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I've been having a lot of feed issues during the later stages of prints. From reading other posts it seems that as heat builds up in the bowden tube the current extruder lacks the strength to continue to push the filament through. I've also noticed that when I manually feed filament that I get quite a bit of friction as the filament descends towards the hot end. I came across this upgrade on thingiverse and it seems to really improve the drive strength.

http://www.thingiverse.com/thing:19551

Does anyone have experience with this upgrade before I make the investment in all of these additional pieces?

Cheers!

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I made one- I like the Mk6 gear, but I don't live in Oz, so I couldn't source the spring listed. I tried several from McMaster-Carr (9657K334 I believe) but I couldn't get it to work without slipping occasionally. I have come to prefer the spring and threaded tension bolt type designs. It's easier to adjust it to just the right tension.

Some things I learned: Make sure you print the Filament Compression Arm at 100% fill - there's a lot of force on it. The shaft pops out of the rear bearing easily, and with the spring pressure on it, it will pop the gear out of alignment with the stepper spur. It could use an e-clip behind the rear bearing or something but failing that, ake sure you get the proper length from the rear bearing to the end of the shaft. Also, make sure you put lock-tite on the set screw in the Mk6 gear, if it loosens, it will slip and bork your print.

I'm currently using tlalexander's extruder with great results. No slipping even on a 30 hour print.

http://www.thingiverse.com/thing:20850

I'm using springs from here:

http://ultimachine.com/content/wades-ne ... rdware-set

and a grooved bearing off of e-bay. Like I said, 30 hour print...

Kyle

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Thank you so much Kyle! My prototypes require about 7-8 hours right now but wow 30 hours...and another user mentioned doing a 42 hour print with the same extruder. The tlalexander extruder looks a bit more stable, I'll give both a try since I have a lot of hardware hanging around anyways and maybe a direct comparison study will help other users in the future.

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@alaris2- Nothing visually exciting, just big - picture half a cylinder filling the bed. I work for a company that makes pumps for power plants and there was some interest in printing a large copy for trade shows. The 30 hour print was half of a 3/4 cutaway section. The third quarter took 16 hours and the impeller took 14 or so. It's on the back burner for now, but it would be nice to get a paying job for my UM one of these days.

Since I'd like to get paying jobs, I'm very interested in improving the reliability of the UM. As such, I've printed and assembled just about every extruder posted up to Thingiverse. The tlalexander extruder is the best option I've come across so far, but I haven't tested the bertho mod yet. I printed it, but I didn't have the right bearing in my junk bin.

The next items on my wish list of upgrades are keeping the table level (which may just a problem on my self made heated bed) and a dual fan mod (improve the surface finish on the side opposite the fan) or maybe, crazy idea, a remote fan using a fish tank aerator and some silicone tubing. Then I can duct the air wherever, and it will work for a dual extruder. I'd really like to run PVA support material.

@LITS4FormZ if it works within your budget, I encourage you to build all the extruders. I don't devote as much time to documenting as I should, but I've learned alot about what I like in extruder design. We could all use more metrics based comparisons on the board here, so yeah, please post your findings.

Kyle

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ah, large cylinders. I printed a 9hr one of those and vowed never again! for a moment I thought you'd downloaded a car.. but you wouldn't do that ;)

I am also looking for paying jobs and find the quality and reliability keeps letting me down. I've just finished re-designing the hot end for vastly improved performance and hope to have some results shortly.

I already upgraded the extruder to Bertho's mod, which is good, but still not good enough.

keeping the table level and to within 50 microns and heated beds are also on my list - if you'd like to share/swap ideas then I'm all ears. PVA support is on my list too actually.

I tried the fish tank air idea already - I had a spare bowden tube. it works very well, but you need a flared attachment at the end to spread the air or it just goes everywhere. you're right, dual extrusion is what it's best used for, I had intended to give Daid the design since he was complaining he had no fans now he had dual extrusion but I never got around to finishing it off. (sorry Daid, but you can have where I got to if you like)

it's great to see people thinking about upgrades

nik

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I had intended to give Daid the design since he was complaining he had no fans now he had dual extrusion but I never got around to finishing it off. (sorry Daid, but you can have where I got to if you like)

I have the printed stock on my dual extrusion machine, it works quite good, but it could use more cooling on the other end of the nozzle (You can visually see the difference on how the object was orientated on the platform)

So it could be better, but it's not so bad that I'm having problems. Else I would have designed something already :)

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I was thinking of a printed ABS ring diffuser with a hose barb on one corner and mounting tabs to fit the long rods. Dual extruder would look like a figure-8 around the nozzles. Maybe add a relay so I could still switch it with the fan pinout. The head would be lighter than a dual fan shroud. Not sure what to print it in when I want to run ABS though.

The best method I've used so far to level the bed has been the tinfoil/multimeter trick. I haven't done it in a while, and I think I need to go back to it. I think my bed goes out of whack when I reef on it to unstick parts which of course doesn't happen as often when the table is leveled and the Z height is set correctly.

Kyle

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I had that same dilemma with the ABS fan shroud, but your diffuser idea sounds about right. I just tried an experimental 8hr print with no fan at all (PLA) and used external cooling (desk fan blowing down over the bed) which worked pretty awesome actually. (and it was in UM silver for a bonus point)

the tinfoil idea is excellent for levelling - I used the sticky kind of aluminum tape that is used for leak proofing garden sheds and have it permanently on the bed. but I find, as you do, that the bed goes out of whack when forcing parts off it.

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