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UP! extruder modification 2, pressure arm

by DrewPetitclerc Jan 29, 2012
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What is the minimum gap between the bearing OD and the top of the gear teeth?

Mechanicaly it is less than 1mm with no filament present, but if you are asking this question I wonder if you understand what the design intent is?

I have used/modified a similar design that is printable. The big bearing I use precludes a filament sized channel close to the gear teeth. This is an issue with Ninjaflex that wants to buckle on its way to the nozzle. The other issue with Ninjaflex is that my 1.1mm minimum gap would not give the gear teeth enough bite. I modified my design and got it to extrude until the filament buckled due to not having a tight tunnel to travel in. Your design constrains four sides as close to the teeth as possible and the small diameter bearing helps with this constrained path. Not sure how close Ninjaflex needs to be held against the teeth as I overshot my modification and the minimum gap between bearing and teeth is 0.25mm. Have you successfully used Ninjaflex with your Up/Afinia printer with this mod?

I have tried ninja flex and it did not work, there is still too much gap around the feed gear and the aluminum block, allowing the filament to bend out, I need to get a longer PTFE tube to run up from my Recreus hot end and have it end against the feeder gear and pressure bearing to stop the bend-out.

I was able to stop the Ninjaflex bend out by carving out the side of ptfe tubing running by the extruder gear (no bearing required) then cutting the top of the ptfe to fit inside the chamfer lead in to the metal hot end. Unfortunately the hot end, as it heats up, causes a block just above the nozzle. I can print for 15 minutes before the clog if I start the print when the hot end is cold. I've contacted Recreus several times about an Afinia compatible hot end. Have not heard back. How'd you get yours?

Turns out I first read about the Recreus hot end on the pp3dp forum where you shared it as an option for Afinia/Up! printers. If you have an email contact at Recreus you can share, I'd like a real contact person rather than the form on their website which has yielded no response.

Remember, to use the Recreus you need to make the mods I've listed here:
As to a contact this is all I have,
Ignacio García

UP! extruder modification 4, Recreus Hot end

where can I purchase the ball bearing?

McMaster-Carr, 7804K125, Miniature High-Precision Stainless Steel Ball Bearing - ABEC-5, Double Shielded, for 3 mm Shaft Diameter, 7 mm OD
About $7.41 each, get a couple.

Hi Drew, Do you think this mod works with UP 3d Mini?
I have slipping issues with alternative filaments.

Thanks a lot!

It should work, but you will need to redesign the "backbone" mount that holds the stepper motor for your "Mini".
I have stayed away from the "mini" design due to all the mechanical issues it has so I have no designs for it and will not be making any in the future.


I have the two metal pieces but I need the rest of the bill of materials you are using. What other parts are you using to screw things together? What size bearings? Are you using a spring for tension or do you have a part number for other pieces?

With these machined parts I am using:
1X McMaster-Carr, 7804K125, Miniature HI-Precision SS Ball Brng - ABEC-5 Double Shielded, for 3 mm Shaft Diameter, 7 mm OD
1X Vlier Plunger 1/4-20 or 6mm thread, plastic nose, long stroke, medium load.
Plus a new printed "Extruder Cable Box New Modified" of my design


Do you have any photos of how you put it together? Half the photos attached here don't come up.

Uploaded STEP files someone asked for a long time ago, sorry for the delay.