I thought it would be easy to modify my U29 model, to represent the body of a diagram G13 Family Saloon but various gremlins struck with a vengeance!
Omit reading the ‘Gremlins’ sections, if you just want to follow the progress of the model itself.
I have now learned the necessity for taking great care when selecting entities to modify in Fusion 360.
For example, when selecting parts of a drawing in, say, the X-Z plane, it is easy to include parts of a drawing that are in the Y-Z plane, by mistake. So, unintended changes are made to the ‘other’ drawing as well. I think this explains how I managed to lower the height of the clerestory, without noticing until I had done a lot more design work. Although I could ‘go back’ to the point where the problem started, I still had to re-do all the work on the window apertures and partitions, to fit the corrected body shell.
I have also found some difficulties when importing old DXF drawings into Fusion 360. Some panels, which had seemed to be ‘closed’ in other software, could not be extruded. I eventually spotted some very tiny gaps, which I managed to fill, although I am still not sure exactly which incantations are needed to make the ‘extend’ command work on drawings imported into Fusion 360. I had almost given up, when the command suddenly started working, for no reason that I could determine!
Having modified the drawing, I tried to save it and this brought up a message that “This file type requires cloud translation, which may take a few minutes.”. For some reason, the ‘translated’ DXF file was unreadable in other programs, such as Studio, Autosketch, or Irfan View. In the end, I decided to go back to Autosketch and repair the file there, so that it now works correctly in both Fusion 360 and other programs.
I mention these things, to show how learning 3D CAD programs can be very frustrating.
Printing the G13 body and clerestory
Once I had modified my carriage design to represent diagram G13, I printed the body and roof, as previously described for my U29 carriage.
This time, however, I wanted to investigate how I might use the 3D printed body as a basis for ‘finishing’ with parts produced on my Silhouette Portrait cutter. For this reason, I omitted the inset panel details, which I had included in my U29 model, and left the outer surfaces smooth. I did, however, include other inset items, such as window apertures and drop-light frames.
There’s nothing really new in this – I’ve simply substituted a robust 3D-printed body shell for the relatively frail laminated plasticard that I had used before. I am impressed by the toughness of the PLA plastic. It’s supposed to be bio-degradable, however, so perhaps it will crumble away in a few years time – I’ll leave it to my Grandchildren to find out!
My planned method was to use my Silhouette Portrait machine, to cut out the body framing from 10thou (0.25 mm) plasticard, and my HP Inkjet Printer to print overlays for the body sides. The ‘registration’ facility of the Silhouette Cutter could then open up the window apertures in these overlays, in registration with the printed body sides.
The Three Printers used for This Project
For most of my earlier carriage building, I printed coloured sides onto HP Photo Paper, although I did carry out some experiments into printing directly onto plasticard (described in posts in JCL’s Silhouette Cutter thread) I found some of my old ‘printed-on-hairspray’ samples in a drawer and they still look fairly good – better than I remember achieving at the time.
The actual printing and cutting procedures were exactly the same as I had used previously, when building my earlier versions of these carriages. To summarise:
“Open the colour image in Studio, copy it and paste it into the cutting diagram. Use the 'Arrangement' command to sent the image to the back and then re-size and align the image with the cutting marks as accurately as possible on the screen (use a magnified image and make sure that 'Snap to Grid' is 'off'). Once you are content with the alignment, turn 'on' the Registration Marks in Studio and Print the image on your colour printer, using the highest print-quality settings. The print-out will include the alignment marks, which will be read by the Silhouette cutter so that the various apertures will be aligned with the colour image.”
I already had all the necessary drawings in DXF files and the colour images as TIFF files, so I could simply open these in Silhouette Studio. The only differences from my previous method were that I printed the colour overlays onto printable vinyl and cut the frames out of 10thou plasticard, to be applied on top of the vinyl sheets.
Finishing the Model
The first task in finishing the detailing of the 3-D printed body was to cut out the frames, using 10thou (0.25 mm) plasticard. After cutting out, which the Silhouette cutter handled very well, I painted the frames black and hung them on hooks to dry. If I were making a lot of these, I would try to source some black plasticard.
Next I printed the body sides from the Silhouette Studio software, using my HP ink-jet printer. I found, after the first test, that the colour setting of my printer needed to be re-adjusted for printing on vinyl sheet, since what should have been ‘chocolate’ came out more like ‘Indian red’. After a couple of test prints, I achieved a more acceptable colour for the lower body sides.
I had found before that the vinyl does not stick well to the body shell after spraying with grey primer so, while painting around all the window opening in Indian Red, I decided to continue painting the whole side with enamel, hoping it would provide a better surface for attaching the vinyl.
It was quite tricky to get the vinyl sheet into good alignment with the window apertures, since there is no ‘slide’ and the adhesive grabs very quickly. As it happened, the first attempt went well but it does need considerable care! The clerestory was particularly tricky because I had to tuck the top edge under the roof overhang, for which I used cocktail sticks to push the vinyl layer into place before tamping down over the rest of the side. It was good to have painted the entire sides first, as any very slight mis-alignment round the windows was not apparent.
Finally, I had to decide how to attach the outside frames, which are rather ‘floppy’, since they are just a skeleton of narrow beadings. I did not want to damage the appearance of the printed vinyl sides by applying excess adhesive. I decided to go back to the can of hair-spray that I bought some years ago for experiments on printing directly onto plasticard. It acts as a mild ‘hold’ adhesive while leaving no visible traces on the surface and I was pleased to find that, in general, it worked well, although adhesion in a few places was poor. I felt, however, that once the main part of the frame was correctly positioned, everything could be made firmer by applying an overall coat of varnish. This was another very tricky part of the assembly and the alignment on my first attempt was not perfect. The ‘First’ lettering on the doors is not quite centred within the frames. I shall continue to experiment, if I try further assemblies of this type.
Overall, this method of construction worked well. I haven’t really broken any new ground, since I have previously added new printed sides and framing to one of the well-known Ratio carriage kits. The only new aspect in the current model was in using all-plastic materials, rather than photo-paper and card.
Perhaps I would have felt a greater degree of satisfaction if I had built a new type of carriage, rather than repeating one I had made before. There is no doubt that the use of a 3D-printed body has resulted in a much stronger overall structure. I’m sure this could be achieved for Silhouette-cut sides by laminating more layers, although that approach brings risks from warping and mis-alignment.
A photograph, which had previously cruelly revealed the defects in my earlier carriages, does show that the new overall structure, especially the clerestory roof, stands up well to close scrutiny.
G13 Family Saloon – final details to be added
For this photo, I placed the body on the Cleminson chassis that I built several years ago for my original Family Saloon. I have nostalgic feelings for the older carriage, which now has a well-worn look but is noticeably out-of-true in several places. The really huge advantage of the 3D-printed body lies in the clerestory roof, which I never managed to fabricate well.
From my point of view, it was all part of a learning exercise, helping me to feel more confident in tackling more complex shapes, where the 3D-printing method will come into its own. I shall now switch my attention to such structures.
Blanche Wilcote is pleased that the new carriage is much less draughty than the old one, which had various gaps along the seams! So that is some reward for my efforts