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Help please - setting switch opening

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Location
Sydney
Gday all!
Just after some advice and scrutiny of my first couple of turnouts. They work fine with wagons of any kind. You know, shoving a teak coach full pelt as quick as I dare works OK too amazingly. The gresley A1/A3s work fine, but the P2 and another loco with single axle front bogie just seem to go over it ignoring the switch blades with the drivers working fine.
The reasons I think might be?
-I have not left enough room between the set bend and the blade. Or the blade is not sharp enough.
-The front boogie might have not enough weight.
-The back to back spacing of the RTR bogie wheels isnt good enough for OO-SF
-The switch blades are too close. I set them to have the same gap as a check rail with the OO-SF gauge tool (DCC concepts). I saw that the flange of the front wheel was going over to the wrong side of the blade. So I increased the gap to the thickness of a PCB tie 1.5ish mm
Decreasing the distance between the switch blades did seem to fix it however I hope that someone can scrutinize the area of the switch, I hope the photos are good enough. There is a chance I got greedy with the looks in setting the switch blades too close?
Thank you for your time.
Ben
 

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Martin Wynne

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-The switch blades are too close. I set them to have the same gap as a check rail with the 00-SF gauge tool (DCC concepts).
@Captain_Mumbles

Hi Ben,

That's a common error. I've even seen it done in P4. :) On the prototype the switch opening is more than double the flangeway gap.

For 00-SF (and EM) the minimum switch blade opening is 1.7mm at the tip. In the UK a convenient gauge for that is the thickness of a 20p coin.

For 00-BF and DOGA-Intermediate the minimum opening is 2.0mm* at the tip. In the UK a convenient gauge for that is the thickness of a 10p coin.

Sorry, I don't know the thickness of Australian coins, and Google is reluctant to tell me. But someone on here will know?

*and also for 00-SF if you adopt the practice of using 16.2mm gauge only for the V-crossings, with 16.5mm through the rest of a turnout (not recommended, but it seems to be adopted by some modellers).

Looking at your photos, I think you may have some solder on the back of the blade at the tie-bar. You need to scrape it away so that the blade can sit snugly against the stock rail at the tip. It's helpful when building with copper-clad tie-bars to file a small angled rebate in the foot of the stock rail before assembly to clear any such stray solder (difficult to do it afterwards). Also make sure that the stock rail is vertical and not leaning outwards, so that the blade can sit against it properly at the top.

cheers,

Martin.
 
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Captain_Mumbles

Member
Thread starter
Location
Sydney
Gday @Martin Wynne .

The closest coin I have is the 10C which is very close to 2mm. I might just accidentally shave one down a bit. I like that idea. Also it had slipped my mind that check rails are bent at the ends for a reason, and so that is yet another reason why that is not a good idea.
I think I will stick with the 16.2 all the way through as it does run really nice for me. It will be a bit of work but I think I would rather modify the first few sleepers of any adjoining flex track to suit. A lot of the time I have a few turnouts in a row so I think It is best for me to build them all at a standard.
You are also right with the small amount of solder that is holding the blade off the stock rail, I reckon I could get a 1-2 thou finger gauge in there. Also, I dont know how but it might have also had just a whisker of roll on that blade rail, probably when I put the curve in it.
The tie bars are only temporary I think, so I will have the opportunity to chamfer the stock rail bottoms when I change them.
I don't know if i really needed to but I filed a nice tiny radius on the inside of the blades so I could slide my finger across the top of the stock rail/blade and not feel a little pinch.

Cheers!
Ben
 
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Martin Wynne

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What do you recommend for O Gauge, I was just going to make the same mistake for my points.
@Murryb

Hi Murry,

For 0-MF (31.5mm gauge) you need a minimum switch opening at the tip of 3.0mm.

For GOG-F (32.0mm gauge) you need a minimum switch opening at the tip of 3.5mm.

(The 7mm exact-scale prototype opening (for S7?) is 2.48mm.)

cheers,

Martin.
 
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Martin Wynne

Admin
Location
West of the Severn UK
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Enjoy using Templot?
Thanks.

Please do not send requests for help direct to me via email.

Post your questions on the forum where everyone can see them and add
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.
Just linking this photo from the Scalefour forum to show that the switch opening is much wider than the flangeway gap:

file.php


Notice also the prominence of the set bend in the diverging stock rail in this view, and that it's clearly essential to the geometry of the switch.

Martin.
 
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