FDM-printed chairs and baseplates

[Phil G]

Hi Martin,
I have been following these posts for a whilst now mainly out of curiosity. It did strike me a whist a go Andy was using his cad knowledge to. "Lets say make rapid progress" There nothing wrong with that, as long as it does not cause confusion by readers of the posts.
Its also interesting that Andy appears, a bit like myself, to be honest in that we can't or could not quite understand why your want to deviate so much from prototypical turnout angles for example.
We have in fact had this very conversion during a zoom meeting. The penny dropped with me during the conversion what you trying to do.

Now I think there maybe away to make all this clearer for everybody.

I will make a few statements which I stress are only my understanding, but if I have it right I believe it all becomes much cleared.
Martin if you agree then a condensed version could possibly be posted on your front page. I am very aware, I am not telling you anything you don't know of course or in fact has not been previously posted. So here goes.

1, The idea of Templot is not to create your own drawings of available ready made track geometry, its to be able to make your own track geometry. To whatever scale or gauge you like, and to be able within reason to manipulate this to fit into the space you have available.

2, Templot has nothing to do with cad, it is in fact a free standing program (created in Delphi I believe) which allows for the construction and manipulation of all forms of track geometry.

3, Templot is a fantastic piece of software, it a tribute to Martin that its been made open source. It is nothing like anything else on the internet, and as such it could be said to have a bit of a step leaning curve. (something I know Martin) has put endless hours of effort into explaining how to use, and thus offset this learning curve.

4, As originally conceived Templot, once the design had been created within the software environment, allowed for the work to be exported to a printer. Thus allowing a hard printed copy to be made. Within the functionality provision has been given to ensure the printer of choice is calibrated to also ensure the hard copy is of the correctly scaled dimensions. The idea being this printed hard copy became a template to allow the user to physically construct there chosen design.

5, Over the years Templot has evolved to what is today a very powerful piece of software, it must also be stressed, its the hobby and labour of love of just one very clever man.

6, Plug track, is an "experimental" and ongoing extension of Templot, it is not yet in anything like it envisaged completed form. It has the same basic goal of allowing for the concept of, if you can draw it correctly within the program (in reality on the screen) then you can make it. It follows as closely as possible the idea of (at this stage anyway) of taking accurate REA railway architecture details and allowing this information to be married and manipulated into the Templot environment, Thus allowing for a 2D template to be converted in to a 3D actual object.

7, I believe the first iterations were using FDM printers, something that does work very well, but ultimately has a scale resolution limitation. With the advent of resin printers the scale resolution limitations have been reduced further, thus allowing for more accurate finer scale details.

8, Further developments, as Martin is open to ideas of how to make plug track as functional as possible, Ideas of using things such as laser's and 3D CNC machine to make parts have been explored. Plug track now has functionality built into it to allow for further exploration of these concepts.

9, It's likely that a combination of different technologies for 3d creation will be needed to optimise Plug track. However there are no hard and fast rules of what to use. Plug track in fact provisions for personal preference, and for what is available to the user at the time.

I guess in a world of marketing tag lines Templot's would be would be something like, "Model railway trackwork, if you can dream it Templot can draw it". for Plug track it would be "if Templot can draw it, Plug track can make it."
phil.

 

[AndyB]

Thanks Phil.

Just in case I have confused many of us here is a pic that might (or might not ) help to explain my thinking.

The difference in angle between many of the crossing chairs over a large range of crossing angles is really extremely small. So even if the jaws are properly aligned with the rail there is no reason to align the rest of the jaws at that angle.

Andy

 

[AndyB]

On reflection, if the jaw faces were slightly curved rather than straight it might not be necessary to rotate the jaws at all. I might even give that a shot.

 

[Martin Wynne]

@Phil G

Thanks Phil. That's a fair summary of what Templot is about. Although you have omitted to mention the primary purpose of Templot, which is to aid the construction of hand-built model track based on the prototype.

