Should you use a Reverse Bowden?

[@TheCyberSpidey]

So Anker can sponsor a video on a 3D printing channel, but won’t send a review unit of their 3D printer to the same channel. Interesting.

[@Deaner3D]

Because Thom is one of the few creators with a clear sponsored review policy/contract. They probably want an advertisement disguised as a review.

[@TheCyberSpidey]

@@Deaner3D I think it's not even that. Not sending the printer to anyone but 2 channels (one of which doesn't cover 3D printers anyway) means that they really don't want reviewers to put their speed claims to test, or look under the hood.
Same with Prusa XL, the preorders are on at the moment with no reviews in sight - but atleast we know that 3D printing channels will receive review units at some point (based on Prusa's previous record).
Anyway good for Tom, his content is good and deserves sponsorships - just a peculiar move from Anker.

[@soundspark]

@@Deaner3D Like the burned in ad, correct?

[@martingerken7094]

Bad content to ad ratio, too!

[@wblteen]

@@TheCyberSpidey Prusa hasn't even finalized the BOM because of supply chain issues. They can't send out a review sample if the release version is very different

[@bigcheesedog2645]

For me, the mod with the biggest quality jump was making a low-friction spool holder, I made one of the many skateboard bearing based spool holders on Thingiverse. It made my layer lines noticeably more consistent. Though the reverse Boden could be useful to me since I have the spool holder screwed to the rafters 4' above the printer.

[@yaVDRgda]

I prefer to us a PTFE tube with 3mm inner diameter for the reverse bowden to get less friction.

[@soundspark]

This is what is specced by Voron 2.4R2 for its reverse bowden.

[@Jobobn1998]

Same. I ended up changing from the 2mm ID after any kinks in the filament were causing too much drag.

[@Balrog132]

The drybox scenario is what i do with my normal bowden setup. Interestingly, the bowden tube fit perfectly in the little hole of the drybox and ensures the the filament doesn't rub away the enclosure hole. The friction of the hole and the bowden tube is perfectly enough to keep the tube in place. On the other side, the tube pushes against the extrude inlet and stabilizes the position by itself. This allows me to have clean filament fed and "going around corners" from the drybox placement without any weird kinking and pulling of the filament at odd angles. On retractions, the bowden tube pushes away a little from the extruder, so the filament doesn't get pushed back through the whole tube back into the drybox. This also allows for easy pulling away and out for filament changing. Pulling friction through two tubes is not noticable to me, retraction only has friction through one tube as before.
In that way, it is not a reverse bowden setup as you showed, but similar enough when you just look at it.

[@MitsumaYT]

Don't use 2mm ID, use 3mm ID, you really don't want that extra drag in a reverse bowden.

[@JeremyCook]

Normally I'd be annoyed by such a long ad, but that power brick thing actually looks pretty awesome.

[@jbergene]

ive been doing this for years and it lets my Direct drive pull evenly on the spool at all times and its not those sudden hard pulls that happens with travel movement. A must have for large printers.

[@j.g545]

never understood how is it not included in prusa kit by default

[@jimlee4649]

Tom - If you figure out the issue causing the surface imperfection, please let us know. I have the exact same issue and haven't been able to figure it out.

[@_..-.._..-.._]

I found this video perfect, I printed a Prusa spool holder and mounted it in my Anker M5C to get rid of the idiotic and weak stock setup and I was running with only a 1” piece of ptfe that I bellmouthed to help guide the filament into the direct-drive extruder. The filament roll was flopping around a bit and tugging but like he showed, it didn’t cause any issues and now my cardboard spools roll smoother as well.

[@dennissmith8199]

Been using one for ten years on my Hypercube. I have the filament spools mounted on the side of the printer, with a little funnel like feeder with a filament out switch on it, where a 4mm PFTA tube plugs into, and another adapter on the top of the Titan direct drive extruder that the other end plugs into. Has always worked flawlessly.

