Atlas Rivarossi 0-8-0 redo

[timwatson]

Hey guys I'm hoping in your collective model railroading wisdom you know of a source for small hollow styrene rod. I'm looking to sleeve some gears and wheels to electrically isolate them.

My outside dia. is .0680" inner dia is .0615" (I can shave these down some or make my hole bigger but not by much) and yes I realize the tolerances. It was suggested in a different thread I try heat shrink tube but I couldn't get it shrunk enough. At this point even thats an option however if someone has a good source.

Any help is appreciated, Tim

-edited title per OP's request. -gfh

[peteski]

Without making them on a lathe from some acrylic or styrene rod, I don't have any innovative ideas.
The only other thing that comes to mind is to make a jig which will hold the gear and its axle perfectly aligned, then use epoxy (like JB Weld, or even 5-minute epoxy) to fill the gap and make the sleeve.

[Chris333]

What wheels are you working with?

[mmagliaro]

I have some questions.

Do you have an axle, going into the center bore hole of a wheel, and you want something to sleeve over the axle
so that the metal axle doesn't contact the metal wheel?

The axle diameter is .0615" ?
The hole bore is .0680" ?   

[nkalanaga]

If MMagliaro's interpretation is right, one way would be to start with a larger rod, drill a hole in it for the axle, then very carefully turn the outside to fit the hole in the wheel.  That would probably be easier than finding a tube the right size, and would guarantee that everything was concentric.

[mmagliaro]

If MMagliaro's interpretation is right, one way would be to start with a larger rod, drill a hole in it for the axle, then very carefully turn the outside to fit the hole in the wheel.  That would probably be easier than finding a tube the right size, and would guarantee that everything was concentric.

That's exactly where I'm headed with this.  I did this on another engine where I wanted to insulate one side of a trailing
truck.   Boring a hole in the center of a styrene rod is dang near impossible.  Styrene is soft and it will deform and smoosh
around even if you drill it gently.

But a brass tube, now you're talking.  Start with that.  Put shrink tube over it with some epoxy and shrink it down.
Maybe you can get a layer of shrink over some brass tubing and that will be your insulating layer.
Brass tubing can be found with really tiny bores, and you could drill that out.  Even doing it by hand with a pin vise,
the bit will tend to follow the existing bore and it will be quite true.  I've bored worm gears out like that and it works
if you are careful.

[peteski]

Yes, drilling a centered hole in styrene (or any material) rod is very difficult. That is why a lathe would be needed for something like that.

I'm not too keen on the heat shrink idea. Not only it is difficult to evenly shrink the tube all around its diameter, heat shrink material itself is IMO too squishy to make a solid sleeve.  The sleeve needs to be made from a harder material than a flexible heat shrink.

[timwatson]

OK the jig is up I suppose. I have been redoing an Atlas rivarossi 0-8-0. It is here so far.

1. I have replaced the frame with an old Atlas Mikado frame (aluminum), machined it to where the motor would fit.
2. I re-motored it
3. Ground down the flanges
4. Blackened the wheels
5. Added tungsten to the shell. It's now 72 g (without any valve gear) instead of the 63 the whole model was. (As of right now in test mode it will pull 18+ cars no problem.)
6. Sculpey is used for the motor mount/cradle.

Chris S. I used a diamond cutter blade in my dremel to cut and shape the pinewood derby weights. Cuts it wonderfully (I have been meaning to share that with you).

Max I've been meaning to tell you this - I used black Sculpey III for the motor cradle. It insulates and is custom fit to the motor so you get a perfect fit everytime. I still glued in the motor however.




Sculpey motor cradle.

Here is the full photo set to date. http://www.flickr.com/photos/nscalerail/sets/72157638113184554/

I love these old steamers but I need to consistently isolate the wheels from the main frame. THATS WHY I NEED THE ROD! 

Thanks for the help guys.

[timwatson]

Pete is right I can't accurately drill a centered hole to save my life. I just suck at that. I can do many things but I need to find a different way to get those axles away from those wheels. I wish I had some tiny swizzle sticks.

The reason I gave those numbers was because I've reamed out the hole already Max. That's the maximum I can sleeve into the wheel and still have a wheel hub intact.

[Philip H]

so are you really looking to isolate the wheels or the axles where they sit under the frame?  If all you are trying to do is keep the axle from touching the fram - and shorting it out - then why not put a layer of Kaypton Tape on the bottom of the frame?

[bbussey]

How about taking plastic or acrylic .068 inch diameter (or close) rod stock and putting it in a lathe to get the .0615 inch "rolling pin handles" to fit the wheels?

Or, conversely, order some RSD4/5 gear-less wheelsets from Atlas (#9423304, $1.75 ea) and pull the wheels to salvage the plastic idler axles for your four drivers.  If not a press-fit, I'm sure the drivers can be epoxy'd in place.

After nearly 50 years, that old RivaRossi body tooling still holds looks good next to contemporary models — especially the IHB 0-8-0.

[timwatson]

You're thinking of this in exactly the right way. The issue is I need to get polarity based power from the locomotive ANDD right now the gear is brass and the wheel centers are metal. So on DCC the whole system shorts out when it goes across the rails. Although a tiny bit of kapton might work on the wheel axle.

so are you really looking to isolate the wheels or the axles where they sit under the frame?  If all you are trying to do is keep the axle from touching the fram - and shorting it out - then why not put a layer of Kaypton Tape on the bottom of the frame?

[timwatson]

The RS wheel set idea is a really good one Brian. I'm not familiar with them do you have any to measure??
Totally agree about the IHB steamer. I really love Rivarossi steam driver wheels when the flanges are turned down.

P.s. Brian I have no lathe the wheels were turned on a drill with a file.

How about taking plastic or acrylic .068 inch diameter (or close) rod stock and putting it in a lathe to get the .0615 inch "rolling pin handles" to fit the wheels?

Or, conversely, order some RSD4/5 gear-less wheelsets from Atlas (#9423304, $1.75 ea) and pull the wheels to salvage the plastic idler axles for your four drivers.  If not a press-fit, I'm sure the drivers can be epoxy'd in place.

After nearly 50 years, that old RivaRossi body tooling still holds looks good next to contemporary models — especially the IHB 0-8-0.

[bbussey]

Tim,

I do not.  But it would be the same as any standard RS3 geared axle, so the diameter could be measured from that.

You always can increase the diameter of the axle cavities in the frame if the Atlas axles are too fat, or line the cavities with styrene if the axles are too narrow.  But it seems that using a manufacturer's existing axle is your easiest path forward.

It might be worth looking at the geared axles also, instead of trying to retrofit the original RivaRossi gear onto a new axle.

[SkipGear]

Tim,
 I'm confused. The wheel centers on the RR steam are plastic. The only way the wheel rim made electrical contact with the frame was when a steel disc was inserted between the back of the wheel and the axle to complete the circuit. The simple answer is to remove all the steel disks which will remove the frame electrically from the circuit and then use wipers on the wheel rims or just rely on tender pickup for the whole thing.