[HOsteam] Rivarossi question - another idea?


Tom Knowles <ncstl@...>
 

Bob,

This is an excellent idea.

Thanks,

Tom Knowles

----- Original Message -----
From: "Bob Yarger" <ryarger@rypn.org>
To: <HOsteam@yahoogroups.com>
Sent: Monday, March 24, 2003 1:37 PM
Subject: [HOsteam] Rivarossi question - another idea?


Keeping in mind that I have never actually turned down flanges in HO
scale,
I've wondered if the following might also work? Instead of using the
model
motor and siderods to do the turning, remove them, just leaving the
wheelset
(probably just one at a time) in the frame. The wheel could then be
turned
with some sort of motor (electric drill, motor tool, whatever) that had a
small rubber wheel attached to the shaft. The motor might be hand held,
or
held against the driver via a spring or screw-type adjustment. The
spinning
driver could then have a file and/or abrasive applied to the flange to
reduce it's height. One might use a lathe-type cutter as described below,
if very light cuts were made. A DC motor (perhaps from an old model)
could
be easily controlled for speed if it were powerful enough. Not sure if
the
frame should be upside down or right side up. One might apply notched
paper
shims between the inside of the driver and the frame to help keep grit out
of the bearing. The experience I've had with lathes and drill presses in
turning wheels (at least in larger scales) is that it is very difficult
to
get them to run true. There always seemed to be a tiny bit of
eccentricity
and wobble if held by the axle, even with careful centering of a 4-jaw
chuck.

Bob Yarger, Editor
Railway Preservation News (free website)
www.rypn.org
----- Original Message -----
From: "Tom Knowles" <ncstl@mindspring.com>
To: <HOsteam@yahoogroups.com>
Sent: Sunday, March 23, 2003 9:37 PM
Subject: Re: [HOsteam] Rivarossi question


Bob,

So you're an ol' 1:1 scale model railroader too? It's been quite a while
for
me, but I try to apply the prototype rules and certain procedures I
learned
"way back when", when useful. The problem with "carbide brake shoes" in
H.O.
scale is the force required of the mechanism to do the work Secondary
problem is the residue from turning gets in the rather loose clearances
of
siderods/crank pins and wears them out very quickly in the process. One
must
do one wheel at a time which stresses that particular rod heavily, too.
I
can't imagine this is easy on either the gearboxes or motor either. A
full
size loco on track with wheel turning shoes has some benefits of scale!

As for re-wheeling, I suppose anything is possible if you want to do it
badly enough. I would have no trouble "adjusting" the journal slots to
take
other drivers. I have priced proper, beautiful replacement (scale)
drivers
at $18 and axle from Greenway products (and for other scratch-building
exercises) and find this prohibitive on my modeling budget. I really
don't
want the drivers any larger, as the 71" is close enough on the Pacific
and
the 54" is just right on the articulated for my purposes. So you see,
I'm
kind of in a quandary. Maybe I should buy one of those cheap ($3-400)
little
Chinese lathes from "Northern" for all the little stuff I often need to
do
on a lathe. Unwheeling and turning seems the best solution for now.

I agree with you about Riv and their penchant for undersize
drivers...probably has something to do with getting the overall look to
be
right with those large flanges of yesteryear. Certainly not needed
today.
What IS needed is a good source of parts for the steam freak....this
appears
to be a dieing art, scale and full-size.

Love to hear more of your Large Scale experiences.

Tom Knowles

----- Original Message -----
From: "Bob Yarger" <ryarger@rypn.org>
To: <HOsteam@yahoogroups.com>
Sent: Saturday, March 22, 2003 2:39 PM
Subject: Re: [HOsteam] Rivarossi question


I remember a couple of articles related to AHM/Rivarossi wheels, that
could
be found today on the MR index of modeling articles.

One, in MR, I think, dealt with turning the flanges down on a Unimat
lathe,
with a specially built homemade fixture to hold the axles. This
seemed
pretty precision oriented, and easy to fail at. Another, in RMC,
dealt
with replacing the undersized wheels with those from another engine,
such
as
replacing the undersize drivers on the 2-10-2 with those from the
Berkshire.
These would fit with the new smaller flanges. As Rivarossi has
changed
things somewhat over the years, I'm not sure if this option would
still
be
available, re: gearing, etc..

In another magazine (perhaps just in the editorials section), one
reader
described turning and applying a thin band of metal to the existing
high-flanged tire, to reduce flange height.

It would be best if Rivarossi would just make correct size drivers for
their
engines. Manufacturing a true-running drive wheel is a precision
matter,
however, and not that easy. It might work if they could just apply
thicker
tires to the existing plastic centers, for correct diameters and
better
appearance. In some cases, the tires would appear overly-thick, but
some
RRs like the Rock Island did exactly that to get more speed out of
their
4-8-4s.

