safely turn down driver flanges in place?

[nickelplate759]

I have an old Rivarossi (not ROWA) 2-8-4 that I want to turn down the driver flanges on.  I don't want disassemble the mechanism - I've heard that one can run the mechanism and use a file to turn down the flange.       I've also heard that this can go horribly wrong.   I'd like advice on how to proceed in order to minimize the risk of destroying the model.   The drivers have plastic centers, so clearly heat would be a problem - it would have to be a slow process.

"Don't" is not the advice I'm looking for.  I don't have a lathe or milling tool or a good way to pull and remount and requarter the wheels.
Pay someone to do it right is a possiblity, but I've no idea where to find someone that would do this.


George

[mmagliaro]

Of all the drivers that need to be turned in this world, I think Rivarossis are the hardest.   The reasons are many.

1. Their attachment is quite fragile on the axle.
2. If you press them off the axles with a wheel puller, so you can put them in a jig or a lathe and turn them,
it is hard to get them back on so they are really
square with the axle and don't wobble, even if you do it with a wheel press or a good jewelers vise.
The axle end is splined, and it's hard to get the little splines back in the same grooves in the wheel hole.
3. The axles are very sloppy in their slots, so if you do this by holding a file on the spinning driver,
the driver tends to try to wobble around.

Having said all that, I have done it, so I won't tell you "don't".   I have had the most success by flipping
the engine on its back, attaching some clip leads to run it, and then holding a small, flat, diamond jeweler's file against
the flange.  Diamond makes a big difference.  It will take off metal more smoothly without as much drag or
heat on the wheel.   Don't use just an ordinary jeweler's file.  It will make more heat, a rougher flange,
and take forever.

Before you start... give yourself every chance.   Clean the axle ends with alcohol on a Q-tip, dry them thoroughly.  Then put a
drop of Loctite onto the axle tip so it flows down into the joint between the axle and the wheel hole.  Don't use so much
that it flows all over the place and binds the axle in the frame!

The LocTite green formulas are designed
for this (to wick into an existing joint by capillary action).  The blue (or red) are not.  So dig around at R/C shops and other
hobby stores.  The R/C shops seem to always carry the green stuff.  Let that stuff harden up good before you start grinding.
This will give you your best chance of a wheel not slipping on the axle.

You will find that the wheel may try to bounce or wobble away from the file until you get the feel of things.
You will find a sweet spot where you can keep steady, but gentle, pressure on the wheel and it will turn nicely against your file.

If you do not have a caliper, you will just have to "eyeball" the flange until it looks like you've cut
it down enough.   You can hold a piece of Atlas code 55 upside down and run the rail over the wheel you are working on,
feeling and listening to see if the flange still bumps on the ties. 

Expect to spend a lot of time on this.  Go VERY slow.  By VERY slow, I mean it will probably take you 10-15 minutes to do one
flange.   Run the engine, hold the file on there for 10 seconds or so, then lay off for 5 or 10, then do 10 more, and so on.
You are correct to be fearful of building up too much heat.

Once you have the flange cut down, hold the file at a 45 degree angle against each side of the edge to put a bevel on it,
and then run the file over the flange a little to gently round over the edge. You don't want a sharp knife edge on it.
A rounded taper is what your are shooting for.

When you are finally all done, use a small soft paint brush and brush brush BRUSH all the metal dust away from the
gears and off the mechanism as best you can.  It won't hurt to wash everything out with alcohol, but you said you don't
want to take the mechanism apart.  That's okay.  You can do it just by brushing.  The gears are big and chunky and
they are more tolerant than modern gears.   It would be a good idea to keep revisiting the mechanism after you are done with this
and run it for a few minutes, so you can brush it clean again.  Some metal debris you didn't catch the first time will likely work its way
into view where you can get rid of it.

Finally...
What happens if you "blow" it?  A driver will slip on its axle, throwing the rods out of sync (out of quarter).  The engine will
jam up on its rods, and now you have to start turning the errant wheel back into position on its axle until you get it smooth again.
You might have to press the wheel off and put some LocTite or JB Weld in there, and press it back on to get it to stay.
It becomes a real headache fast if this happens, so GO SLOW! 

And good luck!   

[victor miranda]

Max's advice is the way to go.
ummmm
the motor you have in there will make a difference.
the black round one is likely to overheat this is one motor you do not want to overheat.
If you can see the armature, it is from the last type of motor
and will hold up better.

if there is no oil on the gears they will shed the filings.
otherwise consider covering the gears with something.
cut a plastic straw in half and tape it over the gears or such.

victor

[nkalanaga]

Pat Sanders at Trainworx USED TO provide wheel turning services.  You could try emailing him to see if he still does.  It's been quite a while since I bought a loco that needed its wheels turned, but his work was excellent, and the prices quite reasonable.

[mmagliaro]

Max's advice is the way to go.
ummmm
the motor you have in there will make a difference.
the black round one is likely to overheat this is one motor you do not want to overheat.
If you can see the armature, it is from the last type of motor
and will hold up better.

if there is no oil on the gears they will shed the filings.
otherwise consider covering the gears with something.
cut a plastic straw in half and tape it over the gears or such.

victor

Hey Victor... that's a fine idea about the plastic straw!  Never thought of that.

And another nice property of having some masking tape covering things is that the filings and dust tend to stick to any
sticky parts of the tape that happen to be exposed - always a plus if you can pull the tape off and a lot of metal mess with it.

[nickelplate759]

Good ideas all, and thank you.   It does have the crappy Rivarossi can motor, but that's the first thing I need to replace as it's already barely functional.  It runs, but one coil is dead so it wont start on its own most times, and of course is pretty weak.

One last question, maybe for Max, then I'll give it a try.  How fast do I want the wheels spinning when I do this?

Georgfe

[mmagliaro]

I don't have any firm recommendation on the speed.  In general, it depends on feel and
how hard I am holding the file on there.  Start with 8 volts so it runs a little on the fast side.
Remember, a light touch is the key here, so lots of light passes of the flange against the file
is what does the trick. 

The "light" touch has to be just hard enough to maintain contact with the flange at all times.  You don't want
that wheel bouncing around, sometimes touching the file and sometimes not.  That will make for a very messy,
uneven flange.   Don't just hold the file and let it "lie" on the wheel.  That will be a little TOO light.  The file
will bob up and down with the wheel, and the flange will come out uneven.  You need just a little *positive*
pressure of the file against the wheel.

The fact that the motor is already on the way out is probably a plus here.  You can use it as a sacrificial lamb to get
the wheels done, and then upgrade it.