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The Great Bear

3d printed GWR coaches - something big...a D51

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Having bought a 3d printed autocoach by Rue_d_etropal (see my layout thread http://www.rmweb.co.uk/community/index.php?/topic/26456-marlingford-begbrooke-making-a-diagram-a7-autotrailer/?p=2973057) this sparked my interest in this technology and its potential use to create rolling stock. My particular interest is the Great Western and whilst the recent Hornby Colletts have filled a huge gap in the RTR offerings there are lots of other types, especially older ones, not available in RTR and not available or easily available in kit form (eg Slaters Toplights).

 

So, with a modicum of cad skills, access to the software and some armchair modelling time to learn 3d modelling in Autocad over Christmas I thought I'd this a give this a go, drawing up a coach in Autocad then printing using one of the online printing services.

 

As a start and to give the technology a tough challenge I thought I'd start with a fully panelled GWR toplight - on the basis that if I and it can do this acceptably other ones will be fine. The chosen protoptype was a Toplight C30. I can't quite remember why I chose a 56' one not a 57', think it was the first one in Russell I came to!

 

Rather than a scienfitic test things, do a little bit a approach, I thought I'd just dive in. So here's some 3d views of the model. (The underframe is a separate model and printed as such but I temporarily combined things for these shots.)

 

p2717841604-5.jpg 

 

p2717841600-5.jpg

 

p2717841603-5.jpg

 

p2717841599-5.jpg

 

p2717841598-5.jpg

 

I am not aiming for 100% fidelity to the prototype, but if I can get fairly close to the Slaters kits mentioned I'd be well pleased. If there are any great howlers in my interpretation of the prototype do let me know, but be gentle, please - my knowledge of coaches and details is limited, but as always I am keen to learn :) Some things l beefed up a bit trying to interpret the guidelines of the various printing sites regarding minimum thicknesses and detail sizes. The above shots I'm aware miss some details, things I perhaps could have added but was impatient eg dymano, door stops. Also in other areas I put detail which might not print. All just a test.

 

I have had this back and have been working on it. More details later on...in the meantime, hope you find of interest!

All the best

 

Jon

Edited by The Great Bear
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Very impressive. Now if you’d done a brake composite or a slip coach I’d be thinking of ordering some! (Or better still Dreadnoughts or Concertinas I might order some of them if they are available! If I might offer some constructive criticism, I think the corners of the waist panelling is too square.

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Very impressive. Now if you’d done a brake composite or a slip coach I’d be thinking of ordering some! (Or better still Dreadnoughts or Concertinas I might order some of them if they are available! If I might offer some constructive criticism, I think the corners of the waist panelling is too square.

Thank you. Yes, you're right about the waist pannelling and I've updated this in the drawing I am working on at the moment. It should look more like one continuous semi circle I think?

 

If I can get this to work reasonably well then other coach types and styles like Concertinas I itend to do. In particular composites (non-brake) are a gap in what I have in my stock collection, the Hornby Colletts being all I have that is remotely accurate. The WS Beckett book on train formations shows several 70' composites on trains in my area of interest.

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Hi Jon

 

Looks highly impressive. What level of cad knowledge did you have prior to starting? I can see myself needing/wanting to learn it at some point

 

David

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Having teased you with the images of the computer model, onto the realisation of it...

 

As I said I am new to 3d printing, so what follows is just my observations so far. There seem to be 3 main providers of online 3d printing services:

  • Shapeways
  • iMaterialise
  • Sculpteo

(happy for anyone to suggest alternatives!)

 

The default material offered seems to be nylon using the Selective Laser Sintering (SLS). This is what Shapeways term their White Strong and Flexible (WSF) material and the other two offer similar. The Autocoach I mentioned earlier used Shapeways WSF. A relatively new technique is HP mutlijet fusion which is similar to SLS but offers thinner parts and allows smaller details. It is more expensive than SLS nylon. Some sites offer resin or other materials as well but again these are more expensive.

 

All the three sites provide tools for reviewing models to see if parts are too thin, whether it can be printed. I found the Sculpteo tool the best, easy to compare different materials. For example the shots below the model of the coach in their SLS nylon material and then their HP multijet material.

 

p2717945378-5.jpg

p2717945377-5.jpg

 

You can see that the mutlijet material is more forgiving of finer details but is around 1/3 more expensive (compared to the economy/slower production SLS). The above showed that my design (after some iteration) was ok with the multijet material but some areas too fine for the SLS nylon. So, wanting to get something printed to see if the concept worked at all, I went for the more expensive multijet material.