It seems strange to have to say that -- you wouldn't expect to read about model locomotives, say, without making that underlying assumption. But for some reason track is viewed in a different light by a great many modellers.

There is more about the basic purpose of Templot on this page of the Templot Companion:

https://85a.uk/templot/companion/origins_intent.php

That page makes no reference to plug track -- it's clearly time for an update.

Perhaps I should add a link to that page on the front page, although I'm never too sure which page that actually is. There is already a link on this page:

https://85a.uk/templot/companion/1_what_is_it.php

It's also interesting that Andy appears, a bit like myself, to be honest in that we can't or could not quite understand why your want to deviate so much from prototypical turnout angles for example.

I'm baffled what you mean there -- I don't want to deviate from anything. But you are referring to the standard angles -- I can show you prototype drawings and calculations for say a double-junction which do not result in the standard angles. And that's how it was done in the old days. In fitting a model track plan into a limited space, much smaller than exact scale, modellers often need to use such methods.

If you want to use only the standard angles in a double-junction, in the more modern way, it means having a different radius in each leg of the diamond-crossing. Which makes the geometry much more complex if you are trying to replicate sweeping curves through pointwork and usually at a much tighter radius than the prototype. But if you want to do it that way, you can use the find intersection function in Templot to create such a diamond-crossing.

Even if I was to restrict the plug track to a range of standard crossing angles, it wouldn't make the slightest difference to the program code or the work involved. I think you are suggesting that such chairs would be created in advance, presumably in a CAD program, and somehow linked into the Templot output?

I haven't the faintest idea how I would do that. It might be possible to add them into the DXF as blocks, but I'm certain I would never be able to incorporate such CAD-derived material into the generated STL file -- you are talking about 3D programming way beyond my abilities. And it still wouldn't produce the desired results -- how for example would such chairs be adjusted by the user to match the rail section in use, or be tweaked for an accurate flangeway gap? And the CAD work involved would be colossal -- just look at the full range of gauges and scales that would have to be provided, with all the differing rail sections and standards.

In any event, it is all too late now. These ideas might have been helpful 3 years ago when I was starting to think about creating 3D-printable output from Templot. But we are now where we are.

My response to these suggestions, more and more lately, has been "why me?". I'm getting old and tired. There is a vast world of 3D computer programming and technology out there, most of it completely alien to me. Where are the youngsters coming along with fantastic new programs to exploit it for fine-scale model track planning? There are plenty of such programs to plonk a Peco turnout in an amazing 3D landscape, but don't folks notice that real track doesn't look like that?

cheers,

Martin.

 

[AndyB]

Hi Martin,

"you are talking about 3D programming way beyond my abilities. And it still wouldn't produce the desired results -- how for example would such chairs be adjusted by the user to match the rail section in use, or be tweaked for an accurate flangeway gap"

I'm sorry but that makes not the slightest bit of sense. Any decent CAD application allows for the placement and orientation of 3-D components as required. Rail width can be easily accommodated by minor adjustments to the jaw model. Also, CAD apps also allow you to combine the various elements into a single element (3-D add in TurboCAD).

And I am not talking theoretically. I have printed a lot of turnouts since I bought my first 3-D printer more than a few years ago. Printing turnouts was one of the main reasons I bought it. Have you actually printed a complete turnout? I have printed a few and I'm pretty sure I posted them here.

I am not suggesting there is anything wrong with your plug track method at all, and if that lets modellers easily print high quality track and turnouts to their satisfaction, that's great. What I am suggesting is you might have taken on a gigantic task that's going to consume your attention for many years to come. But, as you have said "it's just a hobby". Are you really sure about that?

I have some ideas about how we might simplify the entire process but, based on our interactions, I'm fairly sure they will be shot down in flames as usual.

