It can be difficult.

Offset the gaps. If you look at real jointed track you notice that the joints are always offset. The rails provide the stability so that reduces the chance of a kink. 

My thoughts:?

All your solutions would work. I'd pick the one that best suits your materials on hand and your tools and skills. The first photo with insulated joiners doesn't look too bad to me, maybe just pre-bend the short rails to the curve you need and see how that works. If you have PC board ties and can solder pretty well you could glue down a few of them and get the curve fair. If you'd rather spike the rails you could remove the short piece of cork and glue down something that would hold spikes better. Since it's such a short section I'd try one and see how it goes, if it doesn't work out it's not that much length to re-do.....DaveB

How much offset?

Shawn, interesting.  Yeah, I knew about real track being offset, hadn't thought of that on the layout though.  So any suggestions for how much to offset them?  3 ties?  5 ties?  More?  Less?

Thoughts on Dave's thoughts

Dave, that first shot is with soldered connections, no insulated joiners.

Hadn't thought of swapping out the cork for something more solid, thanks!

I had a similar situation

I had a similar situation using Ho track but only needed one gap.

To avoid the kinking, I cut the flex track a little longer than required. Remove both rails from the ties and bend them to the curvature required.

Rail is then slid back into the ties and the track piece then installed. Replace two ties either side of proposed gap (2 at a time) with PCB ties, cut gap last.

PS: re your suggestion of using 4 screws in foam, I have used this method into plywood. I wouldn't use this in foam, the screws get hot, the foam will melt.

Cheers,

Steve.

Doh!

Thanks Steve.  It never occurred to me that the screws would get hot when I soldered to them.   Sigh.  Its been a long week, OK? 

BEFORE you cut the gaps...

G'day ??

BEFORE you curt the gaps, solder some PCB (printed circuit board ties or blocks) to the rails either side of where you plan your cuts.

For your problem I'd recommend either of these 2 approaches -

• at least 3 ties with the cuts staggered, like
  Tie 1> left rail cut> Tie 2> right rail cut> tie 3 
  
  This keeps your rails in gauge at the cut and makes sure nothing can move in the short distance between the ties, 
• or using a single block like in the in-progress example below. 

In the photo above, the rails have been soldered to the adjacent blocks to jump module joints.  How to do it with one smaller block:

1. you remove the plastic ties to fit your block in the middle of the curve
2. solder one rail to the block
3. using a track gauge, set up and solder the second rail to the block
4. using a Dermel or file cut a groove through the copper between the rails. The PCB block remains solid under this groove and maintains your track gauge.
5. with a multimeter - check that you have no electrical conductivity between the rails (across the cut).
6. cut each rail individually with a thin saw or thin Dremel wheel. Ensure that the cut on each rail goes to the from the outside of the copper block to the central groove between the rails. Make sure you cut all the way through the top copper layer with these cuts. This ensures your track isolation at the cut in each rail.
7. check again that you have no electrical conductivity across the block between each rail.
8. Also check that you have no electrical conductivity between on each rail on either side of the cut on each rail.
9. you should be done at this point and have tracks in gauge around your curve with a cut in each rail that won't go SPROING!!.    

Let us know how you go.

Re: Gaps in curves without kinks?

CA the rails to the ties before cutting the gaps.

It works; the whole saga about cutting gaps on a curve can be read starting with "S-P-R-O-N-G" on page 30 of my blog.

Super glue...

Super glue the rails to the ties on your soldered version, and then cut the gaps staggered a few ties from one another. 

Randy

Bend rails

I have had success with pcb ties soldered to rails I bent manually with my fingers and needle nose pliers. The rail joiners provide the final “true” alignment 

Just cut the gaps in the

Just cut the gaps in the straight rails of that turnout to the right.

Bend the rails by hand

I have also confronted this problem on a few occasions. I just slide each rail out of the sleepers, bend them by hand until they are very close to the required curve, slip them back in, cut to length, put the joiners on and hey presto. Ensuring the rails conform very closely to the curve is imperative and not hard to do. When this is done there is no pressure on the plastic (or metal) rail joiners and they'll sit in place as expected and do their job.