 

Two models were printed:

  • The coach body with the interior nested inside it (to save on printing costs) - both the SLS and multijet techniques allow this, some others don't
  • The underframe

p2717963931-5.jpg

 

 

Results after my dinner...

Edited by The Great Bear

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Here's a close up of the 3d printed coach:

p2717683880-5.jpg

The panelling detail including the bollections seems pretty good. Some details haven't come through for being too small, the door hinges and detail on the vents above the doors. The finish as you can see is slightly rough, perhaps a little less than Shapeways WSF but clearly needing some work.

 

One thing I did mess up on was putting the interior inside the body. I didn't leave enough space between the two parts so they were welded together. I had thought I'd ruined the whole thing at this point but decided to do my best to fix things and carry on. So some demolition work with a dremmel was needed to cut this out, cutting the roof and end walls to get this out and then glue the model back together, the ends coming off worst. The result after a lot of glue wasn't particularly neat but painting can cover this.

 

p2717683887-5.jpg

 

p2717683908-5.jpg

 

p2717683922-5.jpg

 

Similar to the autocoach to a spray with Halfords filler primer and some sanding got the surface to a better state:

p2717683827-5.jpg

 

Compared to the Shapeways WSF material my impression was this needed a bit less work. I was perhaps too expedient using the dremmel for some bits of the sanding taking away maybe too much detail. One to learn! Following this a spray with grey primer got me to this:

p2717683818-5.jpgLooking at the photo now, it's clear in my haste I was too heavy with this spray and combined with some excess in the sanding a tad too much detail has been lost. All a learning exercise!

 

So, at this point the body was ready for painting...

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Here's the current state of the coach, body painted (not that well, the droplights and in particular the bollections are a right pain), grab handles added and bits of styrene strip added on for the hinges (as they didn't print), the door handle and the door stops. Some of this I'll try and get to print in the next version to be printed.

 

p2717683794-5.jpg

 

So far it's going ok I think, well enough to keep trying. I don't think my painting has done the model any favours, oh well, practice makes perfect.

 

Thanks for looking

 

Jon

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Hi Jon

 

Looks highly impressive. What level of cad knowledge did you have prior to starting? I can see myself needing/wanting to learn it at some point

 

David

 

Through my work I an familiar with 2d Autocad so the 2d elevation for the coach sides using drawings in books I could knock together pretty quickly. The 3d stuff I picked up fairly quickly, a bit of trial and error to work out how to extrude objects and do complex shapes like the panelling on curved surfaces like the lower coach sides. As I said I have access to full blown Autocad so stuck with what I know. There are free alternatives out there like Sketchup and Fusion 360 that are likely easier to pick up and do just as good a job - best look at other threads here and ask others.

 

Good luck with it

 

Jon

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Hi Jon,

pleased to see you have a go. It is only when you try that you start to realise where the potential problems are. would be nice to see how my design actually came out.

I still prefer WSF, yes you may need more cleaning up(it can vary), but it is easier , I think, to paint. I don't let any spray paint near WSF. WSF will suck as much as you can spray, and when it dries it loses some of the colout(I tried with grey primer). Far easier to hand brush with simple water based emulsion paint.

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Hi Jon,

pleased to see you have a go. It is only when you try that you start to realise where the potential problems are. would be nice to see how my design actually came out.

I still prefer WSF, yes you may need more cleaning up(it can vary), but it is easier , I think, to paint. I don't let any spray paint near WSF. WSF will suck as much as you can spray, and when it dries it loses some of the colout(I tried with grey primer). Far easier to hand brush with simple water based emulsion paint.

 

Thanks, Simon. Another evening or two and the autocoach will be done, will keep you posted.

 

Yes, I must admit so far I'm inclined back toward doing stuff in SLS nylon; with a bit of tweaking, selective thickening and oversizing of details here and there, the design I had done would do for that and it is quite a bit cheaper. From what I've seen to date both iMaterialise and Sculpteo do seem a fair bit cheaper with their SLS nylon than Shapeways WSF. 

 

Having just dived in to the first project to see what can be done, I am doing some more structured testing of different materials/services and design iteration. I am awaiting some prints and will post my comparison in due course. I will be interested to hear your views.

 

I will give just using acrylic paints by hand a go. I can't help but feel I made things worse with the spray paint, which matches your experience.

 

All the best

 

Jon

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I am not certain how other companies work out price, but Shapeways base it on space used in machine. They were losing a lot of money by not using the space properly, so rejigged their system to maximise space used. Unfortunately this means 4mm scale is not as space friendly as other scales. I recommend trying models in various versions, combined and separate, and sometimes the price diffeence is quite significant with separate items actually being cheaper than a combined one(and less hazzle searating components)

Also from my perspective they give access to a worldwide customer base.

