Plastic vs Metal vs Wide vs Narrow N scale wheels

[Sokramiketes]

The narrow wheels definitely came first.  The wide wheels were developed following issues with old Shinohara turnouts at two local layouts, the Reid Brother's Cumberland Valley and Bill Pistello's Union Pacific.  When FVM started selling rolling stock equipped with their wheels, Matt made the decision to use the wheels that just worked with everything.  So that is why all FVM rolling stock uses the "wide" or "standard" tread width.

 

[drgw0579]

One you guys a ways back gave me an idea.  I have shimmed the guard rails.  I think I learned about doing that in an N trak group I was in 30 years ago.  But shimming the bottom of the frog might keep the wheels from dropping down.  The flange depth on all my cars are all the same, so if I got the shim the right height so that instead of dropping in the gap, the flange rides on the shim.

Tried to put a piece of plastic in there.  That didn't work well.  How about raising the area with a bit of glue?  I put a dab of canopy glue on the floor of the frog, and if I need to, I can file it down a wee bit.  Initial tests are promising.  I am trying this on both Peco Insulfrog and electrofrog.  If it doesn't work, I can easily peel the canopy glue out.

If it does work, I'll do this on all other Peco turnouts.

Bill Kepner

[peteski]

One you guys a ways back gave me an idea.  I have shimmed the guard rails.  I think I learned about doing that in an N trak group I was in 30 years ago.  But shimming the bottom of the frog might keep the wheels from dropping down.  The flange depth on all my cars are all the same, so if I got the shim the right height so that instead of dropping in the gap, the flange rides on the shim.

Tried to put a piece of plastic in there.  That didn't work well.  How about raising the area with a bit of glue?  I put a dab of canopy glue on the floor of the frog, and if I need to, I can file it down a wee bit.  Initial tests are promising.  I am trying this on both Peco Insulfrog and electrofrog.  If it doesn't work, I can easily peel the canopy glue out.

If it does work, I'll do this on all other Peco turnouts.

Bill Kepner

Bill, why didn't shimming the floor of the frog (as you called it) didn't work?  I would have expected that to work netter than filling that area with canopy glue.  A shim will have even thickness while glue might not give even thickness along the area.  You just have to figure out how thick the shim has to be.

I would measure the depth of the frog's flangeway then subtract the depth of your wheel's flanges. Then probably subtract about 0.010" for good measure. That will be the thickness of the shim.  But you have to make sure that when the shim is installed it bottoms out in the frog's flangeway.

[mmagliaro]

I suppose shimming up the floor of the frogs could help wheel drop if you go conservatively with it so that your deepest flanges don't bounce.  On code 55, allowing for a .025" flange would be a good target, since it is still common in my experience to find locos with flanges that deep (and they do clear the ties on Atlas 55, so nobody is chomping to turn down all their .025" flanges).

If it's a plastic frog, yes, a plastic shim ought to do.  If it's a metal frog, you probably want to use a thin strip of phosphor bronze or nickel silver, since locos will be rolling on that frog and you don't want to give up the electrical contact.  You would essentially be insulating part of your frog for any engine that rides through on the flange.

[drgw0579]

The problem is that the bottom if the Peco plastic frog isn't exactly flat.  I don't need to raise the bottom a whole lot, maybe .030".  All I need to do is to stop the bounce when he wheel drops in.  That doesn't cause the derailment, it's the sudden jerk when the wheel hits the point of the frog; sometimes that causes it to follow the wrong path.  I haven't done much with the metal frog turnouts; I wonder though if I did use metal, how I would fasten; I can' solder in there!  Glue would not conduct power.  My plastic shims aren't very pretty looking, but a thin layer of Canopy glue is mostly unnoticeable.

The experiments are ongoing and probably will be for a while.  I have outfitted some free-running boxcars with the narrow wheels to compare with the others.  For now I've held off on selling the 72 BMLA wheelsets in the Trading Post. 

Bill Kepner

[mmagliaro]

Bill,
I don't see how the wheel could go down the wrong path when it rides back up onto the point of the frog unless the wheel is too far over to begin with.  If that's the case, the fix really is to shim the guard rails on the outside rails away from the frog (as has already been discussed in here). 
For the record, I used to have this problem with Peco code 80 turnouts and shimming the guard rails was a sure-fire fix.  After that, as long as the wheelsets were in guage, I never had these types of derailments anymore.

