# making perfect flextrack curves...



## tooter

I spend most of my net time reading the Brit narrow gauge forums, and found them to be a treasure chest of useful modelling tips. NG modellers are usually track and turnout scratch builders because so many truly weird gauges have no track manufacturers. 

Anyways, the subject was rail bending and someone had the brilliant insight to put 3 offset screws into a piece of scrap wood and push a rail through them, instead of buying an expensive rail bender. 

I recently got my very first pieces of flex track and had wondered how to put it down to make small radius curves when it had so much tension trying to keep straight. So I thought I'd try out the three screw rail bender idea. Mercifully, one of the flex track rails slipped right out so I took that one rail and pushed it through my home made 3 screw railbender, and slid it back into the flex track sleepers...

*BINGO ! * 

A *PERFECT* 10 inch radius flex track curve with *NO* tension on the track at all!









All the engines and rolling stock have short wheelbases and can easily negotiate a 10" or smaller radius...


















You can even bend one half one direction and the other half in the other to make an S, then just lay it onto position without needing to fight it. You don't even need to nail it down while test fitting. The 3 screw bender can be easily tweaked to make *ANY* radius you want. 

Man, I'm gonna be bending *lots *of flex track on my layout.


----------



## dozer

Awesome, thanks for the tip!


----------



## tjcruiser

Greg,

Very clever idea. Thanks for sharing. Question, though (in regard to a one-direction-only bend)...

Did you "prebend" the inner rail or the outer rail? Would the choice of either affect the quality of the results? I'd be quite interested to see if you can shed a little more light here.

Thanks,

TJ


----------



## tooter

Yes... there is one side which I believe works better than the other. 

Flex track has a fixed tie spacing side and a variable tie spacing side. I bent the inner rail of the curve to be on the variable side, so that the inner ties would be compressed rather than the outer ties spread...










Typical narrow gauge radii can run down to about 6 inchs. The compression limit of the inner ties of HO flex track will allow down to as little as 4 inch radiius curves...

...which is well into trolley territory. 

My general plan is to have within a "regular" layout, a branch line that's a very steep winding climb up into the hills where there'll be logging, or a mine, maybe both. There'll likely be two sidings with loading zones to shuffle freight cars and their loads, and a small manual turntable to both turn the engine around and to offer the selection of a runaround track. 

At the train show, I saw one Z gauge module of exactly what I want to model. It was the only really interesting thing to see in the whole place, and I noticed that it drew a lot of spectator interest just because it was so *different* from everything else there.

I tell you, the 3 screw bender works slicker than snot! 

You push the rail through, rather then pull, so that there is no force affecting the radius of the "extrusion". The rail comes out so consistently smooth and uniform, it'e scary!Then you just eyeball the couple of inches of straight ends and do them by hand.


----------



## tjcruiser

Ya' earned yourself 5 gold stars there, Greg ... well done.

So, I understand your explanation of bending the inner rail, but one thing still confuses me. In your earlier pic that shows the track and the wood block, why, then, is the inner rail apparently not long enough to complete the half-circle? It seems to me that if you bent this inner rail, it should be the one poking in excess out the ends of the bent track, not the outer rail???

I suppose you had previously trimmed that inner rail shorter???

Set me straight!

Thanks!!!

TJ

PS -- Ya' know now that you're gonna have to make yourself a fully-adjustable little bend radius gizmo that let's you "dial in" the exact screw offset!

Do you recall the thread from a couple of months ago where a member had made a custom track bender for making overhead "bridges" for floating / suspended layouts?


----------



## tooter

tjcruiser said:


> Ya' earned yourself 5 gold stars there, Greg ... well done.
> 
> So, I understand your explanation of bending the inner rail, but one thing still confuses me. In your earlier pic that shows the track and the wood block, why, then, is the inner rail apparently not long enough to complete the half-circle?[
> 
> It seems to me that if you bent this inner rail, it should be the one poking in excess out the ends of the bent track, not the outer rail???
> 
> I suppose you had previously trimmed that inner rail shorter???


Yes. 

Before I had learned how to bend the rail, I had pinned down the flex track in a curve bent in the other direction and was practicing cutting the rails with a hand saw. You can see one of the pieces I cut off on the 3 screw bender...












> Set me straight!
> 
> Thanks!!!
> 
> TJ
> 
> PS -- Ya' know now that you're gonna have to make yourself a fully-adjustable little bend radius gizmo that let's you "dial in" the exact screw offset!


No need to. You can just move a screw. I found that I can first set a tight bend and then simply pull the ends to relax the bend until it's where I want it.



> Do you recall the thread from a couple of months ago where a member had made a custom track bender for making overhead "bridges" for floating / suspended layouts?


