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Guys, I have a confession to make: I modded my EZstruder. I modded it like woah.

There have been two ongoing issues with my RMax, first that I haven't been able to print PLA reliably since switching to an E3D v5, and also my ezstruder would occasionally kickback, even with ABS. It was much, much worse with PLA. Recently I replaced the E3D with the new Prometheus, and while it handled PLA much better, the poor extruder still choked occasionally. After putting a heatsink on the stepper driver and a fan on the extruder motor without any effect, I decided to change things up.

The hobbed gear on the extruder is a MK7 (or similar), which has an effective diameter of ~10mm. I bought a MK8, which has an effective diameter of ~7mm, which should therefore yield about 30% more torque, while not limiting my retraction speed nearly as much as a planetary geared motor would. The trouble is that with the smaller diameter, the filament would then run much closer to the motor shaft, so all of the channels in the ezstruder would be misaligned. I tried it, it didn't work. Soo...I did a major redesign on the extruder.

[img]http://i61.tinypic.com/nxownp.jpg[/img]

The upper section was altered so the platform the spring rests in is higher, putting more force on the red arm. The clear plastic cover was replaced with a simple rectangle that serves the same purpose of keeping the spring and arm secure. Most of the overhaul is in the lower section. Everything was moved more towards the center to align better with the filament. The metal groovemount cylinder that the pushfit connecter screws into was replaced with one that has threads for an E3D style passthrough connector, which I printed on my DLP resin printer. This allows the bowden tube to run straight up to the hobbed gear, so the filament is only unsupported there for a few mm. The passthrough connector stops the tube from going down, but retraction made it start creeping up into the gear, so I wrapped some kapton tape around the tube to keep it firmly in place. The other main change was making the whole thing thicker, so I could flip the hobbed gear to have the grub screw closer to the motor and out of the way of the red arm. This meant I had to cut away one side of the top piece so the grub screw is still accessible.

I've just started my first test print with it, which has been running for only about 30 minutes now, but so far there hasn't been any kickback, no sudden *THUNK* sounds, and the PLA seems to be laying down nice and smooth. If anyone wants the files to try this design, I'd be happy to post them. You'll just need a MK8 hobbed gear, a passthrough pushfit, and a couple new screws...I should've made a note of what I was using, but didn't. XD

I'll be following this one!

Looks nice. I made one last year similar in design, but I never bothered to buy the right size of spring and some of my part geometries were unoptimized.

I'm just wondering though, why not just screw the PTFE bowden tube into an M4 nut, then put the M4 nut in a slot near the drive wheel? It would eliminate the need for a push to fit connector. That tape might not hold there forever, and the retraction force will eventually make the tube get pulled into the drive gear and jam.

Generic Default wrote: I'm just wondering though, why not just screw the PTFE bowden tube into an M4 nut, then put the M4 nut in a slot near the drive wheel? It would eliminate the need for a push to fit connector. That tape might not hold there forever, and the retraction force will eventually make the tube get pulled into the drive gear and jam.

I was having underextrusion problems when printing at moderately high speeds (>60mm/minute) on my EZstruder. I got a geared stepper, which eliminated the underextrusion, but the EZstruder was still making some ugly noises (the red part flexing side/side) on retracts. (and no problem with retract speed).

I printed an airtripper with the BSP mount to take one of my black e3d push connects. I drilled out the ~2mm filament hole with a 4.2mm bit and stopped right before the hole below the drive gear. That way, retracts can't pull the PTFE up into the gear. If I were hardcore enough, I'd hack the OpenSCAD file to build in the hole, but this seems to be working.

Very Nice. I'll be looking forward to further posts.

Well, the first print was a success! Three hours to make me this slightly lumpy Buddha:
[img]http://i58.tinypic.com/zx1lu.jpg[/img]

I sat next to the printer the whole time, keeping an eye out for extrusion issues, but it ran shockingly well. No kickbacks, no shredded filament. I'm attributing the somewhat uneven layers to this spool of PLA having sat out through this very humid Seattle summer...it's probably mostly water at this point. XD

I probably should replace the tape with something more permanent, but for now it's holding just fine, so I'm leaving well enough alone while I revel in being able to print PLA without wonky layers, an angry extruder, and malicious jamming. For the sake of curiosity, I tried printing the bearing arm, but it wasn't strong enough. Maybe it would work out of nylon, or PC-ABS?

Glacian22 wrote:Guys, I have a confession to make: I modded my EZstruder. I modded it like woah.

There have been two ongoing issues with my RMax, first that I haven't been able to print PLA reliably since switching to an E3D v5, and also my ezstruder would occasionally kickback, even with ABS. It was much, much worse with PLA. Recently I replaced the E3D with the new Prometheus, and while it handled PLA much better, the poor extruder still choked occasionally. After putting a heatsink on the stepper driver and a fan on the extruder motor without any effect, I decided to change things up.

The hobbed gear on the extruder is a MK7 (or similar), which has an effective diameter of ~10mm. I bought a MK8, which has an effective diameter of ~7mm, which should therefore yield about 30% more torque, while not limiting my retraction speed nearly as much as a planetary geared motor would. The trouble is that with the smaller diameter, the filament would then run much closer to the motor shaft, so all of the channels in the ezstruder would be misaligned. I tried it, it didn't work. Soo...I did a major redesign on the extruder.

[img]http://i61.tinypic.com/nxownp.jpg[/img]

The upper section was altered so the platform the spring rests in is higher, putting more force on the red arm. The clear plastic cover was replaced with a simple rectangle that serves the same purpose of keeping the spring and arm secure. Most of the overhaul is in the lower section. Everything was moved more towards the center to align better with the filament. The metal groovemount cylinder that the pushfit connecter screws into was replaced with one that has threads for an E3D style passthrough connector, which I printed on my DLP resin printer. This allows the bowden tube to run straight up to the hobbed gear, so the filament is only unsupported there for a few mm. The passthrough connector stops the tube from going down, but retraction made it start creeping up into the gear, so I wrapped some kapton tape around the tube to keep it firmly in place. The other main change was making the whole thing thicker, so I could flip the hobbed gear to have the grub screw closer to the motor and out of the way of the red arm. This meant I had to cut away one side of the top piece so the grub screw is still accessible.

I've just started my first test print with it, which has been running for only about 30 minutes now, but so far there hasn't been any kickback, no sudden *THUNK* sounds, and the PLA seems to be laying down nice and smooth. If anyone wants the files to try this design, I'd be happy to post them. You'll just need a MK8 hobbed gear, a passthrough pushfit, and a couple new screws...I should've made a note of what I was using, but didn't. XD

I would be interested in the files. Thanks!

I've tweaked a couple things, here's the latest version: http://www.thingiverse.com/thing:453469. If you make one, let me know how it goes! Also I'd strongly suggest printing one of those small c-spacers to lock the E3D connector in place, but for the life of me I can't find where the file was posted.

I ran an 8 hour print last night at pretty high speeds (50mm perimeters, 100mm infill, 120mm/s retraction) with PLA, and it worked like a champ with my Prometheus.