So, i have moved to bowden on one of my i3 and im having lots of troubles with the filament. The extruder that im using (coldend) is a gregs-wades, modified for 1.75mm filament. The issue that im having is that after some printing the filament curls in a gap under the idler and blocks the extrusion. Any suggestions?
On mine I drilled a 4mm hole down through the extruder exit and push my Bowden tube all the way up to the extruder idler/hobbed bolt. So there’s about a mm of in supported filament
Yep, it’s a flaw in the Greg’s design. If you have a Bowden connector that allows for the Bowden to pass all the way through it, you can drill a hole in the Greg’s that allows the Bowden tube to go all the way up to the hobbed bolt. This will prevent the buckling.
sadly, my connectors wont allow me to just fit the same tube, but i can drill the extruder and get a shorter piece in it. Will do now!
I just drilled out my connectors, Just be careful to not go too deep.
i will fix this extruder with this method, but is there any other alternative to gregs-wades, geared, that doesnt have this issue?
There are probably some derivatives on thigiverse. Personally, I’m using direct drive airtripper as I find hobbed bolts are often a source of filament slipping woes and direct drive seems to be fine for 1.75mm.@Matt_Kraemer1 told me he was working on a Wades variant that fixed these issues but I’m not sure if he’s ready to release it into the wild yet.
Tim, im using a direct drive and with a jhead i cannot print faster than 70mm/s reliably.It starts to loose steps.
I have similar issues with my airtripper and my e3D . I either loose steps or it back drives my stepper.
@Matt_Kraemer1 if you dont mind, i can test your version.
@Nicolas_Arias That should help, I would get the tube even closer to the hobbed bolt, even if you cut it at an angle so it doesn’t get crushed by the idler.
@Tim_Rastall got it, the extruder is installed now, about to start testing. If this solution works, i will do the same to the second extruder.
Cheers!
oh boy, im going gray over this. Filament is slipping on the hobbed bar.
Is there any bowden tube lenght recomendation?
If you can push the filament by hand and get it to extrude then you don’t have too much resistance. How tight is your idler? It should be really tight.
My Bowden tubes are about 700mm
Holy crap I dont think Ive ever gone that tight lol. Ive gone so tight that the filament snaps though.
@Matt_Kraemer1 That’s true IF you have a quality hobbed bolt…
If you have a poor quality hobbed bolt then it is also quite likely a cause of failure. Something worth checking, I’ve read about people solving all their extruder problems by replacing dodgy hobbed bolts / bars.
Check the hobbed bolt’s teeth are all formed ‘well’ and as others have said, the idler must be tight!
What are the symptoms of “too tight” guys? does it just lock up the stepper motor or will it crush and deform the filament too much? anyone had experience?
@Jarred_Baines true, if you look at the picture Nicolas posted, you’ll see its hyena or some other machined variant. Generally too tight is when your idler breaks as @Matt_Kraemer1 points out, as long as the idler and hobbed bolt bearings are sound, you should still have free rotation at high pressure.
yeah, its a hyena, i have another 2 different bolts, i might try them too.
Now i have to have dinner, bath the kids and put them to bed. After that, a nice shot of espresso and back to the bench. I will take the extruder and hotend off the printer and assemble them on the bench, so is easier to do mods and see whats wrong.