Electrical Shorts - By A Tyro!

[CME & Bottlewasher]

Hi,

Something occured to me during the painting and weathering of my shoc vans, that with the whitemetal brake shoes (on the JLTRT shoc van), if they touch a wheel will they cause a 'short'?

This may be an elementary question to an electritian/electronics expert yet to a tyro like me, one who has to do his wiring in a fashion very much akin to painting by numbers, it aint all that clear to me no matter how many times or how hard I look

I have read that some, coat the surface of the brake shoes with a plastic/glue/epoxy etc. so as to prevent such (I of course forgot to do that!).

As always - thanks in anticipation

CME

 

[Pugsley]

Hi,

Something occured to me during the painting and weathering of my shoc vans, that with the whitemetal brake shoes (on the JLTRT shoc van), if they touch a wheel will they cause a 'short'?

Almost definitely I would think. Not only is the brake shoe on each side linked to the other side by a piece of metal, each end of the wagon is linked to the other end by a piece of metal. Someone didn't quite think that design through!

 

[CME & Bottlewasher]

EEEK!

Hi Pugsley,

Neither did the builder think it through!!!

The question is how do I get around it......

Thanks for the tip off

TTFN

CME

 

[CME & Bottlewasher]

I'd have thought you'd have to be very unlucky to get a very bad short through that set-up? After all the brake shoes on both sides of an axle would have to contact the wheel at precisely the same time. I have no idea how conductive whitemetal is - surely as it's a very soft metal it wouldn't be as good as brass, nickel-silver or phospher-bronze etc ??

I would test it somehow. On a plain piece of track, I'd feed 12v DC to the rails, and somehow hold the wires of a 12v bulb to each wheel and it's rail in turn whilst rolling the wagon along; if the bulb lights at all, then yes there's a short from the other side.

Hi Jordon,

Thanks for that - I was hoping that someone would come up with comments such as yours

I will give your test a go and see what transpires.

Thanks again Jordan, much appreciated

ATB

CME

 

[Old Buffer]

Looks like you have the same problem I have with the MMP tank I'm doing, I put mine away while I thought about it, I've started stripping the brakes down and am in the process of making my own brake shoes out of some 4mm paxolin sleepers with the copper filed off. I have heard about coating the shoes with chemical blacking to act as insulation, but I haven't a clue if it works or not.
Alan

 

[28ten]

First thing is to eliminate any sideplay and as they are not sprung you should be ok. But yes they could short. Id be worried about those w/m vac pipes, they wont last 2 minutes

 

[Dikitriki]

Talking of vac (and steam - I have a number of banana vans!) pipes for wagons, does anyone have any recommendations (and pics) for brass replacements?

Richard

 

[Old Buffer]

CME,
Have just had a thought after filing some more paxolin for my brake shoes, I wonder if we could talk Cynric into making some wagon brake shoes out of plastic card, have tried the Slaters loco brake shoes but they are too big and too narrow, the only others I can think of are by Exactoscale (but those are too expensive, just for the use of the shoes). Don't know how much of a hassle it would be, (probably the plastic would melt) but he does have the Darth Vador to do it with and he will let us know.
Alan

 

[28ten]

CME,
Have just had a thought after filing some more paxolin for my brake shoes, I wonder if we could talk Cynric into making some wagon brake shoes out of plastic card, have tried the Slaters loco brake shoes but they are too big and too narrow, the only others I can think of are by Exactoscale (but those are too expensive, just for the use of the shoes). Don't know how much of a hassle it would be, (probably the plastic would melt) but he does have the Darth Vador to do it with and he will let us know.
Alan

Sure can I just need a dimensioned sketch of the brake shoes

 

[CME & Bottlewasher]

CME,
Have just had a thought after filing some more paxolin for my brake shoes, I wonder if we could talk Cynric into making some wagon brake shoes out of plastic card, have tried the Slaters loco brake shoes but they are too big and too narrow, the only others I can think of are by Exactoscale (but those are too expensive, just for the use of the shoes). Don't know how much of a hassle it would be, (probably the plastic would melt) but he does have the Darth Vador to do it with and he will let us know.
Alan

Hi Alan/guys,

This JLTRT kit seems to be fighting me every step of the way.

I would go for the plasticard brake-shoes and hopefully try and clip off the old shoes (yet that is fraught with danger and will b*gger the weathering/painting).....to try stop and play/side play is almost impossible as they seem to rattle about with loads of play anyway

I can try and measure/draw them...

Thanks for the help guys...

ATB

CME

 

[CME & Bottlewasher]

Talking of vac (and steam - I have a number of banana vans!) pipes for wagons, does anyone have any recommendations (and pics) for brass replacements?

Richard

Hi Richard,

Would the CPL ones do the job?

On my JLTRT Shoc, hopefully the vac pipes will be protected by the use of Winterley Couplings and the use thereof...time will tell.

CME

 

[Old Buffer]

Sure can I just need a dimensioned sketch of the brake shoes

Cynric,
Hope these are good enough, it’s the best I can do with my poor abilities and equipment.
I have been checking and there are 4 different types of brake shoes on the all metal kits I have done. I have made a rough diagram of the 2 most used brake shoe types.
This is the one used on the MMP kit and a couple of others.
.
This one is from an ABS kit and a few others.
.
Alan.

