Garden Railway Forum

I've got a rake of 5 Hudson type skip wagons which I think are probably Big-Big Train. I've long wanted a few more but they go for silly money and I'm not that desperate.
There is a website called Thingverse which is a repository for all kinds of objects which folks have drawn and printed and then put up for free distribution. Most of the model railway stuff is for the smaller scales and/or the US and Europe, but I did spy the files for a Hudson type skip wagon and it's been in the back of my mind for some months. With the bad weather forecast for this weekend I downloaded the files yesterday to see what I could do. Basically, as drawn it seems to be designed to match LGB, so the first job was to rescale everything, which was only a few clicks to tell the software I wanted everything reduced to 72%, to get it to a nominal 16mm scale.
It's quite slow printing, the chassis and tub took about 5.5hours each, plus the 4 axleboxes about another hour, the coupling blocks about 30mins and the 4 wheels just over an hour. Normally items are printed at about 20 or 30% solid, which speeds things up and saves material, however I wanted this to be capable of taking some rough handling so I increased the fill to 70%, which explains some of the printing time. The wheels I actually printed at 100% solid. I'm not sure about using the wheels i think I might replace them with 'proper' ones, but they do look surprisingly good profile and actually round, although how well they roll remains to be seen.

Anyway, here are the components, roughly cleaned up, they still need a bit more attention before they can be glued together.
...and here it is clipped together in a dry run, but without the wheels
I calculate that the material cost is approx £1.50 plus axles and new wheels if I decide to change them.

Sounds like good value. Are the frames as strong as cast plastic?

Rik

Not sure tbh, Rik. Probably less strong than an ABS extrusion but I think they are strong enough to do the job though.
The oval chassis frame itself is pretty strong because it is I-section and printed curved so the filaments go lengthways round it, and any internal gaps are printed as a honeycomb so are inherantly pretty strong. The thin vertical sections are less strong because the layers runs horizontally in very short lengths and in the past I have had a problem with them splitting across. Nowadays I solve that by washing the surface of suspect areas with Plasticweld before I start filing and sanding.

This is what puts me off 3D printing in this scale as the finish looks ruff and would take effort to sand and fill right?

Every step of model making requires effort of one sort or another. 3D printing is not the easy solution to all problems but can help when others methods are not available or simply too expensive. As they say, you get out what you put in and a little preparation work of filling and sanding seems a small price to pay.
My experience with 3D printing has been positive and I have seen great results achieved by those who are able to spend a little time.
Each person works to their own standard and can build on that as it suits should the need arise and they gain experience.

Another lovely print there Philip!

I have seen that on Thingverse and thought about having a go but I have a rake of 12 Binnie skips which is enough for me.

Do you find that the plastic weld helps with both the strength and the finishing? I have been wet/dry ing my 3D prints with increasingly fine paper followed by an acetone polish which gives a good finish (if the part is functional and unseen then it may well get less treatment!)

Lovely to see you are still very much printing with excellent results

Tom : I think Peter has said it for me. Yes there is some fettling to be done and it gets tiresome sometimes. However If I were to try scratchbuilding this vehicle from flat stock HIPS, it would take me many many hours to achieve the same thing, without any guarantee that the overall effect would be that much superior.
3D Printing isn't the answer to everything and all that I've done so far has been part of the experimenting and learning curve. There are quite a few things that I would have done differently with what I have since learned, or probably not printed at all..

Jim: The Plasticweld wash does smooth the surface to some extent, in a similar way to the acetone smoothing. However it also softens the surface so it then needs leaving a fair while to completely set again or it drags and clogs the wet & dry, etc. I've only once tried an acetone polish with not very good results, but I think that was down to my impatience and not leaving it in long enough. I've been thinking I'd try it again on the tub for this skip, to see what happens.

Am I right in thinking that acetone polish would have a similar effect to painting with liquid poly adhesive? Is acetone a solvent as well?

Rik

Rik,
Yes it is similar. The 'acteone polish' basically consist of suspending the object in a closed container above a pool of acetone. The Acetone vapour then slowly softens the surface of the model and allows it to flow and 'lose' the layer imperfections. The difference is that being surrounded by the vapour, the effect is even across the model and in the nooks and crannies, where as brushing solvent on tends to be a bit brualist with pools and missed bits.

That looks good and is that sort of thing I would want to produce if I had a printer. Making a master and casting resin axleboxes seems a fag when a machine could do it for you.

£1.50 +...how many can you make me please....