Templot Club Archive 2007-2020                             

topic: 2936Changing closure distance
author remove search highlighting
 
posted: 24 Oct 2016 14:35

from:

Dave Phillips
 
New Jersey USA

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
I am trying to make a custom turnout template to match turnouts already built in a custom fixture. I need to increase the distance between the switch heel and the frog without changing the frog angle and thus increase the closure radius. It's a straight switch, regular V crossing turnout. There does not appear to be any built-in functions to do this with a mouse action, so I've been working with partial templates. The approach I've been thinking of is to make four partial templates, the switch, the frog, and straight plain track main road closure and a curved plain track turnout side closure. I've got the frog by blanking to the entry straight, but can't figure out how to blank from the switch heel to the end of the turnout. I can blank out from the toe end to the the heel but not from the heel to the exit end of the turnout.

I'd really like to do this with a single template since I want to eventually curve it to build curved turnouts. Any suggestions would be greatly appreciated!

Dave

posted: 24 Oct 2016 14:52

from:

Martin Wynne
 
West Of The Severn - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Dave Phillips wrote:
I am trying to make a custom turnout template to match turnouts already built in a custom fixture. I need to increase the distance between the switch heel and the frog without changing the frog angle and thus increase the closure radius. It's a straight switch, regular V crossing turnout. There does not appear to be any built-in functions to do this with a mouse action
Hi Dave,

Try changing to a generic V-crossing. That's at real > V-crossing options > menu items.

If that increases the lead length by too much, go back to a regular V-crossing, and use SHIFT+F11* mouse action to reduce the crossing entry-straight a little.

If with a generic V-crossing it is still too short, try changing to a longer switch. If you post your .box file I can make more specific suggestions.

Explanations at: http://templot.com/martweb/gs_realtrack.htm

but can't figure out how to blank from the switch heel to the end of the turnout.
Just shorten the overall length of the template. F4 mouse action. Or do > snap to switch heel menu item, or do > snap to catch points menu item.

*Templot2 only.

regards,

Martin.

posted: 25 Oct 2016 12:55

from:

Stephen Freeman
 
Sandbach - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Hmm,
not sure about this, in that I think Martin may have mis-understood.

Am I right in thinking that the only way to do this is to use a shorter length switch and or curved/loose heel? As I understood it, the Common Crossing is sancrosanct in this instance, as is the overall length of the turnout? If not then please ignore my ramblings.
Last edited on 25 Oct 2016 12:56 by Stephen Freeman
posted: 25 Oct 2016 13:19

from:

Martin Wynne
 
West Of The Severn - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Borg-Rail wrote:
As I understood it, the Common Crossing is sacrosanct in this instance, as is the overall length of the turnout?
Hi Stephen,

The distance from the toe of the switch to the nose of the V-crossing (called the "lead length") can be changed. This is sometimes done in order to fit a turnout in a given space without changing the switch size or crossing angle.

The lead length can be shortened (at the expense of a sharper radius) by increasing the length of the crossing entry straight on a regular-type V-crossing.

This may at first seem counter-intuitive, but try it and see -- here's an old bit of video showing the effect of adjusting the length of entry straight (SHIFT+F11 mouse action). Note that there is no change to the switch size or crossing angle:

Allow time for the video to download:



Or to lengthen the lead length it is necessary to reduce the entry straight to zero (i.e. generic-type V-crossing).

If that's not enough, further lengthening would require changing to a longer switch.

regards,

Martin.

posted: 25 Oct 2016 15:11

from:

Stephen Freeman
 
Sandbach - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Yes I know, but I don't think that's what Dave wants to do. I think he wants to increase the distance between the switch heel and the vee so as to make a larger radius i.e. make the switch shorter.

posted: 25 Oct 2016 15:59

from:

Dave Phillips
 
New Jersey USA

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
The suggestions that Martin made worked perfectly and allowed me to increase the distance between the heel and V-crossing and increase the closure radius to match the commercial turnout fixture. I changed to a generic V-crossing and increased the switch length from 9 ft to 10 ft. Interestingly, I had tried changing the switch length before my post, but I only tried shortening it, which didn't work. Thank you Martin for your expert advice, and especially for the F4 hint. My blunder on that issue proves I really am a beginner! Thank you Stephen for trying to help as well.

posted: 25 Oct 2016 16:18

from:

Stephen Freeman
 
Sandbach - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
I think you will find that changing the vee crossing to Generic was what did the trick as far as the radius is concerned, rather than changing the switch length. Of course a boxfile might have been best to see what you were trying to do but if it worked for you that's fine.

posted: 28 Oct 2016 18:33

from:

Dave Phillips
 
New Jersey USA

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Okay, I'm still having trouble. I changed to generic V-crossing and changed the switch length, but I still can't match the template to my fixture to my satisfaction. I've got agreement on the crossing angle (number 6), and the lead length from the turnout intersection to the blade tip, but the radius is still a tad low. I've fooled around with switch length, heel offset, and regular (including changing the entry straight length) and generic V-crossings. I have found a couple of combinations of these variables to get the lead length from the intersection to blade tip match, but in all cases the lead radius is too low. The match is much, much better than when I started but I'm not quite there yet. I've attached the box file and a background shape file for your viewing pleasure. Any suggestions would be greatly appreciated!
Attachment: attach_2338_2936_HOn3_#6_2016_10_28_1312_15.box     258

posted: 28 Oct 2016 18:34

from:

Dave Phillips
 
New Jersey USA

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
And the background shape file...
Attachment: attach_2339_2936_HOn3_#6_from_DG_16_10_28_1311_36.bgs     252

posted: 28 Oct 2016 19:21

from:

Martin Wynne
 
West Of The Severn - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Dave Phillips wrote:
And the background shape file...
Hi Dave,

We also need the .sk81 file (from the same folder as the .bgs file), which contains the actual image.

(The .bgs file contains only the size and position of the picture shape).

You could try changing to CLM unit angle instead of RAM.

I assume this is a Fast Tracks jig? They are probably made to CLM unit angles. Templot uses RAM unit angles by default. You can change a V-crossing to CLM by clicking real > V-crossing options > convert RAM to CLM menu item. It will shorten the lead length a fraction.



Crossing angles are normally specified in unit angles, i.e. as a ratio such as 1:7 (sometimes written as #7, especially in the USA). There are two common ways of measuring the ratio:

1. RAM = Right Angle Measure = Templot default and some Continental European prototypes:

ram_angle_diagram.pngram_angle_diagram.png

RAM unit angles are traditionally used by modellers because they correspond with normal engineering practice and are easily set out with dividers -- all measurements are either along the rail or at right-angles to it. Templot uses RAM angles by default for this reason.


2. CLM = Centre Line Measure = most USA and UK prototypes:

clm_angle_diagram.pngclm_angle_diagram.png

Measurements are made along an imaginary centre-line between the vee rails, and at right angles to that centre-line. Neither measurement is along the rail. It's easy to do on the ground with gauging tools which fit across the rails, but more difficult on a drawing board. CLM unit angles are used because the rules-of-thumb formulae which are used by the p.w. gang when setting out pointwork on the ground are simplified, and produce closer approximations to the true mathematical result.

Nowadays with everything done on computers there is no real need for unit angles, we could work directly in degrees or radians. But tradition dies hard and the unit numbers are brain-friendly and easy to remember.

regards,

Martin.

posted: 28 Oct 2016 20:21

from:

Martin Wynne
 
West Of The Severn - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
p.s. Dave,

A few things to be aware of when creating USA prototypes in Templot.

UK switch tips are designed sharp at the toe (zero thickness). USA switch points are typically 1/8" thick at the tip. There is a virtual toe position in front of the toe where the thickness would be zero if the point was extended (called the "vertex length"). You need to add on this vertex length to the "lead to heel" dimension when creating a custom switch in Templot, and when comparing the turnout lead length.

There are two different turnout lead length dimensions.

"virtual lead" is from switch toe to the "fine point" (gauge intersection).

"actual lead" is from the switch toe to the blunt nose of the vee.

The default blunt nose width in Templot is 3/4". For most USA prototypes it is 1/2". The difference between the virtual lead and the actual lead therefore differs (and varies of course with the crossing angle).

You need to change the blunt nose width to 1/2" in Templot, and also be clear whether you are referring to the virtual lead or the actual lead.

The usual quoted radius figure for commercial pointwork is the substitution radius. Most of the radius figures in Templot are the actual radii, and can refer to the track centre-line or the turnout rail. You need to be clear which radius you are comparing.

I think you made a typo in your screenshot, the usual USA heel offset ("spread") is 6.25" not 6.5".

regards,

Martin.

posted: 28 Oct 2016 22:23

from:

Dave Phillips
 
New Jersey USA

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Hi Martin,

The sk81 file is attached. Yes, I'm trying to match a Fast Tracks template/fixture. I'll change to CLM. I'll work on vertex length as well. This suggests that the Templot template switch blade tips should be outside the FT template blade tips. Is this correct? The blunt nose is already 1/2 inch in the provided box file. Yes, the heel offset is 6.25, not 6.5. I had previously read about the blunt nose radius and heel offset for US turnouts, but missed the CLM and vertex length.

Thanks again,

Dave
Attachment: attach_2340_2936_HOn3_#6_from_DG_16_10_28_1311_36.sk81     257

posted: 29 Oct 2016 15:23

from:

Dave Phillips
 
New Jersey USA

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
If I did the math correctly, the vertex length is about 2.5 inches (actual) or about 0.75 mm in my scale. The "blade tips" in the Fast Track template are really the ends of the rail base (flat bottom rail). I've assumed the blade tips at this point are 1/8 inch as Martin suggested and made the Templot template blade tips extend slightly beyond the FT template rail base ends. I changed to CLM as suggested. I think I get a better fit with an 11 ft switch, but the lead radii are still too small. However, the rail head of the lead is within the rail base of the template I'm trying to match. For model making, I guess that's good enough. Nothing I've tried has made the curved stock rail radii larger than the template I'm trying to match within the crossing angle constraint and turnout road - main road intersection to switch toe constraint. Any further ideas? Or is it good enough?