Good point on how to attach a shim on a metal frog.  Maybe that's why I've never gotten around to it.  Wheel drop bugs me mostly on certain steam locos where a driver on one corner of the engine will dive in and out of the frog when it drops.  The engine doesn't derail, but it's visually unpleasant.  I suppose if the shim were just the right width so it fit tightly down in there, it could be glued on the bottom and the edges would still provide the contact with the frog.  It needs to be nickel silver or phosphor bronze, not brass.  If it's brass, it will oxidize and be useless in a few days.  Nickel silver would be the best choice because it would look like the rest of the frog.

[peteski]

Bill,
I suspect that the bottom of the frog has slightly rounded profile.  So when you cut a shim strip you could round its sides to better fit in the flangeway. BTW, Evergreen sells black styrene (which would be much less visible in the flangeway or shimming the side of the the guard rail.  Much less visible than white styrene we usually use.

As for the metal shims, you could glue them in using conductive epoxy. Silver-bearing conductive epoxy us available, but quite pricey. There is also silver- or nickel-bearing conductive paint available, but I do not think that it will dry sealed between 2 pieces of metal. Epoxy hardens by chemical reaction (not solvent evaporation).

[jagged ben]

Bill,
I don't see how the wheel could go down the wrong path when it rides back up onto the point of the frog unless the wheel is too far over to begin with.  If that's the case, the fix really is to shim the guard rails on the outside rails away from the frog (as has already been discussed in here).

Well, maybe, maybe not.  I've had narrow tread wheel sets drop into Peco frogs and just stick there, hard.  So the derailment is either a stringline in front of that truck or an accordion behind, if you don't enforce a slow order.  I'd swear that in a couple cases I've had the front wheel going through the frog jar and twist the truck enough to derail the back axle off the rails. 

The real solution would be to shim the frog itself.  Or to be precise, the wing rails.  That would reduce the space available for the wheel tread to fall into.  (I'll grant that shimming the guard rails may help additionally, and certainly can't hurt.)

For the record, I used to have this problem with Peco code 80 turnouts and shimming the guard rails was a sure-fire fix.  After that, as long as the wheelsets were in guage, I never had these types of derailments anymore.

For the record, were you using narrow tread wheelsets?

[mmagliaro]

Well, maybe, maybe not.  I've had narrow tread wheel sets drop into Peco frogs and just stick there, hard.  So the derailment is either a stringline in front of that truck or an accordion behind, if you don't enforce a slow order.  I'd swear that in a couple cases I've had the front wheel going through the frog jar and twist the truck enough to derail the back axle off the rails. 

The real solution would be to shim the frog itself.  Or to be precise, the wing rails.  That would reduce the space available for the wheel tread to fall into.  (I'll grant that shimming the guard rails may help additionally, and certainly can't hurt.)

For the record, were you using narrow tread wheelsets?

Oh no, this was in the "good old days".  I was running pizza cutter MT wheelsets on code 80 track. I do see your point about what can happen with finer treads.  I never considered the whole wheel dropping down in there.  But the Peco frog clearances are really wide, so I can see how that would happen.  I suppose shimming the wing and the guardrails is the real way to make them bullet-proof. 

[nkalanaga]

Yes, shimming the wing rails would stop wheel drop, as the too-wide frog flangeway is the root cause.  You would also have to shim the guardrails, though, to prevent the flange from "picking the point". 

Shimming the wing rail is exactly the same process as shimming the guardrails, except that the end at the point of the frog has to be trimmed to exactly match the other flangeway.  The guardrail shims are much less critical, just taper the ends so the flanges don't catch on them.  I've never done it, as all of my Peco turnouts are in my staging yard, where appearance doesn't matter.  But it shouldn't be hard to do.

[robert3985]

Every time I read this thread, the happier I am that I decided to start rolling my own turnouts 30 years ago...

I feel bad for model railroaders who commit to the best available product at the time, only to have it go obsolete and virtually non-functional due to changing, more prototypical operating components, such as low flanges and narrow tires...but I'm happy I'm not one of 'em!   