[@53Ericd]

Thomas, thanks for all of your informative videos. One other advantage of a reverse Bowden, I have converted to a direct drive and wanted to continue to use my Smart Filament Sensor without adding the sensor to the print head. Using a reverse Bowden allows me to place the sensor on the printer frame and off of the moving part of the hotend.

[@BurninGems]

Reverse Bowden? You mean a filament guide tube? Been using one for years, didn't know it had a fancy name! Great video again!

[@benford663ify]

Interesting idea. Ironically i do this as well from my dry boxes to my printers. I do want to add you might have missed sone additional forces. Restriction through a bowden does provide resistance and possibly worse then an open spool. Depending on the length of the reverse bowden (or as i call it a feed tube since it doesnt really work like a bowden imo). Also if that add on tube has any coils or bends in it that is going to add to drag. I got all my Teflon tube from a 3d supply store and it came from a spool. So it was already coiled. I have found this to add a ton of drag so straightening the tube is advised.

[@MalvixStudio]

Hey Thomas, that pattern you’re seeing is most likely the infamous issue 602, and is most likely related to the hobbed dual drive gears. The teeth from the gears have a bit of backlash, which causes the filament to not be pushed down perfectly uniformly. That, in combination with the lack of rigidity in the frame.

[@BelviGER]

I have a spoolholder/storage for 15 spools at a time but my rollers aren't optimal, so my drag is a lot higher than on most normal holders
Reverse bowden is a must especially at higher print speeds

[@3DMusketeers]

I have always wondered if the force would be enough to deflect, this is interesting for sure! From the sides maybe, but like you showed, I have not seen a degradation in print quality by having my spools above and forward of my printers.

[@neofitou]

Reverse bowden actually made a big difference to my prints when using 3kg spools on my ender 5. The cartisan printer carrige is more susceptible to issues due to drag and the drag on a 3kg spool is much higher than a 1kg one. When I switched to a 3kg spool my failure rate went up to about 30% from about 10%, and with the reverse bowden it went back down to below 10%. The main reasons for failure being under extruded layers or jammed filament.

[@Glockodile]

Im sure you know this now, but that visual stuff you were trying to get rid of is prusa 602 and is caused by the bondtech drive gear being eccentric due to manufacturing tolerances

[@psharpep]

@Thomas, you may want to double-check your Prusa z-axis assembly. On the three Prusas (MK3) I have access to, when I apply a reasonable amount of downwards force to the top of the extruder stepper (a few pounds), the extruder deflection is imperceptible - much less than what this video shows.

[@rmatveev]

Im 100 percent agree that the tube is IMPORTANT!
I have it on both of my printers (both direct drive) and this drastically improved the print quality and reliability!

[@johnmullen946]

I did the reverse Bowden with my Monoprice Maker Ultimate. Made a big difference in consistency.

[@EeBX]

For reverse bowden it makes sense to use 4mm OD 3mm ID tube instead of 2mm ID that Thomas recommends. Reverse bowden does not need the filament constrained as much as regular bowden and the looser internal diameter reduces friction thus needs less pulling force by the extruder.

[@MostlyInteresting]

When I switch from direct to Bowden and back I started using the tube on the direct extruder. Found that it worked pretty good so I just left it that way.

[@RandomloserDK]

I'm surprised it's not more common, as I've been running the "reverse bowden" on my printer for years.
It solves some big problems, like:
It'll eliminate most of the pulling force on the extruder(A common problem with big spools).
And I've never had a problem with tangled filament since.

[@MassisPipes]

how does it eliminate the force on the extruder? Your filament is still attached to the extruder, and the extruder still has to pull the filament off the spool?

[@RandomloserDK]

@@MassisPipes It's not the force of the filament getting pulled by the extruder motor you eliminate, it's the jerking on the filament spool when the the extruder moves.
Some printers are more affected then others.
Eg.: if you have a side mounted spool, and your hotend is printing close to the spool, then the hotend moves away from the spool to the other side, that move jerks/drag the hotend and spool.

[@MassisPipes]

@@RandomloserDK aah, that makes sense. It also explains why I don't need it, since my machine is a bedslinger with the spool centrally above the X-gantry, so those distance differences are minimal.