Or you could do like we did when I was a hostler and machinist: just
take
out the brake shoe and install a wheel-truing shoe with a carbide
cutter,
then run the engine back and forth on the track applying light
pressure
with
the independent until the high flange was down to less than condemning
limits!

Bob Yarger, Editor
Railway Preservation News (free website)
www.rypn.org
----- Original Message -----
From: "Mike Bauers" <mwbauers55@wi.rr.com>
To: <HOsteam@yahoogroups.com>
Sent: Saturday, March 22, 2003 11:38 AM
Subject: Re: [HOsteam] Rivarossi question




Tom Knowles wrote:
Hey, Ya'll'
Does anybody know if the current revision of drive wheels/axles
for
Riv
engines will retrofit old ones? I wanna change out the drivers on
an
old
Pacific and a Y6b so they'll operate on code 70. Years ago I
turned
the
driver's flanges on a Berk using a file, emery paper and the
engines
own
power. Of course this wore it out so badly as to render it
unuseable.
I
do
not want to do this with these two engines, nor do I have a lathe
to
do
them
on. Seems like replacing is the solution, unless someone else has
a
bright
idea...
Know of a good way to ship them?

I have a lathe and several AHM engines in need of the same fix. It's
time I did the same with mine, like I did with several quite a while
ago.

If you'd like, I could trim yours as well. My favorite method is to
first turn down the flange to height and then re-profile the raw
stub
to
a contoured shape. [I discovered a long time ago that just running a
powered Dremel cut-off disk into the blank end of a lathe cutter
makes
a
really nice notch that has a smooth arc on both sides that looks
just
perfect for trimming a square profiled flange to a smoothly convex
profile.] I've gotten a lot of use from that finish cutter.

I've sort of gathered a lot of AHM from swaps and the like over the
last
few years that need 'the treatment' I gave to my first several. It's
time I got that done.

--
regards,
Mike Bauers
Milwaukee, Wi, USA



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Brian McKenzie <brianCAD@...>
 

Guys,

Reducing Rivarossi wheel flanges is fraught with danger and some of the
ideas advanced will certainly lead to their destruction - as it did for me
in my early hobby days.

Unless individual wheels can be adequately supported by shaped pegs clamped
through the spokes, to the end of a round bar in a lathe, they may not
survive the forces exerted by a turning tool.

A similar set-up works well in conjunction with a Dremel type tool fitted
with a suitable grinding wheel. Ideally, the grinding wheel tool will be
under some sort of steady in-feed control and the wheel should turn
relatively slowly, say 150-200 revs, which is possibly slower than some
small lathes provide.

Look at:
http://groups.yahoo.com/group/HOsteam/files/Grinder%20Workhead.jpg
in the Group Files, to see a device used for applying a slight taper to axle
ends, or for truing wheels. A finer grit wheel than the one in the photo is
used. As axles/wheels rotate about their own axis it is easy to make minor
adjustments/corrections. The electric motor is from an old record player
and the drive belt is sliced from mountain bike tube.

--Brian McKenzie


mwbauers
 

Brian McKenzie wrote:
Guys,
Reducing Rivarossi wheel flanges is fraught with danger and some of the
ideas advanced will certainly lead to their destruction - as it did for me
in my early hobby days.
Unless individual wheels can be adequately supported by shaped pegs clamped
through the spokes, to the end of a round bar in a lathe, they may not
survive the forces exerted by a turning tool.
I see I should post a close-up pic of an AHM wheel set nested in a three jaw mill chuck. It's a very small amount of material in the cross section that gets removed.

A similar set-up works well in conjunction with a Dremel type tool fitted
with a suitable grinding wheel. Ideally, the grinding wheel tool will be
under some sort of steady in-feed control and the wheel should turn
relatively slowly, say 150-200 revs, which is possibly slower than some
small lathes provide.
There are pre-made RP-25 profile cutters available that would cut both wheel taper and flange in one bite from a blank, or re-shape a really poor wheel to proper profile.

The main secret is to securely mount the wheel or wheel set so that it can be cut as a rigid part. In most cases, you are only removing a very few thousandth's of metal. The closer you work to the mill chuck, the more rigid the cut will be. If you can get the part you need to cut near there, you don't need much of an elaborate holding fixture. I find that a 3 inch lathe chuck works well on wheels under two inches real diameter if you nest the outside of the wheel into the mount of the chuck and wind up cutting first from the back of the wheel and then trimming the contour of the snipped flange inline with the flange itself.

