Advantages or disadvantages to having a direct-drive extruder versus one that drives with gears and a hobbed bolt? Printrbot has a direct-drive retrofit kit that I can put on my Jr. for $25, wondering if it’s worth it.
Honestly, I quite dislike direct drive. You’re running everything way closer to the limits than I’m comfortable with. I’d much rather a simple 2:1 downgear, and not having to run everything so hot, than direct drive and trying to tune that tiny little window where things work reliably.
In my opinion, 3mm extruders should be geared and 1.75mm extruders should be direct-drive. The reasons why involve a lot of math WRT step frequency, volumetric calculations, diametric reduction ratios, torque requirements, extruder drive mechanism design, as well as several years of less quantifiable experience and intuition.
So, is that direct drive with a geared stepper (eg PG35L) or just straight of an ungeared Nema or whatever?
That’s a 200-400 steps/rev motor (before microstepping), with or without gearing. I haven’t done much with PG35 or similar motors that have a higher gear ratio on a (usually) 48-steps/rev motor, but generally, it seems like you would to lower the microstepping ratio to get a step frequency in the right range.
I am using direct drive in the Printrbot Simple and I don’t like it, it simply gets too hot (and I have tuned current to the very minimum possible)
I would really prefer a geared extruder.
I’m not a big fan of the direct drive on my v2, honestly. See how you like it on your Simple first.
I have ended up having to do a couple of hacks (including cooling the extruder stepper) to get it to work reasonably reliably.