QU-BD Jams

[vgordin]

... and if you're wondering why I posted in a qu-bd thread, I bought the dual extruder setup on kickstarter but very quickly switched to a Ubis + Jonas Keuling setup that I've seen run without a hitch for countless hours at my local hackerspace. http://www.thingiverse.com/thing:18379

[robotdad]

That dial indicator holder looks nice, looks like it will hold more solid than what I'm currently using. And yeah, my old Greg's was way better than this QU-BD. It worked. Haven't tried the one you referenced, but I might someday.

So I switched out to a Blue PLA from Ultimachine. Still jams. I got in and observed better what's going on though and have some new observations. The gear stops turning once the filament is at a point to extrude. If I hit retract though it will turn and retract. Hit extrude again and it turns, skips, stops. I can push through by hand, but it is usually a little difficult at first, then it can be pushed through easily. The motor is HOT. My extruder motor was never this hot with the Greg's. I tuned the Pololu to 1amp, so I know that should be where it needs to be. I've not checked how hot that is running. I don't have a fan on the board.

So I'm getting really close to throwing the towel in on these. They're beginning to rank up there as one of the worst purchases for my printer endeavors. TechZone electronics will never be dethroned as all time worst, but these are fighting to reach second place.

[gyrogearloose]

That dial indicator holder looks nice, looks like it will hold more solid than what I'm currently using. And yeah, my old Greg's was way better than this QU-BD. It worked. Haven't tried the one you referenced, but I might someday.

So I switched out to a Blue PLA from Ultimachine. Still jams. I got in and observed better what's going on though and have some new observations. The gear stops turning once the filament is at a point to extrude. If I hit retract though it will turn and retract. Hit extrude again and it turns, skips, stops. I can push through by hand, but it is usually a little difficult at first, then it can be pushed through easily. The motor is HOT. My extruder motor was never this hot with the Greg's. I tuned the Pololu to 1amp, so I know that should be where it needs to be. I've not checked how hot that is running. I don't have a fan on the board.

So I'm getting really close to throwing the towel in on these. They're beginning to rank up there as one of the worst purchases for my printer endeavors. TechZone electronics will never be dethroned as all time worst, but these are fighting to reach second place.

What you found out, is exactly the reason why most extruders are geared down. The motor draws to much and gets hot if it has to deliver power with no revs. I have done a similar last ditch try of the QU-BD extruder when I received the replacement drive gear form Denmark. I got the same result as you and have now given up on the QU-BD altogether. My Azteeg board from Panucatt only has 1Amp stepper drivers also. Panucatt have just released 2.5A drivers with heatsink. They would probably do it, but the motors would still get hot particularly with long prints. Gearing down is better and puts less strain on the system.

[robotdad]

Funny, I was just logging back on here to report where I'm at.

So I've tried many retract settings, .1, .2, .5 at many different speed settings. I've tried temp settings up and down on PLA. I've tried different PLA. I've tried fast moves, slow moves. I've tried different layer heights from .2 to .3. And it all still sucks.

The rub to me seems to be in the hot end or thermal transfer zone. I've actually gotten a 2.5 hour run out of it in one print, but that had almost no retraction. It finally jammed at that marker. I really think it is hardening in the tube. The reason being getting it back out after it jams is really hard. The trick I've found is to leverage pliers against the idler end to pull it out.

I think I just need to throw the hot end in the trash. What an expensive stepper motor. I really hoped these guys were decent, but I don't think they understand how this stuff is used. The lack of videos from them of their hot ends working is a really bad tell. Their a step up from TechZone, but not by much. I'd never trust these guys with that new machine their selling.

Like so much in this space I think they got a small test to work, called it good and started selling. The more I get into this the more I recognize even with the established players how their showcase prints actually hide common problems with the equipment.

Bah.

I think the way to go now is to design a mount for the cold end to mount it to a Maker Gear hot end. You wouldn't need the heat sink and that terribly loud fan. Could be a good package for a delta, especially since I can't find any pg35s.

[chelseat]

The fan should be on and at 100%.
The black aluminum block should be ambient temperature. If it is hot, then the heatsink is not couple well or the fan is not on and at 100%. If the block is hot then the extruder will not work.
The motor running for hours should NOT BE HOT. In fact the ones we have running at the shop are barely even warm, even after hours of printing. If the motor is hot then the stepper driver is turned up WAY too high. The Pololu stepper drivers require cooling to even reach 1A of current output.

