Fun with CAD

Martin Wynne · 11 March 2024

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This is a topic for those who enjoy using CAD software in conjunction with their modelling and track-building.

If you are using or intending to use Templot plug track and you have no interest in CAD you can ignore this topic.

• No CAD software or knowledge is needed for Templot plug track.

References to Templot plug track in this topic are about optional extras, additions and modifications which some users are making or discussing.

cheers,

Martin.

Phil G · 11 March 2024

Martin Wynne said:
@Phil G

Hi Phil,

The PEI (Polyetherimide) surface on the bendy tin printer bed will grip at 60degC and then release as it cools down below about 40degC (aided by differential shrinkage). This means that if you want to use a cooler bed temperature than 60degC for less stringing and lower part shrinkage, PEI can be a problem.*

This is presumably why Elegoo include a PVP glue-stick with their Neptune printers, although nowhere can I find any actual mention of it. For use with cooler temperatures, apply a thin film of PVP glue as you would for a glass bed.

I haven't tried doing this on the textured PEI surface, but I have used it on the smooth reverse side. It works ok, but not as well as on glass (it needs more glue on metal).

*It's also a problem if you use the "resume after power outage" function on many printers. Not much point in resuming if the power outage has lasted long enough for the bed to cool down, and the part has become loose.

Sure, by all means post any useful STL (or other files) you have -- that's what we are here for. Just be sure to make clear whether you are talking about something created from or part of Templot plug track, or something entirely separate of your own design. You wouldn't believe how confused some folks are getting in trying to follow all the twists and turns of these recent 3D topics. For STL files, also make clear whether they have been mesh-fixed ready for printing, or are raw STLs straight off your CAD.

Ideally, upload your files in the Resources section of Templot Club. They will then be easier to find in future and create a library of useful files for everyone. Almost nothing has yet been uploaded there, and there is a category specifically for STL files (other). Go to:

https://85a.uk/templot/club/index.php?resources/categories/stl-files-other.14/

Click the Add resource button to upload a file and enter the details. When you add a resource, a topic is automatically created on the main forum to alert everyone to the new resource and for any subsequent discussion about it.

cheers,

Martin.

Hi Martin,
Just to be clear for all, most of the items I have mentioned are on free web sites, they are creative commons licensed to the designer. All are open source and can be modified if required. Avaible from sites such as Thingiverse and pintable's.

They have nothing to do with Plug track as such. They do however make very useful tools to aid in track building, and or other modeling projects.
On reflection, I think the better thing to do here is just add the links, as that will also attribute to the designer, then maybe add some notes about my experience with these projects.
I personally find them a very useful use of FDM printing.

In all cases that I have found so far on web sites, that are offering STL files, they don't need to be mesh fixed. I assume that's already been done. Or not required by virtue of the source location I.E. on quite a few cad packages STL exports, do not require any mesh fixing. I think that maybe handled internally by the software.

(I do wish a lot more of these sites would also offer the STP file version as well, some do most do not. STP being so much easier to edit in cad programs)

Out of interest is anybody on the forum awere of a good reliable free STL to STP converter?

Most Cad package's have a sort of go at it, but in the end you still have the myriad of small tringles, that make up an STL surface mesh model. which I believe is the definition of stereolithography

@James Walters. How does Solidworks handle STL to either STP or solid modeling conversions? I know that's not free, just curious.

It looks as though the paid version of Fusion 360 can do it automatically. The free version is a real pain in the proverbial, as having converted it from STL to mesh you have to try and stich the triangles back to a solid, one face at a time. Freecad is a bit better, but you still end up with a model full of triangles

cheers
Phil,

James Walters · 11 March 2024

@Phil G
Hi Phil,
Converting files in Solidworks is very simple:
https://www.go3dpro.com/faq/article/how-do-i-convert-stl-graphics-to-a-solid-model-in-solidworks

It will do feature recognition too, so editing a file can be straightforward.

