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I would appreciate some input on an idea I've been thinking about for some time now. And especially from those who have experience with the train-li bender.

A lot of people just bend their rails by hand - I've done it in the past myself. You just have to add curvature at the ends of the rails with pliers. This is slightly cumbersome, but perfectly doable. (Some suggest sawing off the straight bit of each rail-end.)
Also, I've never tried hand-bending with ties mounted / two rails / at a time. I'm not sure it can be done.

I'm thinking of making a dual rail-bender, like the train-li, only all bending rollers will be fixed. Instead, both middle rollers will get "slip-on" diameter increasing rings, producing a specific radius track. My reasoning is, that achieving some approximate bend on the rail-ends is enough - the middle of the rail sections can be adjusted to exact radius by simple hand-bending. Also, bending both rails at the same time, with ties mounted, is a goal.

I figure beeing able to bend a few radiuses with corresponding diameter-change rings would do. Perhaps 4", 6" and 8" would do. One would use the 4" ring for curves between 4-6", the 6" for curves 6-8" and the 8" for 8-10" curves.

One thing that surprises me, is that the train-li bender has such long longitudinal distance between bending rollers. It would seem to me, that there is a relatively long minimum piece of track, that it can bend?

Also, I wonder if the train-li bender (or others?) possibly grip the "stem" rather than the "head" of the rails?

Making the cheapo-bender would be very simple. Drill six holes & bolt six ballraces & turn a few adaptor rings. Done. What do you think?
 
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with fixed middle rolls, you might have problems to put the rail through for starting.
 

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Pauli, I've heard great things of the DuoTrack bender (the one Train-Li sells) but the price is pretty steep - $300. I'd be up for a cheaper version. However, the part about still having to bend the majority of the track by hand is not too appealing after just doing this. The reason is it was difficult for me to hand bend (belly bend) the rail into a smooth curve. I got it pretty close but not smooth. The main problem was where I needed an 8' diameter curve. I had an 8' diameter pre-curved section of Aristo, so I knew about what I needed. The problem was when I ended up running a loco through that requires a minimum of 8' diameter curve, I must have bent it a little too much in one spot, it was probably closer to 7.5' diameter for a 6" stretch of the 6' total length. This caused a problem as the loco would derail, but where I had Aristo 8' diameter curve track, no problem.

For larger diameter curves I think your idea is great, and I ran into the same situation you are trying to solve, the ends are pretty much impossible to curve together. Someone posted about attaching pieces together so you can get a good bend even on the ends. But, the main point of my post is, why not go all the way and come up with a duotrack competitor? Coming in %50 or better than the Train-Li would have a definite market. As with the price of track going up about as fast as oil, more folks are finding the flex track economical :)
 

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Posted By Pauli on 07/01/2008 9:32 AM
I would appreciate some input on an idea I've been thinking about for some time now. And especially from those who have experience with the train-li bender.

A)I have no experience with a TrainLi or other rail bender. I have 30 years as a tool and die maker, however.

I'm thinking of making a dual rail-bender, like the train-li, only all bending rollers will be fixed. Instead, both middle rollers will get "slip-on" diameter increasing rings, producing a specific radius track.

A)I can foresee slippage problems with your rings. Why not turn actual rollers the sizes you desire, unloose the bolt and change them out?

My reasoning is, that achieving some approximate bend on the rail-ends is enough - the middle of the rail sections can be adjusted to exact radius by simple hand-bending.


A)It seems to me that bending a piece of rail which by its nature consists of several widths, by hand, might induce stresses caused by uneven pressure that will tend to want to 'work out' over time. I've not seen any data on the metallurgy of these brass rails being sold. That can matter. As Murphy says, usually when it can cause a problem.

Also, bending both rails at the same time, with ties mounted, is a goal.

A) An admirable one. I hope you succeed. I think it's entirely possible.

One thing that surprises me, is that the train-li bender has such long longitudinal distance between bending rollers. It would seem to me, that there is a relatively long minimum piece of track, that it can bend?

A) There is much anguish over 'wastage' at the ends of track. Especially by me. I can think of a couple of 'radius inducers' that might solve the problem. Are they worth the effort to build?

Also, I wonder if the train-li bender (or others?) possibly grip the "stem" rather than the "head" of the rails?

A) I would hope they are designed to put pressure equally on the foot, web and head of the rail. (See above re induced stresses). If they don't, a used sliproll is a lot cheaper and more flexible.

Les
 

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Discussion Starter #5
Thanks for the input!

-Kormsen, I didn't think of that, ehhh /DesktopModules/NTForums/themes/mls/emoticons/blush.gif" border=0>" border=0> That needs to be adressed.

