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Hi There.

I've been watching various topics, and blogs over the past months on 3D printing, and seeing what it looks like and how it comes out... and Ive been rather impressed by what I was seeing...  sadly i don't think the same will be said for me.

I have been looking at doing Ashbury, Metropolitan coaches, or to be exact the Bluebells set, which has a Craven built composite in the middel making a set of 4.I started having a play with some computer programs to do with making a model or Cad, and Ive used various programs in the past problem is that was 8 years ago... and I cannot remember a thing about it... so I'm starting as a complete Novice... so these what you see here will be pretty rubbish.

Ive started using the Google Sketchup program, which a few people I know use, but I guess the program will have its limits, being a free program.

 

So What have I done so far?
Well Ive made 2 coach sides.... very flat ones to be quite fair, as I found the first limitation of the program... or maybe its just me not knowing how to use the program.
 

I would appreciate some feedback and possibly how to fix some areas... As the limits of the program i think are stopping me from creating the inward curve towards the solebar on the sides... hence why they are flat, these are only early models as im rubbish at this type of thing.

Excuse the colours of certain parts its just to tell me what process ive done to each part.

 

BrakeMet3.jpg

Composite412sideBtoscale.jpg

 

 

Thats as far as Ive got for now.

Edited by Bluebell Model Railway
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I can't offer any specific advice re Sketchup, as I haven't used it myself.

 

In principle, the way to draw curved sides would be to draw a series of curves representing the desired shape as viewed end-on, join the curves to form a closed planar curve, then extrude this along the length of the coach.

 

The panelled overlays could be produced in a similar fashion, and the necessary holes "punched" through by drawing the needed shapes on the side view.  

 

Also, rather than drawing thin sides, it may be better to draw the body as a solid, and hollow out the interior by extruding the appropriate shape representing the part to be removed (by doing a Boolean difference).  I assume you are aiming to print the whole body in one piece rather than printing a "kit" of ends, sides, etc.

 

I have just gone through the same steps to hollow out a fuel tank for a diesel loco while maintaining a wall thickness of approx 2 mm so it will be strong enough when filled with lead.

 

I am using Rhino 3D software which I believe is still available as a 90-day free trial, but is somewhat expensive if you decide to purchase.

 

 

post-17456-0-72260100-1359560798_thumb.jpg

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Hello Richard.

 Yes hear what your saying there, It was my original intention to make the whole coach as one complete part but limitations with the program didn't allow me to do this a bit like the curve on the lower side of the body wouldn't let me do that, So started making it as individual componants... if you know what i mean, ive seen a few do it as a whole unit or seperate pieces.

I think I will probably have to look at an alternative program to get what im after... but will see what a few of my 3D modelling mates come up with... as im no good with Cad.

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What you've already drawn almost looks like the masks required for etching brass.  If you look at the etched brass design guidelines on the Hollywood Foundary website or PPD website you'll see what I mean.  Once etched in brass you can then form the tumblehome you want.  Not the route you were intending but I like you have not been able to grasp 3D cad, but i have managed 2D cad to a high enough standard so that I can etch bits in brass.

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interesting idea... I was looking at this route to Avoid the etched brass due to not having the equipment to work with brass, i was looking at getting some in the future, but can't afford it at the present moment. I don't have much knowledge sadly on Etched brass either... but like 3D stuff really.

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I've just been thinking and also reading another thread...

Im limited to what i can do to the model on this program, and I had an idea.. If i remove the bottom half of mouldings I can create the curve of the bottom half of the coach.
I was reading in the 3D Printed N Gauge Pendolino thread about bending an item back if its made of FUD as its resin based... so the idea is if i could get the mouldings printed in that material and then made the bottom half of the coach the way it needs to be, then fix the printed mouldings with glue or what ever is suitable.

Just an idea... seeing as im very limited in what i can do.

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Had a look at the Rhino software... and i have no idea what to do with it if im quite honest... way too complicated for me.

