O Scale HSS – III

Bar Handle
TB_version_3Something like this might work. A piece of 0.030″ thick brass could be used for the handle. A 0.040″ dia hole with a bit of wire would act as the pivot. A hole in the end that the end of the connection rod would fit into.

The bend might have to be vertical so the handle moves the connecting rod far enough to operate the switch .. a horizontal bend might interfere. Thing is .. if someone is good at Photoetching that handle could be given a 3D effect .. something like a H-bar profile

The Real World ..
Got the prints in and it says quite a bit about the limits of the current 3D process. I can get prints that are quite a bit better in FUD .. but that material lacks the strength necessary for this project. WS&F had the strength (I think) but the print resolution leaves a lot to be desired.
printedOn the left is the printed body. This gives an excellent example of the resolution available in WS&F. Look at the center left. That is supposed to be a square shaped projection .. as seen in the drawing. What we got is a rounded edged shape. This again, is simply the resolution of the process. WS&F is a sintered nylon .. meaning powdered nylon is fused by a laser beam – and what we see is what we get .. and all that. To be honest .. I flipped another body side around and it fit well enough even with the rounded edges but the biggest problem was where the feet join together.
foot1A closer look at the left side ‘foot’. To be honest .. this is partly my fault as I got to ‘complicated’ with the design. This needs to be simplified so this coarse printing will be more effective.
foot2The right side. This is a good example of me being ‘overly complicated’. That bit of foot needs to come out straight into a rectangle. That way the rounded corners will fit into the other side much better. As it is that dog-legged bit has just go ‘scrambled’ …
One of the things that I see right off that needs ‘fixing’ .. beyond what I just pointed out is the flange thickness. That needs to be a bit thicker .. the printing process naturally creates a rounding of the edges .. and I have the flange at minimum thickness which with the rounding creates a distortion. I think making it slightly thicker will make it much better.
Version 4
body4Based on the prints I made a few changes. I removed the convoluted area the control rod passes through to simplify that so it MIGHT print ok. I also made the flanges twice as thick. They are now 1.4mm/0.055″ .. which would translate to 2-1/2″ full-size. I think though, with the ’rounding’ from printing right at the edge of the printer’s capabilities this should be ok.
body4cuA closer look. One thing I noticed was that the holes I had placed for NBW didn’t print at all .. so I need to remove them from the mesh (darn it). I suppose I could save a copy just in case I wanted to print these in FUD for some reason (it MIGHT be reasonable to use a FUD copy for a RTV master so they could be cast in resin).

The feet themselves might be better if I reduced the mounting bolt holes from two to one .. and possibly make the hole slightly larger. That will probably force enlarging the foot a bit to leave a wall thickness of 0.7mm minimum.

Version 4b
body4bOk. If you look at the bosses .. my original intent was to put small holes in the center of each so aftermarket NBW could be added easily. Didn’t happen. The WS&F is simply too coarse for this and it didn’t work. I removed them in this version. I had doubled the foot-flange earlier .. now I reduced the mounting holes from two to one.
Ver 3 Test Fit
TestFitA quick and dirty test fitting. I did some light filing where they join at the bottom. I *think* .. I corrected that problem with Version 4. In the meantime .. this actually doesn’t look that bad. I haven’t done anything like a light sanding to remove the ‘dangles’ on the edges.

All in all not too bad .. with the Harp Switch Stand sitting on a dime to give an idea of the size.



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