MakerFarm 8" Prusa i3v Enclosure

[usarmyaircav]

gmay3, that tubing looks like water line tubing. I will have to check the spare tubing I have to see if it would work. I was expecting tubing specifically made for 3d printing. Probably should have known better. Rather like when I was active duty Army, and would send new recruits out looking for an A.S.H. receiver for the helicopters, or send them to supply to get some rotor wash.

[printbus]

In a true Bowden setup, you would use tubing that is pretty specific, with an ID just larger than the filament you are using and PTFE in order to minimize friction and possibly tolerate any heat soaking up from the hot end. Here, tubing is just being used as a guide so just about anything can be used, including the icemaker tubing which I believe is usually polyethylene.

The difference with a full Bowden setup is that the extruder drive motor is located away from the extruder, with filament being pushed and pulled through the tubing. You want as little slop in the fit of the filament in the tubing in order to maintain good control over the extrusion. Here, the extruder motor is still on the extruder, you're just pulling the filament through the tubing, and any loose fit in the tubing makes no difference.

[gmay3]

gmay3, that tubing looks like water line tubing. I will have to check the spare tubing I have to see if it would work. I was expecting tubing specifically made for 3d printing. Probably should have known better. Rather like when I was active duty Army, and would send new recruits out looking for an A.S.H. receiver for the helicopters, or send them to supply to get some rotor wash.

Haha yeah, RepRap folks will re-purpose anything for use with 3D printing! The Wright Bros. re-purposed bicycle parts to make their first airplane!

I wouldn't be surprised if it was the same tube you're thinking of. Honestly, for this application of just routing the filament, any tubing should be fine. I think this PTFE tube is ideal for real bowden style extruders because of the relatively tight tolerance of the inner diameter of the tube and because of the very low friction and high temperature resistance of the PTFE tube! I ordered enough to hopefully have some left over if I ever decide to convert my printer into a bowden style setup.

[usarmyaircav]

sorry if this is distracting from the original topic. I understand the difference between a bowden setup and the Greg's extruder that comes with our kits, but what are the downfall/side effects of going with a true bowden config? It seems that the bowden from my limited reading gives the best speed for extruding.

[printbus]

Seeing if I can beat gmay3 again...

The main advantage a full Bowden setup has is reduction in weight at the extruder. Less weight means faster acceleration, which will reduce print time. The main disadvantage I am aware of is getting retraction set up properly can be troublesome.

I believe the most common application for Bowden setups is on a delta type printer. With the suspended extruder on a delta, I can imagine how weight at the extruder would really slow down how fast it can move around.

[gmay3]

sorry if this is distracting from the original topic. I understand the difference between a bowden setup and the Greg's extruder that comes with our kits, but what are the downfall/side effects of going with a true bowden config? It seems that the bowden from my limited reading gives the best speed for extruding.

No worries. My limited understanding (which may be wrong) is that you can print much faster since all you have to move around is a hot end and a X carriage. I believe that this is most beneficial when you have a printer that has a fixed bed where the the hotend can move in both X and Y directions. It sounds like there is a hysteresis error which I think is a fancy word to describe the lag between when the extruder motor extrudes filament to the time it takes for the filament to reach the hotend nozzle. Other errors added to the system include the diameter gap between filament and the bowden tube, as well as the flexibility of the tube.

Overall, bowden is much faster at a slight quality hit.

If I'm wrong, lets discuss this in depth in another thread! I'd definitely be interested in hearing others weigh in on this! Plus I think a new thread may attract other experts from different places in the forum!

[gmay3]

Seeing if I can beat gmay3 again...

The main advantage a full Bowden setup has is reduction in weight at the extruder. Less weight means faster acceleration, which will reduce print time. The main disadvantage I am aware of is getting retraction set up properly can be troublesome.

I believe the most common application for Bowden setups is on a delta type printer. With the extruder just hanging from some long wires, I can imagine how weight at the extruder would really slow down how fast the extruder can move around.

Ah you beat me again printbus! haha

[AbuMaia]

My current plan was to fix the bowden tube to the top of the frame with maybe an inch or two extra to allow it to flex at the angles needed to have free motion along the x axis. This way the filament should never be bending more than 20-30 degrees and it would be pretty easy to swap out the filament since you'll have access to the several inches of filament above the extruder.

Yeah, I do get quite a bit of bend between the top of the printer and the extruder when I print tall objects. It does bend a bit too right at the extruder, but the guidler is seeming to take the brunt of that; a small notch has been worn away where the filament is rubbing it. So far I've not had any problems from the bends, even when using PLA which I can snap by hand.

[gmay3]

Hmm. That's pretty impressive that it's running so well! I'm not sure how flexible the 3mm filament is but I'd imagine someone running that might have more of an issue.

I was actually originally thinking of ending the bowden tube about an inch away from the guidler entry but I think it would be harder to change the filament with only a little showing.

I'm thinking of designing a part that looks like the top of a cane with a flange on the bottom that will mount to the top of the printer so that the filament and optional bowden tube can be bent around the top with a smooth curve. Might have 2 or 3 slots to hold the tube down securely with zip ties. I might leave an inch or so of the bowden tube hanging down so that it can flex with the filament.

[AbuMaia]

I was actually originally thinking of ending the bowden tube about an inch away from the guidler entry but I think it would be harder to change the filament with only a little showing.

I haven't found that to be a problem. I have a small switch housing just above the extruder through which the filament runs (you can kind of see it in the second picture in my earlier link, it's where the tubing terminates). If the filament runs out, it opens the switch and pauses the printer with an M600 so I can replace it. It does leave about an inch of filament above the guidler, but that's plenty to grab and pull out. It's much easier than trying to fish out the filament after the end has passed the hobbed bolt.