Jump to content

JimFin

A little SCHÖMA

Recommended Posts

I am putting this post in this thread but it could go in many, hope you find it interesting anyway,

 

This started off as a little 3D design project as I fancied a Schoma shunter for Neuburg but the Bemo versions rarely appear for sale.  Thought I might revisit 3d printing a vehicle. Never been happy with the results previously - too much texture and finishing needed, you loose the detail in the post printing process. A bit of research threw up a BEC 12mm tram chassis with 42mm wheelbase. At this point purists should leave the thread, its 1mm short for the prototype. I reckon since the public should never get close enough to notice it was worth a punt.

 

Anyway, the CAD was relatively straightforward -

 

1705501047_187tm22.png.38c47e73bee063e8c00af8f704e39d01.png

 

A few draft prints to were knocked out to check dimensions and the chassis fit before a final high quality print. But as anticipated the body was completely unacceptable - however the underframe was quite decent and I had printed it and the handrail panels as an experiment in e-PLA, an engineering grade plastic that can be annealed in a domestic oven after printing for additional strength.

 

Having modified the BEC chassis to fit and converted it to digital, it runs really nicely, found a German Zimo supplier that is providing a decoder loaded with the appropriate sound file which is on its way.

 

Having decided the body was not up to scratch but having a decent CAD design, I sliced the relevant shapes into SVG's and borrowed SWMBO Cricut Maker to cut them out of plasticard. Quite handy that doing it that way, windows are the negative of a window cut out so able to cut exact fits for those, the headlamp covers and perspex sheet on the handrails. Also cut vinyl window outlines dimensioned + and - 0.5mm of the windows to act as frames for the glazing.

 

Much messing about later and this is the result.

 

IMG_20200531_212945425%5B1%5D.jpg.43473e80dd66d0b7581d81622ed0dbc3.jpg

 

There are parts I am not happy with and may well redo the body - as I have learnt along the way!

 

 

 

 

  • Like 10
  • Craftsmanship/clever 6

Share this post


Link to post
Share on other sites

That looks really good to me Jim.

  • Thanks 1

Share this post


Link to post
Share on other sites

There was a time not too long ago that 1mm out on a wheelbase was deemed close enough by magazine reviews. I think you've done a great job. Have you ever tried PLA+ and if so does it give a better finish?

 

Simon

  • Like 1

Share this post


Link to post
Share on other sites

Looks good to me :)  Could you slice it up and print as flat panels to make a sort of kit to eliminate the texture? I don’t know if certain orientations will give a flat surface? There’s a chap in Japan who did that. 
It’s what you’ve proved works that’s got me seriously looking at a new pc and ‘accessory’ to go with it! ;) 

Share this post


Link to post
Share on other sites
Posted (edited)

Looks like a really good job Jim. Now got me thinking of a print for Shapeways to do one for Santa Maria

Edited by warbonnetuk
  • Like 1

Share this post


Link to post
Share on other sites
1 hour ago, simonmcp said:

Have you ever tried PLA+ and if so does it give a better finish?

Not tried that specific variant but generally use rPLAG which is 80% recycled material (r) with a glycol trace added to the compound to reduce brittleness. 

The issue I have is an FDM printer will never (in current iterations) get anywhere near the surface finish I would want to represent a metallic surface, its simply too course. Great for buildings (see the Neuburg thread) servo mounts, brackets etc. I am waiting with interest to see the Elegoo Saturn when it is released as I may be tempted to spring for one of those.

 

1 hour ago, PaulRhB said:

Could you slice it up and print as flat panels to make a sort of kit to eliminate the texture

Thats essentially what I did, made a plasticard body kit to sit on the printed underframe -

 

191446445_tm22revisedbody.png.ca24ee88ef73c0e402541d35429cf046.png

 

44 minutes ago, warbonnetuk said:

Looks like a really good job Jim. Now got me thinking of a print for Shapeways to do one for Santa Maria

 

I am not precious - attached is a copy of the CAD file. You can work out some of the details yourself! http://www.kwtrams.co.uk/productdisplay/mett42d10-3mm-scale-4-wheel-truck You need to modify for DCC by isolating the motor from the chassis and replace the white metal motor strap with a brass strip to get it inside the frames.

 

 

 

 

1 87 tm 2 2.stl

  • Thanks 1
  • Craftsmanship/clever 1

Share this post


Link to post
Share on other sites

RhB Bob had one done in Om a few years back and even that required a fair bit of sanding as a 3D print ;)

Mark Clark from Locos n Stuff makes custom power bogies in 9mm gauge upwards and is extremely helpful too if you need a smooth running custom chassis, or one made from his universal kits. Highly recommend. 

 

28 minutes ago, JimFin said:

Thats essentially what I did, made a plasticard body kit to sit on the printed underframe -

I’m really just using your expertise here as I’m trying to understand the limitations before I get too carried away ;) I assume that you’d still get lines even printing as a flat panel then? Another chap who is trying out some walls inspired by my roundhouse surprised me by printing them on a support structure at an angle. There was too much suction to the mat otherwise and it damaged the parts getting them off, would this apply here too?

 

32 minutes ago, JimFin said:

I am not precious - attached is a copy of the CAD file.

Nope, exceedingly generous with your creations as I have benefitted from them in N :) 

  • Thanks 1

Share this post


Link to post
Share on other sites
4 minutes ago, PaulRhB said:

I’m really just using your expertise here as I’m trying to understand the limitations before I get too carried away ;) I assume that you’d still get lines even printing as a flat panel then? Another chap who is trying some walls inspired by my roundhouse surprised me by printing them on a support structure at an angle. There was too much suction to the mat otherwise and it damaged the parts getting them off, would this apply here too?

