# Joining HO Flex track



## danpuckett (Dec 31, 2014)

Is it normal procedure to solder each track joint?


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## feldon30 (Dec 30, 2012)

Once you've got everything the way you want it, then yes, I believe that is the practice. For now, we are tacking down all our cork and flex track and switches with small nails and getting everything the way we want it, so that we can make changes if need be. *Once things are really locked down and we've had a number of playtests and op sessions, only then will we solder, glue, ballast and screw.*

One discussion we had at RMU was about how much your layout will expand/contract due to temperature and humidity. What I found out is, it's not the metal that is of a concern, as a difference from 0°F and 100°F will only cause a small expansion. However increases in temperature and humidity will cause the benchwork to expand greatly, as much as 1/4" inch over a span of a few feet.

*The solution is to leave a few UNSOLDERED expansion joints in your track on the straightaways.
*
If you are running drops every 3' segment, then you won't have any issues of power drop. Heck, just with rail joiners I've powered a loco 30 feet away from the nearest power drop, but that's on pristine track and a pristine engine. Ask me again 10 years from now if it will pickup power from such a distance.


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## riogrande (Apr 28, 2012)

I had a garage layout where I soldered all of my flex track and when it contracted, many of the solder joints broke. After that I started leaving most of the straight sections unsoldered and made sure there were plenty of electrical feeds from the bus to the rail so there wouldn't be any dead spots, which can happen when rail joiners fail to pass the power on to the next piece of flex track.


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## sstlaure (Oct 12, 2010)

I don't solder any of mine, but I stagger the ends of the track through corners (don't clip them even with each other, just let the rail on the inside get "longer" and run it into the next section of track.

Remove the ties where the joiners are and install. Let the track have some room to expand/contract as your benchwork WILL move a little with changes in humidity.

Even doing this I had a couple areas on my layout (inside the helix) where I had to re-trim the ends to provide a little extra clearance (due to buckling over time.)

Everything was working smooth for months, then all of a sudden I started having de-rails inside my helix. Got in there and the track had buckled up....


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## DonR (Oct 18, 2012)

If your layout is in a climate controlled area you'll have less need
of soldering. Also, if you have fairly easy access to all of your
layout, then you could 'get by' with using only joiners. But you
can expect to lose some conductivity in some of the joiners over time. That
may be when you would want to start soldering. But, if you have
tracks that are not easy to get to you might want to go ahead and
solder as you install. Often when you are ballasting, the glue will
seep into the joiners and block conductivity, you'll need to solder
those.

Some of my joiners are soldered, some are not. 

Hows that for a very thought out, Maybe?

Don


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## riogrande (Apr 28, 2012)

When I lay a curve with flex track, I cut the inner rail, which sticks out, so that it is even with the outer rail. I only need to cut one tie on each end to allow rail joiners to fit on the ends of the rail.

Regarding climate controlled - i.e. constant temperature/humidity, I agree, the track should not expand and contract much if that's the case.

There are two reasons why hobbyists solder rail:

1) to keep rail flowing smoothly on curves, soldering can help prevent kinking at the joint due to the tendency for the springy rail to want to bend outwards.

2) to have more reliable conductivity from one rail to the next. 

As noted, you don't have to solder every joint and in environments which are not climate controlled, it might be advisable to leave joints un-soldered so rail can float in and out as it expands and contracts. If you do, you can help insure reliable power to all rail if you provide frequent wire connections to the rail, such as every other section of flex track as an example. What I do is solder a feeder to the bottom of many of the rail joiners so that electricity will feed to the rail from ferquent positions along the way.


If you lay the track in the warm, the track will likely contract in the cold, so there will be a gap form - that's OK as long as the gap isn't real big. If lay trak in the cold times, then you should leave a gap so the rail doesn't kink when it expands - perhaps a credit card width may be sufficient gap.


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## CTValleyRR (Jul 26, 2014)

I solder mine in 6-8 foot sections, and leave the joints between those sections unsoldered. I try to avoid unsoldered joints on curves. Each section has it's own feeder.

Issues with expansion and contraction are more due to expansion and contraction of the base (plywood, dimensional lumber, etc.). We just don't have enough metal on our layouts to make that much difference, except in extreme climate swings.


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## riogrande (Apr 28, 2012)

Interesting. Usually if there are any joints I do solder, it's on the curves and leave the straights unsoldered.

Also, I've seen a number of folks in Train Orders forum report that it is NOT the base (plywood, dimensional lumber etc.) which is to blame for the expansion and contraction. I agree with them - it's the metal rail that is doing the expanding and contracting. I saw this first hand when I built a layout in a garage in Indiana. (non climate controlled).

I guess coming to forums may only cause confusion to people asking questions when they get some very difference answers.


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## tjcruiser (Jan 10, 2010)

I'd recommend pre-bending your flex:



tjcruiser said:


> Flex is a great asset. That said, it can be tricky to position and join the flex ends if you have inherent curvature at the endpoint. (The track wants to spring back.)
> 
> However, you can "prebend" the flex into your desired shape, in a manner that it will hold its curve. See Choo Choo Greg's thread ...
> 
> ...


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## riogrande (Apr 28, 2012)

Prebending is only necessary if you use the stiff flex track. I'm using Atlas code 83 and it is springy and will easily conform to the centerline which I've drawn.


