Taken from the forum in 2017

1. Arun Sharma, Jul 16, 2017
I have a potential problem with insulating a pony truck's wheels from touching a valance. I would like to insulate the valance and the only method that would work in this particular case would be to apply a physical barrier to the inside of the valance. However, the barrier needs to be physically very thin.

Possible ideas include applying a smear of epoxy to the valance or thin insulating tape. I think epoxy would work but does anyone know of any super thin and super sticky tape that they would recommend?
Arun

2. Chris Simpson, Jul 16, 2017
If it's a pony truck, and the wheels are not used for pickups, you may be able to live with the occasional short. In a situation where you use the main wheels for pickup, and the wheels have insulated tyres, the chassis is insulated from the wheels and so, if one 'non pickup' wheel touches the chassis momentarily, there is no short. A short would only occur if both sides touched the chassis at the same time. If this applies, then either no insulation, or a thin epoxy barrier should suffice.

Chris

3. Stewart Ingram, Jul 16, 2017
I have used Kapton Tape with some success as an insulator.
It is very thin and provided the surface is clean, seems to stick ok.
Stewart

4. Bob Comerford, Jul 17, 2017
Arun, I used household sticky tape with a smear of superglue to fix a similar problem on a HO loco years ago. It is still there.
Cheers
Bob

5. Steph Dale, Jul 17, 2017
Arun,
Chris certainly has a point, but if you're certain a barrier is necessary I'd use either tissue paper or a Rizzla, stuck in with epoxy. The resulting paper/epoxy composite is remarkably tough, not unlike some grades of Tufnol.
Steph

6. Arun Sharma, Jul 17, 2017
Thanks to all of you - I like Steph's belt and braces solution of a Rizla and epoxy so I'll try that to begin with.
Arun

7. David Smith, Jul 17, 2017
I also use Steph's tissue paper and epoxy resin technique; it's particularly useful behind brake rods that run both sides of the driving wheels.
David

8. David Littlewood, Jul 17, 2017
I have also found the paper/epoxy method works for insulating brake shoes so you can get them close to the wheel without risking a short.
David

9. Terry Cooke, Jul 17, 2017
Black nail varnish does the job.
Terry

10. Les Turnbul,l Jul 17, 2017
I use black insulation tape behind pick ups to avoid the return ends digging in to the chassis through the paint finish, and else ware where there is a possibility of a short to the chassis or body.
Les Turnbull

11. Terry Dumbrell, Jul 17, 2017
Hi Arun, The alternative would be to fit the pony truck with side-control [and perhaps springing] that would stop it fouling the bodywork. That should improve performance too, guiding the locomotive through the curves instead of just being along for the ride.
Terry

12. Arun Sharma, Jul 17, 2017
Thank you Terry but changing the pivot mechanism is simply not possible on this scratch built loco. Similarly Les, I think standard thicknesses of insulating tape are probably going to be too thick for this particular loco in terms of restricting swing of the pony truck.
Regards
Arun

13. Pat Buckley, Jul 17, 2017
My pony trucks have a 6ba pivot bolt with the slot in the head lengthwise along the chassis. A length of .5mm piano wire is soldered into the slot and goes to a inverted U shaped piece of .7mm wire soldered to the top of the pony. A 10ba washer soldered over the top of the U lets the wire stay central and presses down on the pony and provides side control as well. The strength of the springing can be controlled by bending the wire up or down and the pony is held on with a 6ba nyloc nut done up enough for the pony to only drop 2 or 3 mms when the loco is lifted. I have used this system for years and years on all locos with pony trucks and its simple and easy to do and never breaks, although the wire does get rusty.
Pat.
PS. if you need more springing use .8mm wire.

14. Arun Sharma, Jul 19, 2017
Once upon a time people used to dissolve ?mica flakes in a solvent and then paint that onto wire as a lacquer - Anyone know exactly what chemicals were used and whether these solvent mixtures are still available? The reason I ask is that I was using a spool of copper wire yesterday and that wire needed to have its surface coating sanded off before it could be soldered - rather like transformer windings I suppose. It seems to me that that might be a useful solution to my insulation problem.
Arun

15. David Littlewood, Jul 19, 2017
It seems that commercial lacquered copper wire is rather more complex than one might think, see: https://en.wikipedia.org/wiki/Magnet_wire It is possible that polyurethane varnish might serve for low temperature, low abrasion situations, give it a try and let us know. I have to say I would feel more confident with fag paper stuck on with epoxy resin.
David

16. Arun Sharma, Jul 19, 2017 As you say David, insulation is a complex subject. Fag paper and epoxy I think! I believe what I was thinking of was actually Shellac flakes rather than Mica which is pretty insoluble in anything other than Hydrofluoric Acid! Arun 17. John Drakeley, Jul 19, 2017
Hello all
Arun, looking through this topic you have not said which engine you are building. Off hand I can't think of an engine with a pony truck which would foul a valance. So I would really like to know what the engine is. To the lads who have made suggestions, I have made a note of a few for future use so thanks for that. You learn something all the time on this site.
Regards John

18. Bruce Pinchbeck, Jul 19, 2017
Arun
Shellac flakes should dissolve in Meths, add a little at a time until you reach a saturation point. (That's the basis for homemade French polish that cabinet makers use.)
Bruce

19. David Smith Jul 19, 2017
I use old transformer/coil wire (22 gauge) for all sorts of wiring up but particularly for pick-ups. I recommend its use highly and I cannot understand why the use of multi-strand wire with thick, stiff insulation is so popular, particularly with kit manufacturers. This enamel-coated wire is easily straightened (grip one end in the vice and gently pull the other end with a pair of pliers until you feel it just 'give') and then made into neat runs that will defy wayward, multi-stranded wire with its thick insulation. What about voltage drop, I have been asked. What about it? It's only a few inches and even thinner, and much longer, enamel wire is used in the motor armature; OK, I wouldn't use it for wiring up a layout, that's rather a different matter.
David

20. Arun Sharma, Jul 19, 2017
Re: Post #17
You are correct John, I haven't. Come to the Radley Models stand at Telford and all will be obvious
Arun