Phil G · 13 March 2024

Hi James,
That looks very simple indeed, no more triangles in the last photo. Have you tried it?
Assuming Martins ok with this, maybe you could take say an S1 chair. STL from Templot and convert it into a solid. That would be part way down the path of creating SC chairs.
If that all works I would even have to look at purchasing a copy of Solidworks.
cheers
Phil

Phil G · 13 March 2024

Hi James,

Just as a follow up, the attached link suggests it will not work in Solidworks, hence my question. Have you tried it? The S1 chair should be a fairly complex STL file by facet count':

Convert STL in Solidworks

cheers
Phil

Terry Downes · 13 March 2024

Phil G said:
Hi James,
Just as a follow up, the attached link suggests it will not work in Solidworks, hence my question. Have you tried it? The S1 chair should be a fairly complex STL file by facet count'

https://www.reddit.com/r/SolidWorks/comments/186sorb/convert_stl_file_to_modify_in_solidworks
cheers
Phil

Hi Phil, I use SolidWorks and Inventor for my day job and have used Fusion 360. I think You would benefit from creating your custom chair from the dxf file rather than the stl file. I will be doing this myself as I'm modelling a scissor crossing which contains several chairs which are not available within Templot, as yet.
I have just created several test files which I can share with You IF Martin gives his permission.
These were exported from Templot as STL and DXF, imported into SolidWorks 2022 and then exported/save as step formats.

Phil G · 13 March 2024

Terry Downes said:
Hi Phil, I use SolidWorks and Inventor for my day job and have used Fusion 360. I think You would benefit from creating your custom chair from the dxf file rather than the stl file. I will be doing this myself as I'm modelling a scissor crossing which contains several chairs which are not available within Templot, as yet.
I have just created several test files which I can share with You IF Martin gives his permission.
These were exported from Templot as STL and DXF, imported into SolidWorks 2022 and then exported/save as step formats.View attachment 8845 View attachment 8846

Hi Terry,
Thanks for the offer and Info, have you managed to get rid of all the triangles in a step format?
I have a copy of AutoCAD 2022 which was given to me when I left work.
I found the 3D DXF in that version of AutoCAD is horrible, it simply does not capture all the file information. I know that sounds strange given DXF file format was invented by Autodesk but that the way it opens the files. Anyway for whatever reason, its worse then trying STL files to be honest.
As such I had not though about DXF with any other cad package. I should have a go using F360
cheers
Phil

Martin Wynne · 29 March 2024

Terry Downes said:
I have just created several test files which I can share with You IF Martin gives his permission.

@Terry Downes @Phil G

Hi Terry, Phil,

I'm happy with that.

I have moved this topic to the "Members only" section so that we can share my copyright Templot-derived files without broadcasting them to the entire world.

cheers,

Martin.

Terry Downes · 30 March 2024

Hi All, just a quick update regarding my findings relating to opening and potentially editing 3D CAD files exported from Templot (DXF vector files or STL surface mesh files). Please note: I'm no expert in this so, I'm happy for anyone to update, correct or append my findings.

Phil O · 30 March 2024

Hi Terry,

I have the free version of DesignSpark Mechanical and can confirm it does not open dxf files.

Martin Wynne · 30 March 2024

Terry Downes said:
Hi All, just a quick update regarding my findings relating to opening and potentially editing 3D CAD files exported from Templot (DXF vector files or STL surface mesh files). Please note: I'm no expert in this so, I'm happy for anyone to update, correct or append my findings.
View attachment 8983

@Terry Downes

Hi Terry,

Many thanks for that. Just a correction -- for DesignSpark Mechanical the free Explorer edition will not open STL or DXF or any format other than its own RSDOC format. It will export STL, intended for 3D printing. The paid-for Creator edition will open and save STL and DXF and several other formats.

The Creator subscription can be paused for up to 3 months (at which point it downgrades to the free Explorer edition) if you know you won't be using the Creator features. So the yearly cost can be reduced if you keep pausing.

FreeCAD will open STLs from Templot, provided they have been fixed in 3D Builder:

It will also open 2D DXFs for laser, but not 3D DXFs.

I have updated your table:

.....FreeCAD..............FREE.................0....................Y........Y(2D)......verified it opens, but not tried doing anything with it.

cheers,

Martin.