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## mopac (Feb 24, 2011)

danpuckett is getting differences in info. Some do solder and some don't. My last layout
I soldered. Very smooth when soldered and sanded down. My new layout I am NOT going
to solder. Why? You loose all the clickity clack from metal wheels. And I think it is as easy
to solder on feeders as doing the joints. I plan on feeders to each piece of track. I don't
trust the joiners to carry the power over a long time. Joiners are mainly to keep the rails aligned with each other.


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## feldon30 (Dec 30, 2012)

riogrande said:


> Also, I've seen a number of folks in Train Orders forum report that it is NOT the base (plywood, dimensional lumber etc.) which is to blame for the expansion and contraction. I agree with them - it's the metal rail that is doing the expanding and contracting. I saw this first hand when I built a layout in a garage in Indiana. (non climate controlled).
> 
> I guess coming to forums may only cause confusion to people asking questions when they get some very difference answers.


The funny thing is, my info is from guys who have been modeling for 40 years. But personally I'd like to see a scientific test with measurements and so forth to find out if it's really the benchwork or the rail that's expanding and contracting. It's probably impossible just to tell at a glance unless you exactly measure all your tables at different ambient temperatures and humidities.

We need an episode of Mythbusters!


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## gator do 65 (Jan 27, 2014)

As stated earlier it is the lumber unless you're using an OSB or a fiber-based board like masonite.
The only way to lessen this expansion/contraction would be to use kiln dried lumber and seal it to keep moisture out, as this is the main cause not so much the temp.


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## sstlaure (Oct 12, 2010)

No way the steel is expanding/contracting vs your benchwork.

As an Engineer - I'm not buying it. Wood expands/contracts orders of magnitude more than steel does - especially with humidity.

Steel isn't hygroscopic (water absorbant) - wood is.


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## mopac (Feb 24, 2011)

I don't know if the rails contract or expand, but I do know wood will contract or expand.
Here are some examples. I have a couple of interior doors that every winter they stick at the top when opening and closing them. Summer months no problems. I am putting new hardwood floors throughout the house and place I bought the flooring from said be sure and let the flooring sit 7 days inside to acclamate to the house before laying the floor.
That's so it will not contract or expand depending on house conditions.

Humidity is the problem. Not temp as stated earlier.

Your house is much drier in the winter.


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## MtRR75 (Nov 27, 2013)

mopac said:


> I don't know if the rails contract or expand, but I do know wood will contract or expand.
> I am putting new hardwood floors throughout the house and place I bought the flooring from said be sure and let the flooring sit 7 days inside to acclamate to the house before laying the


Also, flooring should not be installed right up to the wall. There must be a small gap to allow the floor to expand and contract. The gap is covered by the baseboards and/or quarter rounds. If you don't leave the gap, the floor will buckle.


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## gator do 65 (Jan 27, 2014)

Ok I see some of you folks are in the cold states as we debate this, could someone take a piece of 36" flex track and measure it at room temp first and let it sit out over night and then re-measure that should give an idea of the contraction! It's just a thought! 

I understand this does not address the buckling issue but in theory contraction could pull up an outside rail in a corner if it were soldered!


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## MtRR75 (Nov 27, 2013)

gator do 65 said:


> Ok I see some of you folks are in the cold states as we debate this, could someone take a piece of 36" flex track and measure it at room temp first and let it sit out over night and then re-measure that should give an idea of the contraction! It's just a thought!


Before anybody tries this, what are you going to use to measure the track with? A steel tape perhaps? -- which is also made of metal -- and if the metal is going to expand or contract, couldn't the tape be subject to the similar minor changes in length?


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## sstlaure (Oct 12, 2010)

Steel is used in many structural applications (concrete) to protect against shrinkage and temperature effect. 

Just read a heat treatment paper talking about a 0.08% length change during heat treatment - you're talking over a thousand degrees in this process. 

So 36" would become (36*1.0008)= 36.0288" - it's insignificant.

I don't see steel changing length with even a 100 degree swing.

The wood/etc that our layouts are built of DEFINITELY expand/contract with weather/humidity. Ever heard a house creaking? The wood flooring example above illustrates this perfectly - the wood needs room to expand/contract or it binds up.


Actually - even better:

Assume 20 degree swing:
Thermal Expansion Coefficient of Steel = 7.2*10^6 (or 0.0000072) (Amount steel expands with 1 degree increase of temp)

So 20* .0000072 = 0.000144
36" * 0.000144 = 0.005"
So a 36" piece of flextrack going through a 20 degree swing made of steel would grow 0.005" - or about 1/10 the thickness of an average human hair.

So even with a 100 degree temp swing - you're talking 0.025" - 1/2 the thickness of a human hair.


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## CTValleyRR (Jul 26, 2014)

sstlaure has this correct. A masterly analysis. Now, if you have 1000 feet of track in your layout, and no expansion joints, a one degree increase will change the length of the track by 0.0072 inches. 10 degrees by 0.072 and so on. Real railroads have trouble with heat expansion for two reasons: 1) they have hundreds of miles of rail, not a couple hundred feet, and 2) they have wooden ties (rails laid on concrete ties are very resistant to heat warping).

For an example closer to home, how many people have wooden doors in their houses that work perfectly in the winter and get stuck in the summer. Or have windows that work in summer and get all drafty in winter. Put another way, why do they also make doors out of fiberglass and steel.

Mythbusters not needed. Only facts. With all due respect to those who have been in the hobby 40+ years, they're wrong if they think the steel is the primary component of expansion and contraction.


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