No. Didn't catch that one... There's really no such thing as an original idea. I got it from the Brits.


----------



## Reckers

choo choo said:


> Yes.
> 
> Before I had learned how to bend the rail, I had pinned down the flex track in a curve bent in the other direction and was practicing cutting the rails with a hand saw. You can see one of the pieces I cut off on the 3 screw bender...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> No need to. You can just move a screw. I found that I can first set a tight bend and then simply pull the ends to relax the bend until it's where I want it.
> 
> 
> 
> No. Didn't catch that one... *There's really no such thing as an original idea*. I got it from the Brits.


That's a good point, but it takes imagination to transfer the idea from one process to another. When I was young, I worked in an air conditioner plant in Kansas. Guess what they did with the coils? They arrived as large rectangles from the manufacturer, then were had-fed into a bending jig to shape them into the conventional rectangle you see in your backyard. As it was fed in, the jig pulled it around a series of smooth, vertical shafts and, with a little air-powered compression, voila! the flat coil became a rectangle. It's pretty much the same process you just described for reshaping the rails.

Nice suggestion, and thanks for sharing it!


----------



## tjcruiser

choo choo said:


> Re: bending different radii ...
> 
> No need to. You can just move a screw. I found that I can first set a tight bend and then simply pull the ends to relax the bend until it's where I want it.


Makes sense. However, if someone really wanted to "Gucci Up" this concept, they could make a little jig with an offset-axis cam in the middle, like the sketch below. (Dimensions exagerated for clarity.) Two outer pins are fixed. Middle one can rotate and then get locked into position with a (red) set screw. Rotating the middle "cam" changes the amount of offset, and dictates the resulting radius ...










Greg, I think you should post a little virtual "tin can" here on this thread. I think a lot of people are gonna use your little gizmo, and maybe they should drop a quarter into the can whenever they do? Could be your early retirement cash cow! :laugh:

TJ


----------



## aionta

*awesome-ness all around*

Wow I really like this idea! I am planning to build all of my HO rail ( code 83 ) for my layout that I am planning.

My sticking point was going to be how to bend the rail consistently

But now that is solved Thanks!:thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup:


----------



## Reckers

Okay....my tweak to TJ's model. 

Instead of a wood block, a metal one: drill holes and use metal rods instead of screws. Call the outer ones guides and the inner (center) one the fulcrum.

For the two guides that form outside of the curve, scribe a line and drill a series of holes to make sets equi-distant from the fulcrum and marching outward. This will allow you to bend shorter or longer-length rails by moving them closer together or further apart, always staying equidistant from the center fulcrum.

For the fulcrum, a series of holes perpendicular to the line of guide-holes. Moving the fulcrum in toward the line of guide-holes will make a tighter curve; moving it out makes a more gradual curve.


----------



## tankist

at that point, instead of rods and screws one might use bearings. a roller skate ones for example. with that i can't say i have trouble to work with flex without this kind of tool. although don't do tighter then ~18 bends


----------



## Reckers

You know, if we just added a mechanism to automatically feed the rail material in and then cut it to length after bending, I think we'd have sucessfully overengineered this thing to death!


----------



## Rocky Mountian

choo choo said:


> Yes... there is one side which I believe works better than the other.
> 
> Flex track has a fixed tie spacing side and a variable tie spacing side. I bent the inner rail of the curve to be on the variable side, so that the inner ties would be compressed rather than the outer ties spread...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Typical narrow gauge radii can run down to about 6 inchs. The compression limit of the inner ties of HO flex track will allow down to as little as 4 inch radiius curves...
> 
> ...which is well into trolley territory.
> My general plan is to have within a "regular" layout, a branch line that's a very steep winding climb up into the hills where there'll be logging, or a mine, maybe both. There'll likely be two sidings with loading zones to shuffle freight cars and their loads, and a small manual turntable to both turn the engine around and to offer the selection of a runaround track.
> 
> At the train show, I saw one Z gauge module of exactly what I want to model. It was the only really interesting thing to see in the whole place, and I noticed that it drew a lot of spectator interest just because it was so *different* from everything else there.
> 
> I tell you, the 3 screw bender works slicker than snot!
> 
> You push the rail through, rather then pull, so that there is no force affecting the radius of the "extrusion". The rail comes out so consistently smooth and uniform, it'e scary!Then you just eyeball the couple of inches of straight ends and do them by hand.


I have a stick of flex it looks like you remove the rail from the ties and bend. Pulling on mine it doesn't move that easy and is a pain to put back in?

I heard no question was to dum to ask so bear with me
Mike


----------



## tjcruiser

Rocky,

On flex that I've used (Atlas), one of the rails pulls out pretty easily. Not hard at all to align / poke it back in.

