Posted: 4/3/2026 3:29:18 PM EDT
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Piggybacking on my TPU thread, I need to figure out how to route my filament from my cereal box (mmmmm cereal!). I am also getting ready to pull the trigger on an MMU unit so that also has to figure in for the future. I'm *assuming the straightest path is the best, but how much, or little, difference does this make? From what I understand TPU likes a straight of path as possible. Do you route over the top of the spool, under it? From the top, side or bottom of the cereal box? Is retraction an issue I have to be concerned with, do I simply drill a hole in the box and run tubing, or, I have also seen some folks use fittings for 1/8 tubing. My printer is backed against a wall and I keep a box over it but willing to change positions if needed. I could build a shelf behind/above the printer for now but keeping in mind the MMU for a later date. * I did see a print of a 2 or 3 color benchy and the wipe tower was bigger than the print, is there really that much waste or was that an extreme example? Thanks all. |
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There are a bunch of models available that you can print to seal the opening and feed through a PTFE tube. Attached File Myself, I've always had issues feeding from boxes with the outer edge of the spool resting on bearings. What usually happens is the spool will eventually tip over or roll off the side of the bearings and bind up somehow. As a whole, I've had the best consistency feeding spools from the center hole. I'll probably end up printing something like this: Attached File I can imagine TPU causing lots of issues with either method because it really doesn't like to have any drag in the feed path. For your setup I would consider placing the box on a shelf above the printer and drilling a hole in the bottom of a box to run the tube through with the filament looping over the top of the spool with the free end pointing down and as straight of a path as you can make. Or put your dryer up there and feed directly from it. |
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Originally Posted By Blob: There are a bunch of models available that you can print to seal the opening and feed through a PTFE tube. https://www.ar15.com/media/mediaFiles/160722/1000017976_jpg-3740743.JPG Myself, I've always had issues feeding from boxes with the outer edge of the spool resting on bearings. What usually happens is the spool will eventually tip over or roll off the side of the bearings and bind up somehow. As a whole, I've had the best consistency feeding spools from the center hole. I'll probably end up printing something like this: https://www.ar15.com/media/mediaFiles/160722/1000017977_jpg-3740747.JPG I can imagine TPU causing lots of issues with either method because it really doesn't like to have any drag in the feed path. For your setup I would consider placing the box on a shelf above the printer and drilling a hole in the bottom of a box to run the tube through with the filament looping over the top of the spool with the free end pointing down and as straight of a path as you can make. Or put your dryer up there and feed directly from it. I like the 'box tops', I was also thinking about feeding from the bottom for TPU. I like Obsessed's version, but can see advantages of the 'ferris wheel' type of holder. I might print one off just to see how it feeds. |
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Printing from a spool supported by the center hole allows filament to become unwound from the spools and tangled. Not as common on TPU but extremely common on other types that have higher torsional leverage on themselves. Attached File Printing from rollers on the edge while feeding from underneath makes this complication impossible. So I'd recommend feeding from bearings while having filament feed from under the spool with it coming up the front edge of the cereal box out out through the lid. |
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Originally Posted By -Obsessed-: Printing from a spool supported by the center hole allows filament to become unwound from the spools and tangled. Not as common on TPU but extremely common on other types that have higher torsional leverage on themselves. https://www.ar15.com/media/mediaFiles/467079/13150_jpg-3740902.JPG Printing from rollers on the edge while feeding from underneath makes this complication impossible. So I'd recommend feeding from bearings while having filament feed from under the spool with it coming up the front edge of the cereal box out out through the lid. I've never had that happen. I have restarted this print 5 times tonight because the spool keeps slipping off the bearings. Center hole supporting has never failed. Attached File Attached File |
I use 1/4" bulkhead push connect fittings, like these I put a ~2" length of Gooch tubing on either side. The inside so the filament feeds nicely through the fitting and on the outside for 2 reasons. The first being a solid sealed connection to your extruder tubing and a way to seal the container when done. Just cut the filament, push it just inside the end of the Gooch, and seal with a binder clip. Easy peasy to grab filament with needle nose, next time you need. I put half a dozen or so reusable/rechargeable silicon bead packs inside the container as well. |
