Topics

Wiring a Helix for DCC

Brian Eiland
 
Edited

I've seen a few references that suggest it is NOT necessary to run the bus-lines along the track route in a spiral helix, but rather just run the track feeders lines down one of the vertical legs (post) to the bus wires at the bottom. I thought this was a good idea.

My question is how many of these vertical connections should be made?

My helix is a double track affair with radii of 32.5” and 29.5”. I have plans to stagger the rail joints, and to solder all the rail joints,...code 100 Atlas rail.

Considering this sort of relatively small radius/circumference, I'm thinking I need only one feeder set of wires for each elevation/loop of the helix. And perhaps these feeders wires might be sized a bit larger than normal??

wirefordcc
 

Our first customer for the new Q&A forum!  Let’s see if this reply works. 

 

Note:  Some people solder joiners on a curve.  Others would debate whether doing this on every joiner wise given expansion/contraction issues.  I’m not experienced enough with doing this to comment on the wisdom of this approach.  I will only address the power feeder question.

 

A good rule is that every piece of track should be soldered to something; whether it be the next piece of track or a feeder.  Since you are going to solder every joiner in your helix, it should be adequate to run a bus up one side of the helix and also half way around the helix.  Definitely do not run the bus completely under the spiral of the helix.

 

I was in a club that supported their helix with threaded rod.  Then there nuts to support each spiral of the helix.  This was simple and made it easy to get the incline of the helix just right.  They applied power to the threaded rods.  The threaded rods became the bus.  Then wires were run from the threaded rod to the track.  The feeders were attached to the threaded rod using star washers that have solder tabs on them.  You should be able to get threaded rods from Mouser, Digikey, or similar electronics supply stores.

 

Allan Gartner

Wiring For DCC

Vollrath, Don
 

Brian, An ideal connection is to have a track bus feeder about every 6 ft. What I might recommend is …

Run a sub-bus up/down along one of the uprights. 14-16 AWG

Add track feeders to the sub bus at each circular pass of the spiral.

Solder the track joints in the spiral for alignment and continuity.

Leave plenty of space gaps in the rails at top and bottom for expansion/contraction.

This should be adequate.

 

But with an approx. 33 inch outside radius, the rail length on each turn will be ~17 ft long…. Or about 8+ feet from the nearest outside upright and track feeder. There is no need to follow the track along the spiral with an electrical wire, but if you are overly concerned, providing a second sub-bus and connecting to each set of rails at each pass on an opposite upright will double the electrical connections and reduce the electrical path to the nearest feeder to be less than 5 ft. A little on the side of overkill.

 

DonV

 

 

From: w4dccqa@groups.io [mailto:w4dccqa@groups.io] On Behalf Of Brian Eiland
Sent: Thursday, June 07, 2018 1:10 PM
To: w4dccqa@groups.io
Subject: [w4dccqa] Wiring a Helix for DCC

 

I've seen a few references that suggest it is NOT necessary to run the bus-lines along the track route in a spiral helix, but rather just run the track feeders lines down one of the vertical legs (post) to the bus wires at the bottom. I thought this was a good idea.

My question is how many of these vertical connections should be made?

My helix is a double track affair with radii of 32.5” and 29.5”. I have plans to stagger the rail joints, and to solder all the rail joints,...code 100 Atlas rail.

Considering this sort of relatively small radius/circumference, I'm thinking I need only one feeder set of wires for each elevation/loop of the helix. And perhaps these feeders wires might be sized a bit larger than normal??

John Cahill
 

I have a similar helix and use threaded rod but never thought to use them as a bus. Interesting concept. I did stagger joints as it helped keep kinks out of the rails. I fed the busses up round the rods inside and outside for the two lines and wound them round the rods taking feeders off to each yard of track (don’t like soldering fishplates to track). Solder as usual to convenient spot on the rails. Hope this helps.

Best Regards,
John

Brian Eiland
 

This subject of track expansion comes up again and again. I even started a separate subject thread on this subject, and it does appear to be a roadbed issue rather than the track itself

Track or Subroadbed, ...Expansion\Contraction problems
http://model-railroad-hobbyist.com/node/33144

What exactly is the problem that almost all us face with our model railroad track seeming to change shape (length in particular), with temp & humidity variations? Can it be attributed to the track alone, or the subroadbed alone?  ...or primarily to __?

I've heard a number of folks who say the expansion/contraction of our rail itself is minuscule compared to that of the wood that most of our subroadbeds are constructed of.?... And that is the primary reason we experience what appears to be a change in track length, but its really the roadbed the track is attached to??





On Thu, Jun 7, 2018 at 3:27 PM, John Cahill <johncahill25@...> wrote:
I have a similar helix and use threaded rod but never thought to use them as a bus. Interesting concept. I did stagger joints as it helped keep kinks out of the rails. I fed the busses up round the rods inside and outside for the two lines and wound them round the rods taking feeders off to each yard of track (don’t like soldering fishplates to track). Solder as usual to convenient spot on the rails. Hope this helps.

