Bonding wire to underside of turnout frog

Model Railroader Electronics and DCC
1

I have heard various conflicting reports on whether it is possible, and even “easy,” to solder power wires to the underside of Micro Engineering turnout frogs. Some say “get in, get out quick and you will be fine” and other have said "no matter how much I file/polish the bottom of the frog, I cannot solder a wire to it. Obviously, there must be something going on.

I had an interesting idea. I have lots of small 2-56 bolts and screws, some an 1" or more in length. I was wondering if there was something like an epoxy or JB weld which I could use to glue a screw to the bottom of the frog (once it was suitabled filed to reveal bare metal)? Of course whatever I use would need to conduct electricity. Has anyone ever tried this?

I would need to drill a hole in the benchwork for the bolt to pass through, but once below the layout I could then wrap a wire around it and solder there, or use a ring terminal or something else.

2

Why not drill and tap?

edit There actually are electrically conductive epoxys. Not much surface area between the end of a screw and the frog, but I suppose it would be possible. I still vote for my 1st choice

3

If you clean the bottom of the frog well enough for epoxy to bond, it should be clean enough to solder to. Unless it is “non-solder” metal. The bond will be much better, too.

I was/am apprehensive about sticking a soldering iron onto the back of a track switch–all that heat going wherever it pleased, and all. So I use a resistance soldering rig. There is only heat when I activate it. And it is localized at the connection of wire and frog, just where it needs to be.

I have soldered feeder wires to the bottoms of all of my switch frogs AND point rails, and it worked nicely.

Ed

4

I would try to drill and tap a hole in the bottom of the frog. I would drill a #57 hole in the bottom of the frog about .06” deep and use a #0-80 bottoming tap for a #0-80 brass screw. That should be enough threads to hold the screw as a contact. The brass screw would be easy to solder to.

I’ve tapped code 83 rails before using that method and it worked OK. The holes went in a bit deep (had the stop set wrong on my drill press), the threads showed so I just cleaned off the threads with a file and I’ve had no problems with it. The rails I drilled were for my turntable and I didn’t want to heat up them up to connect power.

Mel

Modeling the early to mid 1950s SP in HO scale since 1951

My Model Railroad
http://melvineperry.blogspot.com/

Bakersfield

5

Benjamin,

I have soldered about 50 frog wires to ME switches - yes they are are up the scale in soldering difficulty. Cleaning the solder point is difficult due to the recessed nature of the solder point. If you haven’t tried using a super flux (non corrosive) you might try that. I cut the plastic back on the underside of the solder point to prevent the heat of the iron from melting the plastic and ruining the joint with burning palstic residue.

As for conductive glues - I have used a silver bearing epoxy designed for circuit board work. Worked well but was pretty pricey $17 for a pair of small tubes (like .25 OZ). If you go this route make sure the stock is new. I have bought a dried up packages (I’m guessing due to slow turn over).

Drill and tap might work but would be a lot of hassle.

Guy

6

LION has 48 wheel pick-up.

Him not bother to wire double crossovers or slip switches.

ROAR

7

Thanks to everyone for their helpful advice! [:)]

8

I do not have up-close, personal experience with ME turnouts, but is it possible that the guardrails adjacent to the frog are electrically connected to it? That is true on my W/S turnouts; therefore, I just drop a feeder from one of the frog guardrails and do not touch the frog itself.

Dante

9

One aspect of soldering small points in small area is never or rarely explained and explored.

So if necessary I will give you these small advices which I hope could help you.

Nickel silver used to make models rails like ME or brass are subject of oxygen alteration and humidity which is corrosion; on iron this corrosion is impressive and we know it as rust.

This corrosion is a barrier for a good soldering job.

Even if nickel silver shine on first hand, after a while it’s surface is corroded and we need to “wash” this tin corrosion surface to make a good soldering job.

For brass and nickel silver, polishing them, is enough to obtain good soldering surfaces.

First rule, a clean surface, use some brush wire or even polyester brush used for weathering or a piece of wool the same used to wash our dishes to clean brass or nickel silver in small spots.

You can glue these things on a small piece of wood to go on small spots; I didn’t advise you to use sand paper because of the sand dust which can altered the future soldering work.

If you use weathered track, you must clean of a spot from the weathering to obtain the natural nickel silver: a small polish disk in a Dremel do the job, after use piece of wool as I mentionned to finish the cleaning; don’t touch the area with your fingers.

The use of solder flux is sometimes necessary but don’t use acid flux especialy the ones with clorid zinc, the residue are extremly difficult to wash; paste flux with non corrosive additive are cleaned with toothbrush and alcool.

Soldering is made with a good soldering iron and for small spot with a fine pen tip; if you are able to use a soldering iron with variable temperature capabilities like a Weller station, it’s a best; a 25 to 45 watts soldering iron is normaly enough to do your job.

For small spot use fine solder around 1mm diameter or even smaller, fastrac

10

Thank you to everyone who responded. I will try buying super small solder, which I am sure will help.

11

I recommend getting a pound of .020" (half millimeter) flux core solder. It’s about $30, and will last a lifetime of model railroading. Perhaps more.

There is finer solder, but the price starts going up.

Ed