Joining flextrack on a curve...


CbarM

CbarM

HO all the way!
Hey guys, I am laying some track temporarily to see how it all fits. I have a minimum 26" radius on the main and it will all be flex track except for switches. I have laid down 7 or 8 joints of it so far and screwed it down temporarily and cut the inside rail to make it fit but the one problem I am running into is where it actually joins it wants to straighten out and sort of kink the joiner...do you guys have any tips on how to keep flex track curve joints to a smooth transition??
 
Im not sure how to fix that when temporarily laying down track, but when you are ready to fix it permanently I have some suggestions. One tip is to drill a small hole for a track nail on the last tie of your pieces, and nail them down to help elimanate flex. Also, soldering the rail joiners helps prevent that as well. I know exactly what you mean though as we used to have the same problem. Maybe another member of this site will have better advice, but that has worked for us. Goodluck!
 
Having been out of the hobby for the last 7 years, I remember keeping the sliding rail on the outside of the curve and as you approach the end of the flex track, leave 6-8" free and place the next flex and solder the rail joiners and continue bending. Hope I remember correctly!
 
OK sounds good, I found that putting a screw between the last 2 ties and then about 6" up from that helps to keep the curve at the end, but as much as everybody suggests soldering the joints I would like to avoid that if possible for easy track reconfiguration...
 
TRAINFAN9510 said:
Im not sure how to fix that when temporarily laying down track, but when you are ready to fix it permanently I have some suggestions. One tip is to drill a small hole for a track nail on the last tie of your pieces, and nail them down to help elimanate flex. Also, soldering the rail joiners helps prevent that as well. I know exactly what you mean though as we used to have the same problem. Maybe another member of this site will have better advice, but that has worked for us. Goodluck!
Click to expand...
yep what he said ;)
 
bwells said:
Having been out of the hobby for the last 7 years, I remember keeping the sliding rail on the outside of the curve and as you approach the end of the flex track, leave 6-8" free and place the next flex and solder the rail joiners and continue bending. Hope I remember correctly!
Click to expand...

Me, I've always done the opposite way. I keep the sliding rail to the INSIDE of the curve. That way I don't have to remove any extra ties from the ends (except the two (2) from each end for rail joiner room).

Dan
 
Really? I thought the reason for the sliding rail to the outside was that as the track bends, the sliding rail will lean outward which may create a larger width between rails whereas if the sliding rail is on the inside it will narrow the distance between rails which is a far worse thing. Please correct me if I am wrong>
 
Soldering the joiners while the two lengths are lying flat on a bench is the way to go, but do try to slide the sliding rail about seven or eight ties into the adjoining length of flex. That way, the sliding rail will conform to the curvature radius determined by the spikeheads around its foot, and help to make the other rail do the same thing. It would be a good idea to still solder the joiner there, if you use one, but you may find that sliding the rail into the other length by several ties obviates the requirement for any kind of joiner. For the sake of electrical continuity, though, a half joiner is a good thing there, and do solder it. Otherwise, you will have to solder a wire feeder to each rail on either side of the gap to ensure continuity.
 
bwells said:
Really? I thought the reason for the sliding rail to the outside was that as the track bends, the sliding rail will lean outward which may create a larger width between rails whereas if the sliding rail is on the inside it will narrow the distance between rails which is a far worse thing. Please correct me if I am wrong>
Click to expand...

?? I've never had any problem with the narrowing of the track guage laying flex track this way. The NMRA track guage tool still shows it to be OK.

As for joint kinking, When attaching the next section of flex I always leave the last 6" of the already laid track straight. I solder the rail joiners and then continue around the curve. Yes, as a rule I always solder my rail joints on curves, but I will leave some rail joints unsoldered on straight sections.

Dan
 
Selector said:
Soldering the joiners while the two lengths are lying flat on a bench is the way to go, but do try to slide the sliding rail about seven or eight ties into the adjoining length of flex. That way, the sliding rail will conform to the curvature radius determined by the spikeheads around its foot, and help to make the other rail do the same thing. It would be a good idea to still solder the joiner there, if you use one, but you may find that sliding the rail into the other length by several ties obviates the requirement for any kind of joiner. For the sake of electrical continuity, though, a half joiner is a good thing there, and do solder it. Otherwise, you will have to solder a wire feeder to each rail on either side of the gap to ensure continuity.
Click to expand...

Sliding the sliding rail in a few ties on the adjoining piece is actually a really good idea. I never thought about that.
 
OK great info guys!! I have used N scale rail joiners before and they might be the way to go as far as a "half" joiner...now, how does one go about soldering the joiners to the rials without melting the ties? Or should I cut the ties off first?
 
