Scratch Built Polarity Switches! SEEP PM1 unreliability solved!

Knuckles
Posts: 1092
Joined: Fri Nov 18, 2011 9:15 pm

Scratch Built Polarity Switches! SEEP PM1 unreliability solved!

Postby Knuckles » Sat Jun 09, 2018 8:22 pm

Hello gang.


I haven't been posting much here lately as I'm building a small N Gauge layout in my room and it isn't really relevant to P4 and I like to respect that. Got a couple of P4 layouts in the planning and still sorting the loft out for them and the 00 one so all good, I will get back in the saddle when the time is right. For now though I wish to explain how I got around a common problem.

You likely know SEEP solenoid point 'motors' can be tricky as the washer style switch can rub away and also in N gauge the alignment has to be extra critical to make the switch work.

Well, all WAS fine until they started to play up and no amount of re-adjusting would sort it...even though they were aligned correctly and WERE working.

So what was the solution?

Well, I didn't want to disturb the wiring and change anything and they would have to fit in the space available and also mechanically link up and work properly. Buying a switch online was a bit worrisome as I wouldn't know if they would fit and neither do I want to spend more money....so I had a think and decided I'll have a bash at making my own switches. Yep, I did - and they work.

First I drew up a very basic idea on the computer using my SEEP jigs I designed (that worked fine for by the way) as a dummy motor. This had the center point already in position so I measured roughly how much throw I needed and made some dummy posts with a pivot, then the actually base plate and holes were designed as a 1 piece block. Then 0.9mm brass rods were inserted through the holes, the main pivot switch was made from two solder laminated bits of brass with the end filed away in the middle to look like a clothes peg and the other side twisted 90 degrees to make a contact 'paddle' and the switch itself was secured betwixt two Romford crank pin washers. Although free to rotate they seem to make reliable rubbing contact so hopefully they will hold out, the brass pins have a little flex but are generally stiff yet they allow some easy adjustment with pliers so all good.

The main pivot is wired to the frog and the other two posts are joined to the red 'n' black track, simples!

These first three pictures look pretty poor as I had to extend the 'clothes peg' pins with some rod.
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These second two look neater as I learned from the first.
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Now this is how they look installed.
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I have only showed 2 yet 4 were made to fix the issues. If any more play up I know what to do!

They are pretty rough and ready but they work so I don't care as I'm really happy to have found a solution. Other than the materials I already had around and the electric for my 3D printer they cost the grand total of £0's!

A video of the latest N Gauge vlog featuring the switches can be seen here...


https://www.youtube.com/watch?v=YUtjEFD ... e=youtu.be
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.

Knuckles
Posts: 1092
Joined: Fri Nov 18, 2011 9:15 pm

Re: Scratch Built Polarity Switches! SEEP PM1 unreliability solved!

Postby Knuckles » Mon Jun 11, 2018 4:22 pm

Any thoughts on these? Apart from them being a bit rough around the edges. Would like to know what people think or even a better way from those more experienced.
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.

nigelcliffe
Posts: 456
Joined: Mon Jul 21, 2008 8:31 am

Re: Scratch Built Polarity Switches! SEEP PM1 unreliability solved!

Postby nigelcliffe » Mon Jun 11, 2018 5:16 pm

Contact cleanliness is likely to be an issue; they'll work for a bit then become unreliable.

A commercial microswitch costs around £1, and can replace your home made contacts with something designed to keep the contacts working cleanly. eg. one source, there are many many others, probably cheaper
https://www.rapidonline.com/rvfm-sp5-72 ... gs-78-2469

- Nigel

Knuckles
Posts: 1092
Joined: Fri Nov 18, 2011 9:15 pm

Re: Scratch Built Polarity Switches! SEEP PM1 unreliability solved!

Postby Knuckles » Tue Jun 12, 2018 4:19 pm

Thanks Nigel, cleaning them once in a while doesn't worry me too much but I see what you are saying. What puts me off buying the switches is I do not know if I would be able to fit them in a way that the Solenoid throws it which is why I had a go at doing it myself to fit the space/application.

Buying them if I know they'd fit would be easier though.

I think you can get special cleaning liquid that helps?
“He who dares not offend cannot be honest.” Thomas Paine

http://www.shapeways.com/shops/sparksho ... eationsscc
Mostly offering Loco kits & bits in 4mm.


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