I am not sure how Sculpteo work(they are popular with some French modellers), but I believe that with iMaterialise, you have to order at least one of your own designs to have that design available to sell to others. Obviously some only want to print for themselves, but more often than not, someone else will show interest, and also very common for other scales to be asked for.

3D printing opens a lot of doors, many of which some don't realise are there, and might prefer were not here. There is lso the queston of commercial licenses for software used. Most keep quiet about it, but at some point some might have problems.

 

At least I am not the only one doing GWR coaches(apart from the autocoaches/railmotors, I have done the articulated suburban coaches), so I can cut down on items for GWR. I do still want to do some railcars. As far as I am concerned is that the more that is done, by more people, the more interest there will be in models prduced by 3D printing.

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I was thinking about collaborative 3D design of models and I found this service which looks potentially very interesting:

 

https://www.onshape.com/

 

It's free for non-commercial use - so should be ideal to try out.

 

Unfortunately it simply doesn't work on my machine. It may be my high-res display that causes the problem but I'd expect a service like this to have been tested on machines like mine so it's a bit disappointing.

 

So, "Your Mileage May Vary" as they say and it would be really interesting to know other people's experience of the service.

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Impressive work,especially considering you have self taught. I was having a long chat with a brass kit producer regarding the future of brass kits versus 3D.

 

Just to be picky,are you sure the V hangers and vac cylinders are in the right place as my data shows a them against the queen post.#

 

Mike Wiltshire

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Impressive work,especially considering you have self taught. I was having a long chat with a brass kit producer regarding the future of brass kits versus 3D.

 

Just to be picky,are you sure the V hangers and vac cylinders are in the right place as my data shows a them against the queen post.#

 

Mike Wiltshire

 

Thanks, Mike. I expect you are right, the underframe as done was a bit rushed, something to sit the body on and see if the details like the v-hangers would print.

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Before having another go at printing a coach design I'm doing a little test, comparing different printing matetrials on a section of Toplight body shell, similar to that done on the coach as above - though some aspects changed, recess of paneling increased (to allow for some detail losss with my heavy handed painting and finsihing)

 

Running through the samples in order of ascending cost 1st up is SLS nylon in this case from Sculpteo

p2727274851-5.jpg

p2727275203-5.jpg

 

Next, SLS nylon polished from Scultpteo

p2727274850-5.jpg

p2727274852-5.jpg

The photo does not show it so well but it does feel quite a bit smoother than the raw version

 

Dyed HP multijet fusion, from iMaterialise

p2727274846-5.jpg

p2727274849-5.jpg

Disappointing. In theory this should be better detailed than the SLS ones, but this print isn't eg lines for the door aren't showing. Maybe that was the dye? The C30 coach I am working on was printed in this material but by Sculpteo and not dyed and was better.

 

Finally, iMaterialise standard resin

p2727275057-5.jpgp2727275048-5.jpg

Clearly, this is the most detailed print, you can see the detail on the door ventilator bonnets lost on the other ones.

 

All together

p2727275005-5.jpg

From left: SLS nylon raw, SLS nylon polished, Dyed HP multijet fusion, iMaterialise standard resin

 

The resin costs around 1.6 x the cost of the basic SLS nylon. Whilst it is more detailed I am not sure that it is worth it for a coach as aside from the ventilator there isn't a lot of fine detail and tweaking the design might bring some of that to the other materials by exaggerating things. Right now, my preference is toward the polished SLS nylon as for a few quid more it seems a better finish, saving a bit of work.

 

All may change when I paint these - that's tomorrow evening's exercise!

 

All the best

 

Jon

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Standard resin is the best 3D print material out there from any of the upload+print people, the downside is the minimum wall of 1mm which makes it unsuitable for a lot of 4mm stuff. 

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It's really useful to see this kind of experimentation being carried out.

 

Is there a 3D printing technology that would produce the fine detail and smooth surfaces of the injection moulded parts we're all familiar with?

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It's really useful to see this kind of experimentation being carried out.

 

Is there a 3D printing technology that would produce the fine detail and smooth surfaces of the injection moulded parts we're all familiar with?

 

Elsewhere Petri has had good results with Protolabs Microfine Green - http://www.rmweb.co.uk/community/index.php?/topic/96279-project-masters-for-resin-casting/ Significantly more expensive at the moment though

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With the iMaterialize standard resin, is there any surface-finish degradation beneath overhangs, e.g. on the turn-under of the coach side? I can't see any in the photo above.

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What also has to be remembered is that the maximum size for models is smaller for the finer finishes. Onother reason it is prefered by those in smaller scales. Even some OO scale is too big. Some get round this by in effct creating a kit of parts, which in my view, takes away one of the biggest advantaes of 3D printing.