It's the same way all truck wheels, motor heads, and contoured rollers are manufactured in the machine shop at Da Job; just nest securely into trimmed jaws and cut.

Look at:
http://groups.yahoo.com/group/HOsteam/files/Grinder%20Workhead.jpg
in the Group Files, to see a device used for applying a slight taper to axle
ends, or for truing wheels. A finer grit wheel than the one in the photo is
used. As axles/wheels rotate about their own axis it is easy to make minor
adjustments/corrections. The electric motor is from an old record player
and the drive belt is sliced from mountain bike tube.
A slick solution.

--
regards,
Mike Bauers
Milwaukee, Wi, USA


Brian McKenzie <brianCAD@...>
 

Mike Bauers wrote:

I see I should post a close-up pic of an AHM wheel set nested in a
three jaw mill chuck. It's a very small amount of material in the
cross section that gets removed.
Yes please. I can't quite picture what you are suggesting - unless it is
merely gripping one wheel by its tread, with its flange and the opposing
wheel protruding.

There are pre-made RP-25 profile cutters available that would cut
both wheel taper and flange in one bite from a blank.....
Yes, and I have used several with varying degrees of success.

or re-shape a really poor wheel to proper profile.
Probably not. It would wreck it first unless the wheel could be very
rigidly mounted and supported fully (if spoked) in a lathe possessing a bit
of heft.

In most cases, you are only removing a very few thousandth's of metal.
Yes, but it is being removed simultaneously over a wide cutting face, thus
exerting tremendous pressure on the wheel. Brass does turn readily with
form tools but other materials can be troublesome and often tear, because of
a lack of side clearance inherent in form tools. Ferrous materials need
quick tool withdrawal to prevent rubbing, but this leaves a step in the
diameter.

Try it, but best not with someone else's wheels. Then advise us - but
please, not before some practical experience.

--Brian McKenzie


mwbauers
 

Brian McKenzie wrote:
Mike Bauers wrote:

I see I should post a close-up pic of an AHM wheel set nested in a
three jaw mill chuck. It's a very small amount of material in the
cross section that gets removed.
Yes please. I can't quite picture what you are suggesting - unless it is
merely gripping one wheel by its tread, with its flange and the opposing
wheel protruding.
Much like that.... I'll get the pics together.


There are pre-made RP-25 profile cutters available that would cut
both wheel taper and flange in one bite from a blank.....
Yes, and I have used several with varying degrees of success.

or re-shape a really poor wheel to proper profile.
Probably not. It would wreck it first unless the wheel could be very
rigidly mounted and supported fully (if spoked) in a lathe possessing a bit
of heft.

In most cases, you are only removing a very few thousandth's of metal.
Yes, but it is being removed simultaneously over a wide cutting face, thus
exerting tremendous pressure on the wheel. Brass does turn readily with
form tools but other materials can be troublesome and often tear, because of
a lack of side clearance inherent in form tools. Ferrous materials need
quick tool withdrawal to prevent rubbing, but this leaves a step in the
diameter.
Yes, but we are usually dealing with brass and it's alloys on our models, and only trimming the oversized, but still tiny flange, in this case.

As to your experience with ferrous, I've got years of shop observation that show me that is not a concern for the tens of thousands of turned steel and iron truck wheels that have gone through our shop over the decades. You mainly have to use the right speed and feed to cleanly turn a blank round burnout, cut-off, or forging into a profiled wheel with the correct composition cutters and flood coolants.

It really gets down to a secure grip on the back, cutting on the front with a suitable speed and feed for the material, chips that won't get in the way, and using a cutter that will stay sharp during the operation.

Try it, but best not with someone else's wheels. Then advise us - but
please, not before some practical experience.
I'll get some snaps together Monday night after I get back from staying with some relatives that are going through the hospital.

What I have been describing is how I modified my lathe in a few seconds over twenty years ago and have since put several dozens of wheels through; as well as how it is done on much larger wheels in very large batches at the P&H Mining Shovel manufacturing plant where I work.

It has worked for them for over 110 years and it works for me as well.

They have dozens of sets of cut to holding diameter soft jaw inserts for their three jaw chucks at each machine and I've found that a decent compromise cutting that I used has allowed me to use the same jaws on every HO and N scale wheel set I've re-tools so far.

I first thought I would have to buy extra jaws and do the same multiple sizing of the receiver recess. But I never needed to get those additional sets. Perhaps it is because there is only a one inch range of diameter change that I've run through the chuck between coach wheels and the average steamer driver?

I'll get those pics up ASAP

--
regards,
Mike Bauers
Milwaukee, Wi, USA