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…
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.)
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…
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 b
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.
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…
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.
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.
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.
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.
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.
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.
I second the DAP Alex Plus. Translucent is what they call "clear " and it comes out white which is disconcerting until it dries “translucent” which is clear by any reasonable measure.
Case in point, yesterday I was re-aligning a connector track between our pusher track, which connects to the main line at the bottom of a grade, to our engine yard and main yard access tracks. The Woodlands underlay was glued to a styrofoam base and the track nailed into that. Pulling up the underlay caused no damage to it and the DAP was still tacky enough to hold the underlay down in the new alignment. I just had to add a bit more DAP to cover the new alignment portion. I don’t know for how long it would stay tacky but under that foam underlay on top of styrofoam it stayed reusable for a month.
Its a bit like those 3M sticky notes. Sticks just enough to work but not too well.
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".
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.
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