And ...



Reckers said:


> You know, if we just added a mechanism to automatically feed the rail material in and then cut it to length after bending, I think we'd have sucessfully overengineered this thing to death!


Then we'd have THIS ... from Bob (who's posted here at the forum) from ex. CeillingTrains.com (now TracksOverhead.com). Note very clever adjustable roller position on the right ...










TJ


----------



## tankist

Rocky Mountian said:


> I have a stick of flex it looks like you remove the rail from the ties and bend. Pulling on mine it doesn't move that easy and is a pain to put back in?


thats right, when working with Atlas flex you not supposed to take the rail out. 
then there is ME flex that is even harder to flex and it keeps the curve even not nailed to anything.the only flex that rails can be taken in and out of is peco.


----------



## tjcruiser

Hmmm ... maybe I'm wrong. I'm pretty sure it was Atlas. Then again, I think the sections were straight (unbent) when I was pulling / inserting the rail.


----------



## Rocky Mountian

tankist said:


> thats right, when working with Atlas flex you not supposed to take the rail out.
> then there is ME flex that is even harder to flex and it keeps the curve even not nailed to anything.the only flex that rails can be taken in and out of is peco.


 I have know idea what I have and TJ that tool is kinda what you had in mind, I guess there's no end to what can be made or built if one puts his mind to it


----------



## Rocky Mountian

I looked on the back and its Atlas.

The more you know the deeper you get.

Where did I see that 12 step program???


----------



## tooter

tjcruiser said:


> Makes sense. However, if someone really wanted to "Gucci Up" this concept, they could make a little jig with an offset-axis cam in the middle, like the sketch below. (Dimensions exagerated for clarity.) Two outer pins are fixed. Middle one can rotate and then get locked into position with a (red) set screw. Rotating the middle "cam" changes the amount of offset, and dictates the resulting radius ...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Greg, I think you should post a little virtual "tin can" here on this thread. I think a lot of people are gonna use your little gizmo, and maybe they should drop a quarter into the can whenever they do? Could be your early retirement cash cow! :laugh:
> 
> TJ


Yes. One of the narrow gauge Brits had suggested that idea, too. Another to use different sized washers on bolts for varying the radius, and so that the rail could roll through. They're truly *amazing* modellers. Scratchbuilding engines is accepted as the norm. One guy is even casting his own street maintenance manhole covers.... while another creates building and bridge facades using handmade bricks. I'm completely in awe of their abilities.

The bend doesn't really need to be exact. I didn't even measure the screw placement, and just stuck them on to see what would come out. Too tight, just pull the ends a little to relax it. Too loose, move a screw and run it through again. 

And remember it's still flex track...
With a bend already as it's neutral point you have the same flex parameters both ways that it had when it was straight.

My bender literally took 30 seconds to make from a redwood 4x4 scrap and three common one inch wood screws. 

Threading the bent rail back into the sleepers takes time and patience, but it can be done. Doing it on a perfectly flat surface really helps.


----------



## tooter

aionta said:


> Wow I really like this idea! I am planning to build all of my HO rail ( code 83 ) for my layout that I am planning.
> 
> My sticking point was going to be how to bend the rail consistently
> 
> But now that is solved Thanks!:thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup::thumbsup:


Code 83 bends like butter.


----------



## tooter

Rocky Mountian said:


> I have a stick of flex it looks like you remove the rail from the ties and bend. Pulling on mine it doesn't move that easy and is a pain to put back in?
> 
> I heard no question was to dum to ask so bear with me
> Mike


I use Atlas code 83 flex. One rail is fixed while the other slides right out. It does take patience to put the bent rail back in. You just have to take it one sleeper at a time.


----------



## tjcruiser

choo choo said:


> The bend doesn't really need to be exact...
> And remember it's still flex track...
> With a bend already as it's neutral point you have the same flex parameters both ways that it had when it was straight.


Points duly noted. Makes perfect sense.

Brits are a bit nuts / over-the-top. Good for them, though. (If anyone here is thinking about going the full-custom loco route, check out my crazy thoughts re: sterolithography 3D "printing" in the recent Articulated thread.)

Cheers,

TJ


----------



## tooter

tjcruiser said:


> Points duly noted. Makes perfect sense.
> 
> Brits are a bit nuts / over-the-top. Good for them though.


I always admire the self discipline of fastidious attention to small details no matter how it's expressed.


----------



## aionta

When running the rail through the 3 points of the bender do you ever have problems trying to keep the rail vertical?

What I mean is doe the rail (since it is not square) try to twist?

