.
I thought I had finished with the timbering bricks, but I've gone back to add yet another tickbox:
View attachment 4088
Ticking the above option causes a splint to be printed at the full height level with the timber tops, instead of being hidden down in the ballast:
View attachment 4089
I have called these brick
walls. To identify them they are shown hatched on the trackpad.
They must be cut off and discarded to make the brick usable. Which means they must be attached to the timbers by means of splints and webs only, so that they can be cut away easily. You can add as many as you like, anywhere you like. You might like to make them specific sizes, so that they become useful additions to the modelling junk box -- wagon loads? fence posts? There is an option in the menu to change the width and thickness of each one individually if desired. You might even omit the timbering base and combine them with slab shapes as a primitive form of CAD to create point-motor brackets and suchlike.
What are they for? Look at this:
View attachment 4091
Those FDM artifacts on the timber surface look awful (this is EM gauge). They barely notice in the original, but a scoosh of grey primer and a cruel close-up shows them up badly.
To hide them there are two possibilities:
1. rub some filler into the surface. Easy and quick. But it's surprisingly difficult to do that without getting any in the sockets -- which spoils the fit of the chairs.
or
2. switch on the
ironing function in Cura. This adds a very thin film of polymer over the surface to create a top skin. It is slow and increases the print time considerably. But it works quite well to improve the surface -- I have found a flow rate of 5% of the normal layer flow works well to smooth the surface without too much pillowing effect.
Either way, or even if you do nothing, you are likely to want to sand over the surface of the timbers before fitting the chairs. It needs to be done wet with soapy water and Wet-or-dry abrasive paper on a sanding block or plate. Abrading the polymer dry risks melting the surface of the polymer from friction heat, which ruins the process. The wet process avoids this.
But however careful you are, and however flat the sanding block, it's inevitable that the end timbers will get sanded down more than the middle ones, and you then have an uneven top level for the finished track.
That's where the sacrificial
brick walls come in. They protect the end timbers from excessive sanding and help you preserve an even top timber level.
I seem to have written another rambling chapter in
"The Book of Plug Track".
Oh well, the option is now there if you want it. In the next program update.
cheers,
Martin.