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Originally Posted By Blob: I've never had that happen. I have restarted this print 5 times tonight because the spool keeps slipping off the bearings. Center hole supporting has never failed. https://www.ar15.com/media/mediaFiles/160722/1000017979_jpg-3740945.JPG https://www.ar15.com/media/mediaFiles/160722/1000017978_jpg-3740946.JPG Originally Posted By Blob: Originally Posted By -Obsessed-: Printing from a spool supported by the center hole allows filament to become unwound from the spools and tangled. Not as common on TPU but extremely common on other types that have higher torsional leverage on themselves. https://www.ar15.com/media/mediaFiles/467079/13150_jpg-3740902.JPG Printing from rollers on the edge while feeding from underneath makes this complication impossible. So I'd recommend feeding from bearings while having filament feed from under the spool with it coming up the front edge of the cereal box out out through the lid. I've never had that happen. I have restarted this print 5 times tonight because the spool keeps slipping off the bearings. Center hole supporting has never failed. https://www.ar15.com/media/mediaFiles/160722/1000017979_jpg-3740945.JPG https://www.ar15.com/media/mediaFiles/160722/1000017978_jpg-3740946.JPG @Blob why do you think it keeps coming off? Is it during the MMU retraction, would having the container above the printer help for any reason? Maybe feed out to front? Lots of good ideas, I just have to see how I can apply them for my needs. |
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Originally Posted By bmarshall1: @Blob why do you think it keeps coming off? Is it during the MMU retraction, would having the container above the printer help for any reason? Maybe feed out to front? Lots of good ideas, I just have to see how I can apply them for my needs. I think it happens when the running end of the filament gets to the edge of the spool and the pulling force goes sideways which causes the spool to get cockeyed. This happens in all four of my dryers with bottom rollers as well as these dryboxes. It's even worse when the cardboard edges are bent. I modified my S4 with this center support and don't have feeding issues anymore: https://www.printables.com/model/1503413-sunlu-s4-dryer-secure-spool-stand-anti-slip/comments#make.1503413 Only problem with that is the dryer is not sealed so it needs to be running to keep the filament dry. |
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Originally Posted By Blob: I think it happens when the running end of the filament gets to the edge of the spool and the pulling force goes sideways which causes the spool to get cockeyed. This happens in all four of my dryers with bottom rollers as well as these dryboxes. It's even worse when the cardboard edges are bent. I modified my S4 with this center support and don't have feeding issues anymore: https://www.printables.com/model/1503413-sunlu-s4-dryer-secure-spool-stand-anti-slip/comments#make.1503413 Only problem with that is the dryer is not sealed so it needs to be running to keep the filament dry. Originally Posted By Blob: Originally Posted By bmarshall1: @Blob why do you think it keeps coming off? Is it during the MMU retraction, would having the container above the printer help for any reason? Maybe feed out to front? Lots of good ideas, I just have to see how I can apply them for my needs. I think it happens when the running end of the filament gets to the edge of the spool and the pulling force goes sideways which causes the spool to get cockeyed. This happens in all four of my dryers with bottom rollers as well as these dryboxes. It's even worse when the cardboard edges are bent. I modified my S4 with this center support and don't have feeding issues anymore: https://www.printables.com/model/1503413-sunlu-s4-dryer-secure-spool-stand-anti-slip/comments#make.1503413 Only problem with that is the dryer is not sealed so it needs to be running to keep the filament dry. I do like that solution for the S4. I notice after drying the humidity level creep up until it matched the house. Have you thought of designing a thin gasket made out of TPU? I deducted 1 star from my Amazon S4 review for lack of gasket and the F'n small annoying latch 'handles' that can barely be grabbed with fingernails. I hope whomever designed those 'handles' has to use them on every item they ever own from cars, to refrigerators, to cabinets, EVERYTHING! |
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Originally Posted By Blob: I think it happens when the running end of the filament gets to the edge of the spool and the pulling force goes sideways which causes the spool to get cockeyed. This happens in all four of my dryers with bottom rollers as well as these dryboxes. It's even worse when the cardboard edges are bent. I modified my S4 with this center support and don't have feeding issues anymore: https://www.printables.com/model/1503413-sunlu-s4-dryer-secure-spool-stand-anti-slip/comments#make.1503413 Only problem with that is the dryer is not sealed so it needs to be running to keep the filament dry. An issue with the dry box is there isnt much, if any, room to work with for hole support. You also have the added complication that the spool o ly has about 10mm of vertical play so you need different height rollers for different size holes. No reason you couldn't design a support structure that snaps in where the bearings normally snap on. |
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Obsessed, Can you enlarge the flange on the outer edge of the bearing holders to keep the spools on the bearings? Make it an option people could print if they want to ensure the spools stay on the bearings? |
Louis L'Amour, “To make democracy work, we must be a nation of participants, not simply observers. One who does not vote has no right to complain.”
