Phosphor bronze wire as pick ups

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John Bateson
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Phosphor bronze wire as pick ups

Postby John Bateson » Wed Oct 09, 2013 6:04 pm

I have a selection of phosphor bronze wires, 26, 31,36 and 41 SWG. I am trying to understand what is best practice for using this material for pickups from wheels, actually it is my most hated job in the whole world, getting pickups to work properly and look invisible. I get the feeling that 26 SWG is a little too strong and acts as a spring for the axle as well.
So what is 'your' favourite SWG?
John
Slaving away still on GCR stuff ...
Avoiding the soaps ...
http://www.greatcentralmodels.co.uk

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tommallard
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Re: Phosphor bronze wire as pick ups

Postby tommallard » Wed Oct 09, 2013 7:20 pm

Hi John

I agree that fitting pickups is usually put off far too easily... I use material less than 0.3mm, something around 0.25mm though I cannot recall which wire gauge that is. Sometimes I give thought to the intended use of the model - a heavy hauler would use the heavier gauge wire. Too slender wire of much less then the 0.25mm is very easily damaged and obviously this can lead to an ineffective pickup. I always try my best to remove the curve from the wire before starting but it is not too critical

When preparing the pickups, I put in at least two coils which acts to soften the action of the wire against the tyre flange (I stopped trying to align a scraper type pickup with the back of the tyre a long time ago). The coils' offset also allow the PCB strips to be set less obtrusivly into the frames. The pickup acts more or less perpendicular to the wheel. Hopefully I'm not trying to teach anyone to suck eggs.

Ultimately, if there was a straightforward way of using split frames with an outside valve gear loco, I am sure we would all adopt this method! Much more elegant with nothing to snag.

Best regards

Tom

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jjnewitt
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Re: Phosphor bronze wire as pick ups

Postby jjnewitt » Wed Oct 09, 2013 8:50 pm

Hi John,

I use 33SWG which works out at 0.25mm with three or four coils wound into it around the shank of a 1mm drill bit acting against the flange of the wheel. I have used 36SWG on occasions and I'm not sure there's much between the two in terms of use, I just have a lot of the 33SWG wire. Personally I wouldn't use anything less than 33SWG. You're unlikey to get a lot of 'spring' into the wire which, as well as having the effect you mentioned, will also add to the rolling resistance on the wheelsets.

Justin

martin goodall
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Re: Phosphor bronze wire as pick ups

Postby martin goodall » Fri Oct 11, 2013 10:08 am

Are your tyres steel or nickel silver? If steel, don't use phosphor-bronze. It reacts with the steel and there will be a rapid build-up of dirt. If your tyres are nickel-silver, then no problem.

I still prefer straight brass wire for pick-ups, just touching the outside edge of the back of the wheel flange. Needs to be about an inch long from the point where the wire is anchored. I use 0.5mm dia wire, but 0.33mm is said to be fine.

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John Bateson
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Re: Phosphor bronze wire as pick ups

Postby John Bateson » Fri Oct 11, 2013 10:27 am

Martin,
I thought some acoustic guitar strings were steel wrapped with PB?
Almost all of my wheels are from AG - so presumably are steel.

Tom and Justin,
Thanks for your input, very useful, but I will have to have a serious weekend revisiting the mistakes of the past month.
I have a coil of 31 SWG from Eileens and that will be my next trail. I suspect that the 26 SWG is just too strong and may be why I am having so much trouble.

John
Slaving away still on GCR stuff ...
Avoiding the soaps ...
http://www.greatcentralmodels.co.uk

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Will L
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Re: Phosphor bronze wire as pick ups

Postby Will L » Fri Oct 11, 2013 11:23 am

martin goodall wrote:Are your tyres steel or nickel silver? If steel, don't use phosphor-bronze. It reacts with the steel and there will be a rapid build-up of dirt. If your tyres are nickel-silver, then no problem.


I've heard this said quite often but have never seen any evidence. For instance my locos are so fitted (PB wire on steel tyre) and have been running on Knutsford these last 8 years (since Scaleforum 2005 to be exact) and show no sign of a problem.

For the sake of clarity, in this case "No problem" equals wheel cleaned before the show, constant use through two days without the need for a further clean and the locos will still running well at low speed and starting first time every time by the end of the show. Actually I'm not abolsutly convinced they always need the pre show clean either but one does want to be sure.

I've even tried researching the topic to find out if I'm just a lucky boy who has somehow avoided a problem but I can't find anything that suggest that there any sort of effect unless you happen to be running your loco's in an electrolytic solution, you know like salty water. I've write about this before and nobody chose to contradict me then. So lets have some evidence Martin or can we please put this load of.... sorry, urban myth to bed.

Will

Philip Hall
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Re: Phosphor bronze wire as pick ups

Postby Philip Hall » Fri Oct 11, 2013 9:40 pm

When I was a' learning this game back in the days of Iain Rice's courses in Chagford - more years ago than I care to mention - Mike Sharman was quite adamant, I recall, that PB and steel didn't like each other, something to do with oxidation. I have always followed this advice, never having felt the need to question it. Consequently, I have always used 0.3mm or 0.45mm hard brass wire with success. I do recall however that when I took the old 'Taw Vale' to Imrex in 1990, Barry Bean lent me his LMS Kitson 0-4-0ST which had steel wheels and PB pickups. And it behaved impeccably throughout the week, so maybe this premise doesn't hold water, but I still stick to brass.

