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topic: 3141transition curves and other simple questions
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posted: 29 Nov 2017 13:59

from:

madscientist
 
 

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funny I find the difficult things easy and the easy things difficult !!:)

3004_290853_530000000.png3004_290853_530000000.png

heres a new double track oo test track for my club 
transition easements to straight etc , all fine

Now I want to have a transition curve to join the two curves shown to avoid an abrupt reverse curve 
templot complains the two curves are the same hand and radius ( yes they are the same radius ) 

what am I missing 


Couple of quick questions on simple stuff

(a) I can split track at a peg , thats fine , is there a way to rejoin track thats split 

(b) if I have a curve that I want to connect to a straight track , but I want to ensure the straight track remains at a given rotate angle , is there a way to do that . I currently find I have to  tweak the curve , and re-snap the straight track and check that the K remains at zero for the straight . i.e. it would be useful to have a " swing to a K " type option 

(c) I keep trying the linked background notch to a temple peg option , but if I shift the template the link doesnt remain , i.e. the linked background template doesnt follow the control , ??


thanks as always 


dave






posted: 29 Nov 2017 14:38

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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madscientist wrote:
Templot complains the two curves are the same hand and radius ( yes they are the same radius
Hi Dave,

.box file?

I can't answer that without seeing the file. However, CTRL+X swaps the hand of the template, with no visible difference for plain track.

(a) I can split track at a peg, that's fine, is there a way to rejoin track that's split
No, but you can undo changes to get back before the split, if it was recent.

If you have since changed the radius of one or both of the templates, you may be able to use make transition to create a single template with a zero-length transition at the former boundary.

If you haven't, you can use the extend/shorten to meet functions to extend one of the templates to its former length, and then delete the other one.

(b) if I have a curve that I want to connect to a straight track , but I want to ensure the straight track remains at a given rotate angle , is there a way to do that . I currently find I have to tweak the curve , and re-snap the straight track and check that the K remains at zero for the straight . i.e. it would be useful to have a " swing to a K " type option
Almost certainly there is a way to get what you want, but I'm sorry I don't follow what you mean?

c) I keep trying the linked background notch to a template peg option, but if I shift the template the link doesn't remain , i.e. the linked background template doesn't follow the control , ??
It is necessary to work methodically and not miss any steps. Does this old video help?

 http://templot.com/martweb/notch_loco_depot.exe

I'm sure I made a more recent one, but at present I'm in the middle of re-vamping the entire web site, and I can't find it. Ideally I would switch the whole thing off for 3 months. :)

regards,

Martin.

posted: 29 Nov 2017 17:06

from:

madscientist
 
 

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I can't answer that without seeing the file. However, CTRL+X swaps the hand of the template, with no visible difference for plain track.


I sorted this by making a S curve transistion etc , so I dont have the original box file , Ill try and duplicate it 
you may be able to use make transition to create a single template with a zero-length transition at the former boundary.

any video on zero length transitions ?


thanks as always 

Dave 

posted: 29 Nov 2017 17:17

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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madscientist wrote:
(b) if I have a curve that I want to connect to a straight track , but I want to ensure the straight track remains at a given rotate angle , is there a way to do that . I currently find I have to  tweak the curve , and re-snap the straight track and check that the K remains at zero for the straight . i.e. it would be useful to have a " swing to a K " type option
Hi Dave,

I've read that a few times and I think you want to adjust a curve to finish at a specified angle, so that you can attach a straight track at that angle? Lots of ways to do that, here's a bit of video showing one of them:

 http://flashbackconnect.com/Default.aspx?id=kU1YjsYyIZJYO4pK8R9Xtw2

On the other hand it would be far better, quicker and easier to offset the templates a little and then use the make transition function on them.

Model railway curves tend to be far sharper than the prototype, and don't look good or work well if a tangent straight comes off them with no easement between the two.

regards,

Martin.

posted: 29 Nov 2017 17:38

from:

madscientist
 
 

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on the issue of where a curve ends 3004_291235_120000000.png3004_291235_120000000.png
Almost certainly there is a way to get what you want, but I'm sorry I don't follow what you mean 


Had a look at this video and its applies to group linking 

all I wanted to do was link a curve and a straight , such that changes to the curve caused the straight to remain " attached ' , cant see how thats done 

 It is necessary to work methodically and not miss any steps. Does this old video help?  http://templot.com/martweb/notch_loco_depot.exe



thanks 

Dave 


posted: 29 Nov 2017 17:40

from:

madscientist
 
 

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On the other hand it would be far better, quicker and easier to offset the templates a little and then use the make transition function on them. Model railway curves tend to be far sharper than the prototype, and don't look good or work well if a tangent straight comes off them with no easement between the two.

