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napfkuchen

ENDER 3 / CR-10 Direct Extruder

by napfkuchen Feb 9, 2019
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The way the body is standing in the original file causes a failure at the two screw holes that hold the release lever. The original orientation puts the layer lines across these holes so when you put pressure on the spring it can cause the plastic to separate. I solved this by laying the body down flat, with the gear side down on the bed. This way the filament is drawn around the screw holes and adds a lot more strength to them. The end result was a tighter fit of the bearings and better orientation for all of the screw holes.

In Cura I used supports everywhere, zigzag, 10% density, 5mm line distance. I also increased the support X/Y distance to 1.35mm to prevent it from trying to put a support through the center of the release lever screw holes. The internal supports that were generated pop out easily and it didn't take much to clean it up.

For the tension lever I used a 30mm screw with an acorn nut and washer to hold a spare spring for the stock extruder. A 25mm screw, washer, and a nut with a plastic insert holds the lever to the body, and a 10mm screw and flat nut holds the 623 bearing. Two 16mm and an 8mm screw hold a pancake motor to the body.

To grub the 8x50 bolt I put the bolt in the lathe and used a hacksaw to cut a slot on the centerline where the filament should sit. This slot makes it easier to center a 5mm tap as the threads are cut around the bolt, and the slot itself will really grab the filament and should provide a much stronger pull than the stock brass gear.

Because of the gearing, I'll have to reverse the motor direction. There is a setting in the Marlin code (INVERT_E0_DIR) which can be set to true to achieve this. Don't forget to re-level the bed after adding this extruder to compensate for the additional motor weight. I'm hoping to give this new extruder a test run here in the next week...

Thanks for the detailed description. Thats pretty much in line with what I did.

Any tests performed so far? :)

I finally switched to the version I uploaded here a week ago since the previous version finally failed due to structural weaknesses already fixed on the thing. Other then that it worked great for me. The redesign I'm working on - and hopefully get ready to print over the weekend - will be a lot more compact and a bit lighter with slightly shorter filament path. So I'd recommend waiting for that if you want to try it. Also it will use 148 bearings instead of the 608 because of weight and size.

Ok, sounds great, I'll hold out for an update