 

[28ten]

A very quick play, it is not perfect, I would need to muck around with the settings, but it is proof of concept. this is from .75 material which can be laminated to increase the thickness.
I suspect holes are probably better drilled by hand unless I can work out a way to get the laser to spot them in place

 

[Steph Dale]

Hmm, I wonder if we haven't just seen an example of 'run away' thinking and we've solved a problem that doesn't quite exist? I've never had a problem with metal brake shoes shorting on any of my wagons in HO,00,P4 or 0, whether compensated or rigid.

It requires quite a bit to take place - first you need uncontrolled end play and/or float on both axles and then the vehicle has to find itself in a position where it's 'crabbing' down the track for both wheelsets to make contact on opposite sides/rails. If that happens as described I suspect the poor wagon is more likely to derail than short circuit.

CME,
I'd try it and see - I suspect you'll find no problems with it's running and therefore won't need to do anything.

Steph

 

[28ten]

Hmm, I wonder if we haven't just seen an example of 'run away' thinking and we've solved a problem that doesn't quite exist? I've never had a problem with metal brake shoes shorting on any of my wagons in HO,00,P4 or 0, whether compensated or rigid.

It requires quite a bit to take place - first you need uncontrolled end play and/or float on both axles and then the vehicle has to find itself in a position where it's 'crabbing' down the track for both wheelsets to make contact on opposite sides/rails. If that happens as described I suspect the poor wagon is more likely to derail than short circuit.

CME,
I'd try it and see - I suspect you'll find no problems with it's running and therefore won't need to do anything.

Steph

I have to confess that I have never had any problems, I have absolutely no side play and no more than 1mm movement in the suspension. But the axleguards in question are w/m with sliding axleboxes, less said the better........

 

[Old Buffer]

Steph,
I'm trying a concept with the brakes, as in trying to make them operable (as J.B. did with the K2), it might be a once only thing but if I can crack it all my wagons will be the same. There will be a bit of movement with the shoes and yolks, and I am thinking ahead to what might happen with metal shoes.

Guv,
That looks just the business, the holes would be better left to be drilled out rather than trying to laser them.
Alan

 

[CME & Bottlewasher]

Hmm, I wonder if we haven't just seen an example of 'run away' thinking and we've solved a problem that doesn't quite exist? I've never had a problem with metal brake shoes shorting on any of my wagons in HO,00,P4 or 0, whether compensated or rigid.

It requires quite a bit to take place - first you need uncontrolled end play and/or float on both axles and then the vehicle has to find itself in a position where it's 'crabbing' down the track for both wheelsets to make contact on opposite sides/rails. If that happens as described I suspect the poor wagon is more likely to derail than short circuit.

CME,
I'd try it and see - I suspect you'll find no problems with it's running and therefore won't need to do anything.

Steph

Hi Steph,

Thanks for the insight, I was starting to think that way when doing the washing up and ploting on getting the verniers out and measuring up and drawing the brake blocks for Cynric, then I looked at the brake blocks again and they are well away from the wheels - I would prefer them to be closer from a 'looks' point of view.

As an aside I am so glad that I didnt cut off the pin points from the axles - as some have - and that I persevered with the fettling and filing at the build stage - checking as I went - so as to get the 'W' Irons and axle-boxes right. The wheels work okay in the 'top hats' and even the sloppy axle-boxes have er firmed up with my weathering (acrylics and talc)

One sage has pointed out that the brake cross bars are dangeroulsy close to the wheel flanges though - I hadnt noticed that! I shall, par away a little from the inner edges of the rods and give it a go as is.

If I do any more of these kits, then I will ask Cynric if he will be kind enough to make up some brake blocks as a wise precaution (dont worry Cynric there will be no more JLTRT wagons for a long while yet - although I understand that they may have improved these parts), yet with all of the work thus far and the brakes being off of the wheels and the flanges, as you and Cynric say, it's well worth seeing how it pans out..

I am so used to plastic wagons kits, then there are some authors who tell tales of woe about such things and how they coated the brake blocks in whatever gunk is required to stop them shorting out.

As I say my knowledge of these things is limited and with all things electric it's like painting by numbers for me, or a case of easy when you know how. When it comes to electrics and car wiring (in years gone by) professionals have said that I am 'overly cautious' and have used a 'belt and braces' approach etc. rather that I say than having to revist it, do it again or worse!!

Mind you with all of the cyano that I used I bet that everything is insulated anyway

Thanks again guys

ATVB

CME

P.S Nice work on those brake blocks Cynric

 

[Purple-haze]

Just a small point CME,probably all cyano adhesives are conductiveAraldite and similar are not.Hope this helps.

regards

Rog

 

[CME & Bottlewasher]

Just a small point CME,probably all cyano adhesives are conductiveAraldite and similar are not.Hope this helps.

regards

Rog

Hi Rog,

That is interesting - I never knew that, thank you.

I have moved the brake shoes further away from the wheels and parred off a little material from each of the connecting pieces (whitemetal) and now there is nothing near to/touching the wheels. There is little play or end float and it appears that my hard work with the 'W' irons, Top Hats etc. was worth it. I have tested for shorts and ther are none.

What will happen after wear and tear or when used in anger - who knows.....

ATB

CME

 

[Steph Dale]

Just a small point CME,probably all cyano adhesives are conductiveAraldite and similar are not.Hope this helps.

Sorry Mr Haze, sir - but they're not. Once cured they form an acrylate (acrylic), which definately isn't conductive. I s'pose what can happen is a little graphite or metal dust can load the adhesive enough to make it conductive. But I think you'd have to be pretty (un) lucky to achieve that effect...

Steph