Why is the extruder pulley made of Brass ?  

Re: Why is the extruder pulley made of Brass ?

This has be concerned that when I get my new Prusa i3 MK2, that I may have issues with the extruder pulley.

Could someone from Prusa comment on this issue? Perhaps this is a user problem where the pulley is set to be too tight and that causes the excess stress over time?

Re: Why is the extruder pulley made of Brass ?

Hi man!
Use prusa the extruder-pulley of e3d?

https://e3d-online.com/hobb-goblin-5mm ?

Description
A wicked little filament drive gear made from stainless steel with really sharp little teeth cut into it.

These are carefully manufactured on a synchronised CNC processs which gives a sharp, consistent, and clean cut tooth profile that has incredibly good grip.

We've tested these with 1.75mm filaments, from the soft and delicate flexibles to hard and abrasive materials like Carbon-Fibre PLA. All with great results.

These are a great match for our NEMA17 Stepper motors with 5mm shafts to create low cost and simple extruders for 1.75mm filament. These gears are similar in effective radius and usage to a Mk8 Drive Gear.

Attaches to a 5mm motor shaft with an included M3 Set Screw.

Re: Why is the extruder pulley made of Brass ?

Hello

So, I've ordered from steel mk8 hobbled pulley from a local seller while I wait to get get an original one from prusa. And I've been trying to figure out how to get modify firmware, but I've got no clue. Tried to look it up and all, but it doesn't seem there's a lot of useful info about it.

https://www.3djake.si/bcn3d-technologies/direct-drive-gear-mk8

Could anyone help?
Thanks in advance.

Re: Why is the extruder pulley made of Brass ?

Hello

So, I've ordered from steel mk8 hobbled pulley from a local seller while I wait to get get an original one from prusa. And I've been trying to figure out how to get modify firmware, but I've got no clue. Tried to look it up and all, but it doesn't seem there's a lot of useful info about it.

https://www.3djake.si/bcn3d-technologies/direct-drive-gear-mk8

Could anyone help?
Thanks in advance.

Re: Why is the extruder pulley made of Brass ?

I believe the mk8 hobbed wheel is a bit larger in diameter than the prusa one. So it is likely tobgive problems inserting filamment... because tthe filament willl be deflected as it passes rhe wheel.

If this is a temporary change you could try reducing the extrusion multiplier in your slicer program

Otherwise search changing esteps

Regards joan

Re: Why is the extruder pulley made of Brass ?

sorry, no idea why first generation wheels were brass, i believe they are steel now

regards Joan

Re: Why is the extruder pulley made of Brass ?

Thanks for your reply.
Yes, I understand there's a difference in diameter, so I have to adjust flow, retraction and that the hole into extruder doesn't line up perfectly.
But I'm wondering how to modify firmware, what do I have to change? I don't want tko mess things up. 😕

Re: Why is the extruder pulley made of Brass ?

Ok, so I recieved the mk8 pulley and other than being a little bit bigger it fits fine, except because of a slightly bigger diameter it touches the plastic where filament goes inside the hole. I've cut like 0,5 mm away and it works just fine - or at least so far so good.
Works better than it was, so I'm happy as it is.
Other than reducing flow a little bit I didn't change anything at all.

Take care
Jure

Re: Why is the extruder pulley made of Brass ?

Joan is right (as usual), the brass hobbed pulleys are no longer available at the spare-parts section of the prusa shop.

🙄 just noticed that because the brass pulleys of my two printers (genuine MK2 and selfmade clone) are worn out now and at my clone I get extrusion interruptions during the print, regardless of the tension provided by the the two springs. they simply don't bite anymore.

you can see the effect of it at the attached picture:

so I looked for spare parts and was glad to see that they sell steel ones now.

💡 anyhow, because I still had some MK8 gears at hand, I just printed a different extruder body & cover, altered for the MK8 drive gear and changed the parts yesterday at my clone, to get back into business :P.
of course I had to alter the idler a little bit as well (used a smaller bearing, with printed and m3-screw enforced axis) and corrected the e-steps value (to 152 now).