 

I suggest anyone interested looks at prices for different scales of models. I always knew OO scale would be the most difficult, as it already has so many kits and r2r. Withsome of my coaches, O scale works out only a little more than OO, because i does not waste the space inside the coach body. With interest growing in O gauge, this might make it even more tempting. TT scale is almost half the price of OO, and that scale is getting renewed interest at the moment.

When it comes to polished or un polished, I have found unpolished surface can sometimes be as smooth. All in effect they are doing is rubbing down the surface, which might remove detail. Good quality sandpaper(no clogging green stuff) works really well, and you can then avoid some areas with fine detail.

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Standard resin is the best 3D print material out there from any of the upload+print people, the downside is the minimum wall of 1mm which makes it unsuitable for a lot of 4mm stuff. 

 

Yes I had to beef up the walls a bit to get this through the checks. Another downside, well adds to the expense of resin is that as part of the printing process support structures are added which then are cut away afterward. What this means is that you can't nest items inside each other, whereas say for the SLS nylon or MJF you can do this so the coach interior could be printed inside the body (just I didn't leave enough gap, next time better!) which saves on the cost.

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So here's a couple photos of the finished coach:

p2734021123-5.jpg

 

p2734021116-5.jpg

 

The camera rather cruely shows off my poor painting!

 

In additiion to the 3d printed bits the following other parts were used:

Things to improve/lessons from this first go:

  • Increase separation of parts when putting inside one other, so don't get welded together (the mess up with the interior)
  • Glazing, use thicker plastic and a lot less glue
  • Add blobs for door handles, door stops, hinges - subsequent prints have had these
  • Increase/emphasise some details eg louvres on door vents, roof rainwater strips so print
  • Cast pilot holes in 3d printed bits for door handrails, buffers
  • Increase thickness of floor on undeframe - bit too bendy
  • Improve how body affixed to underdrame - didn't think about this when designing
  • More care when sanding and/or get polished finished to ease amount required
  • Painting of droplights and bollections - will try a paint pen
  • Painting generally!

Any other thoughts/suggestions welcome. All a learning exercise not just the 3d design and printing but in general modelling, so the next one should be better!

 

All the best

 

Jon

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Before having another go at printing a coach design I'm doing a little test, comparing different printing matetrials on a section of Toplight body shell, similar to that done on the coach as above - though some aspects changed, recess of paneling increased (to allow for some detail losss with my heavy handed painting and finsihing)

 

Running through the samples in order of ascending cost 1st up is SLS nylon in this case from Sculpteo

p2727274851-5.jpg

p2727275203-5.jpg

 

Next, SLS nylon polished from Scultpteo

p2727274850-5.jpg

p2727274852-5.jpg

The photo does not show it so well but it does feel quite a bit smoother than the raw version

 

Dyed HP multijet fusion, from iMaterialise

p2727274846-5.jpg

p2727274849-5.jpg

Disappointing. In theory this should be better detailed than the SLS ones, but this print isn't eg lines for the door aren't showing. Maybe that was the dye? The C30 coach I am working on was printed in this material but by Sculpteo and not dyed and was better.

 

Finally, iMaterialise standard resin

p2727275057-5.jpgp2727275048-5.jpg

Clearly, this is the most detailed print, you can see the detail on the door ventilator bonnets lost on the other ones.

 

All together

p2727275005-5.jpg

From left: SLS nylon raw, SLS nylon polished, Dyed HP multijet fusion, iMaterialise standard resin

 

The resin costs around 1.6 x the cost of the basic SLS nylon. Whilst it is more detailed I am not sure that it is worth it for a coach as aside from the ventilator there isn't a lot of fine detail and tweaking the design might bring some of that to the other materials by exaggerating things. Right now, my preference is toward the polished SLS nylon as for a few quid more it seems a better finish, saving a bit of work.

 

All may change when I paint these - that's tomorrow evening's exercise!

 

All the best

 

Jon

 

If I may say so, the standard resin is the only one of those materials that would make the game worth the candle for me.  Not only is the detail and definition far, far better than the other three, but that looks like a reasonably smooth surface that wouldn't need too much detail distressing rubbing down.

 

I look forward to seeing what it looks like under a coat of primer.

 

I really admire your CAD work.  Marry that to the right material, and I think you've really got something here.

 

I note the problem with minimum thickness - it brings back to old RTR injection moulded coach bodies that needed after-market flush glazing - but that just might be where the compromise needs to be struck in order to obtain a decent finish and definition.

 

Good luck with it all, it's fascinating stuff.

Edited by Edwardian
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