[@jrdavidg]

I have a modified Ender 5 (Direct Drive) that uses 2 BMG Extruders. One is for DD itself and one is attached to the frame to help feeding filament. It works pretty well and I have some extra time to add a new spool to the feeding system without any kind of issues in the process.

[@PTEC3D]

That's nifty! I tried adding a new filament with the remote bowden setup and because that creates a break in the filament it couldn't retract the old filament in the PTFE so I had horrible over-extrusion and stringing until all of the old filament had been pushed through. Not so much of an issue with a direct extruder but I can see that using both would minimise the amount of unretractable filament.

[@howardcohen2767]

Pushing filament through a boden tube and pulling filament through a boden tube are very different. Pulling is more efficient. You would have no trouble using a flexible or softer filament when pulling it through a "reverse" boden tube, but pushing the same filament might not work at all, or work poorly. Even with a harder filament it is also true, but perhaps to a lesser degree.

[@tammyhollandaise]

We stuck a 5kg roll of filament in a dry box under a table, then ran a 4mmOD-3mmID PTFE tube up to the Prusas. Never had to change or deal with filament problems for several months (in a free-use university maker-space)!

[@MattWeber]

Ive honestly never seen a good reason NOT to use it. Protecting your filament from as many elements as possible between the spool and the nozzle, prevents soooo many problems over time. It is one of the first things I create if a printer lacks it by design.

[@ewbaite]

if you change filament often its more convient to not have the bowden tube

[@DannyMNL]

The Prusa Mk3s with multi-material upgrade already uses a both a normal and a reverse bowden system. It uses a normal bowden system to load filament to the toolhead, and after the toolhead detects the filament, it takes over and the filament loader/selector disengages. The system then acts as a reverse bowden. It actually works pretty well in my experience.

[@tommischubert9861]

Thanks for your Video.
I am printing a lot ABS lately and always had my Fillament outside my Tent in my dry box and wasn't considering that as a problem.
A week back I didn't need my Fillament dryed an had the spool on top of my Printer and was surprised by better Prints. At that time I wasn't exactly sure why but after this Video it all makes sense.
Honestly my steup with the tent on the ground and the dry box on the Table is kind of getto but I was surprised that it Realy made a visual difference.

[@evo-labs]

I used a 'reverse bowden' setup on my custom CoreXY printer (direct drive) that has a canopy so it's totally enclosed. It worked but would often result in the extruder jamming with larger prints. After unsuccessfully trying different PTFE tube sizes, the final solution was to have a connector at the filament end that is free to rotate 360 degrees so that the bowden tube is better able to release tension and not grip the filament at extreme positions.

[@Zzafari7]

do you have the STL of this

[@evo-labs]

@@Zzafari7 The connector is an off the shelf product: P NSF-51 tube fitting adapter with 4mm diameter hole, BSPT thread, as used for water systems. The important part of it (other than fitting the PTFE tube) is that it allows rotation of the tube once fitted. I did create a CAD model for the upright that houses it, but it's nothing special - looks like a square building with a hole down the center of it (top threaded for the tube fitting adapter) and some mounting holes as I used 2020/2040 aluminum profiles.

[@daliasprints9798]

You've presented some motivations in favor of reverse Bowden I hadn't considered before. Personally, I dislike them because they negate one of the biggest convenience improvements of direct drive: not having to load and unload filament through a Bowden tube. I think some of the benefits can be retained by using one or more pulleys with bearings (specially designed not to drop the filament under loss of tension, using some tricks with TPU) rather than Bowden tube.

[@duality4y]

that is like a tiny inconvenience

[@daliasprints9798]

@@duality4y If it doesn't bother you, great. 😁

[@PTEC3D]

I only fix the remote end of the tube in my setup - that way I feed the filament through the PTFE, then can grab the end and just insert it into the extruder motor, really simple and lt it bob up and down with the retraction cycles. Has worked for me like this for nearly two years, works with any setup. Hope this helps.

