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Large radius HO prefab/sectional curve track?

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Posted by maxman on Wednesday, September 9, 2020 4:32 PM
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Posted by Doughless on Tuesday, September 8, 2020 6:45 PM

My last suggestion sucked.

How about this.

Take bendable track like Peco.  Use ribbon rail to form a precisely formed curve, if necessary.  Then just brush glue onto the ties and spikeheads, underneath too, and it should form a fixed three foot section of curved track.

- Douglas

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Posted by trainnut1250 on Tuesday, September 8, 2020 6:31 PM

Stix,

I have a couple of brass cab forwards that won't do anything less than 30" - Since they were released many years ago, I don't know what the paperwork that came from the factory might have specified since it was long gone by the time I purchased them.  My tests showed the locos to very sensitive to anything even slightly less that 30".

 

Guy

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Posted by wjstix on Tuesday, September 8, 2020 4:21 PM

Bachmann code 100 EZ Track goes up to 35.5" radius.

https://shop.bachmanntrains.com/index.php?main_page=product_info&cPath=258_366_367&products_id=2462&zenid=99cpn01rp2rfo74lnbmnqjv3e2

 

FWIW the largest minimum radius I recall ever seeing for an HO product was a brass CP 2-10-4 whose builder recommended 30"R curves. However, an MRN reviewer said it had no problem going around 28.75" Kato Unitrack. So,as has been mentioned, using the 31"R Kato code 83 track could be a good substitute.

Stix
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Posted by selector on Monday, August 31, 2020 6:48 PM

I opted to skip the roadbed, no cork or foam, inside my helix 8 years ago.  However, changes of temps and humidity in the attic above the garage in which my layout sat meant that I had to control stringlining rails, pop-outs, buckling, and other mishaps...especially inside that monster helix-that-was-a-mountain.

So, no roadbed, but I used DAP Alex Plus with Silicone caulking, the clear kind because it worked a LOT better than their 'white' version (at least, that's what I learned) to adhere the rails in place.  This worked very well.  I never had any problems inside that helix except for a single stringline incident with a long consist. None of the joints, including full gaps across sections of the sub-roadbed designed to help disassemble and move the apparatus, ever shifted.

What helped to keep the wood, and therefore the joints, stable was that I controlled humidity in the loft by means of a dehumidifier.

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Posted by trainnut1250 on Monday, August 31, 2020 2:42 PM

 

Skip the roadbed in a helix. It is not necessary and it takes extra time to install it and the extra height cuts down on the overhead clearance.

Jim it looks like you are going to have to go with flex track for the curves.

I laid mine out on a table with the centerlines drawn and soldered them together in a curved shape after I cut the ties and rails to fit. I installed them on the helix levels as I went. Tedious but not difficult, especially if you buy the prefab helix kit. I used atlas code 100.

Guy

 

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Posted by Doughless on Sunday, August 30, 2020 3:24 PM

You could make your own.

Since this is hidden track and asthetics is not a concern, you could make your own roadbed by cutting a piece of 1/4 inch plywood into the radius you need. 1.5 inches wide.  Maybe use Peco track since it holds its curve and is easy to mold. Then mount the peco sections onto the plywood.  You could use silicon adhesive caulk.

Maybe use the ribbon rail guide as the template with which to draw your lines on the ply, and to form the Peco track.

It would form several very solid sections, or one larger section if you're ambitous, of very solid track and roadbed that you could place anywhere.

- Douglas

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Posted by rrebell on Saturday, August 29, 2020 10:06 AM

You can use regular sectional track and solder them together.

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Posted by Overmod on Saturday, August 29, 2020 2:02 AM

doctorwayne
As for the noise factor, I can't predict if it would be offensive or not, but if the locos have sound, just crank 'er up  to eleven, eh!

Well, there certainly is that!

The thing I keep thinking about, though: weren't you the one stressing the importance of lavish and well-cemented interior bracing in styrene construction?  There is less than no doubt that even thin styrene adequately cross-reinforced is an excellent structural material: that sort of design has been a staple of college-engineering bridge building contests for decades.  But how do we do the necessary deck and web stiffening with what will necessarily be at least partial portal framing without compromising vertical clearance?

Now, I didn't think of using the cast tie structure as fully-solvent-welded reinforcement of the 'ribbon' helix.  That might have dramatic possibilities if, for example, a continuous strip were bonded across the tie ends on both sides and to the ribbon.  As mentioned the rail expansion may not be great enough on even a multiple-turn helix to cause physical trouble on an 'all-welded' unitized roadbed-and-tie construction...