Cheers,
Andy

 

[Steve_Cornford]

Hi Andy,
From what I understand of your method, it involves taking some output from Templot, then uses your CAD skills to add components from a library of components that you have designed then printing the result on an FDM printer.
You then slide bits of rail into the resultant turnout base to complete it, in a very similar way to the British Finescale turnout kits (the design of which also originated in Templot).
Not many if us have the CAD skills of yourself or Wayne, and the experiments and development that Martin is now progressing will hopefully give us;-
PlugTrack with No CAD Required .

As far as using Templot in conjunction with CAD I am sure it would still be worth posting your ideas in this discussion as you never know one of your concepts might trigger a solution in the NON-CAD world.
After all how did we ever get from a boiled egg to creme brulee?
I am sure Templot was involved somewhere along the line

 

[Martin Wynne]

"you are talking about 3D programming way beyond my abilities. And it still wouldn't produce the desired results -- how for example would such chairs be adjusted by the user to match the rail section in use, or be tweaked for an accurate flangeway gap"

I'm sorry but that makes not the slightest bit of sense. Any decent CAD application allows for the placement and orientation of 3-D components as required. Rail width can be easily accommodated by minor adjustments to the jaw model. Also, CAD apps also allow you to combine the various elements into a single element (3-D add in TurboCAD).

@AndyB

Hi Andy,

Thanks for your thoughts, but you are mixing up two very different things there:

1. writing program code which can be compiled and run as an executable computer program. I use the Delphi5 compiler and write code in Pascal.

2. using a CAD application to create 3D objects. I know I could do that to design model parts. I have a couple of such CAD packages which I use from time to time -- TurboCAD 2015 and DesignSpark Mechanical Creator Edition (DSM).

What I don't know is how to combine those two things, using dimensions passed from one to the other. If you can tell me how I would do that it would be fantastic and open up many additional possibilities for Templot and plug track.

I intend to use such ideas for some of the fixed track furniture components which don't need any dimensional import from the track template, such as the fishplates. In effect these would just be standard STL files from CAD like any other, but it would be nice to include them in the STL exports from Templot.

For example, here is a simple hex spacer in DSM:

And attached to a raft of Templot chairs:

All I'm doing there is to save an STL from DSM, open it in Templot, and work through it adjusting all the co-ordinates to scale/locate it where desired in the Templot STL export. It's feasible, but hardly much of a step forward if I can't modify the actual dimensions in the process -- say changing the hole diameter in the above example. The code to do that in the STL would be so complex that I might just as well write the component from scratch in Templot.

If I'm missing something obvious here please let me know.

I'm sorry you feel your ideas are being shot down in flames. Perhaps you could explain things with a bit more detail?

For example you have been suggesting using the same chair jaw for all the chairs, at various differing angles. If you do that the jaw rib(s) will conflict with the chair screws, and prevent the loose jaw from seating fully home. If you include the screws with the jaw, in some cases they would be outside the chair outline, and in any event not conform with the REA chair drawings. None of this might matter much in 4mm/ft scale, but in Gauge 3 say, it would be very obvious. I'm trying to write code which works in all scales and gauges, like the rest of Templot. But maybe I'm missing something?

Most of the work for the V-crossings is now done. But I still have the K-crossings to do, and some of the special chairs needed in partial templates, such as the half-bolted chairs and the check rail versions of the bridge chairs. Plus the entire "chair heaving" function to make use of such options. If you have some ideas which would make that easier I would be very pleased to learn from them.

Thanks again,

Martin.

 

[Phil G]

Although you have omitted to mention the primary purpose of Templot, which is to aid the construction of hand-built model track based on the prototype.

Hi Martin,
I totally conceded your right I should have mentioned its primary purpose is an aid to the construction of hand built track.
I am not sure about the based on the prototype though. I fully understand what you mean when you say that, and I don't in anyway disagree with you.
I would however point out the words based on the prototype are quite subjective, and very much open to interpretation. If you are saying Templot allows for far more prototypical track geometry than anything before, or for that matter still anything avaible today, then that is 100% correct.
where the words based on the prototype become subjective, is when you introduce the simple fact its impossible to scale tolerance and clearances. Its also imposable to scale weight.