Phil G · 30 March 2024

Hi Terry,
that's a very good resource table.
One thing though with the latest version of free Fusion 360 (just released last week)you can now open 2D DXF file, in fact after consulting doctor google, it looks as though you have been able to since 2020, as long as you went onto the Autodesk app site and downloaded the free DXF import function. They have now include that feature as part of the STD package.
Non of which is a lot of good if your after opening 3D files though.

Phil G · 30 March 2024

Terry Downes said:
I have just created several test files which I can share with You IF Martin gives his permission.
These were exported from Templot as STL and DXF, imported into SolidWorks 2022 and then exported/save as step formats.

Hi Terry,
Given Martin has moved this post to members only, and is happy to share Templot created files, could you share the two stp files you were able to create? Or alternatively I can give you my personal email address.
cheers
Phil,

Martin Wynne · 30 March 2024

@Phil G

Hi Phil,

FreeCAD seems to offer what you are looking for -- a free program which will convert an STL mesh into a solid:

(After clicking the above, a new top menu item Part appears.)

cheers,

Martin.

Martin Wynne · 30 March 2024

Phil G said:
Hi Terry,
Given Martin has moved this post to members only, and is happy to share Templot created files, could you share the two stp files you were able to create? Or alternatively I can give you my personal email address.
cheers
Phil,

@Phil G @Terry Downes

I have added STP and STEP to the permitted file types for attachments here.

Martin.

Phil G · 30 March 2024

Martin Wynne said:
@Phil G

Hi Phil,

FreeCAD seems to offer what you are looking for -- a free program which will convert an STL mesh into a solid:

View attachment 8992

(After clicking the above, a new top menu item Part appears.)

cheers,

Martin.

Hi Martin,
I agree free cad can open an STL file, however I was not able to get rid of all the triangles, or convert it into a workable solid shape.
I have to admit though I have not tried the method you have found here. I will give that a go tomorrow.
FYI Fusion 360 says when you try and open the STL for one chair, there are over 10,000 facets, which I presume means triangles. So a vast amount of joining is going to be required if that's correct.
cheers
Phil

Martin Wynne · 30 March 2024

Phil G said:
FYI Fusion 360 says when you try and open the STL for one chair, there are over 10,000 facets, which I presume means triangles. So a vast amount of joining is going to be required if that's correct.

@Phil G

Hi Phil,

I've just checked to see how many facets Templot exports. For a single S1 chair with solid jaws, clip-fit plug and support pyramid, the answer is 1,842 facets.

The mesh-fixing process will add a lot more, but I'm a bit surprised at a 6-fold increase.

cheers,

Martin.

Phil G · 30 March 2024

Martin Wynne said:
@Phil G

Hi Phil,

I've just checked to see how many facets Templot exports. For a single S1 chair with solid jaws, clip-fit plug and support pyramid, the answer is 1,842 facets.

The mesh-fixing process will add a lot more, but I'm a bit surprised at a 6-fold increase.

cheers,

Martin.

Hi Martin,
Thanks, that's good info, please note I did not count 10,000 facets. its simply a note that comes up on F360. To be honest, and this is very subjective the same chair in FreeCad looks to have less tringles to me. I can believe 1842 as a more practical number.
just about to have a go and see what I get.
cheers
Phil

Terry Downes · 31 March 2024

Martin Wynne said:
@Phil G @Terry Downes

I have added STP and STEP to the permitted file types for attachments here.

Martin.

Hi Martin, what is the permitted / sensible attachment size? I have created several step files but, they are between 4 and 8 MB each.

Martin Wynne · 31 March 2024

Terry Downes said:
Hi Martin, what is the permitted / sensible attachment size? I have created several step files but, they are between 4 and 8 MB each.

@Terry Downes

Hi Terry,

The attachment limit is 15MB. It would be best to keep well below that if possible. 8MB should be fine.

You can have up to 36 attachments per post, but it's better to put only a few in each post, so that they can be clearly described.

cheers,

Martin.

Terry Downes · 31 March 2024

Martin, sorry, I can't seem to upload step file. Do I need to do anything to enable this? meanwhile, I will try and zip it up and post.

Terry Downes · 31 March 2024

Phil, here is a step file of a S1 chair. Please try and open/amend in Your chosen CAD software.