I am wondering if implicit in some of the 'small-radius long-equipment' video discussion is a stiffened helix with very long clearance to its hangers or supports, this perhaps facilitated by stiffened-gusset outriggers periodically tied across using the tie height and crib spaces for the necessary strength.  

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Posted by doctorwayne on Saturday, August 29, 2020 12:55 AM

Overmod
...I think thin styrene sheet might be excessively fragile in several ways and prone to cracking, especially with age or 'poor conditions' in the train room; the big problem, though, is that I think it would be noisy.

I dunno about the fragile, but I have a lot of fairly large structures on my layout, built from styrene kits, but with all of the walls on the side visible from the aisle, on my around-the-room layout.

The back, roof, and interior bracing was all done using .060" sheet styrene (I've run through at least five or six 4'x8' sheets of the stuff, over the course of several years).  Most of them are removeable from the layout when periodic cleaning is necessary, but all are extremely solidly built, with little warping and no cracking of any sort. 

Here are a few examples...

 

What I envision for the helix would be fairly closely-spaced vertical bracing, but with room enough between them to allow re-railing or removal of faulty cars or locos, if needed.  I'd guess, too, that the vertical thickness of the rail, in addition to the ties being cemented to the styrene, will give it pretty good stiffness, preventing sag between supports.

As for the noise factor, I can't predict if it would be offensive or not, but if the locos have sound, just crank 'er up  to eleven, eh!

Wayne

 

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Posted by PRR8259 on Friday, August 28, 2020 9:26 PM

Any time I have seen one, it was plywood.

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Posted by Overmod on Friday, August 28, 2020 7:32 PM

doctorwayne
Of course, never having built a helix, perhaps there's something I've missed.

It is rare indeed that I get to say this to you, but yes, I think you have missed something.  I think thin styrene sheet might be excessively fragile  in several ways and prone to cracking, especially with age or 'poor conditions' in the train room; the big problem, though, is that I think it would be noisy.  Huge defective helical woofer noisy, perhaps.

Having said that, I think the collapsible helix is an excellent idea,although I think it would be better in wood or 'engineered lumber' and perhaps with strategic use of the right kind of 'structural' biscuit splines to keep the section edges aligned better (and with less overhead compromise!) then just using screwed/glued welting plate from underneath.  I think the thing to do is erect it entirely in tension, then carefully start leveling and putting struts precisely adjusted to length and perhaps with rubber snubber/isolators in on both sides of the helical path as you go up.   How many have successfully used the threaded-rods-in-tension with split nuts for the brackets, as permanent construction, without getting noise?

Another potential advantage of a suspended helix is that it might be arranged to partially 'collapse' by pulling intermediate spirals toward the top up or towards the bottom, down, opening up a couple of specific turns to increase ease of access if GHA becomes needful...

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Posted by rrinker on Friday, August 28, 2020 6:10 PM

 SweepSticks are for more than just drawing the curve - they also fit between the rail and form the radius if flex (or straight if you use the straight ones). 

 Since you need to build the helix up one layer at a time anyway, even a half circle of SweepSticks should do it. They have notches for spiking, too, although I am going to use caulk on mine like always. 

                                      --Randy

 


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Posted by riogrande5761 on Friday, August 28, 2020 5:45 PM

doctorwayne
fter reading your post, it occurred to me that the helix could easily be pre-fabbed, using cut-out arcs (at the required radius) of .060" or 080" thick sheet styrene, wide enought to accommodate Atlas flex track.

yep, there are youtube video's on that.  I'm to the point, and my wife agree's that a prefab helix may be looking real good right now.

Rio Grande.  The Action Road  - Focus 1977-1983

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Posted by doctorwayne on Friday, August 28, 2020 4:55 PM

Overmod
As I understand it ... not having done it, you understand ... making a helix that is relatively 'long' and low grade involves a large number of 'turns' at smooth and consistent 'thread pitch' usually made out of relatively thin material. This de facto trades off access 'from the sides' against lower grade and easier vertical-curve concerns. It also seems to me that making field joints in this construction as opposed to jigging and gluing the whole shebang before "raising" is asking for problems, compared to (perhaps) pre-raising the helix to open up its turns, lay the flextrack with a gauge, then install the thingat desired (and now harder to access' pitch and support structure...