I am sure, like most software, only 5% of the capabilities of Rhino are needed for the sort of things we do.  I probably only use 10-20 commands for the majority of my drawing.

 

I wrote this yesterday on another forum, about my transition from 2D to 3D CAD. It might be useful:

 

I have been using 2D CAD for many years, and dabbled in 3D CAD about 10 years ago for designing a house extension using special purpose home-design software.

 

For this project (see http://wasnmodeller.blogspot.com.au/2013/01/wagr-r-class-diesel-using-3d-printing.html), I started out with free software from Autodesk called 123D, and I first started on a very simple shape, a wheelset, in fact. I thought I might be able to get accurate wheelsets 3D printed to use as wagon loads. I found the user interface with 123D not very intuitive. They had tried to make it clever and "different", but it was hard to control it to do what I wanted in any predictable way.

 

I did start part of the R Class using 123D but it was fairly hard going.

 

Based on a suggestion from another of the S scale group, I trued a free demo copy of Rhino Version 4. I found that Rhino was much easier to learn and worked similarly to 2D CAD which I was used to (Autosketch). Within a couple of hours, I had recreated the R Class short hood which I had started in 123D, and it seemed a whole lot easier all round.

 

I didn't read a book or go through any structured training. I just started off drawing basic shapes and sticking them together. I had some pointers from my brother who does 3D CAD as his profession, for example about drawing complex outline shapes in 2D and then extruding or rotating them to produce a 3D shape. If I got stuck at any point, I read the online help or searched for information on the Internet. There are lots of tutorials and short videos available. Unfortunately, some of the people who produce them don't really understand what they are doing, so you have to discard the rubbish.

 

Rhino 3D is not perfect (and not free), but I have found it pretty easy to learn and it (mostly) does what I want it to do.

 

 

As I starting point to use 3D CAD software, I suggest trying to draw some basic shapes, such as rectangles, and get practice at drawing them to precise dimensions and in precise locations.  Rhino allows typing in coordinates in order to get precise positioning (as does AutoSketch in 2D).  In Rhino, 3D coordinates can be entered as w(x,y,z).  The "w" signifies "world" coordinates which are constant regardless of the direction from which you are viewing the model at that time.  My brother suggested setting the origin i.e. w(0,0,0) at rail level, in the centre between the rails, and at the centre of the model, with the "front" view actually looking at one side of the model.  Thus, positive X coordinates refer to the right end of the model, negative X coordinates the left end, positive Y coordinates refer to the rear, and negative Y to the front.  Z coordinate represent the height above rail level.  The reason for positioning the origin as suggested, is that many models are symmetrical about the centre, so many parts can just be drawn once and copied to the opposite side or end using the "mirror" command.  So, as a first step, you could draw a solid box by specifying its diagonal from w-50,16,15 to w50,-16,18 which might represent the floor of your model.

 

To draw basic shapes, you would need to learn the commands for drawing lines, circles, arcs, rectangles, the commands for moving and copying objects, and the commands for extruding a flat (planar) shape to make a 3D shape.  Other useful basic commands are Curve Connect (which trims and joins parts of lines and curves to make complex shapes), Join, Explode, and Boolean Join and Difference, Move Face and Wire Cut. From then on, it would just be a matter of learning additional commands (e.g. from reading the Help) as you need them.  

 

As with learning any software, it is a matter of starting with something easy and learning extra bits as you need them.  I started using Rhino in September last year.  My first attempt at my diesel loco body (which now exists as a 3D print) is attached.

 

post-17456-0-12893700-1359612359_thumb.jpg

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Very nice, the problem is after reading what you have written there, I had a play with it all day yesterday, without much success, as when i started drawing the program crashed, or stalled and wouldn't let me do anything. So it either doesn't like me or my PC, which is surprising seeing as its pretty fast. So I so fed up with it and removed it, as it didn't work very well,and couldn't work with it. plus only has a limited number of saves on the program before it was useless.

