3D printer uses

[loose nut]

Switch to PrusaSlicer

OK I downloaded and tried the Prusa Slicer and guess what the STL file shows up with all the rifling there. So does that mean that Cura just doesn't show it in the model or can't show it in the model because it can't process it. Neither will necessarily be able to print the rifling, I'll have to wait until my printer shows up and I figure out how to use it correctly. In a lot of ways the Prusa program seems a lot easier to use and there is a couple of things that it can do that Cura can't but Cura has 80% of the slicer market so that is where everyone will migrate too for support.

Boy that Josef Prussa has some ego, has to have his name on everything.

[epicfail48]

OK I downloaded and tried the Prusa Slicer and guess what the STL file shows up with all the rifling there. So does that mean that Cura just doesn't show it in the model or can't show it in the model because it can't process it. Neither will necessarily be able to print the rifling, I'll have to wait until my printer shows up and I figure out how to use it correctly. In a lot of ways the Prusa program seems a lot easier to use and there is a couple of things that it can do that Cura can't but Cura has 80% of the slicer market so that is where everyone will migrate too for support.

Boy that Josef Prussa has some ego, has to have his name on everything.

In fairness to Josef, Prusa Slicer is a forked version of the Slic3r software, made specifically for Prusa printers

As to the model, im guessing that your second guess is correct, Cura doesnt render it in the model because it cant print it anyways. That said, couldnt reproduce something similar in my copy of Cura. Could be that my test model didnt have small enough details, but i dunno

[loose nut]

OK now I tried it with .2 nozzle in ultra quality and it worked, there be rifling??? I thought i had done this before but............................................

[epicfail48]

Welcome to 3d printing! Be prepared for a lot of moments like that...

[hollo]

Two related thoughts about making the change gears. 1. Unless you are planning to make deep cuts on low thread pitches the plastic gear will probably do just fine. The possible failure would be the keyway to lock two gears together for compound gears. Make a metal bushing for the part with the keyway and that probably goes away. 2. How much would it cost you to make a gear to try out? PLA is fairly strong and quite cheap. Why not give it a try.

I finally got round to trying number 2 here. I couldn't find an existing set of files for Harrison M250 change gears, but found some code for doing Modulo 1.5 gears and measured the central keyway bit. It seems to work quite nicely - here is the 22, 100, and 45 tooth set installed as a first go. It runs well and I haven't broken them on a few light passes!