Last weekend I decided I had better get goign on the stuff I need to get done before the next show I will be helping otu at. This includes finishign the detailing on one GP-7, putting a decoder and LEDs and detailing a second one (and swapping the axle gears - pre-emptive strike on the cracked gear syndrom), getting some more coal loads (ordered from Motrak), and last but not least getting resistor wheelsets in all my cars. The first batch actually worked, once I realized it takes about 15 minutes for the silver paint to actually work properly. My next step was to see if I cna paint over the silver because it is very noticeable under the cars as that band of silver flashes past. I paint the sides of the wheels anyway, so while they were in the wheel jig I deiced to paint the axle and resistor as well, using Pollyscale oily black. 3 of the 4 still worked fine after painting over the silver, one decided to stop working. Not sure why. But at least my caboose has 2 resistor and 2 plain wheelsets now.
I also made up 16 more resistor sets. I wanted to let the silver dry thoroughly before painting ont he Pollyscale, so what I did, in assembly line fashion, 4 at a time, was glue on the resistors, then while the CA dried I painted the outside faces of each wheel, then I painted on teh silver conductive stripes. After 15 minutes I checked them with a meter, 10K +/- a little bit, right on. So then I popped them out and did another set.. All 16 worked, this weekend I will paint the axles and pick the first 8 cars to get updated. That was all the spare wheelsets I had, so the 16 I free up on 8 cars will be the next resistor batch.
I'm finding the factory blackening on the P2K wheelsets is very conductive, so there is no need to rought it up with a file to make good contact What does seem to help is to rough up the actual axle a bit, the silver paint doesn;t want to stick to the slippery engineerig plastic and tends to bead up, but a light touch with a file across the axle in one spot seems to make it go easier. It's no big deal to stick the wheelset in the jig with the roughed side up to glue on the resistor and paint the conductive lines.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Good Stuff. Nothing like having a scout to find the do's and don'ts of a project.
Thanks
Springfield PA
I think next time I will try the 36% silver paint, it should be thicker. Or maybe the Busch stuff but no one has it in stock. Except unless I spill it I should never need more than this one bottle for hundreds of cars.
Randy,
What about using silver epoxy? It will hold the resistor and is conductive.
Except you have to make sure it's only on the edges so it doesn't end up makign a short. That's the other thing I didn't mention, I managed to get down a perfect dropping method to get the resistors in place. First I peel out 4 resistors fromt he ammo strip, and set them ont eh bench right-side up. Then I put a tiny drop of the thick CA on each axle with a toothpick. Then I pick each resistor up with tweezers and holdign it right above the glue drop I let it fall in place - keeps the CA off the tweezer which makes the resistor want to stick and not stick to the axle which results in needing to use a finger. Takes only a few seconds to get 4 axles ready to go.
I too have made resistor wheel sets. I use a different resistor and a little different method. Either way will work, and I don't propose my way is better.
I use a 1/8 watt 10K axial resistor. I hold it on the axle then wrap the wires around the axle out to the end at the wheels. I super glue the resistor to the axle. I also check the gauge of the wheels and super glue them to the axles on the outside so they don't move. Then I use a product called "Wire Glue" from All Electronics to make the connection from the wire to the wheels. After it is dry and tested, I paint everything between the backs of the wheels with flat black paint.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Randy, do you use 10k resistors and two per car? Curious as why?
I use 4.7k SMD resistors like in this pic below but I only use one per car and they work great. When thoroughly dry I paint the axles a rusty color and also the wheel, except the tire part.
This is the conductive paint I use and the ammo 4.7k SMD's.
Wadda ya mean I'm old ? Just because I remember gasoline at 9 cents a gallon and those big coal burning steamers.
I use two because most detectors are good to 10-15K, and having 2 axles per car that cna be detected doubles the reliability. Same overall 5K resistence per car, just more likely to be detected. With one resitor per truck, theoretically if a car detaches or os stopped straddling a block boundary it will be detected in both.
Don't forget there's a setting in the BDL that allows you to change it to 20k for detection.
We don't have BDL168's, but at 20K, that's even MORE guarantee that at least one of my 10K wheelsets will be detected. On very humid days or if the glue in the ballast isn't fully dry, the 20k setting might be a little too sensitive.
In case someone is thinking all these resistors will draw too much power - resistors in parallel gets rather complex but when they are allt he same value the calculation is easy: 1/(number of resistors x 1/resistor value). 100 cars, with 2 resistors of 10K per car: 1/(200 x 1/10000) = 1/.02 = 50 ohms. At 15V to the track, that's .3 amps, about 1 better quality loco. Assuming all 200 resistor wheelsets are making good contact.
Interesting info Randy as some of those values I was not familiar with. I thank you.
As far as I only use one axle per car and 4.7k is approximately 3 milliamps x 25 maybe 30 cars on the layout at the same time plus a max of three sound engines ( Only have 12 engines and all are DCC ) at a time on layout I so far have not had any trouble with the cars tripping the signals, even when they are on a signaled siding with no engine.Using the Zephyr-Xtra I'm surely not going to run out of amps on my little 4X8 of approximately 25 feet of main line. Sure wish I had more room but alas I do not.
Then again I model the 1940/1950 times and pull a lighted caboose ( LED ) with all four axles with pick-up, so I don't have a problem with the caboose stopping just inside another block as my signals correspond just perfect.
Since I run DCC and use the Atlas three-light signals I use "NCE BD-20 Block Detectors". Very nice since they draw no current from the rail where Atlas detector does, but that's for DC.
What kind of conductive silver paint are you using? I thought you said something about a bottle ? Mine as shown in an above post is in a pen and very expensive like about $25.00 USD and will do about 100 axles.
I too model the 50's. so I always have a vcaboose, but I pulled the lights from mine as they weren't realistic and the Proto cabooses with lights roll like the brakes are on - actually the are, it's mstly the brake shoe detail that needs to be removed so the wheels roll freely. But I also clipped off the pickup wipers. Maybe on one of my other ones I will remove the single 'glows through the sodes' light bulb and put small LEDs where the oil lamps would be.
Your single axle with 4.7K is basically the same as my 2 axle with 10K each - 2x 10K in parallel is 5K total.
I don't have signals on my home layout, but the club layout does, mostly using RR-CirKits Tower Controllers and the 8 port block detectors - they work the same as the BD-20 with the current transformers so no current draw.
The paint I got on eBay - silver paint is used for preparing slides for an electron microscope. It's a small bottle, less than half filled, which is a carrier (it's not a solvent base - maybe something like Polly-S) and 18% silver. It was about the same price, and I'm pretty sure it will do 100 or more. The same seller on eBay also has the same thing but with more silver - 36%. Naturally, it costs more. About $38 or something. They used to have a 50%. You can also get larger bottles, a large bottle of the 18% is over $100. Silver's not cheap.