Hobbed bolt effective diameter

[sniffle]

Does anyone know what it is?

I'll probably email colin, and ask, but there is a formula for calculating the proper e-steps if you know what that is. just curious if my calibrated e-steps is near the calculated value.

here's the formula for those that are also curious.

e_steps_per_mm = (motor_steps_per_rev * driver_microstep) * (big_gear_teeth / small_gear_teeth) / (hob_effective_diameter * pi)

[printbus]

I've always figured it depends on how the hobbed bolt is cutting into the filament. More cut would equal less effective diameter.

Have you seen the stainless steel hobbed bolt E3D is about to release? http://www.filastruder.com/collectio...bbed-shaft-kit

[AbuMaia]

Ooo, nice. And it's adjustable to fit any extruder. Very nice.

[sniffle]

Want!!

I was just curious because I wanted to compare calculated vs calibrated to see how close they were... I asked colin he told me the proper way I said I know... I'm just curious and if your busy I understand...

Never heard back from him...

[AbuMaia]

I remember asking Colin a while back about the effective diameter. I also never got a reply to that question.

[sniffle]

got a response from colin, he measured the outside of the teeth, it's 6.3mm

[sniffle]

so itty bitty double it;s a nema 14 with 200 steps per revolution a 20 tooth gear on the pulley and a 80 tooth pulley on the hobbed bolt, and the hobbed bot is an 8mm with a 6.3mm cutout measured at the top of the teeth the only thing that isnt really taken into account is the belt and i am not sure how that comes into play

per the equation is

e_steps_per_mm = (200 * 16) * (80 /20) / (6.3 * pi)
e_steps_per_mm = (3200) * (4) / (19.79)
e_steps_per_mm = 12800 / 19.79
e_steps_per_mm = 646.7248481194477136005435464026

my calibrated e-steps are 698, not a bad way to get a good starting point when you arent sure where to begin.

edit: math updated to reflect where i had the wrong tooth count and belt doesnt effect anything.

[sniffle]

updated math, and fixed :-) thae answer was found... it's a good way to find a starting point for measuring e-steps before actually extruding