Ballast Cleaning Train - Part 16 (SLA Resin 3d Print Version)

There is a lot that could go wrong with the design and print of this generator wagon chassis. For a start there is a lot of thin levers, rods and brackets in the underframe that may not print well. Then, there is the distance between axle boxes; did I get it right taking into account fitting of brass axle bearings and free running wheels.

Well, the print (6hrs 42 mins) was near perfect. The only damage was a few breakages as I cut away the intense support structure. (I think the Lychee auto support facility goes OTT on quantity but, it is a godsend for the novice.) Plasticard infills repaired the breakages.

One mistake was to use a hairdryer to quickly dry off the print after water washing. The heat warped the axle box tie bars badly. The print is quite pliable prior to UV curing so, I used various materials with required thicknesses to prop and force the tie bars as straight as possible before the UV curing process. The UV then hardens the plastic allowing parts to hold their shape. The tie bars were much improved although a little warping is still present that I'll have to live with. I really don't want to reprint the model.

The wheel sets fitted perfectly between the axle boxes. However, they did not turn freely. I had made a big design mistake by setting the brake shoes too close to the wheel treads and flanges. The brakes were locked on! I had to snip off the break shoes, cut the brake rods back a little and re-glue the shoes in place. Did I say I really don't want to reprint the model. (It uses a lot of resin and takes too long.)

Talk about printed detail - the individual leaves of the leaf springs are clearly visible! Each leaf must be no more than a quarter millimeter thick.

Postscript: I had a eureka moment about the warped tie bar. I glued a piece of stiff wire behind the tie bar which pulled the bar straight.

To Part 17.

To the beginning.

Read about the SLA (stereolithography) resin 3D printer here.

Read about the FDM model here.