No lines Paul, these are NOT printed, they are cut from styrene sheet using a Cricut Maker and then assembeled just like a plastic kit. This might explain - 

 

 

The printing at an angle and avoiding suction are features of a resin printer rather than FDM - may invest in one later in the year if the price is right, the print volumes on the hobby ones are a bit small and quite restrictive for HO or above, other than small components, but the Elegoo Saturn as I mentioned addresses this quite nicely. 

  • Informative/Useful 1

Share this post


Link to post
Share on other sites

Sorry I confused you there, I realised it was actually done on the cutter but was wondering why you chose that over printing flat sections? 

 

Share this post


Link to post
Share on other sites

Flat sections would still have "grain" its just the way 3d printing works, they would be easier to sand and finish - but I think its a case of choosing the best material / technique for the job. I think too many folk get hung up on one medium for everything e.g. handrails. Why represent them with course printing when, in this instance, a bit of left over Sommerfield overhead line offers a supply of 0.4 and 0.5 mm wire.

 

Now I am just messing about! Do need to fit the Croc detailing though!

 

croc_and_shunter.jpg.4b1b168d79332f1c084a5ab66196afdd.jpg

 

 

  • Like 4
  • Thanks 1

Share this post


Link to post
Share on other sites

Hi Jim

Just found this thread via RM Web alerts on my iPhone. That really is a super little loco - you should be very pleased with yourself in producing that model. If you get it to a marketable form I for one would be interested in buying a kit/3D print body off you. The relatively high price and rarity of the Bemo model are good incentives for a reasonable financial return for your efforts, if you were so inclined.

I have N drive 1015 size motor on a High Level gearbox driving 12mm diameter wheels on a 2mm axle that would be suitable as the basis for a chassis. I was thinking of using it for a Ruston 48DS in P4 until Hornby brought a RTR model!

I am sure you are aware that Mike Thomas has made a HOm model of RhB 4 wheel diesel hydraulic tractor Tm2/2 number 93.  It was described in detail in Continental Modeller for August 2010, p500-503. He acknowledges help from Paul Steadman. His model is a very extensive rework (!) of a Knightwing diesel on a Halling motor bogie.

Regards

John.

Share this post


Link to post
Share on other sites
4 hours ago, Talbotjohn said:

in Continental Modeller for August 2010, p500-503. He acknowledges help from Paul Steedman.

;) 

All I did was supply drawings and some pics. 

  • Like 1

Share this post


Link to post
Share on other sites
On 01/06/2020 at 11:01, PaulRhB said:

Sorry I confused you there, I realised it was actually done on the cutter but was wondering why you chose that over printing flat sections? 

Sorry - missed that Paul - printing flat panels still gives a grained finish BUT not if the visible side is the one which was attached to the base of the printer. The base of the first layer has some different characteristics and comes out as smooth as the glass bed. So a bit of mental origami and if I printed the body panels upside down - it might very well work. There might be a few misfires as that layer would have to be 100% perfect for it to work and its not always! Never usually matters as you don't see it! Given the nature of these panels, might give it a go. Just need to think about how to deal with the louvres. 

6 hours ago, Talbotjohn said:

If you get it to a marketable form I for one would be interested in buying a kit/3D print body off you. The relatively high price and rarity of the Bemo model are good incentives for a reasonable financial return for your efforts, if you were so inclined.

I just do this stuff for fun, as I said earlier, there are bits of the current model I am not completely happy with and Paul has sparked an idea that may well lead me to making another! I will post it here if I do. If it resolves the bits I am not happy with - quite willing to provide a kit of the printed and/or cut parts for you - material cost (maybe £5 to £10) and postage. You would need to source chassis, couplings, handrails, SMD's if you want lighting, paint, decals etc yourself but could write up some notes and maybe some photos of the build record of the next one - but not sure when that might be!

 

You see I have my eye on the Gmf 4/4 28701 - 04 as they would lend themselves to the same approach with a couple of these tucked in it - http://www.kwtrams.co.uk/productdisplay/mentf26s09-tf-gauge-narrow-4-wheel-truck

 

 

 

  • Thanks 1

Share this post


Link to post
Share on other sites

Hi Paul

Apologies for misspelling your surname. I realised it was wrong but thought I had corrected it before submitting my reply.....

Hi Jim,

It is very kind of you to offer to sell me parts if you get the loco sorted to your satisfaction. I am in no hurry. Even having some pre-cut plastic sheet parts is a massive step forward and saves a lot of time and energy. It won't be a lot different to building 009 diesels from flat etched brass parts and I'm quite happy to build my own chassis.

Mike Thomas' article suggests where some of the detailing parts he used on his model, including decals, could be obtained.

  • Thanks 1
  • Friendly/supportive 1

Share this post


Link to post
Share on other sites

Now that is really good , and seeing how not only are the Bemo ones hard to find , they are usually a ridiculous price when they do come up,

 

 

  • Thanks 1

Share this post


Link to post
Share on other sites

As the weather turned wet yesterday - got some modelling time as other tasks put on hold. Sneak preview of WIP - IMG_20200603_151821040%5B1%5D.jpg.32ad2f58dabf82162a2d6fb68a7b946f.jpg

  • Like 5

Share this post


Link to post
Share on other sites

Decoder arrived - 

 

  • Like 3

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.