Best Regards,
John


Don Vollrath
 

Yes Brian. It is the roadbed that contracts and expands far more so than the metal rail. When the roadbed shrinks and there is no place like a gap at rail joints for the rail to slide into it can force a kink to occur. If you have neatly nailed down flextrack in multiple places the rials will kink and make wave-like curves between the nails. So in a multi-turn helix one might be better off soldering all rail joints but only securing the track with one nail per helix turn. Now you will not notice the change in roadbed dimension as the track, ties and all, will move ever so slightly.

DonV

Brian Eiland
 

One nail per helix turn sounds like far to little in a helix spiral? Did you perhaps mean one nail per 36" section of track?? .....Even that sounds questionable.
Brian
*************************************


On Thu, Jun 7, 2018 at 10:17 PM, Don Vollrath <donevol43@...> wrote:
Yes Brian. It is the roadbed that contracts and expands far more so than the metal rail. When the roadbed shrinks and there is no place like a gap at rail joints for the rail to slide into it can force a kink to occur. If you have neatly nailed down flextrack in multiple places the rials will kink and make wave-like curves between the nails. So in a multi-turn helix one might be better off soldering all rail joints but only securing the track with one nail per helix turn. Now you will not notice the change in roadbed dimension as the track, ties and all, will move ever so slightly.

DonV

Timothy Holmes
 

Im listening to this discussion closely, as I am about to begin construction of a helix

TIM

On Fri, Jun 8, 2018 at 7:57 AM Brian Eiland <railandsail@...> wrote:
One nail per helix turn sounds like far to little in a helix spiral? Did you perhaps mean one nail per 36" section of track?? .....Even that sounds questionable.
Brian
*************************************


On Thu, Jun 7, 2018 at 10:17 PM, Don Vollrath <donevol43@...> wrote:
Yes Brian. It is the roadbed that contracts and expands far more so than the metal rail. When the roadbed shrinks and there is no place like a gap at rail joints for the rail to slide into it can force a kink to occur. If you have neatly nailed down flextrack in multiple places the rials will kink and make wave-like curves between the nails. So in a multi-turn helix one might be better off soldering all rail joints but only securing the track with one nail per helix turn. Now you will not notice the change in roadbed dimension as the track, ties and all, will move ever so slightly.

DonV

--

Tim 

San Luis and Rio Grande

Dale Gloer
 
Edited

For what it's worth, on my previous layout I had a 4 turn, 2 track helix in HO with a 27 inch radius.  Each turn was split into 2 parts with detection on each part.  I ran the track feeders down the the track bed supports to terminal blocks that connected to current detectors.  This arrangement was absolutely trouble free.  I used 18 gauge wire for all the track feeders from the terminal blocks.  Don't skimp on wire size.

Dale Gloer

John Cahill
 

I see where Don is coming from and how that would work. I used plywood and it doesn’t move noticeably even with significant temperature changes. 

Best Regards,
John

On 8 Jun 2018, at 13:28, Timothy Holmes <taholmes160@...> wrote:

Im listening to this discussion closely, as I am about to begin construction of a helix

TIM

On Fri, Jun 8, 2018 at 7:57 AM Brian Eiland <railandsail@...> wrote:
One nail per helix turn sounds like far to little in a helix spiral? Did you perhaps mean one nail per 36" section of track?? .....Even that sounds questionable.
Brian
*************************************


On Thu, Jun 7, 2018 at 10:17 PM, Don Vollrath <donevol43@...> wrote:
Yes Brian. It is the roadbed that contracts and expands far more so than the metal rail. When the roadbed shrinks and there is no place like a gap at rail joints for the rail to slide into it can force a kink to occur. If you have neatly nailed down flextrack in multiple places the rials will kink and make wave-like curves between the nails. So in a multi-turn helix one might be better off soldering all rail joints but only securing the track with one nail per helix turn. Now you will not notice the change in roadbed dimension as the track, ties and all, will move ever so slightly.

DonV

--

Tim 

San Luis and Rio Grande

Vollrath, Don
 

A good alternate is to use typical slip-joint type rail joiners with a slight gap in the rails to allow for track-bed movement. Firmly anchor the ties on both sides of each rail joint to help prevent any kinking. Then add an electrical feeder to every section of rail not soldered to another rail with an electrical feeder to the power sub-bus to ensure there will never be any discontinuity.

 

DonV  

 

From: w4dccqa@groups.io [mailto:w4dccqa@groups.io] On Behalf Of John Cahill
Sent: Friday, June 08, 2018 8:33 AM
To: w4dccqa@groups.io
Subject: Re: [w4dccqa] Wiring a Helix for DCC

 

I see where Don is coming from and how that would work. I used plywood and it doesn’t move noticeably even with significant temperature changes. 

Best Regards,

John


On 8 Jun 2018, at 13:28, Timothy Holmes <taholmes160@...> wrote:

Im listening to this discussion closely, as I am about to begin construction of a helix

 

TIM

 

On Fri, Jun 8, 2018 at 7:57 AM Brian Eiland <railandsail@...> wrote:

One nail per helix turn sounds like far to little in a helix spiral? Did you perhaps mean one nail per 36" section of track?? .....Even that sounds questionable.

