Best Direct Drive or Geared Extruder Mounted to Effector for Delta Printer?

This may have been posted before but I was wondering if anyone's using a direct drive or geared extruder mounted on their effector for their delta printer? What's the best one to use? What are the weight considerations?

Edited 3 time(s). Last edit at 01/08/2014 01:02AM by runninfarmer.

What kind of delta printer are you looking at? Most are designed for very low weight on the effector.

Even with a direct drive, you still (probably) need some sort of filament feed tube into the extruder.

I've built a Delta-Pi and am thinkng about using the PG35L extruder that's for the Kossel, but based on the J-head Micro Extruder: [www.thingiverse.com]

Did you use a bowden tube on your delta-pi? I have a scannermashup repstrap with a bowden tube and it works very well.
I only had to calibrate the right amount of filament retract and set a fast retract speed.

I'd recommend using a bowden tube on a delta for sure, but both setups will work.
If you used a direct drive right on the end effector the weight being moved around on a delta head it would slow your printing speeds quite a bit and cause more wear on your delta rod connections.

EDIT: Also, do you plan on using a stepper motor with a gear box? I ask because 3mm filament directly driven by a stepper motor doesn't work very well.

Edited 1 time(s). Last edit at 01/09/2014 05:14PM by TheTechnicalNoob.

I was trying one for a while with Greg's extruder but I started having problems getting it dialed in correctly. There was a lot of friction in my tube and I kept having problems with my gear slipping. I'm only running 1.75 mm filament so direct drive should be fine. I'm going to try a couple different micro extruders which weigh ~200g or less.

The lag issue is something I really dislike about the bowden tube, particularly since I want to print more than one part at a time. Kronos Robotics posted a great article on how they greatly improved their Rostock Max by attaching a modded QU-BD extruder to the effector. That article is here: [www.kronosrobotics.com]

The delta rod connection wear could be an issue and that will need monitoring

On my bowden tube friction is minimal. Sounds like something might be wrong with your tube. It wouldn't hurt to measure it and check if its the right size. The piece of tube that I was shipped was all the right size except for the last 20cm which strangely was a bit more transparent and smaller with very high friction.

Seeing you are using direct drive you should be able to get some fast retract speeds which when properly setup and calibrated should have almost no stringing.
Here [secure.flickr.com] Johann's frog printed on his kossel has very little stringing (none that I can see). I would like to maintain that if you can get the bowden tube setup properly, it has it's advantages. A lot of friction in the tube would certainly mess things up.