I think we all know models have to be a compromise, some aspects more than others. Its the key reason there are so many permutations of gauge let alone scale to choose from.

The fact Templot factors in so many variations to me at least, must mean somewhere in your program variables they doing math on the full size entities, also something you could rightly call based on the prototype.
However the prototype does not have to considered all the compromises we have to face with overscale things such as wheels, flanges and subsequently track component spacing.'
For this reason I think based on the prototype can be a confusing way of describing things.

My refence to angles was more about in the real world, whist I would not argue you can find exceptions, the starting point has to be a series of pre cast components which when assembled in sequence, have to result in something resembling a standard. I know you can tweak and manipulate in order to create needed exceptions. The big hammer being one such tool. or just use the weight of slow running trains to persuade the trackwork to bed.
It was also a reference to what a quantum leap Templot is compare to all commercially avaible track. what I did not appreciate until you pointed it out is the math behind Templot does not worry if the results fall into nice predefined numbers, they are simply results.
So no issue for me any longer, what even angle Templot creates for trackwork be it complex or otherwise.
Phil,

 

[Martin Wynne]

The fact Templot factors in so many variations to me at least, must mean somewhere in your program variables they doing math on the full size entities, also something you could rightly call based on the prototype.

@Phil G,

Hi Phil,

That's right. Almost all the maths in Templot is done using full-size dimensions, and then converted to scale for the output.

Some things can't be of course. There is no prototype meaning for 18.2mm track gauge, or 1200mm radius.

When I said "based on the prototype" the operative words there are "based on". Everyone knows there are many ways in which a small-scale model can't be an exact replica of the full-size equivalent for numerous practical reasons -- not least making a reasonable railway journey take place within the confines of a garden shed.

But you can look at a turnout for example, and see that the person who built it had at least looked at the real thing at some stage.

Or not, in the case of the pictures in a Peco catalogue. The location of the forest in Devon where they grow those bent timbers is still a mystery. And the coffee left in the cups after traversing a 1:4.7 inside slip can't be much. But whole droves of modellers buy such things without apparently noticing how ludicrous they are. Templot is for folks who do notice.

I'm puzzled by your repeated concern about non-standard crossing angles. If you don't want to use non-standard angles there is no reason why you should. Just don't. Templot doesn't force you to do anything you don't want to do.

cheers,

Martin.

 

[Phil G]

Hi Martin,
You are without any doubt the most knowledgeable person I know on all things track.
So as a serious question, do you know the real reason the gauge of 4 foot 8 and 1/2 inches was used? its something that has always puzzled me, it seems such an odd dimension to settle on.
Phil

 

[Phil O]

The usual answer to this question is the gauge of Roman chariot wheels, which made grooves in the road surface and we English found it easier to make horse drawn wagons to the same gauge to make a smoother and easier ride, so when it came to building railways, the gauge was continued, as that's what wagons had always been used, the only change was to add flanges.

 

[Phil G]

Thanks Phil,
I was aware that's the popular internet answer, but that does not much make sense to me, how can something created around 2000 years ago still be used. Especially when you consider the dark ages that followed the end of the roman empire.

The other one on the internet is George Stevenson used 4 foot 8 inch and that quickly got gauge widened to 4" 8.5"
To me a bit more plausible, but still the same question why 4 foot 8? I know you have to start somewhere, and its possible its just random I guess.
I just wondered if there was as I said, a real reason.
phil,

 

[Martin Wynne]

@Phil G

Hi Phil,

There are dozens of answers available -- which usually means no-one knows for sure.

But the first railway wagons were horses and carts which could use rails or roads. They had plain wheels, the flange to keep them on the rails was attached to the rails.

Typical carts had wheels roughly 5ft apart, to the centre of the wheel. This is a convenient size for a horse to pull, and fits through 6ft gates, etc.

