Cable-trunk replacement

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3dwim
Posts: 12
Joined: Tue Apr 08, 2014 6:06 pm

Cable-trunk replacement

Post by 3dwim » Wed Feb 04, 2015 12:50 pm

ONE way to solve problems in the cable-trunk.....

In the first months after assembling my printer (3.0, dual head) I had continuous problems with the first extruder. The results were not consistent, very sloppy, many of the prints showed a very frayed finish and many times the print stopped just halfway in the process. With "stopping" in this context I refer to a situation where the print-head (X), the print-bed(Y) and the Z-axis all kept moving but the print-head would only go left-right hoovering some distance above the object and it would not deposit any (PLA) material on the object to build. Sometimes then it would run OK, but most often it would not. Transporting the machine back to the workshop environment twice resulted in it performing reasonably fine and when going back home the next day the machine would most often refuse to print anything at all.

Add to this my rather newbie status and you will understand I had some hard time sorting it all out.

Trying multiple colors presented me yet another problem: the first extruder would wipe everything from the second extruder from the board. Printing a single object with only the second extruder was impossible. And worse: my X-axis steppermotor started to stumble on it, loosing steps. Luckily this could easily be fixed with a new set srew fastening the pulley for the X-axis. I fixed the heigth alignment problem with the extruder temporarily by mounting the first extruder slightly higher compared to the second extruder, thus clearing the way for use of the second extruder. That one worked and finally I could now print some decent objects, although only in a single colour with this one (the "second") extruder.

I realized some of projects I was working on, ran into a geometrical problem of the X- and Y-as being not exactly square aligned when I needed this for a technical object (a sound-isolated box to contain a blower. Solved that using the adapted firmware, enabling the FEATURE_AXISCOMP option which provided me just enough exactitude to print some objects and also the first panel of of this new project.

At that point my second extruder suddenly stopped working. I disassembled, check, assembled, tested, failed, etc. almost everything. Disassembled, checked, assembled, tested, failed another thing, standing up, walking, stumbling and crawling on and on. After a while I realized the steppermotor of the extruder caused the problem. I also remembered that sound, this "stuttering" from the first extruder, now the second extruder had the same problem. As I was not using the first extruder anymore, I decided to get out the steppermotor, ordered a spare part and re-assembled it. Now I got the first extruder back to work. Examening the old steppermotor and testing the leads of the steppermotor of the second extruder showed me the problems were in the copper leads. I added a new lead for the broken lead of the second extruder and now I had two working extruders.

Back to my project, printing. But now - probably due to all the handling - one of the blowers had stopped. One of the leads had let go of the blower and this was too tiny for my soldering equipment to fix. And worse: that stuttering sound was coming back, indicating the problem was not completely gone yet. I could now see and hear that from the test-lines printed (the two test lines added by KISSlicer). My conclusion was that this printer was not OK and I would probably never get it working properly. One of my friends had a Chinese 3D-printer with which I played a few times. That also had its special problems, even worse than my printer. This friend abandoned this machine, he did sent it back.

What should I do? Have my printer completely repaired? Abandon 3D-printing and find a more rewarding, easier hobby? As I realized the problem was in the cabling, I decided that would be the place to start. Having 22 cables going through the machine and to the extruder heads, all from different manufacturers and different quaulities doesn't help, because when one item fails all have to be disassembled or at least have to be touched because they originate at the parts and then go inside the machine. So Ineeded a cable-trunk with good leads of different diameters, some patch-panel to seperate this cable-trunk from leads of the individual parts, etc.

As I was - and still am - convinced the problems were mainly in the poor quality of the leads used for the cable trunk. Luckily I have a friend working with these kind of cables professionally who supported me in this conclusion. I decided to take out all (!) of the cables going to the extruders and swapped these for a set of leads from some decent cables designed for continuous moving around. This involved creating a custom made cable-trunk of 24 leads (4 x 0.75 mm2 and 20 x 0.25 mm2, including 2 spares). Adding to these some patch-connectors originally designed for printed circuits boards, creating a patch-panel to link the truc-leads to the local leads. I now had my material to start with.

Of course the housing would be home-printed. I still had my second extruder working for a 5 cm. wide lane over my printing bed, this was exactly enough to print the housings for left and right extruders. Now I can swap any part failing without being forced to touch the cable-trunk.

This is up-and-running for a week now, I've printed a lot of items and it is time to show this solution to you. Even the KISSlicer created test-lines are of a good quality I had never yet seen from this printer, I didn't know it could.

Happy Printing,
Wim.
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Niho3D
Posts: 13
Joined: Tue Dec 16, 2014 3:20 pm

Post by Niho3D » Thu Feb 05, 2015 12:54 pm

Great job!I also was thinking (because i had all the cables nicely bound,3.0 dual DIY kit) of the horror if any of the components needed to be replaced.Luckily it has not happened ,yet..

Niho3D
Posts: 13
Joined: Tue Dec 16, 2014 3:20 pm

Post by Niho3D » Thu Feb 05, 2015 12:55 pm

Great job!I also was thinking (because i had all the cables nicely bound,3.0 dual DIY kit) of the horror if any of the components needed to be replaced.Luckily it has not happened ,yet..

By the way can you tell me what was the height difference betwen EXT 1 and 2 that worked for you?

kerog
Posts: 117
Joined: Mon Jun 09, 2014 1:54 am

Post by kerog » Fri Feb 06, 2015 8:36 am

The two hot ends have some play in them, so you can move them manually up or down a bit, within limits. They should be adjusted such that when forced all the way down they are level. As pointed out in the user manual, you can do some fine adjustment by tightening the pieces of the hot end relative to each other. Some people have thought of this play as a good design feature, on the principle that when an extruder retracts it will tend to pull the hot end up and out of the way of the other one. Not sure how well this works, and you would have to make sure that the second extruder was pulled up a bit at the start of the print. Others have adopted the approach of using copper wire above the peek to tighten the fit and keep the extruder levels consistent. That's what I've been doing up until now, but when swapping hot ends in and out it can be a pain to get the adjustment right. I am thinking I will see if the first approach works reliably.

Niho3D
Posts: 13
Joined: Tue Dec 16, 2014 3:20 pm

Post by Niho3D » Fri Feb 06, 2015 10:10 am

I tried leveling them absolutely the same (i have 0,1mm 0,2mm etc gauge sheets) but it did not work too greatly since there is always bit oozing.but i did not get to try skirt or wiping edge yet.

kerog
Posts: 117
Joined: Mon Jun 09, 2014 1:54 am

Post by kerog » Sat Feb 07, 2015 8:43 pm

You can deal with the oozing pretty effectively through a combination of retraction and choosing a "rest" temperature for the extruder not in use. The warmup and cool down times slow down the dual prints a lot, but I haven't found anything else that works well. Cura, KISSlicer, and Slic3r all support this feature, though you sometimes have to check the Gcode to make sure they are really doing what you are asking.

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