-jimtyp, to be honest, my experience with hand-bending, comes from my teens, and not using flex-track to start with. Instead I only had separately bought rails (plain iron - however I "zinked" them against rust), and bent and spiked them down directly to lumber roadbed (with decorative ties in between), around a 10" wooden fixture. The track still looks perfect after +25 years. This experience does not apply though, as I'm thinking of going into floating style track. (Picture attached show a switch I built when I was 14 years of age. It never worked quite properly, as at the time, I did not understand the importance of the guard rails ;-D

-Les, thank you for all your points. The main point for me, is beeing able to bend both rails at the same time, with the ties still mounted. Only today did I see just another new brand of single rail bender (ties unmounted) beeing offered at 100 USD, wich at least to me seems an uninteresting offer. Except I did notice this new brand lacks ballraces - wich was my reason for adding size-rings to the rollers.Maybe I should take your advice, and omit that step. Incidentally, it struck me yesterday, I can make the rings / or rollers, from axle stop-rings, that I only turn down in diameter.

- I would be extra satisfied, if I could come up with a design, that required no lathe work. Or at least, such a small amount, that any friend with a lathe would not hesitate to help out.
I'll let you know if I come up with something useful :D" border=0>" border=0>
 

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I know im reviving an old thread..but there is still more to say! ;)
I was just searching through MLS archives and came across this thread..

I have a large stash of Aristo 8-foot diameter curve sections..sectional track.
I would like to bend some of them out to 12-foot diameter..

If I know (for now) that all my rail is 8-foot dia, and I want to bend it all out to 12-foot dia..
(no other curves needed as far as this particular project is concerned)
would it be possible to build a very simple "non-adjustable" bender for just this one purpose?

and I dont quite understand the bit about the ends not being curved..
some threads mention that rail benders dont bend the last inch or so..that makes sense..
but this thread seems to talk about bending the ends only..then hand-bending the middle..
I dont quite follow how that is being done..

any suggestions for my 8-foot dia sections?

thanks,
Scot
 

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I know that with even the best rail benders running two pieces of rail through the same setting will result in two different bends.
 

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Hi, Pauli

How ar'you ? I'm not sure that did you see our posted in another suject. I think you are talking the home made rail bender. We had done to re-curving 16.5ft to 19ft successfully. I would show you the picture of the home made rail bender. Hope it could bring you any idea. If you find any question or sugestion, I would be very appreciated to hearing your sound.

Having fun with our little railroad in weekend,
Tony

 

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Posted By Scottychaos on 09 Oct 2009 10:10 AM
I know im reviving an old thread..
ANS: I'll say you are! I saw Kormsen's name and almost posted him a 'happy return'!


but there is still more to say! ;)
I was just searching through MLS archives and came across this thread..

I have a large stash of Aristo 8-foot diameter curve sections..sectional track.
I would like to bend some of them out to 12-foot diameter..

If I know (for now) that all my rail is 8-foot dia, and I want to bend it all out to 12-foot dia..
(no other curves needed as far as this particular project is concerned)
would it be possible to build a very simple "non-adjustable" bender for just this one purpose?

ANS: Yes. Two ways leap to mind, A) Three or more pairs of fixed pegs located on a 12' diameter section of a circle. I'd use metal pegs (nails?) in a piece of thick ply, like perhaps 3/4" thick, B) three or more roller bearing also mounted on a base of plywood, laid out such that the radius is 12', as above. You didn't say how long your track sections are.

and I dont quite understand the bit about the ends not being curved..

ANS: That's hard to explain, except that you run out of rail before you run out of roller support for the rail. OTOH, Ralph Brades seems to posit that curves should have a short section of straight before beginning the curve, called 'lead'. You'd do best to verify that with him. If you're thinking of a continuous circle though, I doubt it matters.

One thing someone else brought up is that the inner and outer rails of a curve have different rates of bend. That's because each is part of a different-sized circle, The gauge is determined from midway between the two.

Hope this helps. Note: I have never laid brass rail. I've done a lot of metal-bending, though.

Les


some threads mention that rail benders dont bend the last inch or so..that makes sense..
but this thread seems to talk about bending the ends only..then hand-bending the middle..
I dont quite follow how that is being done..

any suggestions for my 8-foot dia sections?

thanks,
Scot
 

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Bob,

Thank you very much for posting those links. Very much. I too am a simple sort of guy and was going to design my own. You've saved me a good deal of trial and error.

Les
 

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Short sections of straight at each end of sectional track does matter. They get doubled in length as sections are put together. Result is a stepping curve.
As an old metal pounder I'd shape a wood block with a spiral curve face and route the track profile across the face. I have a plastic faced dead blow hammer and know to use a slightly tighter curve than desired to form the rail, because there will always be spring back. Use end grain.