The wooden rails were roughly 3 inches wide, placed at roughly 5ft centres to match the wheels. The gap between them was about 4ft-9in. Roughly.

Someone happened to measure an actual gap one day and made the mistake of writing it down on a bit of paper. The rest is history.

Martin.

 

[Phil G]

Hi Martin,
Thanks
Now that makes much more sense to me. As its a practical and reasonable explanation of how it all evolved
Phil

 

[AndyB]

If I'm missing something obvious here please let me know.

Martin,

The webs are completely independent of the jaws. The jaws are aligned with the angle of the rail while the webs are aligned with the base of the chair. I'm fairly sure the pattern makers figured that out too.

The ends of the rail seat should be aligned with the sides of the chair to provide maximum support for the rail which is what my chairs do. The only compromise I make is that the outside faces of the jaws ought to be parallel with the edges of the chair baseplate but in my case they could be plus or minus one degree off, at most. The jaws always interface correctly with the rail.

But if you are not interested in how I did I quite a few years ago, that's up to you. What I do not really understand is how Templot will be able to programmatically generate the vast number of crossing chairs required. (My method by-passes much of that problem.)

Cheers,
Andy

 

[Martin Wynne]

But if you are not interested in how I did I quite a few years ago, that's up to you. What I do not really understand is how Templot will be able to programmatically generate the vast number of crossing chairs required. (My method by-passes much of that problem.)

@AndyB

Hi Andy,

This getting a bit frustrating. You keep telling me that you have a better method for generating the chairs for plug track. I don't know why you think I would not be interested in that. But although you have explained the design intent, you haven't posted any details of how you are implementing it, or even in which language.

Whereas I am now programmatically generating nearly all the chairs needed for REA V-crossings, in any scale or gauge or crossing angle. That is the "vast number of crossing chairs required" which you mention.

Here for example is the chairing for a crossing angle of 1:7.41 in S gauge (1/64 scale):

Just one chair type left to generate, the DD chair next beyond the wing rails. Also still needed is the NX spacing block in front of the nose. I'm on the case.

Here are a couple of small clips from the Pascal code which generated those chairs programmatically:

---

---

---

One day it will all be open-source, although it would be silly to do that now when it still contains so many unfinished loose ends.

Templot uses the ASCII text versions when exporting the DXF and STL files. Here is a scrap of generated DXF:

0
BLOCK
2
S1OUTJAW
0
3DFACE
8
CHOUTJAW
10
0.6663
20
-1.5341
30
-0.6938
11
0.6260
21
-1.5233
31
-0.6938
12
0.6677
22
-1.5233
32
-0.6938
13
0.6677
23
-1.5233
33
-0.6938
0

As you can see, that is writing out the (x,y,z) co-ordinates for the four corners of a 3D face. Here is a similar scrap from an STL file for the corners of a triangle face:

facet normal 0 0 0
outer loop
vertex 16.588 42.682 1.643
vertex 16.306 42.768 1.754
vertex 16.601 42.758 1.643
endloop
endfacet

If you could post some of your code, or links to where I could find it, that would be great. If I could just see some of your code I might better see how it could be integrated into Templot.

But just saying repeatedly that you have a better way which would save me a lot of work isn't much help if you don't explain where I can get it or how I would use it in the Templot code. Thanks.

cheers,

Martin.

 

[AndyB]

Hi Martin,

In case you have not noticed I am a bit frustrated too.

I'm sure you know I printed complete turnouts quite a few years ago now without having to write one line of code. And if you look back then you will see I did explain my methods. The snag (if it really is a snag) is I used your brilliant Templot in combination with an inexpensive CAD program.

I'm sure you appreciate that I created a lot of sub-components for chairs (blocks) that can be overlaid on a 2-D Templot design to create a perfectly usable 3-D turnout for printing. There are many, many inexpensive ways to create CAD models that are really not all that difficult to learn and they can easily scale chair models to any scale desired.