[@johnandersen8999]

I've been using reverse bowden for a while! For the reason of having my filament mounted lower than the printhead.

[@tlv1117]

I never imagined someone would use a direct drive extruder without a reverse Bowden. But then my printer's spool mount is sideways so it really is necessary.

[@heyokawolf13]

Great info. Thank you! Do you have a link to the small 3D printed parts?

[@rowlandstraylight]

with a perfect spool its of negligable value, if the spool is unbalanced or the filamant gets a little stuck. I found got a different mesh on spools that rocked back at certain points on the spoolholder.

[@rcmaniac25]

I've had a reverse bowden for years because 1) Repbox setup that is in a wacky location. 2) I use a Mosaic Palette which not only does it's own reverse bowden but a mount of some sort was needed on the extruder to hold it (like the slip on that Tom used) and that didn't have to only be used with the Palette... so

[@jurgenstoll2394]

Hallo Thomas, die Stromüberbrückung durch eine Powerbank funktioniert sehr gut bei Kühlschränken etc. Bei Geräten wie Computern oder 3D-Druckern sind sie nicht geeignet, da die Reaktionszeit des Systems zu lang ist. Da stürzt der Rechner oder der Druck ab. Hierfür braucht man eine USV (oder eine Kombination mit Powerbank...).

[@scottbaeder37]

Also great for run-out detection based on actual movement of filament (vs. the ones that just detect a break). Without it, the movement of the head makes it harder to detect if actual filament is being used.

[@SRMWorkshop]

We use a similar setup at work. The direct pull with 2.85mm filament would leave pretty bad artifacts when the spool would get low. Added the bowden, put the spool in an easier location to access and now the printers run much better.

[@Inkomstkatt]

I've had a reverse bowden tube for ages, just because I had tubing left over when I converted my printed to direct drive and thought it looked "naked" without it!

[@2mD]

i have been using it like that since i switched to a direct drive setup, because the filament spool sits inside a drybox on the side of the printer.
without a bowdentube the printhead would pull on that every time the x axis moves...

[@alicec2033]

Does anyone have a link to the reverse bowden parts? I like the way it mounts but I'm not having any luck finding it.

[@b4de4nd]

Have you ever considered making a test about Silica Gel in DIY drybox vs. filament dryers? You have a video about cooking filament to dry it out, but multiple sites suggest that leaving filament in boxes with silica gel for more than 24hours would render the same result. Thougts on that?

[@pmfman]

Instead of a washer for the dryer box, i had a spare push-on fitting for a bowden tube that threaded into the hole perfectly because coincidentally the hole matched the minor diameter of the threads on the fitting

[@licensetodrive9930]

Fascinating stuff, I already printed a modified filament sensor cover for my Prusa Mk3 which I added a bowden tube holder, to help feed flexible filament from sitting in a food dehydrator, which I also added a bowden tube holder to.

[@jawar3222]

Hey! Thanks for the video! Do you have a link to the printed parts? Looking to improve the filament path as I print directly from a dry box. Thank you again!

[@MadeWithLayers]

I've just uploaded the files to Printables! www.printables.com/model/271586-prusa-mk3s-reverse-bowden-mounts

[@jawar3222]

@@MadeWithLayers much appreciated! Thank you for the quality content 👍

[@JohnAldred]

I added one to my Snapmaker 2. Was the easiest way to keep constant tension and stop it from slacking off the spool whenever the print ended and the head rose to the top of the Z-Axis. I use it a lot for TPU on my other printers, too, just to give it an easier path so it's not tugging straight down on the spool.

[@LandonsLaboratory]

I did this to my CR-10 Direct Drive and it definitely helps!