Cheerio!
Bob Gilmore

[leedabsme74]

I've had issues with the narrow-width metal wheelsets on my Atlas code 55.  The BLMA gons were a literal "car-wreck" on my layout– Those narrow wheelsets would derail at the drop of a hat.  For them to work (well) they have to be exactly in gauge and many are not exact enough for derailment-free operation.  The Atlas metal wheels (that aren't the best looking metal wheelset out there) work like a champ.  The FVM wide-width metal wheelsets work great also.  Nope, the "wide's" do not look as good as the "narrow's" but I have a difficult time telling them apart under normal viewing conditions.

For a plastic wheelset, and I still have many, I prefer the Atlas "browns".  The work great on my Atlas code 55 trackage.  The MT plastic wheelsets can be a wee bit more problematic– they'll pick a switch once in a while.

Just noticed this thread and found this worth a comment.  I also had problems with the BLMA gondola.  BLMA wasn't sure which wheel sets were in my cars, so they sent me replacement wheels sets and trucks.  They explained that the original 33" wheel was mistakenly sized by the machine shop as a scaling down of the 36" wheel.  That meant the flanges were too small and the wheels wouldn't proper follow the track.  So I installed all the wheels and trucks into 49 gondolas and still had the problem.  Studying the axles and trucks, I came to the following conclusion.

1)  The axles didn't fit the trucks properly and would not rotate freely.
2)  The trucks were not molded with the same distance between to the two frames.
3)  The bolster pins held the truck too tight against the bottom side of the car, not allowing free motion of the truck on the pin.
4)  When pulling a long train, ie 40 cars, there is so much drag from the axles in the trucks that it pulled the cars off the track to the inside of even wide (24" radius) corners.

My solution was to "file to fit" each axle into each truck.  I used a small jewelers file and filed off the points of each axle till it would spin in the truck.  I also had to dress the point so there were no burrs.  The result was a small amount of play in each axle, about .002 to .004 inches and then the axle would rotate freely in the truck.  I then re-installed the truck on the car, carefully setting the bolster pin in position where it didn't restrict free movement of the truck in on the chassis.  Those cars run pretty well.  I have pulled over 40 of them in a unit train without problems on a N-Trak layout.

[mmagliaro]

It's tough filing down the ends of a pointed axle and getting it to still spin true in the truck frame cones.  I applaud your courage!

When I do this, I remove both wheels from the axle and either:

a) chuck in a Dremel and run the tip against a file and then progressively fine grades of sandpaper down to 2000 grit

or

b) (better)  do it in a mill or lathe, followed by the sandpaper.

The mill produces more perfect results, but the Dremel will do fine.  I do think that getting down to super-fine grits of sandpaper at the end makes a difference.  The axle points are polished that way and they really roll smoothly.

I find that I can get the point to end up true and dead in the middle more easily this way.

[leedabsme74]

It's tough filing down the ends of a pointed axle and getting it to still spin true in the truck frame cones.  I applaud your courage!

When I do this, I remove both wheels from the axle and either:

a) chuck in a Dremel and run the tip against a file and then progressively fine grades of sandpaper down to 2000 grit

or

b) (better)  do it in a mill or lathe, followed by the sandpaper.

The mill produces more perfect results, but the Dremel will do fine.  I do think that getting down to super-fine grits of sandpaper at the end makes a difference.  The axle points are polished that way and they really roll smoothly.

I find that I can get the point to end up true and dead in the middle more easily this way.


I don't disagree with anything you have offered.  I worked on over 100 axles and that was more time than I really wanted to spend.  It started as an experiment with the Rapido axles on their Panorama Line passenger cars.  It worked there so I did it again here.  I would have rather just used a commercial axle, but the warp in the trucks deterred that idea.  But these axles spin very well and it proved to me that you don't have to have a perfect point on them with special lubrications or other stuff to get good operation from them.  I didn't mention that some of the wheels were off center and others would wobble real bad.  I didn't use those.

[drgw0579]

A quick update.  I am finding the shimming the bottom of the frog with Evergreen styrene is working very well on Peco Electrofrog turnouts.  Using 0.010" thick material.   Testing with a train of BLMA gons and I shove back and forth all day without a derailment (well maybe 8-10 times, till I get tired).

Also doing the guard rails with the same material.  Maybe I won't sell the "narrow tread" wheels I had set aside after all.

Bill Kepner