Weird steam related question on 2-8-2 wheelbases

[peteski]

Nothing to add to the general design advice here but will suggest that the gear/ axle issue that @mmagliaro identified would be relatively easy for me to address. 
. . .
  It would not be a major job for my equipment.

Mark, I'm not trying to be cheeky, but lately you seem to be offering your machining services to ether manufacture some new products, or offer assistance on people's projects.  That is nice of you, but I'm also wondering what happened with that tie-strip project you were really into some time ago.  It looked really promising. Did you get anywhere with that?

[scaro]

Nothing to add to the general design advice here but will suggest that the gear/ axle issue that @mmagliaro identified would be relatively easy for me to address.  Bore the gear out and replace the axle, any length needed.   The idea is pretty obvious but the execution requires pretty precise tolerance, especially runout, and takes the right tooling for the lathe used to assure a good result.  I could do this if the only stumbling block in an otherwise good choice would be this gear/ axle issue.  It would not be a major job for my equipment.

Well, that loco is a lot cheaper and they say the later ones ran well. 

Does anyone know what the dia of the Atlas/Rivarossi wheels is? Spookshow's quoted MR review of the Heavy 2-8-2 says it had 60" wheels, I assume to allow room for the big flanges. I don't know if the Light USRA 2-8-2 had the same wheels as the Heavy one.

And how long either loco's driver wheelbase is, front axle centre to rear axle centre?  I used to have a Rivarossi Light 2-8-2 , from one of the first runs, but it burnt out first time I ran it.

[narrowminded]

Mark, I'm not trying to be cheeky, but lately you seem to be offering your machining services to ether manufacture some new products, or offer assistance on people's projects.  That is nice of you, but I'm also wondering what happened with that tie-strip project you were really into some time ago.  It looked really promising. Did you get anywhere with that?

That's still very much in the works.  I had about 3 months "off", working on home projects and preparing for and executing a 6 week 10,000 mile tour of the country.  All is good.   I only got back at this stuff with any real focus for a few weeks now and progress is being made.

I've been especially busy not making anything but with really organizing my shop space, supplies, etc, etc.  Because I have quite a few very diverse projects under way with LOTS of details and little bits, evolving over a few years with equipment additions, tool additions, supplies added, it has developed into a pretty unorganized mess.  I recognized that needed to be addressed if it was ever to be a manageable venture.  This wasn't news as I've been in all of these places before in my life but this was a new effort, starting almost from scratch.  In between, some time has been spent on the design details for the turnouts and fixtures as well as ordering special cutters and supplies known to be needed for those and my miniature chassis.   

As far as offering some machining to some folks, that's very minor in time and effort but is offered when I recognize that it could be HUGE to some of the folks' projects.  With the equipment I have, things like redoing a gear per above is probably not much more than an hour of effort (or maybe two) including start, execute, and finish up to ship.  And because the work is so clearly defined and limited in scope, it is sometimes welcomed as a break from the serious brain drain of working on an original design of a complex device with a million interrelated details, not to mention hours figuring out the machining, fixtures, and such for all of it.  Those are big projects with the effort to complete very heavily front loaded.  Once they are figured and initial runs proving it all out, the rest is pretty straightforward, mindless work of producing parts.  But they can really tax the brain in the design and development stages, literally and physically tiring me out.  Those little jobs aren't that and can afford a welcome break.

[peteski]

That makes sense - thanks Mark.

[mmagliaro]

Well, that loco is a lot cheaper and they say the later ones ran well. 

Does anyone know what the dia of the Atlas/Rivarossi wheels is? Spookshow's quoted MR review of the Heavy 2-8-2 says it had 60" wheels, I assume to allow room for the big flanges. I don't know if the Light USRA 2-8-2 had the same wheels as the Heavy one.

And how long either loco's driver wheelbase is, front axle centre to rear axle centre?  I used to have a Rivarossi Light 2-8-2 , from one of the first runs, but it burnt out first time I ran it.

Rivarossi 2-8-2:
Wheel diameter .352" on the tread = 42.24" in TT
Wheel base (rear axle to front axle)  1.305 = 156.6 = 13.05 feet

The drivers WITH the flanges have a diameter of about 48"  (big flanges).
The old Rivarossis CAN be made to run really well, especially if you dig in and put a super good motor in them,
and put a better tender on with all-wheel pickup.   The drivers themselves are beautiful, with delicate see-thru spokes.
The valve gear and rods are oversize and very plain.  It's a matter of how much work you want to do.

[scaro]

When the mech is older, I get bolder. They are easily obtainable in the UK where I am. Tempting. 

[mmagliaro]

When the mech is older, I get bolder. They are easily obtainable in the UK where I am. Tempting.

Heh.   I sympathize.  Just be aware of some fundamentals you give up by going that route.  One big one is that the drivers
have no bearing blocks.  They are just brass rods spinning in slots in the Zamac frame.  As such, they can never be as low-friction as something like Kato, Bachmann, or Life-Like options.  The engine also isn't split-frame, so you don't get pickup on both rails from the loco itself, only one side.    These are things you most likely cannot do anything about unless you are willing to start machining out the frame and redesigning it from the ground up.  But a gearhead motor like a Faulhaber with a 4:1 on it can get you so much torque that the friction won't matter, and of course, a good tender will compensate for the engine pickup.  Good luck.

[scaro]

Thanks. I have been looking further and the Mississippian Rwy 76 or 77 might be a candidate for something with a longer wheelbase as they have 4' wheels (and steam wheels in TT as in N are historically undersized.) The Kato does sound easier for my level of skill, provided I look at some kind of video tutorial on quartering wheels.

I need to have a hunt for a diagram but as at least one of these units survives, that may be a little easier.