Bad wire in the harness?

This started as a complaint thread but has evolved into something else. After much frustration with the printer exhibiting erratic behavior (which looked at times like an issue with a warped bed), I found that the hot end fan was intermittently cutting out for short periods of time. Mark Tomlinson pointed out that this can allow heat to creep across the heat break. I found a bad spot in the wiring for the fan and replaced that section of wire. This seemed to solve the problem until the print intended to prove the proposition failed at about 85% with a clogged nozzle. I investigated once again this morning and found that there is yet another bad spot in the wiring. I will be replacing both of these wires today all the way from the fan to the power bus on the board.

As I explained in the above linked thread, it appears that a bad roll of wire (or perhaps more than one) was delivered to Robo. Since the bad wiring only presents intermittent failure, it's a difficult thing to catch. Wire is sometimes (rarely, but it does happen) allowed to cool too much as it is being spooled at the factory. This causes the wire to develop tiny cracks which may create opens, or at the very least present too much resistance along the length to allow proper power or signalling to pass through. Robo3D is not to blame for this. It's just one of those things.

If anyone is experiencing otherwise inexplicable clogs or other inconsistent extrusion of material, I strongly urge you to look into the wiring to your hot end fan. This affects printers whose hot ends have been upgraded to E3D or other type, as it is likely that the owner simply used the exact same wires to provide power to their upgraded hot end. Below are some photos of the type of behavior that might indicate this problem:


Note that the loops and perimeters printed more or less fine, but when the hot end's motion changed to 45 degrees of angle, the material began to have problems extruding. This was due to the wire being flexed in a way that caused the intermittent disconnection.

 

Pretty sure the chinese know how to assemble wires, no offense but I trust the chinese working technicians more than some american kids, and I am one.
having said that, bad wire harness is just problem 10 or so of the 99 problems that come with the robo printer... anyone not experiencing this problem is either lying or fixed it themselves, unless you're just lucky. in which you should probably keep keeping quiet cause the rest of us our jealous

what is the preferred solution? yank out all the wires and start over from scratch? where are we getting the new wires from? Does Robo have a responsibility to make their printers actually print or do we need to just rebuild the whole tower of babel all over again?

 

I don't think any overt statement was being made here as to Chinese workmanship. That being said, my experience over several decades of dealing with electronic components made in China is that the quality is pretty spotty. Mostly this seems to be due to cheap materials and stretching the production 'efficiency' too far. But insofar as this thread is concerned, the proof is in the poor quality of the assembly. You just can't argue with it from that standpoint. It is what it is. I trust British, German, and American workmanship where electronics are concerned, more or or less in that order.

 

China is not a person I think is a pretty important thing to remember, there are certainly spotty people all over the place and you can definitely find them wherever you look but at this point if you're looking for people that have been raised their whole life making electronics,
Sort of like in that movie back to the future where the doc says "no wonder this doesn't work it's made in Japan!" "what are you talking about doc, all the greatest stuff is made in Japan" things change, I think China is hitting that point. Knowing how to build and assemble iPhones and air Jordans by the age 6 does things to people.

 

Right, because cheap labor, mass production and poor working conditions are all the important factors in quality control. Everyone knows that.

 

"China is not a person..."? Andreas, you're trying to turn this into a race argument, and doing so back handedly. Nobody ever said anything about individuals as Chinese or American or whatever. Lay off it. China mass produces cheap products. The quality is very spotty. It is what it is.

Now, if you want to talk about Taiwan, that's a different story. Anyway, please stop this ridiculous attempt to bait me into a race argument.

 

God I know I should let sleeping dogs lie but seriously I'm trolling it up again: I make this point again because the only things wrong with these printers are the parts touched in san diego...
be annoyed, I hardly care. I am so grateful for every part of this printer that is Chinese, because thats the only part that doesn't need to be thrown out. It sure does seems like the only thing wrong is the wires not the Chinese manufactured stepper motors or the ramps board..
Thank the Chinese and their quality parts.

 

fully smile

 

That's the way to do it.