After reading your post, it occurred to me that the helix could easily be pre-fabbed, using cut-out arcs (at the required radius) of .060" or 080" thick sheet styrene, wide enought to accommodate Atlas flex track.  Since the Atlas ties are also styrene, ordinary solvent-type cement could be used to permanently attach the track to the styrene "roadbed"  The segments could be joined using the same material on the underside at each joint. 

Regardless of the number of loops needed to gain the desired elevation, the construction could be done as one continous spiral, creating successive curves and installing the track on them as they're created, immediately atop the ones already done - basically a helix collapsed on itself.

It shouldn't then be difficult to carry it where it's to be installed and once the lower end is affixed to its access track, each successive loop raised and secured with vertical styrene strips cut from the same material, with, f'instance .125" strip styrene cemented to the interior face of the strips at proper height-intervals to support the otherwise flimsy roadbed at the required grade.

This would allow all track installation and soldering to be accessible as the coil is built, rather than in difficult-to-handle segments or hard-to-access points where soldering is required.
If I had needed a helix (and thought of it then, rather than many years after installing my 45' long nolix) I think this might be the procedure I would have used.

Of course, never having built a helix, perhaps there's something I've missed.

Wayne

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Posted by Overmod on Friday, August 28, 2020 3:59 PM

doctorwayne
It does beg the question, though...if the area is hard to access, wouldn't it have been easier to do it before adding whatever made it not so accessible?

As I understand it ... not having done it, you understand ... making a helix that is relatively 'long' and low grade involves a large number of 'turns' at smooth and consistent 'thread pitch' usually made out of relatively thin material.  This de facto trades off access 'from the sides' against lower grade and easier vertical-curve concerns.  It also seems to me that making field joints in this construction as opposed to jigging and gluing the whole shebang before "raising" is asking for problems, compared to (perhaps) pre-raising the helix to open up its turns, lay the flextrack with a gauge, then install the thing at desired (and now harder to access' pitch and support structure...

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Posted by doctorwayne on Friday, August 28, 2020 3:11 PM

riogrande5761
Rather than using pre-fab sectional track, why not make your own using flex track. That's been covered already - read above discussion.

Yeah, my bad, as I missed the part about it being for a helix.

I'd built the helix in segments, affixing the flex track at the same time.  Depending on the access, it could be pre-assembled, then, with help, put in place. 

If that's not possible, then perhaps the segments could be assembled on-site - at worst, you'd be in the middle of it while doing the assembly, but it's still a lot less work than using sectional track.

My suggestion was to simply create a length of appropriately-curved track, using flex track on a pattern, rather than attaching it to a base.  Cementing the rails to the ties would make the curve permanent, allowing longer segments of track to be handled, although the length couldn't be a complete circle (or more) in one piece. 
It could, however, be completed as a circle, in situ, with minimal soldering - certainly a lot less than using sectional track, and likely less expensive, too.

It does beg the question, though...if the area is hard to access, wouldn't it have been easier to do it before adding whatever made it not so accessible? 
(That's not intended to be a criticism, as I've managed to stymie myself a few times, too.)

Wayne

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Posted by Overmod on Friday, August 28, 2020 2:40 PM

MisterBeasley
Ribbon Rail makes an alignment gauge for 34 inch HO track.  For building a helix of that size it would be a worthwhile investment.

This gauge is their #1034.  There is one on eBay as we speak for under $9 plus $3.99 handling.  That all by itself should assure kink-free flextrack installation over a trammel-scribed or approximated helix or curve centerline at that radius.

I am not sure why the Ribbonrail gauges don't have slots or guides as the Tracksetta style do -- would it have impaired their precision as gauges to mill slots in the center, or even just put some holes on center for pinning without springback?  That would be of particular value if access is restricted, as for an assembled helix of multiple turns to minimize grade where Kevin's problem having to drill the sub grade for fixation rears its head...

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Posted by riogrande5761 on Friday, August 28, 2020 2:16 PM

jjdamnit

Hello All,

The largest radius sectional track I can recall was 24-inches. 

It was produced by Atlas and is out of production.

Unfortunately, I believe the DYI might be the solution.

Might I suggest Luan plywood as your base? You can find it at most Big Box home improvement stores.

This is available in 5mm (13/64") thickness, just a hair thicker than 3/16" roadbed.

You can bevel the edges; just like roadbed, for a more prototypical appearance and feather the ends on the transitions.

Hope this helps. 

KATO makes 31 inch UNI track - which I already knew.

Luan may be an option for some sort of base to attach flex too.

Rather than using pre-fab  sectional track, why not make your own using flex track.

