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3D printer troubleshooting

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Dave Paine

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#1
Two days ago I tried printing a metric gear for a Southbend. I left this to complete overnight. When I looked at the print the next morning, it was awful.

The shallow depth of field is not showing that the layers started to separate about half way up the gear.

The failure is due to the filament slipping on the extruder gear. If the filament slips then the feed rate through the extruder is not consistent, hence a bad print.

Southbend_gear_print_failed_9396.jpg


The original brass gear on the extruder has very fine teeth.

Creality_extruder_9397.jpg


I tried increasing the filament temperature and did a test print of another file. I stopped this when I heard the extruder gear slipping again.

A close up on a piece of the filament I removed. The point where it slipped is in the middle.

Filament_slipping_9401.jpg


I looked in my supply of spare parts and I had purchased a replacement brass gear. Same OD but fewer teeth.

Creality_extruder_new_gear_9404.jpg


I started a test print again. It did not take long to hear the filament slipping.

This extruder does not have a screw adjustment on spring tension. I increased the spring tension by adding another washer which does not show in the picture.

Now the test print worked well, nice clean print. I decided to give the gear another go. Again printing overnight due to the time required to print.

This time a nice clean print.

Southbend_gear_success_9405.jpg


This is FYI in case anyone experiences similar issue. The gear slipping on the filament makes a noise which will be easy to remember once you have experienced this issue.

I am glad I had a replacement brass gear on hand.
 

Dave Paine

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#2
I recently saw this video with a tip for solving under extruded prints, which may also have been my original problem.

The Hot End tip for 3D printers

In this video the tip is to spray PTFE dry lube into the printer hot end. I thought this was worth trying so picked up a can of WD-40 specialist PTFE spray. The only product I could find locally.

After spraying and allowing to cool, I ran some filament through the printer and happy to see a nice long straight string the same as in the video. Prior to spraying this would have been twisted and curled up.

3D_print_filament_flow_improved_with_PTFE_spray_9437.jpg


I do not know how long this will last, but it should be easy to refresh the spray in the hot end.
 
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