Unusually, I am writing this during an idle moment in our hotel in Malta, and I wouldn't normally check the Forum whilst away. Such is the draw of Scalefour matters! Maybe the sun has got to me. Or the Prosecco after dinner.

Philip

billbedford
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Re: Phosphor bronze wire as pick ups

Postby billbedford » Sat Oct 12, 2013 9:21 am

Will L wrote:
martin goodall wrote:Are your tyres steel or nickel silver? If steel, don't use phosphor-bronze. It reacts with the steel and there will be a rapid build-up of dirt. If your tyres are nickel-silver, then no problem.


I've heard this said quite often but have never seen any evidence. l


Ted Scannell found he had this problem with his Coronation. He found that it was reluctant to go when first put on the tack, but he eventually found that the culprit was the foam in the box that he kept the loco in. Now he keeps the loco in a box without foam and he has no more more problems.
Bill Bedford
Mousa Models
http://www.mousa.biz

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Coronach
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Re: Phosphor bronze wire as pick ups

Postby Coronach » Thu May 28, 2015 7:08 am

I have a kit built J27 with Markits wheels and my intention is to use phosphor bronze wipers as nickel silver wire isn't proving very effective.
I'm finding it difficult to source any though. Eileen's appear to be in no hurry to process the order I placed two weeks ago and I can find no other source.

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David B
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Re: Phosphor bronze wire as pick ups

Postby David B » Thu May 28, 2015 7:48 am

I saw phosphor bronze wire on the Hobby Holidays stand at Railex. The link goes to the appropriate page on Phil's website.

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Coronach
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Re: Phosphor bronze wire as pick ups

Postby Coronach » Thu May 28, 2015 8:00 am

Thanks David.

I believe a solution to my problem is at hand.

All the best.

Dave.

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Guy Rixon
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Re: Phosphor bronze wire as pick ups

Postby Guy Rixon » Thu May 28, 2015 10:01 am

Tom, why do the larger, heavier locos need thicker pick-up wire? Is it to reduce the electrical resistance?

Cheers,
Guy

John Fitton

Re: Phosphor bronze wire as pick ups

Postby John Fitton » Thu May 28, 2015 2:40 pm

Guy Rixon wrote:Tom, why do the larger, heavier locos need thicker pick-up wire? Is it to reduce the electrical resistance?

Cheers,
Guy


Guy,

If I read Tom's post, thin wire has the disadvantage it is easily damaged, but needed for small locos because of their fragility in the first place. Robustness required where the loco can take it, in my own experience.

John Fitton. (PS, apologies for butting in, but interesting thread)

FCA
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Re: Phosphor bronze wire as pick ups

Postby FCA » Thu May 28, 2015 2:52 pm

Split axles/split chassis are the best solution to this problem.
Even the so-called 'American split' system is superior to fiddling with bits of wire; of whatever material.
FCA

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Paul Townsend
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Re: Phosphor bronze wire as pick ups

Postby Paul Townsend » Fri May 29, 2015 10:33 am

FCA wrote:Split axles/split chassis are the best solution to this problem.
Even the so-called 'American split' system is superior to fiddling with bits of wire; of whatever material.
FCA


IMHO the American system is daft. Why throw away half your pickup's potential sites?
As a quarter American bod I freely and instinctively criticise everything from across that pond, but in this case logic is with me as well as prejudice.

FCA
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Re: Phosphor bronze wire as pick ups

Postby FCA » Fri May 29, 2015 11:33 am

You may well say that, I couldn't possibly comment.... except to say that I have used it myself on an 0-6-0 tender engine and it works fine. You only get a numerical advantage with wire pick-ups (aka 'brakes') if you fit them to the tender in addition to the loco. Also bogies and ponies can be used to pick up with split chassis.

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Flymo748
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Re: Phosphor bronze wire as pick ups

Postby Flymo748 » Fri May 29, 2015 11:04 pm

Coronach wrote:I have a kit built J27 with Markits wheels and my intention is to use phosphor bronze wipers as nickel silver wire isn't proving very effective.
I'm finding it difficult to source any though. Eileen's appear to be in no hurry to process the order I placed two weeks ago and I can find no other source.


It sounds like you're sorted now, but just to give Eileen's the benefit of the doubt, consider that with ExpoEM and then Railex, they've probably just done the two busiest back-to-back weekends of their entire business year.

They've probably been working like mad just to keep stock levels up. No connection, etc, but a very frequent customer.

Cheers
Flymo
Beware of Trains - occasional modelling in progress!
www.5522models.co.uk

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Coronach
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Re: Phosphor bronze wire as pick ups

Postby Coronach » Sat May 30, 2015 8:20 am

To be fair, I suspect that's a correct assessment and I've used them to satisfaction many a time. I was just conscious of not getting anywhere fast with a project I'm keen to complete. :-)

All sorted now though.

Thanks all.

Dave.


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