[@PTEC3D]

Great video, easy to follow, described the problem and shows the solution, and is super easy to do.
I made my own printer enclosure and the filament feeds in from the roof, and I came to the same conclusion and found benefit from using PTFE to take the filament pullback force out. It worked whether I had the standard Ender3 extruder/bowden setup or an aftermarket direct extruder, and in neither case did I use a fiitting at the extruder drive - the teflon tube just goes from being fixed at the top to loose at the entry into the extruder gear. That makes it easier to thread the filament, and the tube still does its job of preventing the printer from trying to pull itself back up the filament. The PTFE is slippery enough that the extruder motor never notices the little 'hop' the PTFE does (from extrusion/retraction cycles) and as the tube is fixed to the same enclosure the printer is mounted in there's no force transmitted to the printer frame. And you get a quick visual confirmation that the retractions are happening.
Here's an idea for a future video though if you feel like getting hugely frustrated: Minimalist filament 'splicers.' I found some on Printables that can be printed, then I found a commercial metal unit on a certain Chinese multi-store-market site. But you need good eyesight and manual dexterity for these fiddly little gizmos and due to age and medical reasons I have neither. I still managed to actually make a few splices in PLA with the three units I tried but results are a bit random and sketchy and prone to breakage. Cheers, @prawnheads1

[@MaxGoddur]

Now I need two of them to use as UPS for my freezer and refrigerator.

[@RomanoPRODUCTION]

Thomas the Reverse You-Bowden-Tuber. This video is a tropical storm. Thank you Thomas.

[@VenelinEfremov]

Very long reverse bowden adds quite a bit of friction. Best to use 3mm ID teflon tube.

[@stabbyronnie]

You're right! Prusa did pay a lot more to pretend that their printers are better! "Reviewers" took the payment and here we are!

[@Trantor475]

I have a bowden hotend, and i added a bowden tube from the extruder to my filament box/dryer to protect it from dust and humidity. Since I installed it I had 0 clogs or problems at all.

[@coledavidson5630]

Wdym there's no way to avoid reverse Bowden in an enclosure? I can't see why I'd need it when the entire spool is inside the enclosure

[@BrianKimminau]

Hey Thomas!
Design up a way to always have slack between the DD printhead and the filament roll.
I have always wished there was a way to somehow motorize/other, the filament roll to always have some slack. On fast retractions/movements sometimes the filament roll will wind and unwind (roll out/roll in) which ends up putting bad pressures on the extruder.
I own a 3d Printing retail business/farm/service and this is something I have always thought about. I ended up making all filament roll Holders with a more Clutch style assembly. Bearings roll too smoothly etc.
Thank you for your content!

[@htrabj]

This was a super helpful breakdown - thank you! My space is very limited and I need my filament to sit next to my Prusa 3 instead of on top. Thanks to this video, I know exactly how to swirl my space, and why!

[@misamokuzelpizu]

i have been using a teflon tube from my dry box to my printer for years, just for dust and moisture protection. since i have been doing that i havent experienced any clogged nozzles. (but i also clean my nozzles now and then)

[@alejandroperez5368]

Me too. I made my own dry box which has three output couplers to which I connect the PTFE tube, which goes to my direct-drive hotend.

[@dondo8661]

Hi Tom, it would be very interesting to see you trouble shoot the weird extrusion pattern

[@zeugundso]

I advise against using a 4mm OD 2mm ID teflon tube and instead go for a 4mm OD 3mm ID teflon tube for lower friction

[@BurninGems]

You'll need that powerhouse come winter... Great video!

[@sargfowler9603]

It's really just a guide tube isn't it? My Anycubic 4 Max Pro has one.

[@DoctorrMetal]

Yet another nice video and what a coincidence. I was thinking about exactly this yesterday for my Ender 3 S1!

[@TheZombieSaints]

I have an hemera modded ender 3 v2 and Ive often wondered if I could do exactly this if I was to take my spool holder off the top and have in on the ground... Question answered. Thnaks heaps bud 👍

[@Baurophon]

What i'm missing here is the issue that some filaments like PLA will break after only a few days without use in these tubes. While this is not a big issue with bowden systems, it is kind of annoying in reverse bowden systems.

[@peterpiwowarski8689]

The Prusas at least have a sensor, which should keep it at "annoying" instead of "print-wrecking".