If you are not very proficient with a soldering tool, then maybe removing one tie on either side of the solder and then replacing them is the answer. Mind that you do file down the spikehead nubs, and also a very shallow scrape into which the now thicker joint will rest. If you fail to do this, you will get a hump there.

Otherwise, you can place a metal object on either side of the rail joint, but touching the rails well. These will act as heat sinks. Even rolled bits of soaked paper towel draped on either side of the joint will help to keep heat from melting the ties if you decide you'd rather leave them in place.

Get your iron tip clean and hot, then clean again, then tinned. It would help to have a thin sheen of non-acid paste flux inside the joiner when you apply it, and then when you touch the hot tinned tip of the pencil or iron to your joint, you'll get a quick fzzt and then you remove the tip...you're done.

As for the half-joiner, I mean using your Dremel-type rotary tool's thin cut-off disk to cut a scale joiner in two.
 
OK sounds good, I have just been slicing off the rail spike on the end ties to slide a joiner in, but might have to carve a lil bit of a divit to avoid the humps. I am goin to the LHS this week to get some roadbed n what is better, the cork split sections or the woodland senics 24' continuous roll for doing curves? Are they the same height in case I decide to use both? Also along with the paste flux I will pick up, is there any specific type of solder to use?
 
You should be sure to get the acid free solder. Try to get the thinest solder available to get it down close to the rail joiner.
For the cork, just do the math for best price.
 
Bringing this back to the top.

I had thought I had an epiphany last night. Trying to figure out how to avoid kinks I came to the realization that sliding the rail into the other section avoided it for the most part. I went much more than a few ties, I went about half way into the other section.
Then I read this thread lol.

Anyhow, what I wanted to question was this:
Selector said:
Get your iron tip clean and hot, then clean again, then tinned. It would help to have a thin sheen of non-acid paste flux inside the joiner when you apply it, and then when you touch the hot tinned tip of the pencil or iron to your joint, you'll get a quick fzzt and then you remove the tip...you're done.
Click to expand...

Coming from an electronics back round soldering surface mount devices on PC boards and other things, doing as described is a quick way to make a cold solder joint.

Do you guys not have problems with that? Or is the "quick fzzt" not a good explanation of the time it takes to actually heat the rail enough to get the solder to wick in on its own? The flux has its place, but letting the flux wick the solder in rather than the heat of the rails is a cold joint.
 
I have 45 years as a ham radio operator and am all too aware of the perils of cold solder joints!

However, I seldom depend on the rail joiners to conduct track power, so a cold joint in a track join doesn't matter much to me. I mainly care about a solid mechanical connection, since each section of flex gets its own feeders. In that case, the "quick fzzt" method is probably OK.

- Jeff
 
Here is what I mean...let my images speak for themselves. A quarter of a joiner, obtained by using a jeweler's filamental saw, the sliding rail inserted six or seven ties deep, and soldered as I described.

DSCF1751crres.png


I then ran a locomotive all the way up the track, about 18', including over this section, and it passed by without a hitch. Notice that the feeder is soldered to the same place, but on the outside of the far rail.

In truth, it isn't really an accurate description of the time it takes to make a solid solder...the right kind. I would touch the tip to the joiner, about 3/4 second later the fzzting would start, at which I would expect the solder already on the tip of the iron to begin to wick into the heated zone. Total time with the tip touching the joiner, maybe two full seconds. Sometimes I will also touch the thin solder filament to the other end of the joiner and watch fror the solder to soften there. As soon as I see it begin to shorten/liquify, I consider it done.
 
Last edited by a moderator:
D94R said:
Bringing this back to the top.

I had thought I had an epiphany last night. Trying to figure out how to avoid kinks I came to the realization that sliding the rail into the other section avoided it for the most part. I went much more than a few ties, I went about half way into the other section.
Then I read this thread lol.

Anyhow, what I wanted to question was this:


Coming from an electronics back round soldering surface mount devices on PC boards and other things, doing as described is a quick way to make a cold solder joint.

Do you guys not have problems with that? Or is the "quick fzzt" not a good explanation of the time it takes to actually heat the rail enough to get the solder to wick in on its own? The flux has its place, but letting the flux wick the solder in rather than the heat of the rails is a cold joint.
Click to expand...

Actually, as long as the two items don't move, wicking solder with flux will not create a cold joint. Using solder with a ratio that has a low or no margin of temperatures where it is plastic (between solid and liquid) will minimize the chances of creating a cold joint even if the two items are moved. It's when the solder is in this transition phase where cold joints form.

Also, don't solder ALL the joints. You have to allow for expansion and contraction due to temperature changes. If you don't, your track will kink up by itself.
 
But do solder all joints around a curve correct? And allowbsome joints on the straight section to have some joints unsoldered to allow for expansion?
 
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