Tony in Gisborne, Australia

The way I have had good results

I model in N scale

I use Fastrack turnouts and ME weathered code 55 track

FT turnouts have already build in gaps near the frog to isolate it

No matter some times I need to cut gap in a curves and course kinking track is on the way

After some try an error I come with this solution 

First I put my track temporary in place to see if it's ok

I mark with a pen the place where a gap need to go

I take of the track and cut away four plastic ties under the gap emplacement two for and two aft

I solder in place four Pcb ties of FT

I put back the track and glue everything in place

I cut the gap when glue is dry, I use diamond thin disk on a Dremel  to cut the gap

This don't disturb the track alignment since the track is firmly soldered and can move and the ties are glued in place ( I use white vinyl glue to glue my track in place on cork)

Sometimes minor adjustment to align track are needed with a plier but this make a steady curved track in place

If you need more gaps in this curve avoid to make them parallel but offset them from a few ties in the same way as described

Except in curves I try to not solder join rail I let them free for expansion and contraction of track but my rule number one is every piece of track has his own power feeders.

Hope this could help

You could also safe the trouble by isolating the frog of the turnout

Before FT turnouts Inused Peco code 55 track and turnouts 

All N scale Peco turnouts at this time had a live frog

It's easy to isolate the frog by using the Fastrack method and cut the rail with a jeweller saw to make an isolated live frog ( videos on FT site http://www.handlaidtrack.com explain the process)

You must solder underneath a wire on the Peco frog wire to power the frog as usual

This don't change nothing to the quality of the turnout and his running qualities 

This avoid in many case the need to cut gaps in connecting curves between two turnouts

Can the alignment of the two

Can the alignment of the two switches be nudged to make the short curve a bit straighter?

Pre bending the rails will help as the rails will not want to go back to their original straightness. Possible to pre-bend the rails and just hand spike them on wood crossties?

I would use an insulated rail joiner on the top rail of the left switch and the other insulated rail joiner on the bottom rail of the right switch (original pic); the two other joints can be soldered.

@ Wazzzy Insulated joiner

Using insulated joiner in N scale is easy but these joiners are oversized and clearly visible even painted 

Second they don't have a kind of rigidity 

So they  are able to show a kink because not enough force to keep the track alignement especially in curves.

This  is the reason I ended by soldering a few PCB ties glue the track in place and cut the gap

cut the gaps in the straight rails of that turnout to the right

Yeah, Tim might have the easiest solution. Depending on how the turnout is built it might be possible to cut a gap near the frog ? ......DaveB

Great inputs, thank you!

Thank you for your many comments and questions.  Several good ideas I that I hadn't thought of!

Could I move the switch to straighten the curve?  Well, yeah, but for two reasons I don't want to.  Practically, doing so changes the geometry of the rest of the stuff off the top end, with the worst part being making a tail track way too short.  The other reason is I've already soldered what you see and I hate unsoldering track.  

I don't generally like soldering my track joints, especially turnouts as that makes them harder to reuse on my next layout.  I did it here because that was the only way I could get the short section of flex track to bend and not kink at the joints.  Also by progressively grinding down the inside rail and then soldering, I was able to force and retain the exact curve I wanted.

Could I use offset insulated rail joiners?  Huh, I never considered offsetting it.  But I would think that at least one of the two rail joints would still kink since, as Marc points out, they aren't that ridged. 

Could I use any number of PCB ties fore and aft of the cut?  If the gaps were offset, it might work.  If they were aligned, its workability has got to be based on the degree of curvature:  a tight curve would probably still kink... (there is simply no material to force the the rail to maintain the curve in the blank area between the two ties, they would go just as straight as they did on my test.

Could I use a wide block of PCB in place of several ties?  Yep, thanks Oztrainz, you showed exactly what I had in mind.  My only objections are the resulting look of the block that even ballast won't help, and that it is a lot more work than other options.

