poles that I measured. That about what a good stock HO slot car armature measuree, of course there only 3 poles.

Impossible?  Not.  Just hook up the ohmmeter across the brushes of an assembled motor (after first running it for a while to clean the commutator).  Yes, depending on the position of the commutator the readings might be different but you can turn the motor shaft by hand to get few readings and arrive at an average.  A good analog ohmmeter comes in handy for this (no constantly changing numbers).

I'm looking for something other than the color of the motor housing materials to verify what type of a motor it is. Specifically for those 3 different Atlas motors you've mentioned.

[rodsup9000]

Thanks Victor.

Rodney

[rrjim1]

Piece of cake for me, but if you haven't done this before, I manufactured HO Slot Car Speed parts, lots of brass/bronze wheels.  I would make something to hold the other side of the wheel. A short piece of brass rod with a small hole drilled into it would work just fine.

[mmagliaro]

I'm no machinist.  All I did was chuck the axle in my vertical mill (don't have a lathe).
I clamped the cutting tool into a mill clamp on the X-Y table, and just eased the cutter up against the tread
by turning the handwheel.   I spotted the location of the cutted into the tread completely by eye,
and just kept checking the depth of the groove with a caliper every so often when I was getting close.

The cutter is just a steel tool blank that I shaped with a diamond cutoff disk and a Dremel to get
a little rectangular nub at the end of, and that's what I used to cut the groove.

Just oil, go slow..

The width of my cutting nub is 0.88 mm

[rodsup9000]

Thanks Max, that is what I was looking for.

Rodney