couple of tips to pass along to my fellow Robo'ers

Just some things to make the whole experience a tad smoother. Some of you may have already figured this out but for those who haven't.........

1) A filament change is usually performed by heating the extruder up to too high of a temperature leaving a good bit of the original filament, molten in the hotend. This then requires "purging" the old out once the new is installed. I have found that by heating the extruder to 170c the filament will soften in the hot end but not become molten. This allows you to extract about 99% of the old filament. Its possible slightly higher or lower temps may work best for your setup.
2) See attached photos. What some refer to as a 'jam' when the filament buckles in between the splined drive bolt and the inlet hole leading down in to the extruder. Use a 27.5mm piece of .125"x .015" wall brass tubing (available at most hobby shops. K&S is a common brand) and miter one end to clear the bearing. The tubing is a little too small in diameter so it needs to be bent slightly and/or crushed with pliers to get a snug fit but it doesn't take much. Just a little interference. If its loose it could come back up into the bolt on retraction. Installing the tube will require you to turn the big gear to help feed it down the hole.
This added support in an otherwise unsupported area has resulted in no more jams for me. Now if I get it wrong and it strips the filament I simply push the filament along to get things moving again. Also I use the E3D hot end so the tube length may be different if you are using something different.

 

I used a safety pin and heated the tip hot red, then jabbed the pin into the hole and you can feel the hot tip going into the filament. I wait a few seconds and then pull out the remaining filament. This is on the stock hot end.


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Hey guys. couple more things I have found to be helpful. The first is to buy a cheap pocket 60X microscope off Ebay (about $10) and print a adapter for your phone so you can really see whats going on with your prints. I machined mine from Al on the lathe but a printed one would work just as well. I stole this idea from our pals in China. I also downloaded an app that lets me zoom in more and use gray scale, etc. for added contrast.
The second think is go to Lowes and buy Dupont Teflon 'non stick' dry film lube ($5). With your hot end cold (its flammable) brush this stuff all over the places buggers normally stick to. Nozzle, heater block, etc.. Heat up the extruder and it will bake on a nice Teflon coating. I have about 4 hours on my first application running at 260c and its holding up great.

 

I'm loving the first tip about the brass tubing to prevent the clogs! I need to try that one, as I've had quite a few of those kinds of clogs lately...

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Thanks Denys, I have come to realize that filament tension needs to be set consistently too so for different materials I have determined "X" number of turns on the screws needs to be set. Usually between 3 and 31/2. My extruder is working very well although I rarely push it with high feeds/speeds.

 

i used to have this issue but then i fixed it with a tube of my own, but after a few hours it started jamming even without buckling. jerry said he'd send me a new extruder.

 

that makes sense. since the drive has a concave shape a slight side load would wedge the filament to the other side