Why does the filament stop extruding???

Hi all

I've built a from scratch ord bot type printer, it does a good job that I'm very happy with.

However just lately its started to stop extruding at different heights.?? Now it showed up on a fan duct that i printed that must have been about 10cm high. It printed the bottom 8-9cm fine then started to 'thin out'. it finished that print and was usable(see attached) while i tried to figure this out. Now thinking its the wade extruder setup that isn't pulling the filament from the reel steadily enough (i have it on spindles that dont take any strain to pull the filament) I decided to try the mk8 bowden and remove the weight from the x axis in the same move.

in this set up there is a spring loaded leaver that hold the filament, youll know what i mean, and i just tried to print that. its only what, 1cm high. it got half way up and started to thin out so much that it looked more like support material than the main object.

The temp stays constant at around 197c. when i stop the print and the head homes then the filament easily flows as the head cools and i dont find any blockages.

Any ideas ??

Thanks for your time

Mike

Looks like filament slippage to me. Clean the grooves on your hobbed bolt from any plastic and make sure to tighten the idler afterwards (the "spring loaded lever"... I've had the same problem and it didn't really stop until i really tightened the idler, more than i thought was necessary). In my experience this stuff happens either when heat starts to creep up the extruder, essentially softening the plastic and causing the extruder to slip, up to the point that the hobbed bolt strips the filament flat (use a fan to cool the extruder (non-heated parts)) or in prints with lots of retraction (basically prints with multiple smaller areas in a given layer), looks like that could be the problem since the uniform, lower part of the print looks fine. either slow down the print or adjust your slicer settings (slower and/or fewer retraction, fiddle with the settings ). Good luck.

Edited 1 time(s). Last edit at 10/28/2013 08:07PM by Core.

Hi myk68,
Disclaimer: I'm not an expert on this, but I've read about it.

It sounds like its a time related thermal failure - sound like the cold end is getting hot, or the thermal break is, so the filament may be getting soft. Try adding a small fan blowing on the thermal break, or on the stepper.
The other thing I've read is that if you have a teflon sleeve in the hot end it may have deformed.

Hope that helps.

are you using retraction? slow down retraction speed to 10mm/s

Thanks for all the replies

I have tightened the idler on the extruder and managed to print with no issues or problems a set of wade herring bone gears. like was mentioned i had to really tighten it alot more than i thought i would.

retraction is already set to 10mm/s

think im going to re position the drive and try a bowden type set up. at least this will remove the weight from the x.