Advice please

[James Walters]

Hello all,

I'm hoping some experts might be able to offer me some advice regarding a scissors crossing on an S curve. Let me explain...

In our S4 area group, we have been discussing the idea of each building a simple plank, with the idea that each plank will be able to connect to a central hub. All of which is to be very simple and give us something to play with at our meetings. The boards themselves will all be laser cut and interchangeable, so in effect we can mix-and-match where boards go. I anticipate the 'planks' being almost-disposable, and being knocked-up to demo track building, various scenic techniques etc.

Here is the basic concept for the Hub board.

So, on to my question(s):

1. Is the scissors in this example likely to work and/or is it buildable? There has been conflicting advice as to whether or not it is buildable and so ask here for some expert advice. Suggestions to alternative approaches would be very welcome too.

I hope it's not too big an ask.

As a novice, I'm still finding my way with the techniques required to complete the scissors itself, and close inspection will show that the V crossings and K crossings need work. I'll attempt to solve these once the basic concept has been established.

Attached are the .box and .bgs file

I hope it all makes sense. For information the Hub Board is proposed to be 1200mm x 450mm.

James

 

[Martin Wynne]

@James Walters

Hi James,

It all looks buildable and workable to me. A couple of points to think about though:

The inner radius on these turnouts is down to 35" which is definitely on the tight side for P4. It would likely need some gauge-widening for long-wheelbase stock. Which would complicate the scissors somewhat. It would be worth trying to ease the radius a bit instead. There seems to be a couple of inches at the top right to lengthen the S-curve, and you might be able to reduce the track centres between the top and bottom lines a little.

Easing the radius would also help with the running clearance on this double-track. As you can see I added dummy vehicles to check. There is a clearance, just, but it might be wise to increase the track centres through the scissors a fraction. Not too much, because that would cause difficulties with the check rails for the outer V-crossings in the diamond.

cheers,

Martin.

 

[Martin Wynne]

@James Walters

p.s. James,

With a bit of tweaking I have got the radius to 42" which is a lot better for P4:

There was a strange wobble in the straight track top right.

Straightened out at 270mm centres from the lower track.

All symmetrical. Outer turnouts are B-6.5 curviform.

Middle turnouts 1:8.5 generic with non-prototype 1:40 model switch (I assume this is not intended to be based on a prototype).

But no plug track (yet) for that switch.

Touched only geometry, timbering now wrecked.

cheers,

Martin.

 

[James Walters]

Thank you Martin that is really very helpful.
To confirm your assumption, this is not based upon any prototype, and will really just be a test track. The snaking 'S' shaped scissors appealed as something through which stock could be tested. The increased radius you have achieved will give anything I make more of a fighting chance at avoiding the cess.

Thanks again. I'll post updates on this occasionally as I'm sure our 'planks' will give lots of opportunities to test track ideas and hence share useful experience.

Would you be able to share the modified .box file please?

Best,

James

 

[Hayfield]

James

For what my tuppence is worth, the biggest area for concern is the crossover between the furthest two Vees, if this is straight it makes it much easier to build. My reasoning is that inertia will take the stock through the crossing, once a curve is introduced inertia will push it sideways

An interesting idea in the making

 

[Martin Wynne]

@James Walters

Hi James,

Here's the BOX file.

I set the double-track at the corners to 7ft way so that you can directly attach sharply curved modules.

I've made a start on one of the vees and adjusted the check rail ends to clear. It's a bit tight but doable. Over to you to finish it, do the others, remove the rail conflicts and shove the timbers.

It might be possible to redo it with closer track centres in the scissors, which would make checking the vees easier.

cheers,

Martin.

 

[James Walters]

Martin, this is fantastically helpful. I'm having a play with it now, and forensically examining what you've done.
Thank you so much.