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Originally Posted By turtle2472: Obsessed, Can you enlarge the flange on the outer edge of the bearing holders to keep the spools on the bearings? Make it an option people could print if they want to ensure the spools stay on the bearings? Yeah shouldn't be a problem. I can also make them 1mm wider to allow an inner flange as well that can be sandwiched. There is only 0.75mm gap but somehow it sounds like spools are getting caught there? Ive never had such an issue but should be easy enough to design around. |
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Originally Posted By -Obsessed-: Yeah shouldn't be a problem. I can also make them 1mm wider to allow an inner flange as well that can be sandwiched. There is only 0.75mm gap but somehow it sounds like spools are getting caught there? Ive never had such an issue but should be easy enough to design around. Originally Posted By -Obsessed-: Originally Posted By turtle2472: Obsessed, Can you enlarge the flange on the outer edge of the bearing holders to keep the spools on the bearings? Make it an option people could print if they want to ensure the spools stay on the bearings? Yeah shouldn't be a problem. I can also make them 1mm wider to allow an inner flange as well that can be sandwiched. There is only 0.75mm gap but somehow it sounds like spools are getting caught there? Ive never had such an issue but should be easy enough to design around. Obsessed - for those that have already printed many, many, of these. Is there a way for you to simply design an add-on. Maybe an axle with a MUCH larger flange. The spool can't fall off it it hits a flange, kinda like train wheels but with the flange on the outside. To me at least it seems like a simple solution to just print 4 new axles vs. a whole new spool holder. |
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Originally Posted By bmarshall1: Obsessed - for those that have already printed many, many, of these. Is there a way for you to simply design an add-on. Maybe an axle with a MUCH larger flange. The spool can't fall off it it hits a flange, kinda like train wheels but with the flange on the outside. To me at least it seems like a simple solution to just print 4 new axles vs. a whole new spool holder. That's what I was implying. It will just be axles. |
| I only recently realized I didn't have to print everything on a plate that comes with a design. I have piles of those axles and won't use but a handful ever. I'm not going to be printing them in the future until I actually need them. Assuming an "upgraded" version comes out I might print some of those to have on hand, but likely only those. |
Louis L'Amour, “To make democracy work, we must be a nation of participants, not simply observers. One who does not vote has no right to complain.”
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Originally Posted By bmarshall1: I have a couple of cardboard spools that I have dropped that are so bent I'm not certain even the spool edges could fit once straightened. I did the same think with my spool of TPU Air.....I printed these out and super glued them on the spool. I've since fed it from a cereal container with Obsessed spool holder design multiple times without any issues. https://makerworld.com/en/models/468007-ams-polymaker-2024-cardboard-spool-ring#profileId-377133 I use Obsessed cereal box holder, adapted to fit slat wall.  I only print TPU directly from the cereal containers. I designed a replacement top that has printed TPU gaskets, along with a screw on lid that has a printed TPU gasket. With this setup, the TPU never leaves the box and setup is quick and easy. 
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EP429: Today's lesson - Don't provoke ARFCOM. People will see your butthole.
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Originally Posted By -Obsessed-: That's what I was implying. It will just be axles. Originally Posted By -Obsessed-: Originally Posted By bmarshall1: Obsessed - for those that have already printed many, many, of these. Is there a way for you to simply design an add-on. Maybe an axle with a MUCH larger flange. The spool can't fall off it it hits a flange, kinda like train wheels but with the flange on the outside. To me at least it seems like a simple solution to just print 4 new axles vs. a whole new spool holder. That's what I was implying. It will just be axles. DOH! I just realized we said the same thing! |
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