Martin Wynne · 31 March 2024

Terry Downes said:
Martin, sorry, I can't seem to upload step file. Do I need to do anything to enable this? meanwhile, I will try and zip it up and post.View attachment 9005

@Terry Downes

Hi Terry,

oops! My fault, sorry. Now fixed.

I'm making too many mistakes nowadays. Time for a boiled ogg.

Martin.

Martin Wynne · 31 March 2024

Terry Downes said:
Phil, here is a step file of a S1 chair. Please try and open/amend in Your chosen CAD software.

@Terry Downes

Hi Terry,

STEP opened fine in DesignSpark and FreeCAD.

STEP not supported in TurboCAD.

p.s. it's 5am in New Zealand, so Phil won't be around for a while.

Martin.

Terry Downes · 31 March 2024

Martin, This is only an observation and is not stopping me achieve my objectives but, I thought it worth mentioning.

I think the dxf output scaling may not be working correctly. I have exported many stl and dxf chair files out of Templot over the past few days and successfully opened within SolidWorks. But, every stl file comes in correctly scaled as mm and every dxf file comes in 25.4 x larger e.g. inches.
I have managed to correct this within Templot by altering the export scale from 100% (default) to 3.93700787401% as below.

the resultant dxf opens in SolidWorks at the correct size.

Martin Wynne · 31 March 2024

Terry Downes said:
Martin, This is only an observation and is not stopping me achieve my objectives but, I thought it worth mentioning.

I think the dxf output scaling may not be working correctly. I have exported many stl and dxf chair files out of Templot over the past few days and successfully opened within SolidWorks. But, every stl file comes in correctly scaled as mm and every dxf file comes in 25.4 x larger e.g. inches.
I have managed to correct this within Templot by altering the export scale from 100% (default) to 3.93700787401% as below.View attachment 9012 View attachment 9010
the resultant dxf opens in SolidWorks at the correct size.View attachment 9011

@Terry Downes

Hi Terry,

Did you tell SolidWorks to do the import in mm? There is no units information in a DXF file, just numbers.

I don't know SolidWorks, but according to Google, you should see this dialog during a DXF/DWG import:

Change the drop-down to mm before importing the DXF file.

If that's not working, you could change this option in Templot to inches, so that the dimensions in the file are actually in inches and will import at the correct size:

cheers,

Martin.

Phil G · 31 March 2024

Hi Terry/Martin
Success, with opening a Stp file in AutoCAD but then a fail, in so far as I can't slice it

I get this strange message one item found, but it just will not slice it.
So more out of desperation I exploded the stp file, and as expected got a lot of triangles. So I though why not try union (Autocad version of Boolean add) It came up with a message saying faces must be co-plainer. So I though oh well that did not work, Still I will try and slice again. To my amazement this time it sliced the file perfectly.

It's a bit of a faff but in the end I can now get exactly what I want.

just as a foot note, yesterday I was also able to get free cad to convert an STL to a Stp, and it also gave me a wireframe file. Unfortunately I could not slice that either, so I gave up.
I have just gone back and tried the same trick as using Terry's Stp file, sad to say on the Freecad version that trick does not work.

Terry could you please post some of the other standard chairs in STP format if you don't mind.
Thanks for all the help guys. much appreciated
Cheers
Phil,

Martin Wynne · 31 March 2024

Phil G said:
Terry could you please post some of the other standard chairs in STP format if you don't mind.

@Phil G @Terry Downes

Hi Phil,

You can't just say "standard chairs".

You need to specify the model scale, the rail section they are intended to fit, whether you want solid outer jaws or slots for loose jaws, the type of plug-fit, and for the check rail chairs, the flangeway gap. Plus other details which can be changed such as the key direction and offset. Also the amount of shrinkage allowance you want in the export file.

I do get a bit irritated when folks refer to Templot as if it produces a standard of-the-shelf product. I see this on several forums when folks talk about Templot does this or Templot doesn't do that, and particularly annoying is "I put the track plan through Templot" as if it's a fixed sausage machine.

