Last call for rebuilt Rivarossi can motors

[mmagliaro]

For the last 2-1/2 years, I have been offering a rebuild/upgrade service for the old Atlas/Rivarossi motors that had such a penchant to melt down or otherwise self-destruct, and were otherwise not very good motors even when they were running. Although considering they were developed in 1968, they were an impressive achievement for their time.

All the details you might want about this project may be found here: https://www.therailwire.net/forum/index.php?topic=51553.0  if you were not aware of this.

This is the "end of life" announcement.  I'm down to about my last 10 custom-manufactured magnets for these, and when those are gone, I will not be doing any more.  So if anybody thought about it before figured, "ah, well, maybe later", or didn't even know about this and now discovers it and would like one, now's your last chance.  When the magnets are gone, they are gone.

[kiwi_al]

You have mail 

[u18b]

I'm down for two.

[Slim Rail Mike]

Please put me down for one of the motors. An email was sent.

[wm3798]

Max, you have earned your place in heaven with this project.
I've got an 0-4-0 that would benefit from the surgery, but if you're out you're out.


All the best,
Lee

[mmagliaro]

Lee, thank you!
Actually, all 10 are now spoken for.  But if somebody flakes on me, I will let you know.

[u18b]

I mailed my two today.

[delamaize]

PM sent.
Hopefully I'll get lucky

[wm3798]

Max,
Obvi. there's at least a minor market for these.  Perhaps we could have a conversation about what's involved, and we can see about getting the magnets and armatures sourced.  No need for you to do all the labor.  A good set of instructions, and an appropriately set price point, and I think there's a DIY product to sell here.
Lee

[mmagliaro]

Lee, I appreciate that idea.  But I can tell you it took me 2-1/2 years to go through about 200 magnets.  So while there's a market, there isn't a very big market.  Armatures are less of a problem, as at least currently, one can still buy batches of these inexpensive Mabuchi
motors that have just the right size armature and shaft that they can be made to fit into the can.

Sourcing the magnets basically means coming up with about $400 to buy another batch of magnets, assuming I can still get them from where I got them the first time.

As for other complications of such a "kit" for people to do this DIY...
It may look like it's all just "drop in" pieces, but that was by design.  I did all the hard work so that customers could just "drop in" the
motor in their engine.  But there are a lot of very delicate, specialized steps required to put one of these together.

In the interest of making people realize how tricky this task is, and so that if somebody else ever wants to try to do this,
here's a "stream of consciousness" dump...

- The armature will not just drop in to the Rivarossi can.  It has to be carefully compressed to push the commutator section closer to the coil section.   The inside nose of the can has to be machined out "just so" in a lathe to allow a little more room for the commutator to
move deeper into the can.  (If you really want to know:  Bore the inside of the nose out .025" with a 17/64" drill bit.  Then machine
.025" with a 5/32" end mill.  Experimentally, using cobalt drill bit, and running the lathe at 220 rpm produces the smoothest finish and most accurate depth of cut.

- The brush holders have to be bored out in a lathe so the slightly larger brushes and springs will fit.
(again, for those who want the details... .081" drill bit, bored in .260"  And I MEAN .260"... not .240" or .280".  If you don't
go deep enough, the brush spring and brush won't sit in the holder well enough to sit straigh and allow for assembly.  If you
drill a little too deep, you'll bust the top of the holder out... and of course, you need a collet or other appropriate holding
fixture to be able to mount that little brush holder in a lathe.

- The two bronze bearings (one in the can and one in the plastic brush cap) have to be reamed out with a 1.5mm chucking reamer because they are actually bored just a hair smaller than 1.5mm. The Rivarossi original armature shaft is "sort of 1.5mm", but is actually about .003" smaller, so that a true 1.5mm shaft won't go in the bearings with out reaming them.  Even after you do that, there is a lot of imprecision of the bearing alignment in the Rivarossi motor.  Think about it.  A bearing pushed into a plastic end cap, which is then snapped into the
back of a metal can?  No way does that make sure the two bearings are aligned within a few thousandths of an inch.  Soooo.....
Once you ream the bearings, you have to put the cap on and ream them again.  Then, if the armature shaft still doesn't spin freely in
there, a few twirls of a round file into each end of each bearing, to open up some clearance where the armature shaft comes in and goes
out of each bearing, may be necessary.

