Garden Railway Forum

Something weird going on with my resin prints and I'm out of ideas, so any thoughts welcome.

OK, I'm trying to print a 4-wheeled coach ( F&B All Third), flat on the bed. The Brake Third and Composite were done the same way with no problems, but this All Third is being weird. Basically what is happening is that the printer is adding approx 2-3mm to the bottom of the print, before carrying on upwards and everything else is fine. The net result is that the floor of the coach is about 5-6mm thick instead of 3.5mm. It also of course affects the bottom of the panelling and solebar areas, and that can be seen in the print picture below, where the bottom area seems to be narrower than it should be and the bottom beading has disappeared. Plus there is a tendency for it to try to split horizontally where the bottom of the floor should be, as though it is actually sitting on a raft.

I have the 'lift' distance set at zero, and I have 'no raft' set. The SketchUp drawing is fine ( it's basically the same as the previous two coaches with the windows altered.) The Chitubox visual is fine, The sliced G-code reconstruction is fine, but what comes out of the printer has the extra thickness. The prints are well stuck to the bed all over - actually a bit of a struggle to get off but quite doable.
This composite picture shows: (a) the SU drawing, (b) the Chitubox ready to slice, (b) the actual print, (c) the G-Code sliced file reconstructed.
FWIW, the small circular ears on the corner are to reduce any tendency to lift and are 0.5mm thick. I 've tried printing without them and it makes no difference.

They are all the same, apart from the physical print... HELP!!!!

Might be a long-shot, but is the body actually sitting on the main workplace in SketchUp?
I had a similar problem with one of my designs and it took me a while to track down the issue, but I appreciate that SU is a lot more sophisticated than TC

Rik

Sketchup doesn't have a main 'bed'. It just has the normal three axes and you can be anywhere in space, but the important thing is that it is truly flat to the x-axis and y-axis . i.e not at an almost imperceptible angle. I have had that problem in the past but unfortunately not on this occasion.
However I think I may have found the answer, but still don't actually know what the problem is. Unfortunately I've run out of resin ( wasted it on failed prints!) so can't be certain until Mr Amazon gets here tomorrow.