General 3D Printing Thread


 
Brian - yep. bowden + coreXY will be fast. http://www.flickr.com/photos/116032124@N07/12243292086/ And yeah, the main advantage is no more moving bed. A secondary advantage is that the X and Y motors are sharing the load of moving the printhead, which should lead to fewer lost steps. Finally, the whole thing can be enclosed if you design it right. :D

Tom - Yeah, that'd be cool. I missed last years robot fest, and my daughter loves watching the printers make stuff so she'll dig the fest. CoreXY might be very doable with extrusion and openrail. Actually, VERY doable. Gotta go draw. :D
 
I'm in the process of building my next printer. I decided to make a taz clone.




I'm cheap and wanted to use as many local materials as possible. The tubing is 3/4 square aluminum. I upgraded the y motor to nema23. Hopefully this will allow me to increase y acceleration. My x3 pro just arrived so hopefully it will be melting plastic soon.
 
Guy Barton said:
Tom, that is a really sweet setup you have there. I love the printer and that it is running on rails. I'll bet the accuracy is way up there. Is that an Auber PID controller? What kind of heater are you running?
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The PID controller was just the cheapest one I found on amazon prime. I think it was $18 with free shipping about a year ago. I originally bought a miniature space heater that I hooked up to an SSR, but I soon found out that when I closed the chamber door with the heated bed and hotend at temp that the chamber temp climbed up very quickly and actually exceeded the temp that I was shooting for. I ended up cutting a hole in the chamber and attached a 120mm fan that can be controlled by the PID (in cooling mode) to blow in ambient air and control the temp.
 
I think it's a much better idea to move the print bed in the z direction rather than the y direction. Moving the mass of the bed by small increments up or down is going to yield much more reproducibility than large back and forth excursions where acceleration becomes a big issue.
 
Thanks for the information. Looking forward to putting this thing together. I especially like the counter-sunk holes in the aluminum bed.
 
I think my nozzle is plugged. My extruder is strugling to push the filament though, I get poor extrusion, but can't see anything wrong with the setup.

I put the nozzle on the stove (gas) and burned it out clean, but it just started acting poorly again shortly after. How do you clean the entire extruder? Other ideas?

dave
 
The method I use if I feel like something is jammed in the hotend is to ramp the temp up to your max. I believe you have a ptfe liner so don't go above 240ish. Then take some filament and jam it through the hotend by hand and then yank it out really fast. Cut off the end of the filament and repeat this procedure about 5 times or so. Then connect everything back to normal and run some filament as usual. If that fails and you are using ABS, soak the nozzle in a jar of acetone for a few hours and then use a fine wire to fish out any junk. You could probably also put it through an auto-cleaning in your oven but your wife may kill you.
 
It's possible the ptfe lining has failed too. I've had that happen several times where I had to replace it. Ended up getting an e3d hot end to replace the j-head that came with my kit.
 
I have a J-head hotend, when it needs cleaning I remove the nozzle and pull the resistor and thermistor out (leaving metal nozzle only) then use a blow torch to burn it clean. Use a wire as Tom suggested or a micro drill bit (I think #77 is about the right size for a .5 nozzle) to ream the hole clean. Finally, I bath the inside with acetone using a q-tip until it comes out clean, I have also found with my .5m j-head nozzle a q-tip stick with most of the cotton removed fits nicely into the final chamber right down to the bottom. I don't know if this is the "proper" way to clean it or not, but it's worked for me....
That said, my print quality had been dropping a while ago but it didn't improve after a cleaning the J-head like before. Like you, I couldn't find anything wrong with the printer or hotend, I was getting some pretty heavy curl as the filament left the hotend (usually indicates a partial clog). Being frustrated I pulled the J-head again, this time I inspected the hole where the filament is extruded from the outside with a magnifying glass. To my surprise the tip of the nozzle was deformed and uneven. I guess it ripped into one of my bulldog clips pretty good and it took a bite out of the tip of the hotend is all I can figure. I sanded down the tip a bit until it was flat again and my print quality came back up to where it should be...
 
JNeillIII said:
It's possible the ptfe lining has failed too. I've had that happen several times where I had to replace it. Ended up getting an e3d hot end to replace the j-head that came with my kit.
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I've had the ptfe liner fail on my j-head too. The replacement ptfe liner was a tight fit going into the nozzle and also in one spot on the body. After having trouble with the ptfe liner a second time and fiddling with it a bunch I got out the drill bits and cleared the tight spot in the body so the ptfe liner went through all the way without resistance and also forced a drill bit through an old/tight ptfe liner and loosened up the spot where the filament would start to bind, since doing that the ptfe liner hasn't been troubling me.

Bottom line, the filament needs to go through the ptfe liner easily while it is inserted into the body, so if/when you have your j-head apart push some filament through the body and ptfe liner (with the nozzle removed) to see if the filament is binding up in there....
 
I have also had issues with jamming caused by to much force on the hobbled bolt. it was deforming the filament to much and causing it to stick in the ptfe tube. The filament was not uniform so it was an intermittent issue that drove me crazy.
 
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