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Tuesday, 20 July 2010

Tech Zone Techniques - Part 4

Step 10: Wiring the steppers
Not much to go wrong here really, as I had wired the stepper sup to my CNC stepper boards before, I kind of knew what I was doing. I also made up a power lead which I have wired up to my variable bench supply for now. (This will be replaced with a PC based ATX supply for the final version).

Step 11: Testing Times
Next up was testing the electronics. I tracked down the Testing RepRap Electronics page on the wiki and started following that through.

I ran into some trouble with the motherboard not returning any temperature results and not looping, so I asked on the forum. In summary, note the following when using the hardware:
  • If you don't get the temperature readings looping, then your USB cable may not be autoresetting the hardware
  • Plug in the the USB
  • Hit the rest button
  • Start up the host software
So, I managed to get the desired results for the motherboard and the extruder controller (sans stepper driving), so I decided to move onto to testing the stepper boards and opto's.

For the steppers I followed these steps (for each axis - results further down) (BTW: follow these steps at your own risk, the wiki steps are more detailed and isolate issues, I already knew my steppers work):
  1. Wired the stepper to the controller
  2. Ensured the stepper was in the middle of the axis (as I wouldn't know which way it would travel)
  3. Wired the power to the stepper board
  4. Wired the stepper board to the motherboard
  5. Connected the USB
  6. Reset the motherboard
  7. Opened the RepRap Host
  8. Changed to the XYZ tab, and set nudge to 10mm and feedrate to 300mm/min
  9. Switched on the power
  10. Clicked the right arrow (>)
  11. Clicked the left arrow (<)
  12. Moved on to testing the Opto's
Y-Axis results
  • I did the Y-Axis first as it made sense in my wiring config
  • > caused a small movement (and was repeatable)
  • <>
  • Off to the forum to figure out what's wrong (read about this before somewhere)
  • Ah... Seems I got the Opto connected the wrong way around. The picture wasn't very clear (that's my story and I'm sticking with it).
  • While fiddling with this I noticed that the opto LED (which on the TechZone boards is normally on) was not switching off when blocked.
  • I swapped out the other opto's and found that 2 of my three boards had the same problem.
  • I've been trying to stay out of the TechZone flaming that's been happening on the forum (I won't post any links, searching for TechZone will find many), but I do think the quality of the soldering leaves something to be desired. I spent a lot of my spare cash with them (it's the single biggest purchase in my project) and wasn't too impressed. I reckon could do it neater and I only tend to solder copper pipes for plumbing and automotive wiring.
  • Anyway, off to figure out how to fix my opto's (given I know next to nothing about electronics, this will be interesting).
Following on from the Y-axis, I had mixed results with the others. I eventually figured out that I had to tweak the pot on the stepper boards to get the steppers running properly. I turned them anti-clockwise a bit at a time until they didn't work and then back a bit till they did again.

I then found that my Z-axis motor would run great when the belt was freed off, but wouldn't run the axis. I have just located a more powerful motor on my scrapheap as my Z-axis doesn't even have the extruder mounted yet. (May have the go the bowden route).

Current state of play is X & Y axes work. Z-axis being fiddled with....

2 comments:

  1. My guess is that you're going to have the same problems I been having with the techzone boards. A maker down in Australia has been trying to get the boards working with ReplicatorG:

    http://www.cgsy.com.au/?p=133&cpage=1#comment-30

    Lambert and Kimberly have tried to help but they haven't been able to provide working firmware for the extruder board.

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  2. I've had a look at the link, and from what I can make out the problem is that ReplicatorG doesn't work with the 5D firmware. I hadn't investigated before, but it seems ReplicatorG needs special firmware. I would have thought this is a problem with the firmware/software combination, not the electronics per se.

    Is a bigger problem the fact that the Extruder board is being hacked via firmware to support stepper motors and different comms, etc when in fact the electronics should have been revised to properly implement the new route. I know this is an Open Source project, but I don't have enough electronics knowledge to make the changes I mentioned.

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