My real concern is that you are creating something really excellent that you will not be able to maintain, and to a great extent you are reproducing things that can be created by other much more maintainable means long after you and I are gone. To be blunt, you are recreating a wheel that was invented a very long time ago. The idea that others will jump in and support your code later is, I rather suspect, incorrect.

I see nothing wrong technically with what you are doing. I'm sure you will make it work. But I think, in the long term, it's a trap for you and those who use it.

I'm happy to explain my methods in much greater depth if anyone is interested.

But do keep going.

Cheers!
Andy

 

[AndyB]

Hi Martin,

Just another thought.

What happens if someone would like to modify one of your chair designs for some reason that you did not foresee? Will they be able to import it into some CAD program to modify it slightly and/or will they be able import their version back into Templot?

I'm really not trying to be cute. I'm just trying to be practical. (I directed hardware/software development for 40 odd years and although my code writing skills are very rusty I do have a bit of clue about some of this stuff )

Cheers!
Andy

 

[Martin Wynne]

@AndyB

Hi Andy,

Thanks for your thoughts.

Since I ceased to supply Templot commercially 12 years ago, it has been simply a hobby project for me. I do what I'm doing with Templot because I want to do it, and because I enjoy doing it. A hobby doesn't need any more justification than that.

Whether I'm doing it right or wrong doesn't come into it.

In fact I know I'm doing it all wrong, because over the years many folks have told me so.

I'm very happy to share what I'm doing with anyone who wants to follow along -- right or wrong. I'm happily providing details of the machines I use, materials, ideas, tools, sources of supply. But no-one is under the slightest obligation to take any notice.

If you have alternative methods and ideas, please do share them here. Code, links, materials, suppliers, etc., so that others can join you. For example you mentioned that it was necessary to modify your 3D printer by changing the pulley size. Perhaps you could post details of the part numbers, suppliers, circuit diagrams, etc. Saying that you have a better way doesn't help anyone if you don't provide the practical details for them to follow you.

What happens if someone would like to modify one of your chair designs for some reason that you did not foresee? Will they be able to import it into some CAD program to modify it slightly and/or will they be able import their version back into Templot?

Sure they will be able to import it into a CAD program. Templot is currently exporting DXF and STL files for that very purpose. Just click these options to avoid having any print shrinkage adjustments applied:

Once it's in CAD they can do whatever they want to modify it. And then 3D print or laser cut the results as they wish.

The fact that you ask this question makes me wonder if you are actually using Templot now? It seems a bit unfair to find fault with it if you are not.

As for importing chair designs into Templot, I'm intending to provide for custom designs to be loaded and used. Obviously there is no point in loading design parameters which Templot doesn't use, such as most of the fillet and blend radii. Templot's chairs are stylised geometrical designs, not exact scale models of the prototype. There would be no point trying to load a chair design which used inclined rail for example, because Templot wouldn't know how to locate it on the rail.

Here are some of the 2D chair dimensions which could be customised and loaded into Templot when that is possible:

// length dims from gauge-face
// all full-size inches ...

S1_chair_outlong:=9.25; // Standard Railway Equipment 1926 S1 ordinary chairs
S1_chair_inlong:=5.25; // chair length 14.1/2"
S1_chair_halfwide:=4; // chair width 8" wide/2

S1_inbolt_1x:=0-2; // REA y always 1.75" in from end of chair
S1_inbolt_2x:=2;

S1_outbolt_1x:=0; // one outer screw/bolt on chair centre-line
S1_outbolt_2x:=0; // if 2nd bolt same as 1st bolt, it is omitted

S1_bolts_from_end:=1.75; // 1.75" on all REA chair screws

S1_chair_crad_inner:=1; // corner rad 1"
S1_chair_crad_outer:=1;


S1J_chair_outlong:=9.25; // Standard Railway Equipment 1926 S1J joint chairs
S1J_chair_inlong:=5.25; // chair length 14.1/2"
S1J_chair_halfwide:=5; // chair width 10" wide/2

