Best technique for curving rail?

Discuss the prototype and how to model it.
Triode
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Best technique for curving rail?

Postby Triode » Wed Oct 23, 2019 10:29 am

Can anyone recommend a reliable method of forming gentle curves in rail; for example curved stock rails for turnouts? I can't seem to avoid creating a slight vertical component to the bend so that the rail no longer lies flat across the sleepers.

I thought about installing the rail without pre-bending and letting the chairs hold it in place under tension, but I'm not sure if this would be a good idea when using plastic functional chairs.

Any suggestions would be much appreciated.

Thanks,

Liam

Proton
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Re: Best technique for curving rail?

Postby Proton » Wed Oct 23, 2019 11:08 am

Hmmm. I have made a lot of turnouts using the Brook Smith method, and have never pre-curved the rail, and this hasn't caused any solder joint failures. I have also constructed a lot of turnouts using code 83 flat bottom rail soldered onto PCB sleepers, again with no pre-curved rail. I haven't made any using chairs, but bullhead rail is so easy to curve surely the force exerted on a handful of chairs would be minimal.

PBM.

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Serjt-Dave
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Re: Best technique for curving rail?

Postby Serjt-Dave » Wed Oct 23, 2019 11:24 am

Still knee deep in track making and with most of my track curved. I always place the rail between the first two fingers and thumb and pull the rail though them gently applying pressure to get the desired curve. It's almost like stroking the rail if you get what I mean. I've not had it where the rail distorts.

Dave

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Noel
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Re: Best technique for curving rail?

Postby Noel » Wed Oct 23, 2019 11:55 am

I tend to use thumb and forefinger only, with the rail against the middle section of the finger, as I find that works better for me; use whatever method suits you. Otherwise it's as Dave's method. You don't have to try and get the curve right first time; do it gently and repeat as necessary. I find pre-curved rail makes it easier to get the gauge right in critical areas of points, for example, and minimises the risk of unwanted movement during assembly; the first chairs glued on the curve are under considerable stress at the start if you use straight rail for a sharply curved line and chairs may distort. Pre-curving rail is less important for large radius curves.
Regards
Noel

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grovenor-2685
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Re: Best technique for curving rail?

Postby grovenor-2685 » Wed Oct 23, 2019 2:00 pm

I also use the thumb and fingers method and have not had problems with unwanted vertical curves appearing.
Bullhead rail naturally curves horizontally due to its shape, this can be a problem for tight curves in chairs as the curved rail will not naturally take up the 1:2 inclination so a tiny bit of vertical curve, in the right direction would help. But if its visible its probably to much. :)
Flat bottom rail is usually the one to give problems as the extra width in the foot makes its natural curve include both horizontal and vertical components.
Regards
Regards
Keith
Grovenor Sidings

PhilipT
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Re: Best technique for curving rail?

Postby PhilipT » Wed Oct 23, 2019 4:05 pm

I've had this problem too and find that, with nickel silver rail, I have to be very careful to avoid it happening (when bending I try to apply a bit of downward pressure to the ends as well as the bending force to counteract the tendency for the head to rise). I have put it down to the additional material in the head of the rail making the head stiffer than the foot and allowing a bit of extra stretch in the foot. Is it also a problem with steel rail (which, being less springy than N/S, requires less effort to put in a permanent bend)?

BrianW
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Re: Best technique for curving rail?

Postby BrianW » Wed Oct 23, 2019 6:04 pm

Far from gentle and not P4, I used this method to produce extreme curves in flat bottom code 75 rail for the hidden section of my London Underground 00 layout. The rail stayed dead flat even after these extreme curves, so it should work for gentle curves.
201RailBendingJig.JPG

202CurvedRail.JPG

Experiment with bolt offsets, pull the rail through (don't push it), flat bottom fits under washers, web runs on outside of washers. For bullhead try cylindrical spacers instead of washers.
It is also possible to produce short lengths of curve with straight each end. Fit rail under outer washers, push middle washer/bolt into place, then pull rail back and forth.

BrianW

nberrington
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Re: Best technique for curving rail?

Postby nberrington » Thu Oct 24, 2019 12:55 am

This gizmo is pricey but is fantastic:

https://www.handlaidtrack.com/tl-0004

PhilipT
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Joined: Thu Mar 05, 2015 4:18 pm

Re: Best technique for curving rail?

Postby PhilipT » Thu Oct 24, 2019 6:14 pm

Has anyone tried using the GW Models roller? It would be a bit cheaper than the item suggested.

allanferguson
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Re: Best technique for curving rail?

Postby allanferguson » Thu Oct 24, 2019 7:34 pm

PhilipT wrote:Has anyone tried using the GW Models roller? It would be a bit cheaper than the item suggested.


I have, and it worked well on curves down to about 1m radius. There's always the wee bit at each end which has to be discarded, but that's no matter

Allan F

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grovenor-2685
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Re: Best technique for curving rail?

Postby grovenor-2685 » Thu Oct 24, 2019 9:10 pm

BrianW's homemade unit above is essentially the same as the 'handlaidtrack' product and much cheaper than that or a GW roller. :)
Get hold of 3 ball bearings and you can build your own 'handlaidtrack' clone simply enough. Find bearings on Aliexpress.
Save wear on your fingers and thumb if you hace a lot to curve, but does the same job.
Rgds
Regards
Keith
Grovenor Sidings


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