Brian

*************************************

 

 

On Thu, Jun 7, 2018 at 10:17 PM, Don Vollrath <donevol43@...> wrote:

Yes Brian. It is the roadbed that contracts and expands far more so than the metal rail. When the roadbed shrinks and there is no place like a gap at rail joints for the rail to slide into it can force a kink to occur. If you have neatly nailed down flextrack in multiple places the rials will kink and make wave-like curves between the nails. So in a multi-turn helix one might be better off soldering all rail joints but only securing the track with one nail per helix turn. Now you will not notice the change in roadbed dimension as the track, ties and all, will move ever so slightly.

DonV

 

--

Tim 

San Luis and Rio Grande

Stephen Lamb
 

This is how I constructed my helix:-

https://www.youtube.com/watch?v=PueNBxQd8No

The Bus is clipped to the inner edge of each 9.5mm thk board which are cut out in 120deg arcs using a template which also positition holes for the M12 screwed rod stantions. Each length of rail has a soldered tail running from the bus and completed as each level is added.

Dale Gloer
 

John,  the expansion/contraction issue with any kind of wood is mostly related to the humidity of the environment, not so much on temperature.  Plywood should move a lot less than dimension lumber but is not immune to it.  I live in a semi-desert climate with large differences between summer and winter temperatures and therefore large swings in humidity.  My benchwork is all plywood and I still get issues with seasonal expansion and contraction.

Dale Gloer

Stephen Lamb
 

I sealed all surfaces and edges of the plywood segments with a 50/50 water/PVA mix.and have not experienced any problems with expansion or contraction although the monitored humidity fluctuates between 45% and 84% with temperatures between +5degC and 24degC. The shed  has automatic frost protection that kicks in at +5degC. The inner walls are lined with plywood to inhibit condensation and are constructed with vapour barrier membrane/50mm polystyrene insulation and 50mm air gap as so are the walls and ceiling. There are adjustable slots in the ceiling to provide ventilation.

Charles Brumbelow
 

Has anyone experimented with sealing the roadbed to reduce expansion and contraction? Shellac might be satisfactory and inexpensive.

Charles

John Cahill
 

Guess my next layout will be plywood painted with diluted PVA to seal it! We don’t get extremes in temperature but humidity can go from very dry temperate climate to cold wet, and change can be fast. 

Best Regards,
John

On 9 Jun 2018, at 16:15, Dale Gloer <dale.gloer@...> wrote:

John,  the expansion/contraction issue with any kind of wood is mostly related to the humidity of the environment, not so much on temperature.  Plywood should move a lot less than dimension lumber but is not immune to it.  I live in a semi-desert climate with large differences between summer and winter temperatures and therefore large swings in humidity.  My benchwork is all plywood and I still get issues with seasonal expansion and contraction.

Dale Gloer

Brian Eiland
 

PVA,....basically wood glues we use so often?

I also found this...
http://www.instructables.com/topics/What-is-the-difference-between-PVA-glue-and-Elmers/

On Sat, Jun 9, 2018 at 6:48 PM, John Cahill <johncahill25@...> wrote:
Guess my next layout will be plywood painted with diluted PVA to seal it! We don’t get extremes in temperature but humidity can go from very dry temperate climate to cold wet, and change can be fast. 

Best Regards,
John

On 9 Jun 2018, at 16:15, Dale Gloer <dale.gloer@...> wrote:

John,  the expansion/contraction issue with any kind of wood is mostly related to the humidity of the environment, not so much on temperature.  Plywood should move a lot less than dimension lumber but is not immune to it.  I live in a semi-desert climate with large differences between summer and winter temperatures and therefore large swings in humidity.  My benchwork is all plywood and I still get issues with seasonal expansion and contraction.

Dale Gloer

Flash Gordon
 

HI Charles,

Interesting idea, but can you still get Shellac. I think that was made out of bug stuff. Everything is so synthetic now.

Google info:

Shellac is a resin secreted by the female lac bug, on trees in the forests of India and Thailand. It is processed and sold as dry flakes (pictured) and dissolved in ethanol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish.

Ed S


On 6/9/2018 6:20 PM, Charles Brumbelow via Groups.Io wrote:
Has anyone experimented with sealing the roadbed to reduce expansion and contraction? Shellac might be satisfactory and inexpensive. 

Charles

Harlan Boyce
 

Just use a latex outside house paint. Get a light to medium color. Put a couple of coats and you will be fine

Boyce's iPhone

On Jun 9, 2018, at 5:20 PM, Charles Brumbelow via Groups.Io <mrb37211=yahoo.com@groups.io> wrote:

Has anyone experimented with sealing the roadbed to reduce expansion and contraction? Shellac might be satisfactory and inexpensive.

Charles


Charles Brumbelow
 

Speaking of helixes and their wiring...

https://youtu.be/-hPuNFjRTZA

Charles