Templot is a tool for your workshop. You set it up to produce the specific output you want for your railway, and much of the time that will be unique to you. There are no "standard chairs". There are some default settings which enable Templot to run from start-up, but the idea is that you change them to your specific requirements. Especially the model scale because I'm fairly sure you don't want T-55 chairs. There is no guarantee that the defaults in one program update will be the same in the next one. For example the default timber thickness was 9.72 inches in 243a and I changed it to 10.08 inches in 244a. It might very likely change again in future updates, and change again for use in the larger scales. The assumption is that if you are not happy with those dimensions you change them to whatever you want. And the same with all the other dimensions.

cheers,

Martin.

Phil G · 31 March 2024

Martin Wynne said:
@Phil G @Terry Downes

Hi Phil,

You can't just say "standard chairs".

You need to specify the model scale, the rail section they are intended to fit, whether you want solid outer jaws or slots for loose jaws, the type of plug-fit, and for the check rail chairs, the flangeway gap. Plus other details which can be changed such as the key direction and offset. Also the amount of shrinkage allowance you want in the export file.

I do get a bit irritated when folks refer to Templot as if it produces a standard of-the-shelf product. I see this on several forums when folks talk about Templot does this or Templot doesn't do that, and particularly annoying is "I put the track plan through Templot" as if it's a fixed sausage machine.

Templot is a tool for your workshop. You set it up to produce the specific output you want for your railway, and much of the time that will be unique to you. There are no "standard chairs". There are some default settings which enable Templot to run from start-up, but the idea is that you change them to your specific requirements. Especially the model scale because I'm fairly sure you don't want T-55 chairs. There is no guarantee that the defaults in one program update will be the same in the next one. For example the default timber thickness was 9.72 inches in 243a and I changed it to 10.08 inches in 244a. It might very likely change again in future updates, and change again for use in the larger scales. The assumption is that if you are not happy with those dimensions you change them to whatever you want. And the same with all the other dimensions.

cheers,

Martin.

Hi Martin,
Sorry my bad, by standard chairs, I simply meant S1J, L1, and P, and maybe a CC chair as well, I am mindful of the effort required by Terry. The point being at this stage its more about, as you like to say "experimentation".

I don't even mind if the chairs have any plug on or not, given the more detail there is the bigger the file size is, it may be better to be plug less. (again I don't mind either way works for what I am trying to do here)
To be a bit more specific the above mentioned loose jaw chairs, with just one jaw, all set at the default settings will be fine for me at this time.
cheers
phil,

Martin Wynne · 1 April 2024

Phil G said:
Hi Martin,
Sorry my bad, by standard chairs, I simply meant S1J, L1, and P, and maybe a CC chair as well, I am mindful of the effort required by Terry. The point being at this stage its more about, as you like to say "experimentation".

I don't even mind if the chairs have any plug on or not, given the more detail there is the bigger the file size is, it may be better to be plug less. (again I don't mind either way works for what I am trying to do here)
To be a bit more specific the above mentioned loose jaw chairs, with just one jaw, all set at the default settings will be fine for me at this time.
cheers
phil,

@Phil G

Hi Phil,

But you still haven't said what model scale or for what rail section?

If the files are posted on here you won't be the only one downloading them. And then I just know what will happen -- someone will download the files and print them, and then post elsewhere that "Templot chairs don't fit my rail" or "Templot chairs don't match this other track".

And then I have to write a whole load of explanations all over again, and again, and again. I just can't do it any more.

Files posted here need to have a full detailed description of what they are intended for.

cheers,

Martin.

Phil G · 1 April 2024

Hi Martin,
It does not matter what scale, as I can rescale to suit.
but if you want me to state a scale I am currently working on 1:1 in order to directly compare with the dimensions given In the REA paperwork. ( only be cause its easy to take dimensions that way. Once compete I can rescale back to EM SF or 1:76.2 scale.
And yes I know your chairs are stylised, I just need a refence point, the REA give me one.
cheers
Phil,

Terry Downes · 1 April 2024

Martin Wynne said:
@Terry Downes

Hi Terry,

Did you tell SolidWorks to do the import in mm? There is no units information in a DXF file, just numbers.