 

I think what I will do is work with what I have, and work with the limitations, but turn it to my advantage, may mean making more parts but, at least I can so what i want with the program and how it works, it took me a couple of hours to work out Google Sketchup, easy to use, simple interface, is a shame really you can't do more with it, as it would be a blindingly good program, especially for me, as I hate CAD, or 3D, i prefer to draw not let a computer do it.

 

I'll have a look in to doing it a different way, and see how it goes, should take a couple of hours.

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Hi

 

Probably the easiest method in Sketchup would be to draw the end cross section of the coaches and use the Push-Pull function to extrude the flat surface into a solid of the required length. You can then draw a rectangle on the flat underside of the solid and Push-Pull again to hollow out the interior.

For the beading on the curved surface of the body below the waist, I would be inclined to draw up a "laminate" of the required thickness of the beading (presumably half an inch to an inch) in the same way as extruding the coach body, and then punch holes in it to create a "fret" which can then be attached to the hollowed-out bodyshell. The Offset function should be helpful when drawing up the cross-section of the laminate.

In order to punch the holes, you would need to create some "punch tools" using the same method as extruding the body. To save effort, use the Make Component function so that each tool can be repeatedly used. The punch tool can then be positioned at the required point (ie passing through the laminate) using the Move function. Once in position, right-click on the punch tool (using the Select cursor) and select Explode from the menu that appears. The punch tool will then no longer be a unified component but a series of highlighted lines and surfaces. Select Intersect Faces from the Edit main menu and then With Model from the sub-menu that appears. Sketchup will work away for a bit and the highlighting will disappear. Now, you need to delete all the projecting parts of the punch tool. All that should remain is the outline of the punch tool cross-section on the curved surface of the laminate. Use the Select cursor to highlight the surface contained within the outline and then delete it. Repeat for the surface on the other side. You should now have a hole in the curved surface. If you need more punch tools, select the Components menu from the Window main menu. Once all the holes have been opened out, use the Select cursor to highlight the whole fret and use the Make Component function (you will then be able to load another instance of this component and create a mirror image using the Flip function). Use the Move function to position the fret on the bodyside.

As can be seen, the process is cumbersome but straightforward once one gets the hang of it (I used the same process to punch out window apertures in the curved bodysides of Mk.1 coach bodies). The method is presumably equivalent to Boolean joins in other applications.

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Delichon

 

The process you described is exactly the same as what I described, except that the terminology is a bit different between Sketchup and Rhino, but the principles are the same.  E.g. Push-Pull in Sketchup = Extrude in Rhino, The "Punch Tool" in Sketchup = Wire Cut in Rhino.

 

Clearly, both programs provide similar tools to do the job in hand.

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Thanks for your advice chaps, during a power cut this morning... I have used some info and tips given to me and I have got around the problem :)

Im still awaiting the Etched ends from Dart castings to give me a reference point on how sloped the sides are... but hopefully some progress made.

 

Composite412sideAslopedsides.jpg

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Very nice, the problem is after reading what you have written there, I had a play with it all day yesterday, without much success, as when i started drawing the program crashed, or stalled and wouldn't let me do anything. So it either doesn't like me or my PC, which is surprising seeing as its pretty fast.

 

You probably need a better GPU. What is fast for general work is not necessarily up to running this kind of software well. Workstations built for 3D CAD still have 4 figure price tags where the first number is usually not a 1 and the graphics card will make up around half the total price. 

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I disagree.  

 

Both Rhino 4 and 5 install and run fine on my slow Celeron machine running XP for relatively simple models.  Rhino is certainly more tolerant of a low-spec machine than AutoSketch 123D, which wouldn't even install.  By the way, I bought my Celeron PC for about $300 in 2007 second hand ex University, mainly to operate my computerised signalling system which is also does very well.

