Adding electrical pickup to passenger cars

[PanAmShay]

Altoona--do you know if Kato made trucks with pickups in a similar wheelbase as the Rapido?

Don't know if Rapido 6 wheel truck has the same wheel base as the Kato 6 wheel truck.  Kato 6 wheel truck part #800135 I believe is a Pullman prototype. Kato #800094 is a Pennsy prototype.
 
Judd Barton

Sorry, I was not clear in my question.  The Rapido car has 4 wheel trucks that are a much shorter wheelbase than the Kato trucks I have.  Do you happen to know if Kato made shorter wheel base ones?  I Haven't come across anything yet.  Thanks!

For reference:
the Rapido trucks have a wheelbase of .591"/15.0mm
the Kato 4 wheel trucks across 5 cars have a wheelbase of .702"/17.85mm
So the Kato 4 wheel are much longer

[PanAmShay]

I have actually done this before with tender trucks.

It's not that difficult to design.  The truck frames are the easy part.  The hard part is the electrical pickup... 

Lemosteam, very cool!  If you have interest in helping (for $, of course) with the 3d printing of trucks, let me know.  I have 3 spare kato chassis, so plenty of their brass pickups and split wheels.  I could cut the Kato brass pickups to get the right wheelbase.  Since the trucks do not need to be injection moldable, one could 3d print recesses for the cut pickups, or just glue them in.  I would just need the trucks.

An update from yesterday:

I did some more fine tuning of the ESU wheel wipers on the Rapido car.  I have those picking up two wheels per truck, for a total of 4 pickup points, with a left and right rail at each end of the car.  There is almost zero flickering before the capacitor has charged up and none after the cars have been on the layout for a bit.  It still won't roll down a grade on its own, but the added rolling friction doesn't seem to cause any derailment issues in running.  I have seen issues with microtrains coupler disengagement in draft-buff-draft scenario around curves, but not sure if that would be related to rolling resistance.  I tried to put long shank n-possible couplers on these cars, but they couldn't navigate our relatively tight layout curves (R315)

On the Microtrains Observation Car with 6 wheel trucks, I opted to try homemade brass strips wrapped around two axles (full credit to Model Train Technology: https://www.modeltraintechnology.com/product/n-brass-1mm-wide-axle-pickup-strips/.).  I already had a .004" sheet of brass that was easily cut into strips with scissors.  This design is MUCH easier to install than the ESU wipers, and requires half the wiring.  Even though you have 4 pickup points still, each end of the car only picks up one rail.  I found the rolling friction to be similar to the ESU wipers on the Rapido car, but the pickup was much worse.  After the capacitor was charged up, the lights mostly flicker free, but not completely.

I did consider sanding out the MTL trucks and drilling pockets for some cut down Kato brass inserts as Peteski suggested, but I considered it too risky as a first step w/o backup trucks on hand.  I think I will see about 3d printed trucks and if that is too challenging will swap out the brass strips for the ESU wipers.

[Maletrain]

Lemosteam, regarding the fabrication of the brass strip axle point pickup pockets:

From my firearms brass cartridge reloading days, I was thinking of just cutting/filing brass sheet material into the desired shape and then using a punch and die setup as you describe in your drill press to form the pockets for the axle points.

Not sure why you went with etches - maybe to save effort on the gross shaping process for the part?

Heating the sheet brass (to very dull red) and then quickly dipping it into water will soften it.  (The opposite of what happens when doing the same thing to steel.)  That should make it relatively easy to form the pockets with the punch and die.  The brass should not need to be hot at the time the dimple is made  for the axle point.

And cold forming the pockets will reharden the brass material in the pocket area, which should slow any wear-through.  Hitting it more times than needed to form the dimple should harden it more.

So, if you just 3D print the trucks with the appropriate recesses for the brass parts, and provide a 1:1 drawing showing the shape for the brass inserts and marking the axle center locations, as a customer, I would be willing to make my own brass inserts.

FWIW, the brass pickup "ears" on my Kato caboose truck measure 0.016" thick, and the "ears" on my Bachmann tender trucks measure 0.012" thick.
K&S sells 4" x 10" brass sheet 0.016" thick (Item 252).  I cut those sheets with an old paper cutter and small tin snips.

[Lemosteam]

I went with etches because I wanted many, and because the accuracy of the dimple locations relative to my truck fitment required accurate trim edges within the tool else the resulting part may not fit the truck pockets. Not impossible but finicky.  Thanks for the info on the heating and hardening.

Wish there was an easier way to get fine-blanked metal parts.

[peteski]

When installing metal whiskers which will contact the axles do not wrap them around the axle like it was done in the tender trucks of the original Model Power 4-6-0 and 4-4-0 locos. That greatly increases the drag.  The metal  whiskers will work just as well if they simply contact the axle at a single point (assuming they are springy enough to be under tension). Of course multiple thin whiskers will produce more reliable contact than a larger flat one.

