I tested out the new extruder gears from Ali and just wanted to give you guys my results. The helical gears looked interesting as they could give more consistent and smooth extrusion and the CNC aluminium construction looks good but…
The CNC aluminium part retains a lot of heat. On the stock gears that part is polymer for a reason. After going from ASA or ABS prints, switching to PLA I kept having non stop clogs on the extruder. After I disassembled the extruder I could feel how hot the aluminium part was, so its a bad design decision. Printing PLA only had no problems due to lower temps. Just wanted to give a heads up to anyone thinking of trying them.
Genuine curiosity here - are there issues with the extruder gears, or is this solving a problem that doesn’t exist? Something in-between?
I ask because I have a few thousand hours on my machine, and if there’s a better option out there for when things eventually do need to be replaced, I’d like to get the best available.
so in theory if you can get the gears to mesh more consistently you get reduce the extruder “pulses” and get smoother looking walls. Its a known issue with all extruders. I wanted to try mainly for the helical gears, as they should mesh smoother.
So in your opinion, did it work? If smoothness was the ultimate goal, I would assume a double helix would provide better results, but the single helix is a definite improvement over a spur gear.
I would think then that something like Bambulabs PETG-CF would be the minimum that could be used. I use that as an example because I use PETG-CF frequently. I think it prints at 255 nozzle temp and the bed at 55.
I just read a pretty exhaustive tutorial about the Chimera hotend for the Bambu X Printers. It’s essentially a step-by-step way to fit rev6 nozzles to the hotends that you can buy from Ali Express that use the short nozzles. I’ll post the link to the entire thing to Printables below. Anyway, in the tutorial the author strongly suggests that you change to the CNC nano-coated gears. He says he uses them for all his printers. This suggests that perhaps there is something else going on here.
My gears arrived yesterday and I proceeded to print pretty much non-stop with Bambu PLA and Bambu-CF. My results did not agree with the authors in any way shape or form. I immediately noticed that the printer was noticeably quieter. I can attribute that to the helical gears. I ran a flow test from 20 to 40 as I Installed an E3D .60 ObXidian hot end two weeks ago but never ran a flow test so this was as good a time as any. It blew through that and looked great until it didn’t at about 34. Also, the black gear doesn’t appear to be metal, as I assumed. It’s some kind of polymer. For the price, I’d buy these as a replacement set in a heartbeat over the OEM Bambu gears. Considering what it takes to disassemble and clean the things, I’m just going to replace them when I clean the unit. They’re $15.00 on Ali Express. The bottom line is in my opinion and with limited experience, they’re quieter, and higher quality, under my 5x magnifying arm they have fewer tool marks than the OEM Bambu units. They may have other attributes that the nano-coating provides but I can’t tell. At this point, the positives out weigh the negatives, at least for me. Your mileage may vary.
I’m just curious, if the filament is thicker in parts does this change the meshing of the gears as they move apart or not grip the filament as hard if the filament is undersize and possibly cause the banding problem. I do realise it’s “ball hair” differences but it could be a problem. I only have a couple of years experience with 3D printers and mostly on Raise3d E2s so I could be talking out my hat.
As I said I had no problem with PLA. The problem was going from a high temp material to a low temp material due to heat retention in the aluminium gear arm. I guess if you can let it sit and cool for a while it wont be a problem, but I like my printer running as close to 24/7 as possible. If you dont run engineering materials, and just print PLA I guess my criticism is irrelevant.
It’s interesting that the Bondtech revolution of going all in on dual hob gears seems to be reversing. A lot of folks are circling back to a single hob and a bearing. Apparently dual can have issues with extruder accuracy that is easier to control with a single.
