Author Topic: Complicated Software  (Read 3619 times)

0 Members and 1 Guest are viewing this topic.

Offline John Candy

Coach Vacuum Brake Cylinder
« Reply #45 on: Apr 25 2021 10:31 »

The brake cylinder is in 4 parts, main body, domed top and the two supports (which locate over the trunnions on the main body).

The actuating lever and V-hangers will follow as a separate file .

available at:

http://gauge3.info/openscad/Vacuumbrakecylinder.scad

John
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

Brake components
« Reply #46 on: Apr 26 2021 00:43 »
The Snapmaker spent 30hrs producing a Gresley coach Ist Class side module, so the "minor" parts had to queue.
The brake cylinder is now complete (in black PLA rather than green PETG) and took 2hrs 58 mins to print.
When assembled it is free to pivot, making it easier to align with the other brake linkages when positioned on the coach underframe.

http://gauge3.info/openscad/Vacuumbrakecylinder.scad






The files for the V-hangers and the brake linkage are
http://gauge3.info/openscad/Vhangers.scad
http://gauge3.info/openscad/vacuumbrakelinkage.scad

Printing the brake linkage took just 18mins but the V-hangers (a set of 4) took 2hrs 56mins.

John


« Last Edit: Apr 26 2021 05:39 by John Candy »
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

Stone's Glass Vane Vents.
« Reply #47 on: Apr 28 2021 09:43 »
Stone's Glass Vane Vents.
Some early diagrams of Gresley LNER open coaches and catering vehicles were fitted with Stone's vents to the large windows. These vents were composed of seven glass vanes which pivoted through 180 degrees, about their (vertical) centre . This was to enable the passengers to direct them to adjust air intake according to the direction of travel. In the 1930's, the design was superseded by the more familiar sliding pattern but many Gresley coaches retained the Stone's type until withdrawal in the 1960's.

One of the designs to carry Stone's pattern vents, for which I have prepared side modules, was dia.4  , an Open First.

I have been unable to find a detailed drawing, so have had to rely upon photos and small drawings of coach sides to extract info. Drawings do not appear to reflect the actual appearance in photos and different photos do not appear to show same detail.... more than probably result of reflections according to angle of photo.

The OpenSCAD file I have prepared shows what I believe to be a good representation but any comments/suggestions welcome.

I don't yet know whether it will be possible to print batches in a clear transparent material or whether a pattern will need to be printed, from which to prepare a mould for casting in clear polyester resin.

John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

Gresley stock roof ends.
« Reply #48 on: May 01 2021 18:35 »


One of the "bugbears" (for me) in building Gresley gangwayed coaches, is the complex curvature of the roof ends.

I decided I will cast the domed ends which have, at their inner ends, a recess to accept 3mm thick timber planking for the plain section and, at the outer end, are shaped to engage with the carriage end casting.

   The pattern for the mould (from which the parts will be cast in polyurethane resin) has been 3D printed, taking just over 6hrs (a good reason for casting rather than printing multiple parts).

Rendering the OpenSCAD file almost crippled my PC..... it took four minutes to make the calculations and display!

If I contemplate programming more complex designs, I may have to look at upgrading the PC.
The file is at http://gauge3.info/openscad/gresleyroof.scad

John.







My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline cabbage

Re: Complicated Software
« Reply #49 on: May 01 2021 18:59 »
No John, your PC is just fine! I have just ran the same script on MINE and it come out at 3 mins 27 seconds. The problem is that you are using massive amounts of virtual positional calculation for a 3space object before you produce it.

There are other methods that would produce the same shape - but to be honest yours is about as simple as it gets. It might be a bit CPU intensive - but there is nothing wrong with it.

Regards

Ralph

Offline John Candy

Re: Complicated Software
« Reply #50 on: May 01 2021 22:34 »
Thanks Ralph.

I needn't worry then ... just need to be more patient and drink more coffee!
I haven't had such a long wait for an image to resolve for nearly 30 years....... then with a Pentium 75, 10MB and a hand-held scanner!

 Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

Gresley stock roof ends.
« Reply #51 on: May 02 2021 09:38 »
In the end I had to print the pattern a second time.
There was shrinkage problem with the first attempt..... it was undersized by about 1.5mm in width and that prevented it fitting over the coach end. I had not experienced any such problems with the dozen+ previous items, all using the same reel of PLA. The roof end was (by far) the tallest item so far printed and I am wondering whether the weight caused compression of the lower layers and led to the problem or the heat from the bed not penetrating to the upper layers perhaps caused inconsistency in layer thickness as the PLA cooled faster and did not "spread" as much as lower layers.

I revised the program to compensate (incidentally, the uploaded OpenSCAD file is the revised version) and the second print was a good fit. It has been fettled (to remove the surface striations) and the corners profiled to provide a good match with the pattern for the ends.

Now ready to prepare the mould for resin casting.

Regards,
John.


My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline IanT

Re: Complicated Software
« Reply #52 on: May 02 2021 11:41 »
Very impressive work John.

I very much like the idea of using 3D printed parts (as patterns) for casting, resin or otherwise. You really do seem to have made great progress with Open SCAD and your 'component' designs will be a very useful asset to other G3 modellers, myself included. Thank you.

Regards,

IanT
Nothing's ever Easy - At least the first time around.

Offline cabbage

Re: Complicated Software
« Reply #53 on: May 02 2021 11:52 »
I have just finished updating the OpenScad section of the G3WIKI. I will have some Gresley Teaks to build for my EE-1 loco to haul out of Brassica. I thankyou for the parts to print. I will load the queue and go to sleep. This is what machines are for!!

Regards

Ralph

Offline John Candy

With help from a bit of "Blu Tack"!
« Reply #54 on: May 02 2021 12:40 »
Roof end loosely attached to an end pattern with Blu Tack.

Now going to check whether the garage has warmed up enough to mix some silicone rubber for the moulds .... it was bloomin' freezing earlier!

Regards,
John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

Passenger window vents.
« Reply #55 on: May 02 2021 14:35 »

These vents are to fit into the 4ft windows of both sides of LNER Open stock and the passenger compartment  side of end vestibule coaches (the corridor sides of end vestibule stock had different window widths). They also fit windows of the passenger sections of catering vehicles. Early LNER stock had the Stone's pattern but the sliding type soon became the standard fitting for new coaches.

The Stone's vents were entirely of glass except for the outer frame. I have printed in black PLA since I intend making a mould to cast in clear polyester resin. You could print from clear PETG or other filament but (as I understand it) you will not be get a "see through" result .... just a translucent effect.
The Stone's vent can be fitted either left or right facing ... the attached pattern has recesses top and bottom, which sit over the glazing of the main window.   

https://gauge3.info/openscad/LNERStones4ftvent.scad
https://gauge3.info/openscad/LNERsliding4ftvents.scad

The opening toplight for the lavatory window is
https://gauge3.info/openscad/LNERLavwindow.scad

John
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

Passenger (dis)comforts
« Reply #56 on: May 03 2021 12:56 »
In 1934/5 the LNER decided to "get trendy" and built open coaches (intended largely for excursion work)with the style of seats found in motor coaches and cars and of that period........but they began to receive complaints that, for longer jouneys, there was a lack of neck support, as provided by more traditional railway seating!

The Gresley stock I am currently working on included diagrams which were built with this type of seating and I have produced an OpenSCAD file for this type of seat, based on this photo of a preserved example of dia 186. (rather a long link URL).

