Sunday, January 31, 2010


I have written before about my concerns regarding loco reliability and recent sales of locos fit with that.  However I have also been thinking very carefully about points too.

There are 3 issues:

1) DCC 'friendly' issues regarding shorts between point blade and stock rail.

There are more detailed sites about this such as wiring for dcc ( but the principles are well explained here:

Basically, an out of gauge wheelset may bridge the gap between a stock rail at -ve and a point blade at +ve.  This causes a short, which in DC operation would just result the loco momentarily stalling before recovering.  However in DCC this kind of short would reset the command station as decoders are very sensitive to shorts - the command station shuts down to protect the decoders.

I have in the past dismissed this as a minor issue as it shouldn't happen too much and I will make sure the back to backs on locos/stock are correct.  Having thought about it though the plastic centred wheels with metal treads that are used almost uniformally in my stock do sometimes come apart and I can see that this shorting thing could be more of a problem that once thought.

So, it would be far better to join the stock rail to the point blade so it is the same polarity and make a cut just before the frog.  The frog remains power routed and the problem is solved.  Insulfrog points just need the wires carrying current over the dead frog to be cut and the blades to be linked to the stock rails.  The insulfrog creates the gap and no cutting of rails is required.

In 009 peco electrofrog points are difficult due to the way that they are made.  Half way along the point blade there is a rail joiner which acts as a pivot.  This is within just a few chairs of the frog.  So if you try and put a break in the blade as suggested the piece of rail left behind wobbles terribly and comes away at the pivot.  In OO this is not such a problem as the point is considerably longer. 

People have suggested filling the gap created with araldite or some non conducting filler, but this is not really a proper solution either for long term reliability.

The real solution is to find points that don't have this pivot in them.  Most hand built points are not made that way and so are some others such as those made by tillig.

I am therefore carefully considering whether to dig up my peco points and either get some specially made for me (with electrofrogs) or move to insulfrog tillig points.

2) Solenoid versus latching point motors

The solenoid motors I have installed are not latching, so they don't hold the blade against the stock rail as if it were locked there. 

They are also very strong in their action (although I need to do some more programming on mine as they aren't strong enough at the moment), which puts stress on the points unneccessarily.  Might tortoise slow action (and latching) motors be a better bet?  The problem is that these require quite some depth of baseboard.  I have just under 70mm of depth, a tortoise needs 85mm - a problem!

I would also need a different type of accessory decoder too - the wabbit.

so this is getting expensive!

Seep latching motors could be a possibility too, but they only have one aux switch, causing problems for my point indicator LED wiring. 

I think I'll stay with peco for now on cost grounds, but I may need one of these for extra ummph where I have set things up to throw two solenoids at once

3) Check rail clearances

I have never been happy with this element of peco points, which in many cases require filing to accept even the finest flanges.  Tillig points are much better in this regard.

If you want to see what a tillig point looks like, check:

The 'massive' problem being that they are insulfrog.

So, do we prefer DCC friendly but insulfrog tillig, over DCC unfriendly but electrofrog peco? Or should I get some hand built points that are electrofrog and DCC friendly?


Michael Campbell said...

You could wait for the Peco "main line" 009 points? Or if you are brave, see if you could remove the pivot fishplate and find a way to pivot the blade some other way. A brass pin under the rail into a brass tube set into the baseboard perhaps?

I've never used them but the Fulgurex point motors are slow action but low profile. Would a CDU not help throw the solenoid motors?

Michael Campbell said...

You could always try the Conrad point motor, they are cheap though I've never seen them in use. Go to and search for "point mechanism"

Colin Lea said...

thanks michael, I will post about fulgurex...

stephen said...

Someone on one of the forums (NGRM?) recently suggested exchanging the rail joiner pivot for an insulated one and using that as the break.

Colin Lea said...

now that's a thought. I see a plan coming together here - fulgurex motors and insulated joiners - nice!