- The brushes themselves have to be filed a little bit shorter because as-is, they would put too much pressure on the armature, and while it runs, the added friction makes it start at too high a voltage, and causes excess brush wear and clogging of the armature if you don't shorten the brushes.

-  I mentioned machining the can (above).  That means you need to press OUT the nose bearing before you can machine the can.  Then you need to press that bearing back in.  I made a special little tool that slips just inside the can, with a nipple and ram on the end of it, so I can put the can under the vertical mill and use the mill to come straight down and press the bearing back in.  AND the can is supported ina  special jig that supports the nose of the can so it doesn't get busted out of the can by the pressure of pressing the bearing back in.

- Once you locate the "S" pole on the magnet, wrap it with one layer of .002" Kapton, then insert it into the can, with that "S" pole spot
right over the lower brush holder position.  But when you put the armature in, now the shimming and adjusting begins...

a) Make sure you put enough thrust washers to get the commutator under the brushes.  I use a mix of .020", .010", .005" and .003"
nylon, bronze and stainless steel.

b) It is CRUCIAL that the armature have a TINY bit of lateral play in the assembled motor, but not too much.  "Too much" is something I just judge by gut feel, but it's less than .005", I can tell you that. 

c) LATERAL PLACEMENT OF THE ARMATURE.   Picture the armature sitting inside that magnet ring.  If it isn't centered front-to-back,
the magnet wants to shoot the armature either forward or backward.  When you assemble it, you will feel this because the armature
will be slammed against either the front or rear bearing.  VERY BAD for smooth low-speed starts.  It will all work, but low speed performance will be lousy.  So you need to add shims to the armature OR sometimes I need to add a thin large stainless steel shim ring
to move the magnet itself, so that the armature TOTALLY floats in there - so you can gently nudge it back or forward, and it will return to
a center position where it is not binding on either end.

================================================
And of course, on top of all this, there is the usual-but-not-easy task of pressing the old worm off (if an 0-8-0 or 0-4-0) and pressing it on the new motor.  And there is a whole separate list of steps to take the steel strip off the trailing truck and replace it with a brass one to
thwart the magnet's desire to pull the trailing truck up in the air.

=================

Whew, yeah.  So... I seriously doubt anybody is going to be able to do this, or would want to.

[Slim Rail Mike]

Max you make it sound so easy.

You obviously weren't making money doing these.

I'm glad i got one.

Thanks

Michael

[wm3798]

Well, I'm glad we passed through this corner of Oz when the opportunity presented itself.
There are now 200 Rivarossi steamers out there that will outlive civilization itself, and perhaps even cockroaches and telemarketers.  I'm glad to be in possession of eight of them.



Another tip o' the hat, Max.

Lee

[mmagliaro]

THANK YOU, Lee.  I very much appreciate your praise.

Believe me, even though it was very time-consuming (took me something like 6 months to get the process down, plus the months of figuring out how to acquire the magnets), it was a heck of a lot of fun.  And besides, I wasn't ready to get back to scratchbuilding another steam loco just yet (but that mood won't last forever... )

[peteski]

And besides, I wasn't ready to get back to scratchbuilding another steam loco just yet (but that mood won't last forever... )

You are a mad man Max!  In that case I suggest N scale John Bull.   

[mmagliaro]

The final bell has tolled, folks.   All the motors are done and sent out.  It's been a lovely and worthwhile ride.

Peteski... no John Bull for me.  After the "Rocket", I'm done with early 19th century locomotives that are no bigger than the end joint of my pinky!

To be completely up and up, the "next one I want to do" for a long time has been a kitbash job on the Atlas Shay, and that's where I think I'm headed.  There were three that ran around here in Oregon not 10 miles from my home back in the 1920s that are "pretty close" to the Atlas model.   The frame and boiler need to be shortened, and the internal drivetrain, while pretty good, runs way too fast for a logging locomotive, so I want to change the gearing to increase the ratio to get super-smooth motion in the 1-5 mph range.  And finally, there's the whole piston assembly on the side.  While Atlas did a good job for a commercial model in N Scale, there are a lot of moving parts on that 3-cylinder assembly that were simply left out.  That's probably the place where the "Mad Max" work is really going to come in.  Take a peek at the Bachmann HO Shay and you can see all the uppy downy roundy-roundy parts that should be in there that are missing on the Atlas model.