Current State of QU-BD One-Up 3D Printer project

UPDATE: The current state of my QU-BD One-Up 3D Printer project is that the printer is finished but I am having problems with the preferred host software, Repetier.

After assembly there was a significant gantry sag. The One-Up gantry is supported only on one side. The other side sagged badly, making bed levelling impossible. Googling around in the Internet indicates that this is a common problem with the One-Up. First I implemented QU-BD’s instructions of “Making Everything More Rigid“. While it helped a little bit, it did not cure the significant sag. After more Googling I found a cure that I could believe in. It is in a YouTube video by user Purpledotcom. I implemented a pully system that is based on Purpledotcom’s, but with a couple of changes. I used some woven nylon cord and screen door pulleys from my local ACE Hardware store. For tensioning I used model Car turnbuckle. Specifically, I ordered, for $3.95 e/w delivery,  “Redcat 1/10 Lightning EPX Pro On Road Car Toelinks Turnbuckle Camber Links” from eBay seller taz_hobbies. With this rig installed, the sag is gone and I can properly level the bed.

One-Up from front

One-Up from above

One-Up from above

Next I installed the generally preferred preferred host software, Repetier. The software installed on my Linux desktop with ease. I powered up the QU-BD One-Up, inserted the usb and clicked CONNECT in the Repetier window. Bingo – it connected! So far, so good. Next I started fabric8r.com user WinterKill’s procedure for setting the printable area. Determining the X-axis went just fine – or at least it seemed to. However, when I switched to moving the Y-axis the bed only moved once and nevermore. Furthermore, Repetier froze. In fact, it froze the whole desktop. I had to CTL/SHIFT->BACKSPACE out of the session and log back in. Later I found that if I opened up a terminal window before starting Repetier that, upon a freeze, I could switch to the terminal window and kill mono, which would kill Repetier and get everything back to normal. I hate mono – its Microsoft roots bring their garbage-ware into the Linux world.

I noticed that the command window in Repetier indicated that each command incremented a counter of commands awaiting completion. Obviously something wasn’t right in the usb communications.

One thing that was discovered in additional research is that the printerboard delivered with the One-Up has the solder blob  jumper USBPWR connected. This causes the One-UP’s external power supply’s 5VDC to be simultaneously connected to the USB’s 5VDC line (schematic). Other people have reported this causing damage – even of the usb cable heating up. Anyway, the usb port that I was using stopped working for the One-Up. It will still work for other things, like communicating with and charging my cell phone, but it will no longer bring up a /dev/tty port. I unsolder the solder blob  jumper USBPWR and now must use another, undamaged usb port on my desktop.

It is reported that the printerboard, as delivered, has problems communicating with Linux. There are some reported cures involving use of standard baud rates instead of the non-standard 250000 default baud rate of the printerboard’s marlin firmware, but this requires rebuilding and reflashing the printerboard firmware.

I tried to get Cura and Pronterface working but I kept getting Python errors that I was unable to resolve. I gave up on these.

I was successful in getting Octoprint to work. It isn’t as slick as Repetier but it may do the job. No problem with the usb serial port set to 250000 with Octoprint.

So, this is where I currently am. I am putting aside the One-Up for a while and will tackle it again at a later date – I am currently tired of fiddling with it.

UPDATE: I seem to have resolved the mono serial port baud problem and Repetier seems to work at standard baud rates, meaning still not at 250000. I compiled and installed mono e/w a serial patch per iceblu3710’s instructions at THIS-LINK.

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