S1J_inbolt_1x:=0-2; // REA y always 1.75" in from end of chair
S1J_inbolt_2x:=2;

S1J_outbolt_1x:=0; // one outer screw/bolt on chair centre-line
S1J_outbolt_2x:=0; // if 2nd bolt same as 1st bolt, it is omitted

S1J_bolts_from_end:=1.75; // 1.75" on all REA chair screws

S1J_chair_crad_inner:=1; // corner rad 1"
S1J_chair_crad_outer:=1;


L1_chair_outlong:=7; // Standard Railway Equipment 1926 L1 bridge chairs
L1_chair_inlong:=3.5; // chair length 10.1/2"
L1_chair_halfwide:=5.5; // chair width 11" /2
L1_chair_jaw_halfwide:=2; // chair jaw 4" /2

L1_inbolt_1x:=0-3.75; // REA y always 1.75" in from end of chair
L1_inbolt_2x:=3.75;

L1_outbolt_1x:=0-3.75;
L1_outbolt_2x:=3.75;

L1_bolts_from_end:=1.75; // 1.75" on all REA chair screws

L1_chair_crad_inner:=1.75; // corner rad 1.75"
L1_chair_crad_outer:=1.75;


And these are some of the 3D dimensions which could be customised:

chair_plinth_thick:=0.875; // chair plinth is a nominal area inside the outline perimeter
L1_chair_plinth_thick:=0.500;
P_chair_plinth_thick:=1.250;
SC_CC_chair_plinth_thick:=1.125;
X_chair_plinth_thick:=1.125;

chair_edge_thick:=0.375;
L1_chair_edge_thick:=0.500; // 236d as plinth was 0.375;
P_chair_edge_thick:=0.375;
SC_CC_chair_edge_thick:=0.375;
X_chair_edge_thick:=0.375;

chair_plinth_spacing:=1.0; // from chair outline to edge of plinth

seat_thickness:=1.75; // seating thickness under rail

key_length:=6; // 6" keys for REA
key_deformation:=7/64; // 235b 7/64" squashed between rail and chair jaw (ensures integrity in STL file)
key_pad_taper:=0.25; // non-prototype taper fit to model rail. 1/4" = 3 thou end clearance in 4mm/ft scale

// key for solid jaws ..

sj_key_pad_length:=1.25; // 1.25" non-prototype max area of full key thickness for easier sliding fit to model rail

// key for loose jaws ..

lj_key_pad_length:=key_length-1.0; // 5" non-prototype max area of full key thickness

S1_seat_top_halfwide:=3+15/16;

S1J_seat_top_halfwide:=4+15/16;

L1_seat_top_halfwide:=3+15/16; // L1 seat top same as S1

// outer top ...

S1_outjaw_height_top:=seat_thickness+rail_web_face_top_from_rail_bot_mm/inscale-1/32; //REA (95R inclined)= 5+11/16; jaw top is 1/32" below key top, mod for vertical rail // from base

S1_outjaw_depth_top:=0.5; // behind ribs

S1_outjaw_half_rib_space_top:=1+3/8; // half-width between ribs (bolt space)
S1_outjaw_rib_width_top:=5/8; // i.e. total jaw top half-width = half_rib_space + rib_width = 1.3/8 + 5/8 = 2"

S1_outjaw_half_width_top:=S1_outjaw_half_rib_space_top+S1_outjaw_rib_width_top; // used to match inner jaw width to outer

S1_outjaw_rib_depth_top:=0.25;
S1_outjaw_rib_rad_top:=S1_outjaw_rib_width_top/2-3/16;
S1_outjaw_fillet_rad_top:=S1_outjaw_rib_depth_top-S1_outjaw_rib_rad_top-1/64;

S1_outjaw_slope_mid:=17.5; // side slope 1:17.5 down from top to middle
S1_outjaw_slope_seat:=9; // side slope 1:9 down from middle to seat
S1_outjaw_slope_plinth:=5; // side slope 1:5 down from seat to plinth

// outer middle ..