Chelsea - QU-BD

[robotdad]

The extruder fan is on at 100%. The report on the motor being that hot should be disregarded, sorry for not clarifying that one. That happened on an earlier run where it had jammed hard. So I think it was overexerting itself while stripping filament.

The heatsink is room temp. The extruder now is warm, not hot. The pololu has a heat sink on it, but no active cooling. I can try that. It is tuned per multimeter readings to 1amp.

I also forgot to note that I did put thread lock on the set screw on my mk7 gear. That has stopped that from slipping.

I'll also say I never used ABS with it which more people seem to have success with. Trying it now, but all I have left are scraps, so can't do much. After one successful half size tree frog, that was a little ratty looking my current print is really over extruding. Realized I haven't calibrated esteps for this, so that's probably what's going on. Anyway, before I completely through in the towel I'll give a try at using these with ABS.

A very disappointing purchase. I wouldn't recommend anything from you guys to anyone. I'd love to reconsider someday. That won't happen until I see someone else, in person, with one of your products working as designed by you. I have a hard time believing you're actually printing parts with these in your shop. What are you guys actually doing, extruding from a fixed position into the air and calling it good?

[SystemsGuy]

Chelsea - I'd be interested in a response as well. I've had 4 QU-BD's through my hands now, and have gotten rid of all but the last. It would be grand if you could post some videos of the RPM or Revolution frame printing with one of your current generation of e.xtruders

I've taken the last one and polished the drilled shaft hole, retrofitted my version of Bart's spring idler, and replaced the Raptor with a Mk7 style drive gear, and I now have a working extruder. I will probably have to replace the nozzle as well since you milled it with no shoulder and it will eventually touch something in a bad way.

In the grand scheme of things, the list of "fixes" is pretty trivial, and if you look, the basis for your design from Makerbot is running into the same issues with their delrin plunger design. The machining on the filament chamber is better on theirs than on yours, but that's something y'all could fix as well.

I was so tempted to hope on the RPM wagon, but I'm just not convinced yet...

[chelseat]

Robotdad: What stepper motor are you using? Per your previous post, it sounds like that the motor is not making enough torque if it skips when trying to extrude. The motors that we supply have enough torque to, while feeding filament to shear the filament. If the filament is can be fed by hand without a ton of effort then that at least in general, eliminates the hot end as being the source of your problem.

When assembling the extruder did you make sure to hand tighten the nozzle to the block, then hand tighten the stainless barrel to the block, then slightly loosen the nozzle, slightly tighten the barrel and then use a wrench with something in the heater element hole to REALLY tighten the nozzle? The coupling of those two pieces is extremely important, especially with PLA for reliable printing.

What setting do you have for your extrusion multiplier in Slic3r and what nozzle size?

The current generation of filament barrels are extruded before being machined. The original ones were drilled rod, so the current ones are smoother in the ID. I would be happy to send out replacements if you guys want to give that a try. We planned to work up a mount for the Revolution and RPM for the current extruders.

Chelsea - QU-BD

[robotdad]

I'm using your stepper motor. The skips from a previous post I have been tracked down to not motor skips but the mk7 gear set screw was working itself loose. Loctitie fixed that. Yeah, I can always feed the filament by hand. Well until your QU-BD extruder jams. Just because I can push through by hand does not mean you can rule out the hot end as the problem. I'm including everything below the gear as what I consider the hotend, primarily the barrel and nozzle. After every jam it is very hard to remove the filament from the barrel. It really seems like melted pla is coming back up into the thermal transfer zone and solidifying. Why, I dunno. It seems connected to retract moves, but not always. Something with lots of retraction certainly exacerbates it.

Yes I did the hand tighten loosen tighten thing. Very glad I watched your videos, you really need that in the written as well. Nozzle size is .35 in the slicer and extrusion multiplier of 1.

I ordered my extruder back in November, maybe early December. No idea if its drilled rod or not. The barrel is the part I'm most suspicious of as causing the issues. If your telling me you've improved the machining there I'd be happy to take you up on the replacement offer and give it a try.

[mhensen]

Mine is also from the december series and the inside of the barrel is indeed rough!!