I agree , but sometimes thats what the punter wants ?



posted: 29 Nov 2017 17:42

from:

madscientist
 
 

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I've read that a few times and I think you want to adjust a curve to finish at a specified angle, so that you can attach a straight track at that angle? Lots of ways to do that, here's a bit of video showing one of them:
thanks , I had never considered the orbit action , now I know 
I tried this , given my marked up example  I put in my previous message  here , it didnt  do what I wanted 

regards 


dave




Last edited on 29 Nov 2017 17:47 by madscientist
posted: 29 Nov 2017 17:48

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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madscientist wrote:
I agree , but sometimes that's what the punter wants ?
Only because he doesn't know any better.

That situation cries out for a short easement, so tell him that's what he is getting.

Martin.

posted: 29 Nov 2017 17:52

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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3004_291235_120000000.png3004_291235_120000000.png

Delete the curve. If you do make double-track on the two templates above it, you will get exactly what you want with the minimum of fuss.

You can then shorten the straight if necessary.

Martin.

posted: 29 Nov 2017 18:07

from:

madscientist
 
 

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Martin Wynne wrote:
3004_291235_120000000.png3004_291235_120000000.png

Delete the curve. If you do make double-track on the two templates above it, you will get exactly what you want with the minimum of fuss.

You can then shorten the straight if necessary.

Martin.
that curve was created exactly like you say , it was double tracked from the inside curve 
but the end position is not correct to then snap on a straight 

this is what I get 

3004_291307_410000000.png3004_291307_410000000.png

posted: 29 Nov 2017 18:25

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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madscientist wrote:
that curve was created exactly like you say , it was double tracked from the inside curve 
but the end position is not correct to then snap on a straight
Sorry I didn't realise that was part of a transition curve.

It's difficult to make suggestions without the .box file.

In that case:

1. make double-track on the straight.

2. make the control on the transition curve.

3. click on the straight template.

4. extend/shorten to meet for the transition curve.

Simple and quick. :)

If you post the .box file I will make a bit of video showing that.

Just noticed you have posted it in a different topic. Hang on.

Martin.

posted: 29 Nov 2017 18:48

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madscientist
 
 

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martin to make things easier 
heres the box file of just the single track 

heres a scruff video of me following the process ( ignore the error near the end ) 

Note that I cannot use the extend feature 
Attachment: attach_2590_3141_Daves_scruff.mp4     257
Last edited on posted: 29 Nov 2017 18:50 by madscientist
29 Nov 2017 18:50

from:

madscientist
 
 

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single track box file 

Attachment: attach_2591_3141_singletesttrack.box     235

posted: 29 Nov 2017 18:56

from:

madscientist
 
 

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if I reverse the final extend, making the S curve the control and try extend I get this 

3004_291356_250000000.png3004_291356_250000000.png

posted: 29 Nov 2017 19:03

from:

Martin Wynne
 
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Hi Dave,

The reason for that is that the upper transition curve (from which you created the lower one) was misaligned with the straight. Consequently, so was the lower one.

In order to make the video, I had first to correct it.

Here's the video clip:

 http://flashbackconnect.com/Default.aspx?id=ueSTP8X4r6mKuQmxXcZanA2

.box file attached.

regards,

Martin.
Attachment: attach_2592_3141_dave_shortened_transition.box     237

posted: 29 Nov 2017 19:10

from:

madscientist
 
 

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can you explain how you fixed the error , your video seems to being after that point, i.e. how did I introduce the error in the first place 
These curves were first done  by creating the desired radius , then swinging through the required angle , then easement to straight and then joined to the straight 

I dont understand how I introduced an error 

regards 

dave



posted: 29 Nov 2017 19:14

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Hi Dave,

Obviously I don't know how you created the misalignment, but I will make another bit of video showing how I corrected it.

regards,

Martin.

posted: 29 Nov 2017 19:17

from:

madscientist
 
 

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I really appreciate this Martin, its may solve a few misalignment issues Im always having

posted: 29 Nov 2017 20:07

from:

Martin Wynne
 
West Of The Severn - United Kingdom

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Hi Dave,

Here's a clip showing how I corrected the misalignment:

 http://flashbackconnect.com/Default.aspx?id=UKjit_b0iB1Su0trziMkAg2

cheers,

Martin.

posted: 29 Nov 2017 20:13

from:

madscientist
 
 

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Martin thats brilliant , I reworked the curves anyway while you where making the video and I corrected my own mistake

great stuff and many many thanks for your patience , If you ever get to the home of Guinness, there a good night drinking on me to be had ( not that I am reenforcing any cultural stereotypes mind you) :thumb:

regards

Dave
Last edited on 29 Nov 2017 20:14 by madscientist


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