Wheelset holders for mass painting/weathering

[ednadolski]

I would think that you don't want paint in there...

Agreed, one approach is to coat the axle points with Maskol or such.

[CNR5529]

As mentioned earlier, I found the paint just rubbed off easily. But YMMV...

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This is one axle before rolling back and forth a bit in a truck, and one after rolling back and forth a bit in a truck. If really concerned about gumming up in service trucks, just use one dedicated truck for this task and "clean" the axle cones.

But... that would be a funny solution to the dreaded slinky!

not really.... just changes the exact point at which the slinky occurs.   I can deminstrate MT-equipped cars doing the slinky even when all of them are equipped with drag springs.

From an engineering standpoint drag springs (in the form of coil springs half wound on the axle) are only somewhat effective in reducing the slinky effect, because in reality its the wrong component to use. In a mass-spring-damper system, you dont really want to add more springs to stop the original springs from oscillating, you just end up changing the frequency at which the oscillation occurs. What you really want is a damper to do this job. The drag spring is somewhat acting as a weak friction damper in this case, but also as a torsion spring acting on the axles... In some cases, critical damping is achieved to eliminate the slinky effect (via stiff enough drag springs spread out throughout the train or short enough train for a single drag spring to be effective), but in most cases as you noted, its not enough and merely changes the rate of slinkiness. Slinkiness being the technical term 

[craigolio1]

As mentioned earlier, I found the paint just rubbed off easily. But YMMV...

(Attachment Link)

This is one axle before rolling back and forth a bit in a truck, and one after rolling back and forth a bit in a truck. If really concerned about gumming up in service trucks, just use one dedicated truck for this task and "clean" the axle cones.

But... that would be a funny solution to the dreaded slinky!

From and engineering standpoint drag springs (in the form of coil springs half wound on the axle) are only somewhat effective in reducing the slinky effect, because in reality its the wrong component to use. In a mass-spring-damper system, you dont really want to add more springs to stop the original springs from oscillating, you just end up changing the frequency at which the oscillation occurs. What you really want is a damper to do this job. The drag spring is somewhat acting as a weak friction damper in this case, but also as a torsion spring acting on the axles... In some cases, critical damping is achieved to eliminate the slinky effect (via stiff enough drag springs spread out throughout the train or short enough train for a single drag spring to be effective), but in most cases as you noted, its not enough and merely changes the rate of slinkiness. Slinkiness being the technical term 

I like trains. Haha

[BCR751]

How many sets can be done before the jig becomes too caked with paint?  And, which brings up another question, can the paint be removed by some method without damaging the jig?

Doug

[CNR5529]

Well, I don't have an exact answer for what the total life of these tools will be, but I can tell you that 1500+ wheelsets were painted on my four 33" holders, and the clamping face of the jigs are still white. Of course how one paints will have an effect here, if you go out of your way to spray in the gaps and put down heavy coats, it may lead to a shorter useful life... but I wasn't being extra careful or light with the paint either.

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I haven't tried stripping the excess off yet, as I haven't found a need to.

[BCR751]

Thanks for that info.  I'm going to pick up a jig for each of the wheel sizes and give it a go.  Great idea and thanks for making these available.

Doug

[davefoxx]

Just drop the tool in a pan of 91% isopropyl alcohol, and it should be good as new.

DFF

[CNR5529]

Glad these can be of use to you Doug! (And everyone else too!  )

@davefoxx awesome, I'll test that out later and report back.

[ednadolski]

The drag spring is somewhat acting as a weak friction damper in this case ...

I'd be willing to bet that's all it was ever meant to do.   Rather than any actual design, it seems more likely to me like something that someone just tried because they had a few springs lying around on the work bench.  And it does mask the symptom, as least for some use cases, so so if the other side-effects are livable, then why not?

Ed

[peteski]

I'd be willing to bet that's all it was ever meant to do.   Rather than any actual design, it seems more likely to me like something that someone just tried because they had a few springs lying around on the work bench.  And it does mask the symptom, as least for some use cases, so so if the other side-effects are livable, then why not?

Ed

Since I don't believe those "friction springs" are used on any other MTL or even Kadee product, I think this was more than just a happy little accident.  Those springs also use wire thicker than the one used in the N scale coupler springs.

While initially they might experimented with using springs to increase friction, once they finalized the design, then had those custom made, just for that purpose (either in house, or by an outside source).

These springs only have couple of turns. I think they were designed strictly to add friction (not to provide counter-oscillation).