Twisting filament

Hi everybody
Filament from Robo3D (bought with the printer) is twisting during printing.
It causes it to make nodes if I don't spin the spool regularly.
It's annoying because I can't start long print tasks without being there.
Do you have this problem too?
Thanks

 

Does somebody ever try to motorize spool rotation ?

 

I am working on something right now. Not much farther than using my Logic Analyzer to figure out which commands are sent to the extruder to extrude so I can feed just those to a second stepper motor to turn the spool without sending the retract commands as well. Will report back.

 

I have my spool directly above my printer. The filament always feeds nice and straight.



I got the .stl here http://www.thingiverse.com/thing:267039

 

Ha that's funny I was about to link that .STL, that's my starting point. The best spool holder I have found as it is offset so the filament comes off the spool and feeds directly down without having to bend back.

 

Hi
I use this one
http://www.thingiverse.com/thing:216117
But it twists.
With side mount spool holder (the stock one) it twists less but still a little.
Maybe my spools from Robo3D are badly rolled ?...

I'll try the one you advice...

Thanks

 

What do you mean by 'twist' exactly? That should help diagnose the exact problem.

The Robo3D rolls aren't of bad quality, but they do use really small diameter spools. This means when you get down towards the middle-end of the roll the filament is coiled really tightly and hard to use. That's why I only buy big spools. But the problem with that spool holder (and most others) is that they are centered over the feed slit. This means when the filament comes off the spool it comes off anywhere from 2-5" in front of the slit and has to bend back to feed down it. The spool Irwin linked is offset to the backside of the printer, so when the filament comes off the spool it can feed directly down the slit.

 

I've got mine hanging directly above the printer. Seems to do the trick.

 

How do you compensate for the effective spool diameter that gets smaller as the spool empties? There are a lot of ways to do this but is it really necessary to have a motorized feed? Is anyone having issues with spool holder friction? The first printed overhead spool holder that my son and I designed used ball bearings but we found that it spun way too easily and had to add friction back.

Unfortunately we had an embarrassing spool changing incident that ended up with a cracked bed. Locktite superglue for glass works wonders. We now have a modified side mount holder that works just fine. It does use this guide which works great http://www.thingiverse.com/thing:255541.

 

My Spool Holder seems to be working flawlessly, zero issues so far (Knock on Wood) I am only about half way done my 1kg spool (which has the larger ID) so I will find out as I print more and near the end of this roll.

 

Some pictures to show the problem :


I think that the filament is twisting while extruded and this twisting makes it turn in the spool, and sometimes the next "turn" goes on the current "turn" and it blocks filament.

 

That almost looks like that end is the wrong end. Being pulled from the interior. Can you find the other end?

I would suggest unraveling the spool and winding it back up yourself. Once unraveled (the easy part)Use a cordless drill with a hole saw bit that matches the hole of the spool, get it wedged in there. Pin the filament to the spool via tape or something. Sit down, start the drill on low and have your the arch in your foot (with a sock, no shoe) over the loose filament to provide some resistance. Roll the spool up yourself in even layers back and forth row by row. Should take no more than an hour but should solve your issue.

 

Thanks to all for the help.
It is not the end of the spool, I can see the end attached near the center.
I designed a filament guide to help it unroll from the spool vertically. Printing it just finished, I'll publish it on Thinggiverse if it works, and I'll tell you.

 

No need to. It would have to be a very long print (8+ hours) for the diameter effect to cause any real issues. I was having friction issues, but printing the offset spool holder linked above fixed it. Now I am just continuing my project because I like to tinker .

Denis, it looks like you may have been right about a poorly wound spool. I have never heard anyone else say this about R3D's spools so I think it is an isolated incident, but it does look poorly wound nonetheless. I don't think filament twisting along the roll (or even yaw) would cause what you are seeing, but I have no experience with this issue.

 

Here it is :
http://www.thingiverse.com/thing:288586
I'll test it tomorrow.
I used it to unroll and re-roll a few meters of filament, seems to guide it well...