Hi Martin, I was getting the option to change units when opening a 2D DXF but no option when opening a 3D DXF. But, after messing about with SolidWorks import settings I managed to get the 'change units' dialogue to appear during opening of a 3d dxf file and now bingo, everything is working brilliantly. Many Thanks.

Phil G · 1 April 2024

Hi Martin,
re clearances for chairs in rail seats as per above I have a question. The attached is cad screen shot of a section of an S1 chair drawn full size
and then super imposed over a drawing dimensioned to RAE spec the section It is my best effort at getting a 2D side view of a REA drawn S1 chair (full size, its also only showing the gauging jaw for clarity.)
My question is does the 0.3504 thou gap between the section of Code 75 rail scaled up ( shown in tan colour) and the edge of your stylised chair (which is quite close) represent a clearance, noting 0.3504 at 4 mm scale would only be .0045 thou? Or have a missed something in the way I have the sectioned chair in relation to the REA dimensioned drawing (shown in red). Currently I have the gauging jaw butted directly to the rail which is clearly not correct. The more I create a working clearance the closer to your chair profile it becomes.
cheers
Phil

Phil G · 1 April 2024

Hi Martin,
Just to clarify the STP file S1 chair Terry generated was to 4mm scale, loose jaw S1with a clip fit plug on it, I simply rescaled this up by 76.2 thus giving me a full size chair on my screen, all be it, its in mm, The dimension on my cad are currently set to imperial, so that I can read off directly in decimal inches. I have sectioned off both the plug and then sectioned the chair directly in half on the 8 inch width. thus giving me a section right though the chair.

At this stage its more of a curiosity, (experiment) because having failed to convert a Stp file in Freecad, I changed track and started to draw an S1 chair with dimensions directly from the REA drawing. at full size.

For the rail I have both the correct 95LBs rail drawn, and the code 75 rail dimensions, again scaled to to match full size. Both on separate layers.

I am currently trying to understand, what is actually possible inside a cad package. There is no way this has or will ever have the incredible flexibility you have designed into Templot, but that not what I am trying to do here.

What I am ultimately trying to do, is find a cad work around, for the chairs which have not yet been created in Templot.
My thinking maybe wrongly, is the best option would be full size and then if anybody wants to use these Stp files once generated, they simply rescale to suit there needs. There is no way we can provision for fit options, as that would be far to hard without generating the chair programmatically as you are doing.

As a much longer term project, I would like to see if I can create an meaning full STL file for a LNWR chair. or series of LNWR chairs but as I said that's long term thinking.

cheers
phil,

Terry Downes · 1 April 2024

Phil G said:
Hi Terry/Martin
Success, with opening a Stp file in AutoCAD but then a fail, in so far as I can't slice it I get this strange message one item found, but it just will not slice it.
So more out of desperation I exploded the stp file, and as expected got a lot of triangles. So I though why not try union (Autocad version of Boolean add) It came up with a message saying faces must be co-plainer. So I though oh well that did not work, Still I will try and slice again. To my amazement this time it sliced the file perfectly.

It's a bit of a faff but in the end I can now get exactly what I want.

just as a foot note, yesterday I was also able to get free cad to convert an STL to a Stp, and it also gave me a wireframe file. Unfortunately I could not slice that either, so I gave up.
I have just gone back and tried the same trick as using Terry's Stp file, sad to say on the Freecad version that trick does not work.

Terry could you please post some of the other standard chairs in STP format if you don't mind.
Thanks for all the help guys. much appreciated
Cheers
Phil,

Hi Phil, with Martin's help, I have now completely mastered the import of Templot generated dxf files into SolidWorks. So, please find attached a smaller, cleaner step file for your evaluation. S1 CHAIR with loose outer jaw - 00-SF - code 75 rail - default settings.
Let me know whether you can open, edit, slice etc within your chosen CAD software.

Phil G · 1 April 2024

Hi Terry

Terry Downes said:
Hi Phil, with Martin's help, I have now completely mastered the import of Templot generated dxf files into SolidWorks. So, please find attached a smaller, cleaner step file for your evaluation. S1 CHAIR with loose outer jaw - 00-SF - code 75 rail - default settings.
Let me know whether you can open, edit, slice etc within your chosen CAD software.