Dave

posted: 29 Oct 2016 16:39

from:

Martin Wynne
 
West Of The Severn - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Hi Dave,

I spent a long time looking at this, and I think you have done very well to get that close.

Can you clarify what you are trying to do? Are you trying to match a Templot turnout to:

1. a USA prototype 3ft-gauge turnout? Do you have some prototype info for that? I have quite a lot of data for USA standard-gauge, but not for narrow-gauge.

2. a Fast Tracks template? Do you know what data it is based on?

3. a turnout constructed in a Fast Tracks jig?

Those are likely to be 3 different things. If it is a ready-built turnout, your best option may be to turn it upside down and scan the rails directly as a picture shape.

Looking at your posted picture shape, which I assume is a Fast Tracks template:

2_291123_210000000.png2_291123_210000000.png

The turnout curve appears to have been drawn tangential to the exit road at a location approximately at the end of the wing rail. Hence it appears to be a larger radius than can physically be fitted between the switch and the intersection point.

In other words it is drawn as a curviform V-crossing as far as that location, with a crossing angle of around 1:7. If you wanted to replicate that exactly it would be necessary to use partial templates (I'm not aware of any such prototypes).

Also it is drawn with the switch blade open (presumably the assembly jig isn't like that?), making it difficult to follow the intended geometry, which can only be determined from the stock rail.

regards,

Martin.

posted: 29 Oct 2016 17:15

from:

Dave Phillips
 
New Jersey USA

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Hi Martin,

Thanks for taking the time to help me along with this. I seriously doubt the template I'm trying to match is some prototype. It is presumably the template of a turnout built in the corresponding fixture, and I bet the fixture has some "anomalies" from prototypes for manufacturing purposes.

I'll take some time and fool around with partial templates next, or maybe just fool around with the V-crossing.

Thanks again for your help!

Dave

posted: 31 Oct 2016 03:19

from:

Martin Wynne
 
West Of The Severn - United Kingdom

click the date to link to this post
click member name to view archived images
view images in gallery view images as slides
Hi Dave,

You may find it easier to get a match to the Fast Tracks template if you import it into Templot as an EMF metafile. The advantage of metafiles is that they can zoom without pixellating.

In Templot 213a the background picture shapes don't support metafiles (they do in the next program update coming soon*), but they are supported on the sketchboard, and sketchboard items can be displayed on the trackpad.

I'm limited in what I can post here because I don't want to upset Tim Warris at Fast Tracks by infringing his copyright. I think the following falls within "fair dealing for review".

This is a H0n3 template downloaded from Fast Tracks: http://handlaidtrack.com

converted to an EMF metafile (from PDF) and then added to the sketchboard (metafiles have a transparent background):

2_302134_490000001.png2_302134_490000001.png

It is obviously a shorter turnout than the one you are using.

And when zoomed in:

2_302134_480000000.png2_302134_480000000.png

You can see that this is a big improvement for aligning rails and taking measurements.

To get these thin lines, click the modify tab on the sketchboard control panel, tick the replace all lines box, and set the line width to 1 dot.

There are several vector drawing and CAD programs which will convert vector PDF files to EMF.

I used Inkscape, it's free and open source from: http://inkscape.org

After opening the PDF file, you can edit out any unwanted stuff, and then save in EMF format. Set a known custom page size, so that you can enter the same size for the metafile image on the sketchboard.

*I seem to have written that many times over the 12 months since 213a, I really must try to get it ready soon. :)

regards,

Martin.



Templot Club > Forums > Baffled beginners > Changing closure distance
about Templot Club

Templot Companion - User Guide - A-Z Index Templot Explained for beginners Please click: important information for new members and first-time visitors.
indexing link for search engines

back to top of page


Please read this important note about copyright: Unless stated otherwise, all the files submitted to this web site are copyright and the property of the respective contributor. You are welcome to use them for your own personal non-commercial purposes, and in your messages on this web site. If you want to publish any of this material elsewhere or use it commercially, you must first obtain the owner's permission to do so.
The small print: All material submitted to this web site is the responsibility of the respective contributor. By submitting material to this web site you acknowledge that you accept full responsibility for the material submitted. The owner of this web site is not responsible for any content displayed here other than his own contributions. The owner of this web site may edit, modify or remove any content at any time without giving notice or reason. Problems with this web site? Contact webmaster@templot.com.   This web site uses cookies: click for information.  
© 2020  

Powered by UltraBB - © 2009 Data 1 Systems