Thanks

Aaron


----------



## tooter

aionta said:


> When running the rail through the 3 points of the bender do you ever have problems trying to keep the rail vertical?
> 
> What I mean is doe the rail (since it is not square) try to twist?
> 
> Thanks
> 
> Aaron


Nope. 

The screws are almost all the way down so that the rounded edge of the head fits right into the indentation between the top and base of the rail. This keeps the base of the rail flat on the surface of the wood. It's suprizing how little the rail resists curving, even with the very small radii curves I'm making for the layout. Most modellers *won't* be going anywhere *near* that extreme, so it'll be even easier.  The the screws apply constant uniform force. The rail in the picture of the flex track was drawn through three times with absolutely no problems, as I was practicing with it. 

Greg


----------



## aionta

Thanks Choo Choo!


----------



## Rocky Mountian

View attachment 3419


View attachment 3420


I had a few sticks of flex so I thought I would try it out. What I found is you can't get to radical with the bends and keep in mind what engines you have. This little layout will only run short wheel base, SD 40 and down.


----------



## Rocky Mountian

I don't know why but I had a hard time posting so I kept it short.

I also wanted to say that when I first came to the forum asking what my brother's trains were worth someone said ( why don't you try it out you might like Model Railroading ).

Well all I can say is I'm having a ball, so thanks.


----------



## Reckers

It's nice to have you with us, Rocky. Welcome to a family of addicts!


----------



## Rocky Mountian

Reckers said:


> It's nice to have you with us, Rocky. Welcome to a family of addicts!


 Know kidding.
I just added this back drop to my carpet layout.


----------



## tankist

last night a friend stopped by. a year ago he was joking about my endeavor , then as my layout continued to take shape the jokes died down. when i installed DCC and demonstrated independent operation of two engines (and my panel) i got a honest "wow" out of him. but last night was priceless - showcased the ex-Dozer Railways INC. BLI SD40-2 that Tankist Railways INC received in a barter deal. as the engine upon command commenced the start-up sequence sound, eyes widened and sound of a dropping jaw could also be heard. as he said, sound is the last thing that was missing. 
and even being not into trains at all, he couldn't take his finger off the horn button for to long while driving around. personnaly my reaction was not that different, sound is something.

RM, as much fun as old carpet layout can be (0 sarcazm. had one of these till i was 10, had fun laying down watching the train pass) your only starting your climb, lots of exciting features and things still await.


ADD


Rocky Mountian said:


> ..This little layout will only run short wheel base, SD 40 and down.


hmm, i wouldn't call anything 6 axle as short...


----------



## tooter

Rocky Mountian said:


> View attachment 3419
> 
> 
> View attachment 3420
> 
> 
> I had a few sticks of flex so I thought I would try it out. What I found is you can't get to radical with the bends and keep in mind what engines you have. This little layout will only run short wheel base, SD 40 and down.


That's right, Rocky... 
The Roundhouse 0-4-0 EMD 40 has no problems, and the 0-6-0 Mantua Goat does just fine because the middle drive wheels have no flanges... however, the Roundhouse logging loco can't...










Long wheelbase rolling stock can also have problems with small radii turns besides looking funny. Luckily the bends aren't irreversable... you can always set some screws the other way and relax the bend.


----------



## Rocky Mountian

I don't know my locomotives yet, here a picture of the engine I was trying to discribe.


----------



## tankist

is it GP7 pictured? i can hardly distinguish between hoods of that era


----------



## Rocky Mountian

tankist said:


> is it GP7 pictured? i can hardly distinguish between hoods of that era


 I need to get my engines down.

I have several of these, so that helps alot.

Thanks Tankist.


----------



## Rocky Mountian

Here's another one that I don't know what it is. I looked on e-bay till my eyes couldn't take any more.


----------



## Rocky Mountian

Here's another pict.


----------



## Boston&Maine

That locomotive is an FM Trainmaster: http://en.wikipedia.org/wiki/FM_H-24-66


----------



## Rocky Mountian

Thanks Boston Main I don't think unless I would have seen one I would have ever got that one.


----------



## Rocky Mountian

I was looking on American rails.com, I didn't see this one on there but this one must be in that GP7-9 series maybe un-maned unit I don't know for sure. It's good to know the years that these were in service. The web sight good for us that don't know s... :laugh:


----------



## tankist

that's a "calf" , always MU'ed to its mother "Cow" (engine with actual cab).
ot it maybe a strange chop done by someone


----------



## Rocky Mountian

Looking the engine over real good it has been modified and a good job as it was hard to see. It's a GP-7 with the engineer cab cut out new peices put back in and also some wire loop put in from the front to about midway back on top.The horn and stacks have been removed also.
I don't know what it was going to be. I wish I did I might be able to finish it.


----------