I think what Ralph was referring to is a Transistion Curve, a spiral curve from straight to the radius. Picture your self behind the wheel of your car, it's the distance you travel as you turn the wheel until you enter the curve. The ommission of the transition curve makes sectional track toy-like TO ME. Yet it's what I have....

Thanks for the link.

John
 

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John,

Re: Ralph's transitional curve from straight to curved: that's essentially--perhaps exactly--what he said. Your point about leaving it out and causing a toy-like action of the train is an excellent illustration.

I think the only advantage to using a mechanical bender is that the 'springback' can be eliminated by bending a slightly tighter radius than wanted. That takes a bit of fooling and depends to some extent on like batches of metal. Might a form and hammer on T rail induce a twist? (I know-- "only on the first one, then there'd be a depression in the block")


Whatever demerits hand forming might have over a Train Li or the like, it sure beats that price all to pieces!

Les
 

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Les I was only talking about the ends that don't get rolled.
I also tried to mention routing a grove of the track profile across the face. The foot/base of the rail will be most likely to twist. If you go a tad tighter it's easy to open aas needed.
The plastic faced dead blow hammer or a leather mallet won't ding the surface.

John
 

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John,

Yeah. Routing a profile will kill a lot of birds with one stone. Before I decided to use strap iron (actually, copper) I was sketching the shape of a T rail to see how hard it'd be to grind a router bit to do it all in one pass. Now I don't have to.
And it'd of been hard in a home shop.

Sorta off the subject, but the first thing I'm going to build for my lathe is a grinder attachment using a Dremel tool.

Sort of more off the subject, I'm not a fan of dead blow hammers. It's just me, I learned my beans before I found out about such things--we used cast soft lead hammers--and I learned to 'listen' to the 'feel' of a blow. Kinda hard to explain, but I expect you know exactly what I'm getting at. Our hammers were iron shells where you replaced the heads by rolling a piece of tin/whatever and fixing it in place with a worm clamp, then melting lead into the thing. (Had to preheat the cast iron head, though, else the new heads chilled too fast and fell out.)

One thing, I was really lucky: 'most all the old guys would patiently stop whatever they were doing and show me how to do whatever I needed.

This board is a lot that way.

Les
 

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Les,
I don't own a router, but I could cut the profile with a hand saw because it's a curved face. Clamp depth blocks to the blade if I don't trust my eyeballs... could also be done with a circular saw and cutting guides.

Lead and silver don't mix...well actually they do and that's bad... leather or plastic is my knowledge base and the dead blow reduced fatigue.... in our shop I was the 'old' guy!

John
 

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Hi Jnic,

I built one of roller skate wheel rail bender's 3--4 years ago. I used a harbor freight vise. It workes ok, I have $12 to $15 in it.

Chuck
 

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This is the one I built for bending one rail at a time.



The "crank handle" is absolutely useless. I have to PUSH the rail through and sometimes the rollers do not rotate at all while the rail is pushed through.

I emphasize that I PUSH the rail through because the bend radius formed will come out wrong if I "pull" the rail. The rail cannot be "pulled" at the correct angle to keep the curve right.

I formed the rollers on my lathe to be the mirror image of the rail profile (well... I got "close"), in an attempt to provide pressure points along the entire profile to eliminate kinking that might occur in places that were unsupported (especially the foot of the rail) and reduce the possibility of the rail taking on a lengthwise rotational twist (corkscrew or wind).

After I took the photo and tried the thing I found I could not adjust the middle roller easily, so I drilled and threaded a hole through the side, in line with the adjustment slot so I could put an adjusting screw in to press on the middle roller shaft to hold it in position.

I used LLagas Creek Niclkel Silver rail and plastic ties. To make it easier to put the ties on the rail I routed two grooves in a long board to hold the rail upside down at the correct gauge with stops at one end to keep the rails from sliding in the grooves. To do the curved sections, I had to make an 8-ft radius compass to hold my router (a Dremel Moto-tool with their router base) to make curved grooves (at two different radii to keep the gauge proper). I made a guess at a setting for the bender and ran one rail through and it was not bent quite enough, so I made one adjustment and ran it through again and when I laid the rail on the board it "fell" neatly into either one of the curved grooves... It didn't matter that the grooves were not exactly the same radus. Sliding the ties on from the end was then a simple matter.

If I were to need to use it again, I will move the two outter rollers closer to the middle one to shorten the amount of rail that does not get bent, but, in reality, that may not be necessary as I have had no problems with these short legths of non-cuvred rail where two sections of track meet. I only cut the ends of the inside rail of most sections when making my loop-backs. In general the joint pairs are not staggered... I just cut one end of the inside rail at each track joint.

But, if I ever need to bend rail again, I will probably buy one of the dual rail benders and this one will sit on the shelf and look pretty (it is all polished brass!).
 
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