Hi Terry,
I can open it no problem, in fact it converts from a STP much faster, but then once again I can't slice or do anything with it. It even if I explode first, So far only the first file you converted to STP which I think was a STL originally, works.
cheers
Phil,

Martin Wynne · 1 April 2024

Phil G said:
Hi Martin,
re clearances for chairs in rail seats as per above I have a question. The attached is cad screen shot of a section of an S1 chair drawn full size
and then super imposed over a drawing dimensioned to RAE spec the section It is my best effort at getting a 2D side view of a REA drawn S1 chair (full size, its also only showing the gauging jaw for clarity.)
My question is does the 0.3504 thou gap between the section of Code 75 rail scaled up ( shown in tan colour) and the edge of your stylised chair (which is quite close) represent a clearance, noting 0.3504 at 4 mm scale would only be .0045 thou? Or have a missed something in the way I have the sectioned chair in relation to the REA dimensioned drawing (shown in red). Currently I have the gauging jaw butted directly to the rail which is clearly not correct. The more I create a working clearance the closer to your chair profile it becomes.
cheers
Phil

View attachment 9022

@Phil G

Hi Phil,

You have rather lost me there.

For plug track, all dimensions are from the gauge-face of the rail, not the centre-line:

This is also the dimensioning of REA S1 chairs when used on the GWR/BR(W) -- as Paddington drawings May 1959.

For plug track the gauge-face is held at these dimensions, and the foot of the rail is rotated from the drawing to be vertically below the head.

The above rail section is my best match to the C&L/EMGS code75 rail, but batches do vary.

On some model rail sections the foot width is not the same as the head width, even though called bullhead.

I don't know where your 0.3504 dimension comes from -- the gauging jaw should fit close against the rail web, otherwise it wouldn't gauge the rail.

p.s. your 1.5188 dimension is a bit of a mystery -- the seating depth below the rail for standard REA chairs is 1.75 inches = 0.58mm at 4mm/ft.

cheers,

Martin.

Martin Wynne · 1 April 2024

Phil G said:
Hi Terry

Hi Terry,
I can open it no problem, in fact it converts from a STP much faster, but then once again I can't slice or do anything with it. It even if I explode first, So far only the first file you converted to STP which I think was a STL originally, works.
cheers
Phil,

@Phil G

Hi Phil,

Bear in mind that STL files from Templot may or may not have been mesh-fixed in 3D Builder (or elsewhere). It's important to know and state which you are working with.

The DXF files from Templot are NOT mesh-fixed.

cheers,

Martin.

Phil G · 1 April 2024

Hi Martin,
I only picked the center line in order to take out the rail inclination, as to the dimensions there directly from the LMS 1928 PDF which is on the forum, that also clearly references 7 inch from the gauge jaw side and 7.5 inches from the key jaw side. and is in the center of the rail at the seat. if I rotated the inclination at the top of the gauge jaw face, its likely to end up with the rail in the same place as your posted image.
I drew the red profile from the REA drawing before I dropped in your S1 chair not the other way round, What I did note is the base matches up but the gauging rail does not, however if I pushed over the red outline, (correctly drawn I believe)to match your end of gauging jaw, then profile is very close indeed. to be honest when scaled back to 4mm there not far off at all. I will try changing the rail rotation position.

Your right about the 1.5188 its not measured to the right place it is 1.75 as per the REA drawing from the base of the chair, you will note its a measurement is space.

My code 75 rail is not a measured piece of rail, its taken directly from the EMGS manual and then scaled up by 76.2

cheers
Phil,

Phil G · 1 April 2024

Martin Wynne said:
@Phil G

Hi Phil,

Bear in mind that STL files from Templot may or may not have been mesh-fixed in 3D Builder (or elsewhere). It's important to know and state which you are working with.

The DXF files from Templot are NOT mesh-fixed.

cheers,

Martin.

Good point. I am not sure if Terry mesh fixed out of Templot or not, I have presumed he did.
I certainly mesh fixed my Templot exports. when trying to get them to work in Freecad. but I could not get them to do what I wanted.
cheers
Phil,



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