That's been covered already - read above discussion.

 

Rio Grande.  The Action Road  - Focus 1977-1983

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Posted by jjdamnit on Friday, August 28, 2020 2:01 PM

Hello All,

The largest radius sectional track I can recall was 24-inches. 

It was produced by Atlas and is out of production.

Unfortunately, I believe the DYI might be the solution.

Might I suggest Luan plywood as your base? You can find it at most Big Box home improvement stores.

This is available in 5mm (13/64") thickness, just a hair thicker than 3/16" roadbed.

You can bevel the edges; just like roadbed, for a more prototypical appearance and feather the ends on the transitions.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by RR_Mel on Friday, August 28, 2020 1:50 PM

riogrande5761

As for sweepsticks, if those are meant to draw an accurate center-line, I have a home-made trammel that can do that:

It does some down to a convenience vs. cost thing. 

A scratch built helix made from 1/2 inch wood subroadbed is what I was originally planning and with that I can simply and nail the track down as I add to the helix.  

 

I made my own helix using the old school way too.  I was short on hobby money in 1989 so I went cheap on everything on my new layout.  The lowest cost ¼” ply back then was OSB, I bought a 4’x8’ sheet and used my jigsaw to cut 30” radius center 4” wide sections, made a splice under the joints with scrap OSB.

I used 1”x2” supports both sides every 10” notched (⅜”) for the curved OSB (slip fit).  I went with wood screws and Elmer’s wood glue on every joint on my layout.

I used Midwest Cork roadbed and Atlas track nails, the OSB wouldn’t accept the nails (too hard) so I ended up drilling pilot holes for every nail and screw.

I ended up with a 1½ loop helix with a 10” gain equaling 3.6% grade.  That was 31 years ago and never a problem, super sturdy!

The helix is partially covered with my Red Rock Mountain (green).



Mel


 
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Posted by doctorwayne on Friday, August 28, 2020 1:20 PM

Rather than using pre-fab  sectional track, why not make your own using flex track.

If you have a place where you can draw the curve radius on a solid surface that will accept small nails or screws, simply put down a piece of flex following the drawn curve, then tack it in place and apply cement to the interface between tie and rail.  I'd guess that perhaps every 5th or 6th tie might be sufficient, but it might need a little experimentation. This will give you sectional track in longer pieces, requiring less on-layout soldering.

Once the joints have hardened, trim the ends of the rail as necessary, then repeat the process as needed.  When you have sufficient pieces, solder them together while each piece is at least partially on the drawn radius. 

This will likely become more and more cumbersome to handle as you add new sections, but you could simply do segments of a size easier to handle, making for less make-them-on-the-layout joints.

Using ordinary sectional track would require many more joints, so why make the task more difficult?

Most of the curves on my layout are a 34" (or greater) radius, but the're all laid on cut-out 3/4" plywood roadbed, with a drawn centreline.  While it was pretty-well all within easy reach when installing the track, had it been difficult to reach, it would have been easy to simply put together a number of roadbed sections, add the track at the workbench (or on the floor, if necessary), then, perhaps with a little help, feed the whole shebang into the area where it's supposed to be.

Wayne

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Posted by riogrande5761 on Friday, August 28, 2020 12:59 PM

BMMECNYC
 

You could try Micro Engineering track.  It generally holds its shape once you bend it.  It does take some getting used to working with it, but this would probably be easier and cheaper than using sectional track in the long run.  A Fast Tracks Sweepsticks guage will help you get it exactly the radius you want.

https://www.handlaidtrack.com/sweepsticks-ho-curved

I already have plenty of flextrack and personally don't care for the difficult to form ME flextrack.

As for sweepsticks, if those are meant to draw an accurate center-line, I have a home-made trammel that can do that:

It does some down to a convenience vs. cost thing.  I can do it with flex track; I have the abilty and the skills but am looking for an easier way.  If I need to use flextrack, I'll have to do some mulling over how I can lay it given the option I am considering - pre-cut gator board helix.  Even my wife has approved it although it costs a good deal more than a scratch-built helix made out of wood.

A scratch built helix made from 1/2 inch wood subroadbed is what I was originally planning and with that I can simply and nail the track down as I add to the helix.  

Ribbon Rail makes an alignment gauge for 34 inch HO track.  For building a helix of they size it would be a worthwhile investment.

A possible aid, but normally I just lay flex track and use Atlas track nails nailed in on the center-line I draw with a trammel - old school and worked very well on past layouts.

