Aristo Wide Radius Switches

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Editors note: There is a complementary page on Aristo Wide Radius switches you should read also: Ted's WR Turnout Vignette


These switches are described as 10 foot diameter (5 foot radius). The As of December 2008, they have been produced in 3 versions, read further down on how to tell the differences. (There is a new frog available as a replacement part as of January 2009, which have been integrated into production switches) The most pertinent thing about the versions is the first version can have trouble with locos with "skates", shorting at the frog. The other differences are more subtle and affect reliability and tracking.

They have a number of operational problems, and you can make drastic improvements by a few simple modifications.

Like all Aristo track, measurements and dimensions given are approximate, and actually I don't think there is actually a single case where the advertised dimension is accurate. The switches do indeed match the "10 foot diameter" Aristo track in curvature.  It can be substituted perfectly anywhere in a "10' diameter" curve, although since it's curved part is shorter than a normal piece of sectional track, a short section of curved track must be added to exactly replace one piece of sectional track.


To tell what version you have: (Thanks to Ted D.)

The first version had metal guard rails for the wing rails. There were also metal guard rails for the frog, which caused many people to have shorts from locos with "skates". I'd avoid this if you have USA or LGB.

The second version has plastic guard rails. There were thin insulated wires providing power to the frog rails. Many people had problems, but you could replace the wires with heavier gauge.

The third version seems to have somewhat reduced frog height. The original ones had the plastic frog so much higher than the rails, the cars really went bump. The wires powering the frog rails are heavier and not insulated. Now they are thick enough to carry a lot of current. Unfortunately now the failure point becomes the wire to screw connection. There are metal straps to power the point rails, rather than wires. Much better here.

In 2009 we got the 4th generation with a better frog, the rails are now flush with the top of the frog, and the flangeway depth at the frog is 3mm (NMRA minimum)

Problems / weak spots

Unfortunately there are a number of weak spots and need quite a bit of work to be reliable.

The major items are:

  1. Point rails don't fit "into" wing rails well.
  2. Inside edge of point rails have an abrupt radius.
  3. There is friction, drag, or excessive slop in the points (the moving rails).
  4. The flangeways on the guard rails (the outer 2 rails) are way too wide.
  5. Frog flangeways not deep enough.
  6. Frog way higher than point rails and other rails.
  7. Electrical continuity problems.
  8. Gauge problems in many places

As of January 2009, numbers 5 and 6 have been significantly improved. The new frogs eliminate these problems. You can order replacement frogs for $1 each including shipping. Do it if you don't have the latest frogs, much better than filing and cutting. They are easy to swap out, just a few screws. In 2005 Tim Brien told me he was under the impression that the raised frog was so that it would lift the USA trains (and probably LGB) pickup skates so they could not short out the rails just past the frog (a common occurance with skates, especially the really big ones of MTH) Tim had complained for some time to Aristo about this and also the insufficent flangeway depth, especially if you trim down the top of the frogs.

Let me make a strong recommendation: ANY one of the problems listed above can be the source of your problems with a wide radius switch. I recommend you read this entire section.

If you do anything at all, mill down the frog and deepen the frog flangeways or replace the frogs. (unless your switches were manufactured in 2009 or later). Next shim the guardrail flangeways. The other mods will help, and of course if you have electrical problems you will have to take action.

Point rail fixes

The point rails typically don't "fit" very closely to the wing rails.

You will want to file the side of each point rail so it fit closely to the wing rails.

Also file the inside of each point rail so there is a smooth transition for the wheels, sometimes they are too abrupt.

A tip from L. Grote is: if you wind up disassembling the switch, the underside of the point rails have sharp edges, which add drag when the turnout is thrown, put a small radius on these edges where they bear on the tie strips.

Pivoting and/or Moving Parts

The pivot points for the point rails may need adjustment. Some seem to have a lot of slop in them, some (rarely) are too tight.

They are secured underneath by a screw with a spring under the head. The screw pivots in the wide tie strip.

Check the switch by manually operating it. Disconnecting the switch motor (electric or manual) helps in checking. Ideally, if you hold the switch vertically it will "throw" by the force of gravity alone.

I'm wondering if drilling out the hole slightly larger and thus repositioning it, and then adding a bushing would lessen the slop and better align the point rails with their fixed counterparts. So far, matching the point rails to the wing rails seems to work well enough.

Guard Rail Flangeways

This is a big problem, and, fixing it, combined with fixing the frog, usually changes a bad switch into a perfect one.

The problem is that guard rails flangeways are way wider than what is recommended. This allows so much side to side slop in the wheelsets that one wheel will try to climb up on the frog, instead of following the frog flangeway. You can normally see this by derailments.

I have measured a number of my wide radius switches, and they measure 3.32 to 3.8 mm. So in general, they are way wide. The NMRA standard S-3.3 says 2.69 to 3.33mm, and the Aristo gauge is 2.76 mm. In accord with trying to keep my methods to something that most people can do, I am following the Aristo gauge. So, based on that, my flangeways are about 0.020" to 0.025" too wide in most places.