Could I pre-bend the rails by hand?  Atlas flextrack only has one track that is removeable, but I bet taking out the loose rail I could still hand bend the remaining rail in the web, just have to be really careful.   it probably would work, I just didn't think of it before I soldered it.  I will definitely consider this for the future.

Could I cut the gaps in the straight portion of the turnout?  I did consider this for the bottom diverging route, but there is no support left after removing ties for the joiners.  But in a case of my self-imposed blindness, I never considered doing that for the straight route of the upper switch.  My skill with the cutoff wheel will probably end up cutting through both frog rails though.  That might be a problem powering the little bit of track next to the frog, it depends on where Peco physically feeds the frog rails...   This might be the simplest solution for the future.

Would offsetting the gaps solve the problem?  Wouldn't that just create two kinks instead of one?  See my next posted comment (Spoiler alert, Richard might be wrong.)

Could I use super glue?  Nope, no way, not a chance that will work.  Period.  Ever.  End of discussion.  I know this for certain.  Just like the problem with the PCB ties:  the rails are in gauge at the tie where you put the super glue, and there is no support for the ends of the rails beyond the tie where the problem is.  But, see my next posted comment.  (Spoiler alert, Richard is definitely wrong!)

Super glue can't be the answer, can it?

Several of you were certain that super glue would solve my problem.  I knew it wouldn't.  And it was real easy to set up to prove you all wrong.  So I did.  And I was wrong.  Worked like a charm!

I didn't think it would work because there was nothing supporting the gapped rail between the two ties, so there is nothing to glue to.  But in reality, there IS the webbing between the ties that follows the curve just as the rail does.  So as long as I don't cut through that web, or cut where there is no web, I do have a solid base, just like the PCB block idea.  

So I glued down a another scrap of track, this one eyeballed to the same radius as my actual track.  I located a section with with webbing under all the rails and marked two spots 4 ties apart.  (Probably could have done just two ties apart.)  Flooded both sides of the rail at the gap sites with thin super glue.  Permanently glued two of my fingers together.  Discovered that super glue melts foam.  Cut the gaps, making sure I didn't cut through the web.

Wow.

Perfect.  

No kinks.

Other than my crappy cutting skills, it looks good.  Getting better at cutting gaps though.  Just keep practicing...

I think part of the reason this worked so well is because it is a broader curve.  I am far less confident that offsetting the gaps helped much.  While there are very valid mechanical reasons for the prototype to offset joints, I'm not sure physics apply to our models.  To determine for sure, more experiments would be needed.  I leave that as an exercise for the reader since I'm satisfied with my results.  But I'll probably offset my gaps on curves in the future.

I am certain that the super glue is the primary reason this test worked so well.  Just as certain as I was before that it wouldn't work...

Thank you all for your advice!  Back to laying track.

another approach

All good suggestions, but there may be an easier solution right under your nose.  Leave the soldered joints as they are provided you are satisfied with their appearance and operational performance.  Cut a gap in one stock rail of each turnout, i.e. not the rails which form the frog.  The gap should be cut as close to the edge of the guardrail to provide as much stability as possible.  I believe this will work because the turnout rails are bent to shape at the factory and the ties are hard, rigid plastic unlike the Delrin ties of flex track.  I hope this helps.  Good luck!

Brilliant Ted!

Interesting what blinders we have.  Even after Tim's and DaveB's comments cutting on the stock rails never occurred to me.  Yep, that would work too, and be much easier to do!

super glue

I used super glue in my first helix and it worked like a charm, but after 3 years of expansion and contraction due to heat in my garage the curves started to get disbanded.  I now use a thin coat of Loctite power grab construction adhesive and it holds great.   I also use those color translucent push pins to hold the track in place, for about 20 minutes, while the adhesive really takes a set.   They fit nice and snug on N scale track .  the little skirts on the pins put the pin right in the center of the track and if you have drawn a curved radi/ center line  it goes down quick and easy  and smooth.

then once dry you can cut those gaps  I use a .009" cutting disk