Bottom line is it sounds like nobody has identified any ~34"R sectional curve track other than what I had already found (i.e. Kato 34 1/8 inch 10 degree curve sections).

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Posted by MisterBeasley on Friday, August 28, 2020 11:33 AM

Ribbon Rail makes an alignment gauge for 34 inch HO track.  For building a helix of they size it would be a worthwhile investment.

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Posted by Anonymous on Friday, August 28, 2020 11:15 AM

riogrande5761

Since I plan to run 89' auto racks and TOFC flat cars and this will be a helix, my thoughts are the broader the better.  I have room for 34 inch radius and an increase in 3 inches (over 31"R) at that range or radius could make a significant difference, especially since there will be grade and "grade equivelent" effects at play too.

KATO does make the 34 1/8th but it would take a boat load of them and cost a small fortune.  So I may look at ways to mount flex track onto something precut to drop in in sections and connect them together.

 

You could try Micro Engineering track.  It generally holds its shape once you bend it.  It does take some getting used to working with it, but this would probably be easier and cheaper than using sectional track in the long run.  A Fast Tracks Sweepsticks guage will help you get it exactly the radius you want.

https://www.handlaidtrack.com/sweepsticks-ho-curved

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Posted by riogrande5761 on Friday, August 28, 2020 11:02 AM

Since I plan to run 89' auto racks and TOFC flat cars and this will be a helix, my thoughts are the broader the better.  I have room for 34 inch radius and an increase in 3 inches (over 31"R) at that range or radius could make a significant difference, especially since there will be grade and "grade equivelent" effects at play too.

KATO does make the 34 1/8th but it would take a boat load of them and cost a small fortune.  So I may look at ways to mount flex track onto something precut to drop in in sections and connect them together.

Rio Grande.  The Action Road  - Focus 1977-1983

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Posted by SeeYou190 on Friday, August 28, 2020 10:48 AM

I have had nothing but excellent experience using Kato track form hidden trackage. If your equipment will run on a Kato 31" curve, that could be an excellent solution.

I use Kato 22" track as my hidden minimum. and I do need to make some concessions in equipment, like 4-8-4s just will not run on it.

I would imagine nearly anything will run on a hidden 31 inch curve.

I can send you a circle of Kato 31" track to try out, but you would need to send it back.

-Kevin

Living the dream.

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Posted by PRR8259 on Friday, August 28, 2020 10:43 AM

I had ALL Kato trackwork, then at a point in time improved some radii with Walthers/Shinohara sectional curved track.

Better train stores may still have some of that Shinohara sectional curved track in stock--that's how I found mine--in the Bowser retail train store (also affiliated with Toy Train Heaven).  However, that Shinohara track comes in full circle boxes.  It IS reasonably priced IF you can find it, and came in 2" radius increments, so they would have something close to 34" or 36" radius.  Bowser has no more of it as I bought the last boxes they had.

But you might find some if you called around.

Otherwise, I've had very good experiences with the Kato track.  The worst thing is the clickety clack of track joints, but that isn't much of a problem.  It's actually quieter track than either Atlas or Shinohara when they are installed on Woodland Scenics soft (black) foam roadbed--the Kato track, glued down with Liquid Nails once you get the configuration correct--is quieter (I skipped the foam roadbed wtih the Kato track).

The reason I just removed the Shinohara curved track and reverted to ALL Kato trackwork is because the ballast/glue mixture slides off the Woodland Scenics black foam roadbed--the end result did not look good on my layout and I grew tired of fighting to get grey ballast to adhere to the black foam roadbed.

John Mock

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Posted by riogrande5761 on Friday, August 28, 2020 10:38 AM

SeeYou190
hinohara used to make them in code 100, but they are probably impossible to find now. The Kato 34 inch ten degree curve matches their #6 turnout to bring the diverging track back to parallel. Kato makes a ~31 inch curve in 22.5 degree sections. It will still take 16 pieces to make a circle. This might be the best you can do right now.

I regularly work with flex track and could lay with it, but my job would be made much easier if I could use pre-fab in this one hidden area that needs to go full circle.  I am aware of the KATO 31 inch curves, but really want to stick with 34 inches in this application as I do plan to run 89' cars and the larger radius would be significantly better.  My mainline minium is planned at 32" (or larger where possible).

Right now my only options that am aware of are the Kato 10 degree pieces, or flex, which in this case would be harder to install, but doable.  If no such beast exists. then thanks for looking.

Rio Grande.  The Action Road  - Focus 1977-1983

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