I have glued a piece of 0.020 styrene to the inside of the existing flangeway. It has worked great. Some people use a piece of brass shim stock, but you have to wrap it around the ends of the guard rail, no way to glue it unless you put epoxy on the end. I used Plastruct Bondene liquid, which is a styrene and ABS plastic solvent glue, worked instantly. After fixing the center, I applied more glue at the angles of the guard rail ends, bent the plastic around it, and held for a second. After gluing, wicking some more glue all around the joint, and then trimming with an X-acto knife did the trick. I did 4 switches in place in 1/2 hour.

Some people have removed the plastic guard rail and replaced it with a metal one. Great looking for sure, but what a lot of work.

On the forums, one person used brass .015" shim, bent over the ends, so it springs out in the middle of the flangeway. Another is trying .025 shim, I think he is trying to glue it to the existing plastic rail. I think it's a lot harder to glue brass to the plastic guardrail than what I have tried.

I'll see how long the styrene lasts, but this is a huge difference in running. Where I could not back a train through a crossover made of two wide radius switches at any speed, now I can run a 15 car train at pretty high speed backwards through the crossover.



Frog Flangeways (this problem improved in 2009)

First, note that if you trim the height of the frog, you will affect the flangeway depth. So if you are going to perform that modification, do it before this one.

The flangeways are too shallow, no matter what. So instead of the wheels rolling on the frog, the flanges hit the bottom of the frog flangeways, and bounce up in the air.

The Aristo gauge is within the NMRA spec, spec is 3.0 mm minimum, and the Aristo gauge is 3.04 mm... Some people recommend more depth, like 3.5 mm, but so far using the Aristo spec/gauge this has worked well for me, and I'm trying to recommend methods that are easy for others to use.

Find a metal file that is as close to the width of the flangeway as you can find. Hold on edge, at about 35-40 degrees, and push it in the flangeway, like a scraper/chisel. You need to do both paths. Use the track gauge to check the depth, and be sure to lower the "approach ramps" at each end to make a smooth transition.

An idea from K.C. Marshall: he glued 3 fine tooth hacksaw blades together to cut the frog flangeways deeper. I'm going to have to try that. 


Frog Height (this problem mostly corrected in 2009)

The frog sits way higher than the rails around it on pre-2009 frogs/switches.

This causes a visable bump and derailments. I believe this was done early on to avoid trains with "skate/slider" power pickups from touching both rails at the frog and shorting. This is a common problem not only with Aristo switches, but other manufacturers. Aristo does not use these "skates", but USAT, LGB, MTH, etc. do.

If you do this modification, be aware you need to check for this problem with your locos with skates. I have USAT locos and no problems. People have thinned the width of their skates or bent the outer edges up to avoid this problem, or removed them completely.

Also, if you perform this modification, be aware that you will be making the frog flangeways even shallower. They are too shallow to begin with, deepening the flangeways needs to be done no matter what, so that part of the frog modification should not deter you.

The fastest and best way I have found to level the frog with it's surrounding rails is to take a router (the kind with a 6" or larger round base) and put a flat-cutting bit in it. 3/8" diameter is a good size. Now, make sure the bit is flush with the base. All you have to do is just slide this over the frog, the base rests on the rails, and the frog will be higher and the router will rapidly trim it exactly level with the rails. This will take about 20 seconds. You cannot make a mistake.

An added bonus is that you can even do it with the switch already in the ground. Make sure that the switch has not "bowed" from being in the ground. (Check with a straightege first in both directions).

Some people sand or file the frog down, but that also scratches the rails, as you have to sand/file across all the rails. This method certainly takes longer than 20 seconds.

Some people have suggested shimming the adjacent rails up where they meet the frog. Don't do this. All you will wind up with is a "hump" right in the middle of the switch, the worst place to not be level. This method has also caused the pilot trucks of some steam engines to "catch air".

Replacing WR turnout frogs: Replacing Aristo WR turnout frogs


Power problems

There are wires that feed power from the frog rails to the wing rails. The wire is under screw heads that fasten to the rails. In the first 2 versions the wire is thin and insulated, too lightweight to handle the current of several locos for a long time. The third version has thicker wire, but still somewhat puny if it is to pass many amps.

This is a significant weak point in the design. Right out of the box, the screws are often loose and this is the reason for the majority of new users having power outages. If the screw is loose, then the connection can fail or worse, heat up. I have a melted tie where the connection was poor, and all the resistance created so much heat, it melted the top of the tie off over the wire, and I burned myself on the rail.

The only solutions seem to always feed power from the frog rails to the wing rails with some other method. Right now I use 2 external jumpers to connect the frog rails to their corresponding wing rail.

Since I use Split Jaw clamps on all 6 rails of the switch, I simply make two 5" jumpers (I use solid wire) with ring terminals crimped to each end, and then put under the heads of the Split Jaw screws.

As added bonuses, you can do this mod in place, and you can inspect it without pulling the switch up. Pointing the terminals down allows you to bury the jumper in the ballast.

If you have brass, you could solder jumpers directly to the rails from the underside. Soldered connections can corrode over time, so put a dollup of grease or insulating rubberized paint or something, especially since you probably won't pull the switch up each year to see if the connection is ok.

Shorting problems at frog:

Issue found with WR frog, information and picture courtesy of Ted Doskaris


Other tips

Check all the screws for tightness, and you can either loctite them or put a dab of silicon on them.

I've not gotten any long term results on which is better. The silicon might keep corrosion down, but the loctite might keep them from loosening better.

Weather Underground PWS KCACARLS78