 

I did run into problems with lack of memory with the final stages of unioning and STL file export for my very complex diesel loco body, and had to have these steps done on a 64bit PC with 8GB RAM.  However, I completed all the design work on my slow PC up to the point of final unioning.

 

If I embark on more models of similar complexity, I will upgrade my PC.  Until then, I will continue to do designs on my XP machine especially for small-mediumly complex models.

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Some progress over the last few days, I have completed one side of the coach, which can be fliped and made in to the other side quite easily. I will continue this on the Brake 3rd, as well as develop the All 3rd model... and the ends of the coaches.

 

Composite412sideAslopedsides-1.jpg

Composite412sideAslopedsidesb.jpg

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A small update as Ive been busy with other things, and have been struggling with this 3D stuff, so I have put it on the shelf for a while as Ive reached the limit of my skills.. which is a shame so I will shelve it until I can find some help or assistance to complete the models.

CompositeAssembly412-1.jpg

 

LongandshortBuffers.jpg

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It seems a shame to give up now.  You seem to be doing quite well.

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agreed it was a shame... so I continued while I had not much to do.
I have made all 4 coach bodies... I did a test upload to Shapeways last night... amazingly didn't find any faults... which is suprising to say the least. Considering i made them... 
Attention is now on the chassis.... Im still not decided on how to go about doing it, but I know I would like to use some rtr bogies, but sadly not the right type... and designing my own... is a beyond my skills at this point in time.

 

Heres a few snap shots of some assembled coaches..
 

All3rdAssemblyc.jpg
Completed a few days ago, All 3rd.

MetBrake.jpg
Brake 3rd.

 

CompositeAssembly412-3.jpg

Composite 2 of these will be produced.

 

 

This is a very early stages of the Chassis, I have measured some castings I have of Vac cylinders and Battery / Electrial boxes... as well as scaling the 7ft wheel base in to 4mm.. about 28mm. its still very much work in progress....

Chassis.jpg

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The diagrams of the Ashbury's in the Jim Snowdon Metropolitan Stock book are very good - In fact they were used by Clive Thomas to produce his etched brass Chesham Set (now sold by London Road).

 

Might be worth looking at producing the other steam era variants.

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I have scans from both or most of the books, I have someone on the Bluebell having a look at the ones there taking a few photos for me. I have worked on a few areas of the chassis, figured out that the chassis will hold 15 - 20 grams of weight. Its progressing slowly but getting there slowly... just working on finding a rtr bogie to go on them or looking at doing my own but will have to look in to someone doing that as im very limited on skills for 3D design. Give me a pencil and a piece of paper anyday.

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I for one would be happy a design that allows you to use r-t-r bogies (eg Bachmann LMS ones as they a fairly flat sided) and have an overlay of bogie sideframes of (near?) correct design.

 

This would add weight, ensure it runs ok over normal track, and doesn't over complicate the project at this stage. 

 

(Not sure of dimensions but eg B4 bogies are also flat sided - use which ever comes nearest in dimensions and is readily available as a spare).

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The problem is the wheel base... these coaches are very short in all sence of the word...  wheel base is 7ft of the bogie, in 4mm 28mm,  only ones that fit in to that size.. is the reproduced Airfix GWR suburban coaches. Ones with the wrong bogies on... but the correct ones, should have a 28mm wheel base, but need a closer look to compare them, and look at others with the correct wheel spacing of 28mm... not an easy task...

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I have recently ordered some 16.5 mm gauge, 24 mm wheelbase test bogies in Prime Grey from i.Materialise, and they should arrive on Monday with some other bits.

I haven't attempted to detail them at all, I just wanted to see how the material is in terms of flexibility and robustness.  

I designed one with holes to take brass bearings and another with built-in conical bearings.  Part of the test will be to see if they spring apart enough to install the wheelsets without breaking or other catastrophe.

Once the mechanics are proven, e.g. getting the correct bearing spacing, etc., it should be relatively easy to design bogies of different wheelbase and styles.

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