How To: Setting the Filament Drive Tension Screw
Posted: Mon Aug 24, 2015 10:33 pm
What! We have no write-up on this yet?
Setting the tension screw on the filament drive can be a bit tricky. You want the tension to be firm enough to just catch the filament and guide it through, without smashing it in any way, since that causes problems with jamming and stripping the filament.
The tension screw should never be cranked so tightly that the two vertical uprights touch - there is supposed to be a fairly even gap between those uprights of approximately 1.5 - 2.5 mm. That's just an estimate, you can't really measure it precisely, and you can't set the tension by measuring the gap. It's going to change slightly for different kinds of filament.
What you can do, is have a bit of fun playing Sherlock ( ) by examining the end of the filament that goes into the drive, and make adjustments based on what you see after you retract the filament completely.
Since a picture is worth a thousand words:
Both the first and the last conditions on the chart are preceded by no filament coming out. But if you have been printing along happily and you suddenly have nothing extruding, (accompanied by a thunking sound),it's a stone cold bet that your filament diameter has swung up and you've stripped it. Retract the filament, and re-measure the diameter. Look at the tooth marks and loosen the tension if needed. (You will probably want to cut the over-sized length out of the spool.) On the other hand, if you are loading it and it doesn't feed, but comes out easily when lightly tugged at the top, that's an indication that the screw might need to be tightened a touch. In any case, it is always safer (from a non-jamming standpoint) to reverse the filament out and look at the end before you tighten that screw. Deep tooth marks are a no-no.
This is what you are shooting for. These are PLA, but you want about the same "bite marks" on whatever filament you are printing. That's going to mean adjusting the tension when you switch from one kind of filament to another, PLA to PETG for example, or any of the softer filaments. (And even though it doesn't necessarily belong here - remember that the softer the filament, the slower you print/extrude it.)
Tip Update: I jump back and forth between PLA and PETG on a regular basis, and i was getting a little tired of having to adjust that tension screw. Sometimes i'd completely miss the mark and wind up having to go through several iterations to get it reset correctly. One of the guys had mentioned making a mark on the bearing to see if it was turning on another post, and I decided to put that idea to use for the tension screw as well. It's a tremendous time saver......
Once you have the tension set correctly for a particular filament, make a mark on the 12:00 position of the screw. For mine, PLA is marked in black Sharpie marker (not very neatly, but i'll fix it later). So anytime i'm printing PLA, i make sure that the black mark is in the vertical position on the screw.
PETG is marked on my screw in red Sharpie, so when i print PETG, i make sure the red mark is up at the top.
That's it, and it's super easy. Notice how close together the two marks are - you don't have to tighten things up much when you switch to a different filament. But that tiny bit of turning can make all the difference.
Setting the tension screw on the filament drive can be a bit tricky. You want the tension to be firm enough to just catch the filament and guide it through, without smashing it in any way, since that causes problems with jamming and stripping the filament.
The tension screw should never be cranked so tightly that the two vertical uprights touch - there is supposed to be a fairly even gap between those uprights of approximately 1.5 - 2.5 mm. That's just an estimate, you can't really measure it precisely, and you can't set the tension by measuring the gap. It's going to change slightly for different kinds of filament.
What you can do, is have a bit of fun playing Sherlock ( ) by examining the end of the filament that goes into the drive, and make adjustments based on what you see after you retract the filament completely.
Since a picture is worth a thousand words:
Both the first and the last conditions on the chart are preceded by no filament coming out. But if you have been printing along happily and you suddenly have nothing extruding, (accompanied by a thunking sound),it's a stone cold bet that your filament diameter has swung up and you've stripped it. Retract the filament, and re-measure the diameter. Look at the tooth marks and loosen the tension if needed. (You will probably want to cut the over-sized length out of the spool.) On the other hand, if you are loading it and it doesn't feed, but comes out easily when lightly tugged at the top, that's an indication that the screw might need to be tightened a touch. In any case, it is always safer (from a non-jamming standpoint) to reverse the filament out and look at the end before you tighten that screw. Deep tooth marks are a no-no.
This is what you are shooting for. These are PLA, but you want about the same "bite marks" on whatever filament you are printing. That's going to mean adjusting the tension when you switch from one kind of filament to another, PLA to PETG for example, or any of the softer filaments. (And even though it doesn't necessarily belong here - remember that the softer the filament, the slower you print/extrude it.)
Tip Update: I jump back and forth between PLA and PETG on a regular basis, and i was getting a little tired of having to adjust that tension screw. Sometimes i'd completely miss the mark and wind up having to go through several iterations to get it reset correctly. One of the guys had mentioned making a mark on the bearing to see if it was turning on another post, and I decided to put that idea to use for the tension screw as well. It's a tremendous time saver......
Once you have the tension set correctly for a particular filament, make a mark on the 12:00 position of the screw. For mine, PLA is marked in black Sharpie marker (not very neatly, but i'll fix it later). So anytime i'm printing PLA, i make sure that the black mark is in the vertical position on the screw.
PETG is marked on my screw in red Sharpie, so when i print PETG, i make sure the red mark is up at the top.
That's it, and it's super easy. Notice how close together the two marks are - you don't have to tighten things up much when you switch to a different filament. But that tiny bit of turning can make all the difference.