https://lh3.googleusercontent.com/bc_HDGA7UsEEToRucY1DO-wFGQw6Qe4NdOrd1XJDRvp3z-74uABS7boWIn8Vnq8NQBmNbDOFnSXvav2R21avbk_lcHDgzSOZzG2nJEv1S1WcLArsJE33Ggaq2BNIEaZgliGD4jZbsyp0EAxb5uMSnkLxF_z6FoiHHD4y5kS8e8nDjLd4otwmTJWiSTkdTl_TC10BD2-q7XqycU91wiWNegQLIQYq3K2veeY_24rAOoqhgosFtA16JjkX9oLQ2DLYmP5EgWBvbV6WqNsGjCD-fUTxiMt-sdjWhR14A1npI-PVEgExG9aUkayA4TP2Ua-fkfqlP7RyZ8s8WyYxC8jKHynyDw5ONXVypk8xoOaE6d_ls847srLYMCBuWpvFYKaC2oaw8ieMhwthhtKe08GXpmyF-YswXjDFSi23VbB6osGW97MaweNNGRwokOcGs9vkGF5iM1uc6kwNUw5XBBkCvTQ2CmlSs58PJuSj3Z_xyf9AYfPS6gkfeZrApAsTM3fzQjurLoOkK0ngf5c0L6XCdI3P6Rk7_y46QNz5BI251iM=w846-h635-no

Since I intend to use as basis of a pattern for casting, the pedestal for the seat is in a separate file.

Pair of seats http://gauge3.info/openscad/LNERtouristseats.scad

Pedestal for seats  http://gauge3.info/openscad/LNERpedestalforseat.scad

More traditional pattern seats will follow for 1st and 3rd class.

John
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

3rd Class comfort restored!
« Reply #57 on: May 04 2021 07:09 »
After the spell of building Open 3rd coaches with trendy motor coach style of seating, the LNER reverted to the traditional bench type seat!

https://www.svrwiki.com/LNER_52255_Open_Third#/media/File:52255_interior_RH.jpg

The pattern here is for two-a-side 3rd class Open stock. The "wings" are separate from the main seat and are "handed" (the armrest top rolls being printed on the outside face). The wings were fitted on the gangway edge only, the other edge fitting flush with the coach wall. When assembling, fit the wing flush with the back edge of seat and the with the lower edge of the squab.

The support legs are printed separately, again for convenience of using as patterns for resin casting.

Main seat structure http://gauge3.info/openscad/LNER3rdOpenSeating.scad
"Legs"  http://gauge3.info/openscad/SeatingSupport.scad

Next will be seats and tables for the First Class Open/catering cars.

John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Candy

First Class Comfort
« Reply #58 on: May 04 2021 14:48 »
These are the 1st Class seats (2+1 arrangement) as fitted to LNER 1st Class Open stock prior to 1928, when it was decreed that future First Class seating should be more like armchairs, with a central division/armrest on the double seats.

The wings are thicker than for the 3rd Class (more padded) and should be used in pairs, glued back-to-back, fitted on the gangway ends of each seat unit plus a single on the other end with the arm roll rest facing the seat(i.e. three printed/cast wings required per seat unit.... handed to suit the location).

Double seat unit : http://gauge3.info/openscad/LNERdoublefirstseat.scad
Single seat unit  http://gauge3.info/openscad/LNERsinglefirstseat.scad

John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.

Offline John Branch

Re: Complicated Software
« Reply #59 on: May 04 2021 17:08 »
John,
I have been following the unfolding saga of LNER coach parts and 3d printing with great interest.  I really look forward to a blow-by-blow account of how such parts are used in the preparation of moulds for batch production of cast resin components.

I have had open scad installed for some time, and I have paste-and-copied both your and Ralph's texts for various components, with complete success.  I have also played around with them to try and identify which bits of text affects which bit of the object being defined.  I have to admit defeat, as I cannot work out the process you follow to decide what goes where.  For instance, why do you not start at the origin (0,0,0), but at some other point?  What does "Translate" mean etc etc. I'm not asking you to explain, but could you point me at an idiot's guide that does not assume even a basic level of understanding?  I'm fairly adept at 2d design using an Autodesk product, but this is very intuitive.  I need a mental image of how what I write will be interpreted on screen, and none of the texts I have seen so far says, "seat" or "coach end" to me.  Do you start with pencil and paper and work out all the coordinates of all line junctions in 3-d space before starting to write? Maybe I am a lost cause, but I would love to post one day that my machine is busy printing a Pullman table lamp  whilst I quaff a pint of Tribute!
Best,

John