[@Donnerwamp]

I'm using a more or less "Doublebowden"-Setup when printing directly from my DIY drying box. This somehow reduced the ammount of clogs and slipping, but that might just be placebo.

[@charleslambert3368]

stack like 12 extruders withg bowden between them

[@TDOBrandano]

Not just placebo. If you leave the filament in its holder for some time, it can literally gather dust, and accumulated dust will eventually cause a clog. An enclosed holder, like a drybox, prevents that. On my 3mm printer I use a 4mm ID reverse bowden from a spool holder built out of a 5L clip down lid box.

[@roberttrescott2741]

Agreed, the reverse bowden is a necessary upgrade. However, filament retraction will separate poorly coupled tube ends due to the bowden tube/filament internal friction. Rapid retracts exacerbate the tube decoupling nearest the extruder. I've had to add a PTFE fitting on top of my Ender 5 with the direct drive extruder conversion.

[@Trust_me_I_am_an_Engineer]

Running the filament from your drybox through a teflon tube to your direct printhead also keeps the dust off. I use 3/5 mm tubes (not so floppy as 2/4 and less friction). Excellent video, Thomas! I'd still recommend a dust filter on top of the direct printhead, although the 0.6 mm and up nozzles are more forgiving when it comes to dust particles.

[@DustinGorman]

Tom, can you please share with me the STL for the bowden tube clip and the revised extruder cover? I want to use the mk3 inside of a Ikea Lack enclosure, but obviously the spool holder will not fit. I have the Prusa Mini on top, so I want to put the filament inside on rollers, and use this setup. PLEASE :)

[@MadeWithLayers]

www.printables.com/de/model/271586-prusa-mk3s-reverse-bowden-mounts

[@KrisRyanStallard]

I've used a "reverse bowden" for a long time as a filament guide. Very handy. I didn't notice any change in print quality though.

[@zeendaniels5809]

I don't know... On this one, looks like a spool holder with bearings would take care of all the problems easily.

[@yellovvcake]

but how could you fix those ripples, got htem myself and cant find a thing ot that

[@JamesArmstrong3]

fore sure, I have been adding that to every printer I have ever touched for years. It does really help.

[@gabortoth3300]

The even more sophisticated method is, if you use a second (bowden style) extruder together with the direct drive extruder, simultaneously. I call it twin-extruder and I use it on every big machine I have. The bowden extruder has an independent mounting from the printer frame, so the filament dragging forces are not affecting the frame at all (think of 8kg spools...). Another advantage is, that if the two extruders are working together, the bowden extruder can help out the direct drive one if it would come out of juice, by pushing the filament into the gears. Hereby you can gain ~ 20 to 40% more flow compared to only one (direct) extruder.

[@philipdesborough9783]

I have been using this because I did not want the lazer runout sensor on my print head. my flashforge creator had this stock.

[@BigAlS4]

Perfect timing!! I just bought a filament dryer for my PETG spools and was trying to figure out how to feed it to my mk3. Great vid!

[@DejitaruJin]

Reverse bowden was great just for filament guiding on my Ender 3 knockoff, and it's even more critical now that I'm using both an enclosure and drying box.

[@allwoundup3574]

I wish I could get back the time I spent watching this. You spent so much time talking without actually saying anything or answering the question in the title.

[@mysteriousfox88]

i use a closed loop for nylon printing using the mmu2 m6 pc extruder cover

[@kimmotoivanen]

Negating ease of loading and unloading filament in direct drive extruder 😅
Don't get me wrong, there are valid use cases for reverse bowden, as shown. (Having better prints without spool on top is not one of them)
Is that surface pattern created by dual gears in extruder? Or small diameter gears? Are they present when printed with same filament but bowden style printer?

[@PTEC3D]

Only attach the bowden at the other end not at the extruder motor, that way you can push the filament through the tube, then feed it separately into the extruder. Well worth having.

[@sypernova6969]

​I tried something like that for a ewhile, and it negatively impacted the quality of the print, I think there was too much friction. I should revisit but set it up properly....

