Some beta test feedback for @Brook_Drumm and others working with the new gear extruder.
The new +printrbot (beta test) extruder gears are not working for me. I believe the the space between the gears is too small for normal filament. Also the feed tube is very snug. I printed the housing with Cura and great dimensional accuracy - the bearing, nuts and bolts all fit.
First test was PLA with no hot end to reduce resistance but it could not push the PLA consistently. No current setting could push the regular PLA, from low to burning hot full blast high. Nor could it feed in the PLA without assistance torque by removing the chamber cover and pushing a gear tooth a bit with jewelers screw driver.
Next I tested with Eco flex pla from FormFutura. Worked very smoothly without hot end. Put the hot end on and ran at least 300mm through (238C) while calibrating the gears. 128 steps / mm worked well.
Then I tried to print an iPhone case. Failed in first layer with a jam, dang it. Loud clicking sound. I could neither extrude nor RETRACT. I had to open the gear chamber and yank upward while doing 100m retract to get the filament out. The filament was eroded and had a radius formed in it. Not sure how it could do that in the tiny space available around the gears. I wish I has some clear PLA to reprint the chamber cover., then I might be able to see what’s happening.
Interesting… I have been printing NinjaFlex like crazy in the last 5 days, and I had an issue just once (where I had been at fault; I pushed the filament for no reason).
May it be that the 3d printed parts of the extruder are not up to dimensions?
@Ivan_Krasin Are you using the new gears?
@Ivan_Krasin Thanks for the info. I may try drilling out the feed path to 2mm and test again with flex.
Have you tried regular PLA yet?
Yes, I have. No issues at all.
I thought the bearing went before the gear on the motor shaft and the other two are for both sides of the other gear.
The cover for the chamber has a recess for the bearing on the motor shaft so thats where I put it.
There are two on the other part as well. Maybe some official build diections are in order.
I got three bearings. Two on the gear with its own shaft. One COULD put the odd bearing in the piece closer to the motor. I’ll try that too along with 2mm drill thru the feed path.
Doing a test with PLA right now. A few clicks while making brim, so I raised temp 3C to make PLA even more liquid (less back pressure). No clicks since 2nd layer.
Changes were drilling out filament path to with 2mm drill and moving the bearing to the inner wall. Current drive set at mid point.
The bearing on the shaft is intended to go on the front. Maybe we should ship the fourth or remove the back bearing pocket to avoid confusion.
We have kicked around adding some sort of adjustment for the idler gear. But it adds complexity and possibility of error. Of course, if your extruder isn’t working, an adjustment would solve it.
Ya I started with ring gear on outside. Will try it there again tomorrow. I suspect the fix was 2mm drill thru the feed path.
What diamter is the filament after it has passed through the gears? If it is crushed too much it could easily cause jams…
I am going to make a suggestion that is almost certainly stupid but just possibly not. What would happen if you put a vertical slot into this design along the line of filament travel, bridged by bolts above and below? Would something like that add just enough play to accommodate 20 or 30 microns in filament variation, or would it all end in skips, plastic creep and cracks?
@Alan_McNeil you can also make the filament path completely smooth by inserting a piece of ptfe tubing in the upper and lower feed tubes after drilling them out. Mine was i.d. 2.0mm. I’ve seen this used by others for printing ninja-flex as well. Worked well in the aluminum extruder as well. Makes the feed holes smooth and brings them right up against the gears.
