Filament pulley grub screw removal
The filament pulley isn't aligned properly, but the grub screw is stripped and I can't unscrew it. I've tried a variety of different hex wrenches, but it's not the wrench, it's the junk grub screw (this is the spare, as the original came stripped and wouldn't even screw in).
So I've a couple of questions... 1) how can I get this thing out so I can adjust the filament pulley? 2) What can I replace it with since this thing is junk... has anyone replaced this with a similar part?
Re: Filament pulley grub screw removal
Hi Neil,
I had the same issue, the kit actually comes with a replacement grub screw so I think that pretty much acknowledges the problem.
I had to whip out the rotary tool and carve a - slot in the grub screw (VERY carefully so you don't mess up the gear!) and then used a standard screwdriver to unto the screw. Then I just used the spare from the kit.
It might be worth replacing this grub screw with a heat treated grub screw in the future IMO but once it's aligned properly you likely won't have to undo it again. Just be careful tightening it, it doesn't have to be very tight IMO.
Re: Filament pulley grub screw removal
thegrub screws are hardened, but the metal around the hex socket is very thin and being hardened it is brittle. so you are likely to damage it if you over tighten.
if memory serves me well they are 2mm long, 3mm jams between the gears
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
Re: Filament pulley grub screw removal
thegrub screws are hardened, but the metal around the hex socket is very thin and being hardened it is brittle. so you are likely to damage it if you over tighten.
Thanks for the FYI Joan, I wasn't sure they were since I use comparable grub screws for other applications and the included ones seem very soft, perhaps my other grub screws were a slightly different diameter.
Re: Filament pulley grub screw removal
Well... I've tried rubber bands. I've tried epoxying in a sacrificial hex wrench. I've tried drilling through the grub screw to remove it in sections, and I've had ZERO luck trying to remove this. Basically, the printer is non functional and never going to BE functional until I get this set screw out, and that doesn't appear like it's going to happen without once again taking EVERYTHING apart and replacing the motor and pulley assembly.
This is a RIDICULOUS design flaw on a printer that costs this much as a kit. I might expect this on a cheap, $250 kit out of some no-name factory in China, but on this? And that it comes with a spare means they KNOW this is an issue, and it is easier to spend $0.03 to bandaid it rather than fix the design.
I've a many hundreds of dollars paperweight at the moment. It calibrates beautifully. But it will never print. What a waste.
Re: Filament pulley grub screw removal
Re: Filament pulley grub screw removal
Tried that. Didn't work. I JUST, however, managed to get a hole drilled through and tapped to M3x0.5. Since the set screw seems to be smaller than that, I've ordered some hardened set screws (impossible to find locally) and will see if that work. If not, I'll work my way up to a #6. I can find #6 set screws locally and they're less liable to get stripped like those crappy tiny ones that are supplied with the kit.
A #6 set screw likely would have been a MUCH better design decision in the first place. Less liable to strip, as there's more metal involved. Easier to find. And there's PLENTY of room for it in the pulley gear.
Re: Filament pulley grub screw removal
Tried that. Didn't work. I JUST, however, managed to get a hole drilled through and tapped to M3x0.5. Since the set screw seems to be smaller than that, I've ordered some hardened set screws (impossible to find locally) and will see if that work. If not, I'll work my way up to a #6. I can find #6 set screws locally and they're less liable to get stripped like those crappy tiny ones that are supplied with the kit.
A #6 set screw likely would have been a MUCH better design decision in the first place. Less liable to strip, as there's more metal involved. Easier to find. And there's PLENTY of room for it in the pulley gear.
While a larger grub screw would be nice, the parts supplied with the MK3 kit are pretty standard across the printing community. I wouldn't want parts that I can only get from specialty suppliers when something fails.
Re: Filament pulley grub screw removal
While a larger grub screw would be nice, the parts supplied with the MK3 kit are pretty standard across the printing community. I wouldn't want parts that I can only get from specialty suppliers when something fails.
All fine and dandy, but given that M3 set screws are available everywhere here, and 3mm only available from specialty suppliers, I went the way of the one I can get ahold of. M3 set screws are used all over.
Also, given that the crappy 3mm set screw needed to be drilled out in order for me to even get the thing to work? Didn't have a choice. I'm not paying additional money for a new Extruder motor and pulley assembly because they supplied crappy set screws with the $800 kit. I've already had to re-dye half the screws in this kit because of bad threads, and many didn't even come with hex holes. All in all, this was an overpriced flop.
Re: Filament pulley grub screw removal
Worth noting that the extruder gears are 3rd party from Bondtech and IMHO they are overpriced. It is not a Prusa design.
Re: Filament pulley grub screw removal
Worth noting that the extruder gears are 3rd party from Bondtech and IMHO they are overpriced. It is not a Prusa design.
That's good info. Somewhere to properly focus my ire. 😉
It's a finicky beast, to be sure. But with new, hardened m3 set screws in a nicely tapped hole (and a hell of a lot of tinkering), I have filament loading. At least enough to do some cold pulls and remove the blocks. Now to recalibrate.
🙂