[@JBothell_KF0IVQ]

ive been doing this for a while from my multi-spool dry box to the filament sensor on my ender 3s1. it works a treat... just have to make sure the filament unrolls nicely from the spool or we have a bad day

[@Tims_Projects]

Did it years ago.
Can I put a link to it?
It shows a Mechanism to adjust for retraction when using this type of feed.

[@JeansWithPockets541]

With the drybox behind the printer, it looks like adding a reverse bowden setup would mostly help the filament not be so easy to snap.

[@PeterHertel]

I've been using this for years, but mostly to avoid the filament unspooling too quickly and tangle.

[@tomyocom5886]

Regarding reverse Bowden tube for keeping moisture OUT. Has anyone tested for TUBES sucking moisture (condensation ) from outside the Tube to inside the tube and onto the Filament , WET TUBE SYNDROME @TY This seems more apt to happen than keeping moisture out.

[@glenjones4009]

Please share links with me how to set bowden tube to Eibos Cyclopse dryer. He touched on it but would like to see a bit more detail and instructions. I am a bit slow.

[@Veptis]

My extruder needed the filament to be inserted really carefully and precisely. You even needed to cut it sloped to help guide it in. So I don't think this would work for that extruder.

[@GregAtlas]

Using 25k spools on my custom modified Ender 5 Plus systems at work would actually lift/bend the x gantry on a full spool and is the reason why I ended up swapping it to a regular bowden setup so the stresses are on the frame instead (with the added benefit of being able to feed from the bottom) but I have been wondering if a reverse bowden would help with this as well.

[@adamfilip]

consider adding a 2nd feeder extruder that mirrors the primary extruder, near the spool

[@sheeeple2069]

Why not also do tests when the spool is not on the top? How big of a difference will the tube make?

[@andyspoo2]

The Anker looks amazing....until I saw the price! I'm not saying it's not worth it, but it's well out of my budget.

[@ASURMlN]

Shouldn't the weight of the spool turning on the smaller diameter spoolholder be the main cause of the issue? Because of friction?

[@86abaile]

Should be obvious it's not needed to combat forces (which is more suitably solved with bearings), if anything it just adds drag to the filament path. I used to use a short piece as a guide path to direct my filament into the extruder to prevent snagging. Since I upgraded to direct drive I use a length to constrain the filament path to avoid it getting caught in the X or Z axis.

[@Brendan9300]

Nice i did something simlar but i will improve after seeing this

[@Mobile_Dom]

ha, anker are sending me the 535 and the solar array, I should have asked for the big boy :P

[@elvinhaak]

Well, and now check and calculate the drag...
It depends on filament a lot how much drag you will get but with some filaments it added enough drag with the reverse bowden that the direct-drive was getting into clicking, with it removed, the clicking was gone again.
Another point for drag is of course a filament-sensor (of the cheap kind with just a switch) which all adds up to the path. For now I go with normal PETG, PLA and ABS and especially flex without the bowden on my printers but with a drybox and those filaments I will probably go there again.
I was thinking, why not get 3mm bowden for reverse? Same positive factors but not soo much drag added ?

[@Lidocain777]

Interesting ! I've been using Reverse Bowden intuitively when going from Bowden to Direct Feed. Though, my prints don't show the artifacts yours do...

[@yvindhansen2199]

Your physics explanation at aprox 4min in is not right. The bowden tube purpose is only to give a narrow path to the rather unstiff filament. Since its like pushing on a string it need to be restrained in a tube. The fillament then will have a typical sinus wave or spiral buckle behavius inside the tube. This give friction points that add adtional axial loads (therfore the tube is fixed at each point.) There is no cancelation of extruder push forces from the tube. The forces need to be absorbed by the frame either way. Direct drive hotend will aslo need to pull on the spool either it have a tube or not. Its purpose is then to give a better path to the hotend, nothing more.

[@kmcderm133]

Could we avoid the need for a bowden altogether if the spool holder was motorized in sync with the extruder, to unspool the filament at the same rate that the extruder/toolhead is asking for it?