[Maletrain]

I went with etches because I wanted many, and because the accuracy of the dimple locations relative to my truck fitment required accurate trim edges within the tool else the resulting part may not fit the truck pockets. Not impossible but finicky.  Thanks for the info on the heating and hardening.

Wish there was an easier way to get fine-blanked metal parts.

What I would do for my own models is less demanding than what you were doing to achieve time-efficient mass production. 

If I have an accurate drawing for the dimple locations on the part, I could use that to spot mark a brass part to center the punch in the proper locations for the dimples.  Then, all I need to do is put the punch in the drill press and the die on the drill press table, slide the die around to be directly under the punch and then securing it in place.  Then all I need to do for each dimple is lower the punch to the par surface and align it with each mark before pressing each dimple into the brass.  More time consuming than having a set of punches and dies that are aligned by a jig based on an edge of the piece.  But, more versital for different trucks, and not so time consuming that I would not do it to get a train lighted.

[randgust]

What you're all talking about here is exactly what Dirk perfected in the ATSF Models parts.   Resin printed truck sideframes, brass (drilled, not dimpled) inserts, but soldered and hard-wired for full pickup, both sides.   And he cut axles in half and put a styrene cylinder to convert them to insulated half-axles.   So all trucks got full x * y pickups, just like Kato does.   The genius forehead slap was taking commercial wheelsets, cutting them apart, taking the NON-insulated halves together on a splice to make full pickup wheels.

Dirk can't continue due to illness, but rather than reinvent the wheel, see if somebody wants to make a deal on tooling & technique.  I know he's out of wheels, I got the last ones.

I've done lit cars a bunch of ways.  My entire passenger train is lit with easy-peasy, and yes, they are temperamental, need cleaning, etc.  But I don't run night enough to make a problem out of it.   The end result is pretty much perfect.   But see below, I've got my own DIY.

But I've also done about 10 caboose marker lights using Richmond Controls, which have a rather conventional track pickup with an ultra-cap so that after they charge up the flickering stops and it may take 10 minutes before they go dark.

I imitated that myself in DC to illuminate a Kato drumhead by adding a bridge rectifier with a Keep-Alive, dropping resistor and the LED in the drumhead along with the markers.  Conventional stock end-axle pickup in the Kato coach.   That's a winner for sure, I'd do that one again.   Same deal, it flickers until it fully charges, then steady.

[nkalanaga]

Another method I've seen done, but never tried, is to thread a coil spring onto the axle, then solder a wire to it.  The spring should fit snugly, but not tight, so the axle can rotate freely, but no matter how it or the wire moves, the spring will still make contact.

I'd suggest soldering the wire first, then putting the spring on the axle.  Unwind a little of the spring, and solder your wire to that, so the solder doesn't fill the spring.

Basically the same idea as Peteski's "multiple whiskers", but in one unit.

[Lemosteam]

I did exactly this with an MT spring back in the 80's to light a caboose.  I still have it.  Lotsa flicker but powered electronics could solve that, right @peteski .

Added bonus? Less slinky effect.

[peteski]

Loose spring is an improvement over the strip wrapped around the axle but with the spring being loose, there isn't a positive pressure applied for reliable contact.  But yes, with added deflicker or keep-alive circuitry this is not a major issue anymore.

[Maletrain]

For the 3D printed option with space included for axle point pickup inserts, I am thinking that we really don't need all wheel pickup if we put capacitors in the cars along with the rectifiers and resistors.

It would be a lot simpler to make and install if one side of the truck had the brass insert, and the other didn't.  That way, there would be one rail pickup at each end of the car, just like with the axle wipers, but much less rolling friction.

That would then not require cutting wheel set axles - just put the "hot" wheel on the side with the axle pickup and let the hot axle roll in the plastic (resin) cup on the other end.

And, the electrical connection between the trucks and the car interior could be a simple metal screw in the bolster hole.

That also halves the amount of effort to make brass pickup inserts and the cost of the wheel sets needed.

[Wutter]

I was considering doing the axle point pickups but found that it was a lot of work to retrofit onto a truck frame that wasn’t designed for it. I ended up using a Phosphor Bronze strip wrapped around the axles which was pretty easy to implement. A wire is soldered to the middle of the strip and feeds through a hole next to the bolster into the car.

To reduce the rolling resistance I wrapped them tight first to form a circle around the axle and then slightly unbent them so they were really only touching the top and bottom of the axle. One truck picks up from the left rail and the other picks up from the right rail. Using peteski’s flicker free lighting circuit seems to be enough to avoid any flickering even though the strips aren’t perfectly gripping onto the axles.

If you decide to use the spring I could also see that working well on the axle area if the relaxed inner diameter of the spring is smaller than axle, that way the axle is expanding the spring and you're getting more of sprung contact as it rolls.