So, I posted this to the Makerbot google group also, but my post isn't showing. I hope it's because of a technical problem, and not just me being impatient with moderators approving my first post or something…
Anyway, hi everyone, my name is Jeff and I'm working on a Thing-o-matic owned by my local makerspace. The machine is running with Jetty firmware and up until recently, an MK7 extruder. I've had consistent problems with the extruder in terms of feeding issues, admittedly most of which are caused by low ambient temp in the shop. For more consistent behavior, I've built a no-hob extruder (Thingiverse thing 28430).
The extruder is working great in terms of filament feeding. The problem I'm having now is getting the machine profile and skeinforge profiles set up appropriately and I'm hoping someone can help.
I've read all the threads I can find about calculating steps per mm, although I've been unable to find one specific to replicatorg and the ToM with a geared extruder. Based on the math provided by the extruder designer (in the instructions section of the thingiverse page) I have the steps per mm set to 970. I've created a new machine definition in the /machines/thingomatic-advanced.xml file based on the original settings and added the new stepspermm value, and I've confirmed (through the machine information menu option) that the value is being loaded.
The gearing is giving me fits. I figure with a 47/9 gear ratio (5.222) and the new driver gear giving an additional 1.89 ratio (old was 10.58mm, new is 5.2mm) I *think* that gives me an effective drive gear size of 1.07mm. I plugged that into the ProfileMaker on Makerblock and generated a new profile. The resulting print had an extrusion speed that was WAY too slow based on the 20mm test cube I printed.
Has anyone swapped in a geared extruder onto their ToM? If so, can you either find a flaw in my math, or thing of something I've missed? I'm inclined to think I missed something somewhere in a config file or in the app because even increasing the stepspermm value dramatically in the XML file doesn't appear to change anything.
Thanks for reading,
Jeff