Saturday, 26 September 2020

Axleboxes

If you look closely at what I have achieved so far with the 3D printer it has been very much a case of how to join circles and squares together and how to curve and chamfer edges. I've made plenty of progress and this summer seems to have been very successful in terms of how few failed prints I have had.

Over drinks one evening, my friend Simon was showing his progress on an early GWR horsebox. It has the most intriguing axlebox and spring arrangement where the ends of the springs are connected to J hangers rather than directly onto the solebar which is the more traditional way of doing it. Of course, I decided this was the next challenge I needed.

As always, there is a lack of good photographic evidence since most photos of wagons have the underframe in shadow. There were a couple of good pictures so dimensions were taken and the following was drawn up.

The axlebox itself is still a collection of squares and circles but the spring was the challenge and was built up from 3 point arcs. A circle was put on each end of the top leaves and then it was about trimming the shape to form the circle. It was a couple of hours work but I learnt so much about how to build up more complex shapes. It came out alright but when offered up to the vehicle my interpretation of dimensions was off.


Revisiting the dimensions led to a design that had more depth to it, the axlebox was chunkier and the width was narrower. I also needed to improve the printing supports. I am surprised it printed with what I did on the first pass.




In this form they have gone onto the model. I've learnt quite a bit more about printing and it is nice to give something back to my friends who have been so generous with their time and support for my modelling.

Sunday, 20 September 2020

Welshpool Coaches & 3D Prints

 Another huge break between posts. How does that happen? The last 3 months have been largely devoted to 3D printing. After the success with the side windows on Triumph I knew I had to get back to the Welshpool & Llanfair Pickering coaches. The big outstanding task was the roof. How to do it? How to roll it and then the fittings. What were the best fittings, the torpedo vents and the oil lamps. After a couple of purchases that really weren't what I was looking for, I decided I must surely be able to design and print suitable ones.

I've been following Vladimir Mariano on YouTube and he has some excellent courses that have been advancing my skills at 3D design. I had to learn a few more commands but eventually I came up with the following design. There are no drawings for these so they are an interpretation of all the photographs I could lay my hand on.

Having the design is one thing, working through the practicalities of printing took more effort. Essentially the printer prints upside down so you have to think about supporting edges that are in free air. There are also issues around where resin can collect and build up in unexpected places. The final design looked like this - you chop off all the unnecessary bits after printing.

There are nearly always supports required with 3D prints and if you let the printer software add them then they conspire against you and make these size prints take 3 times the time they should. I have developed my own technique for adding supports within the CAD program which is working so far for me. I also replicate items to create strips of 12 items, 5mm apart which nicely fits the printer build plate

Bearing in mind the body of these lamps is only a few mm high they are a tad challenging to photograph but here is the best I could achieve with my camera


The torpedo vent was done in much the same way. There are some drawings but their accuracy is not assured and the photographs are challenging simply because most are taken from ground level and the Pickering coaches had an enormous rain strip which consistently hides useful detail. the WLLR does have some replica coaches but with anything replica there are going to differences with the original and I have no way of knowing what is accurate.

Again, only a few mm high so hard to photograph but the end results do seem to have been worth it.

I have also done the guard's stove chimney for the composite coach along with a brake cylinder to go under the coaches. Who knows, the coaches may make an appearance soon!

3D Printing in Winter

I had previously suffered some disillusion over a very low success rate with the 3D printer but I've had quite a run of success over the...