S1_outjaw_height_mid:=2+7/8; // from base

S1_outjaw_depth_mid:=1+7/16; // behind ribs increased from dwg to allow for vertical rail

S1_outjaw_half_rib_space_mid:=1+3/8; ; // half-width between ribs constant (bolt space)
S1_outjaw_rib_depth_mid:=5/8;

S1_outjaw_rib_width_mid:=S1_outjaw_rib_width_top+(S1_outjaw_height_top-S1_outjaw_height_mid)/S1_outjaw_slope_mid; // make side angle on jaw

S1_outjaw_half_width_mid:=S1_outjaw_half_rib_space_mid+S1_outjaw_rib_width_mid; // used to match inner jaw width to outer

S1_outjaw_rib_rad_mid:=S1_outjaw_rib_width_mid/2-5/32;
S1_outjaw_fillet_rad_mid:=S1_outjaw_rib_depth_mid-S1_outjaw_rib_rad_mid-1/32;


There isn't space here to add more, there are pages of this stuff. Eventually it will all be customisable to whatever anyone wants.

The bottom line is that Templot is what it is. If someone isn't happy with it, the obvious solution is not to use it. Use something else instead.

cheers,

Martin.

 

[AndyB]

Thanks Martin,

Of course I use Templot. I used it to create my turnouts. I have not attempted to use the 3-D features because it's not possible to create a complete turnout just yet. Hopefully it will be possible to do that soon. It's great to hear it will be possible to interchange Templot 3-D chair models with other CAD methods. I think that's the best way to alleviate any unnecessary pressure on you.

I will be more than happy to explain my techniques and the modifications I made to my printer although that might be slightly tricky as it was so long ago and the company that made my printer ceased trading some time ago . I do not know to what extent those mods are actually required now. It could well be that current printers can achieve the same results without any modification at all. The main reason I did not go into any detail about that was because you made it 100% clear that you were not interested in modifying printers and I do understand why you prefer that they are not.

My main point is that if anyone wants to get cracking and print their own turnouts there are alternative methods that have existed for quite a while that leverage your excellent templates to produce, what I would consider (others may disagree) quite satisfactory turnouts for peanuts. They are definitely not as crisp as injection molded parts but without the benefit of magnification they are quite satisfactory and fully functional.

If you want to take a shot and printing any of them yourself, please let me know and I'll post the files. To date, I don't recall you ever asking. I might actually have posted some of the files in the past but I honestly cannot remember now.

Apologies if this is distracting you from the task in hand.

Cheers!
Andy

 

[AndyB]

Some of us have been known to muck about with flat bottom rail although I remain firmly convinced it will never catch on.

These are some chairs that might represent some sort of fixtures on FB turnouts. Printed in PLA in FDM on timbers that are really much too thin to be of any use.

 

[AndyB]

I'm sure I'm repeating myself. Here is the rendering in Turbocad. (It's interesting that the actual 3-D print looks quite a bit different )

I did a sneaky and highly unprototypical thing with these chairs. If you look at the rendering you can see that the chairs are either labeled IN or OUT. To reduce the chance of chair damage when the rail is inserted the chairs have almost no grip on the rail bottom. The chair jaws alternately push on the inside and outside of the rail. The rail is effectively "woven" between the chairs. The amount of the weave is extremely small but it's enough to hold the rail firmly in place.

It might be more obvious what is going on if I make a print where the inside and outside jaws are alternately completely absent. I don't think I ever tried the same trick with bullhead rail/chairs but I think it should work for them too.

 

[Martin Wynne]

@AndyB

Hi Andy,

This topic restarted at:

https://85a.uk/templot/club/index.php?threads/fdm-chairs-in-0-gauge.991/

cheers,

Martin.