What is the best substrate to do alignment with?

Discussion in 'General Discussion' started by Dave Hylands, Sep 25, 2014.

  1. I was wondering what the best material to do the cartridge alignment tests would be?

    I was going to try plain paper, and perhaps one of the glossier photo papers, but I figured I should ask and get the opinion of the "experts".

    I'm planning on printing on FR4, but didn't want to waste my FR4 doing alignments.

    Also - if a print on FR4 doesn't work, what's the recommended way to remove the traces and start over (or maybe that's not recommended).
  2. Michael Reed

    Michael Reed Staff Member

    When we do alignment, we always use the Canvas Paper - standard office paper would work but the inks bleed a bit farther and the Nitric Acid begins to stain the edges a bit, this just makes it a bit more difficult to tell when the alignment is good. One of our engineers, Rob is actually working on an updated alignment set now that will be a lot easier to use and take far less time.

    Sometimes FR4 may be a little easier to identify your alignment on but it's probably not worth wasting it for. We do often 'clean off' FR4 prints to print over them again but the only problem with doing that yourself is making sure that the surface roughness remains optimal for the ink.

    By that I mean that we've sand blasted the surface of the FR4 with a particular grit for particular periods of time for what we found to be the optimal 'wetting'. If you want to find a sandpaper grit that works well for you - please do but at your own risk. Just BE CAREFUL when sanding FR4 as inhaling the fibres can be very dangerous - if you're not familiar with these dangers, please do your research first (sorry if I seem condescending, just prefer to err on caution).

    I don't have a recommended grit for doing this at the moment because we always use coarse sand blasting grit and not sandpaper. If you work something out though, please let us know! I'll put it up in the FR4 wiki (or you can if you'd like).
  3. Michael Reed

    Michael Reed Staff Member

    If you want to do some tests without ruining your piece as well - try out some stuff on the reverse side.
  4. Some more alignment questions:

    1 - What size is the alignment png supposed to be? Depending on the size of my browser window (I tried Firefox and Chrome under Windows and under linux) I've been able to get 1280px-Alignment2.png, 1024px-Alignment2.png, 640px-Alignment2.png, 400px-Alignment2.png, or 320px-Alignment2.png

    2 - Is the alignment per-cartridge? So I want to align for FR4, then I need to align with a Silver and an Ascorbic+, even though I'm printing the alignment on canvas paper? Or should I align with Silver and Ascorbic, and then plug in the Ascorbic+ to print on FR4?
  5. Answering part of my own question. I was able to figure out where the wiki stores all of the files, and using this URL: http://wiki.cartesianco.com/File:Alignment2.png I could get the original file (which appears to be 1500 x 1500 pixels)
  6. After converting the Alignment2.png file, it generated a 6,384,580 byte .hex file.

    It printed less than half. I converted the file again on a different computer and got the identical .hex file.

    The original png file is 1500 x 1500. Here's a photo of what it printed (twice). It didn't print any errors in either case.
  7. Johns

    Johns Staff Member

    Hey Dave, sorry for the slow reply. Its really strange that only half (looks like exactly half) would get printed. It doesn't seem like either silver or ascorbic printed after that. What does the printhead do after it stops printing. Does it keep moving? My first thought would be that your printers calibration is slightly off. When the printer thinks it's against a limit switch it will move but not print. It should give you a message over the terminal about this though. If you haven't already I would runs calibration and try again. What was your print_overlap? I will generate a hex file to check it' the correct size. If a calibration doesn't work let me know.
  8. I ran a calibration before doing this. The first print (on the right) had the starting position with the head on the y limit switch at the front of the printer (the starting position was around x=12000 y=0
    For the second print, I moved the head away from the limit switch.

    In both cases it just stops after processing when it gets to that particular point in the file. For the second print, no limit switches were hit.

    Everything was still at the defaults that the software was installed with. My laptop that's connected to the Argentum is currently tied up doing a 3D print, but when it's finished (in just over an hour), I'll fire up ARC and see what it has for defaults.

    I was running the ARC software under windows (in case that makes any difference). I know that Mac/Linux have different line-ending intepretations and such.

    Here's a zip file with the .png and .hex file in it:

    The CRC's are shown here (useful to see if you files match):
    541 >unzip -l -v Align.zip
    Archive:  Align.zip
     Length   Method    Size  Cmpr    Date    Time   CRC-32   Name
    --------  ------  ------- ---- ---------- ----- --------  ----
     6384580  Defl:N    84798  99% 2014-10-01 13:11 82d266fc  Align.hex
       49073  Defl:N     7582  85% 2014-10-01 13:11 7e67af57  Alignment2.png
    --------          -------  ---                            -------
     6433653            92380  99%                            2 files
    Last edited: Oct 1, 2014
  9. Rob

    Rob Chief Problem Wrangler Staff Member

    Hi Dave
    I just printed the hex file you provided and it seems okay on my printer. We're still looking into the issue - it's possible that the stepper drivers are overheating. You could try printing with the back panel removed and if the problem persists, try a fan?

    I've also just compiled an installer for an alignment wizard that will eventually be integrated into ArC. If you use the wizard, the actual prints are much smaller and will potentially not result in overheating if that is the cause. Be careful with the alignment wizard as you need to start with the carriage homed. It will then move to Y 12500 on its own. The print is also quite long at the moment and will cover the entire width of the printer. I would suggest using a full letter sized page of standard paper initially and then use linen paper if you want to increase the resolution.

    Alignment wizard

    I also attached a hex file that I generated of the test pattern if you wanted to try that as well.

    Hope that helps in the mean time.

    Attached Files:

  10. Problem solved. For some reason, the Align.hex file on the sdcard was truncated. I swore I used the proper eject, and I was also sure I copied the file a second time. Sometimes attacking the problem after a good sleep helps :)

    Now to line things up. I'm assuming that the light colored areas are silver + asorbic, and that the dark colored areas are asorbic only? This was printed on some "inkjet" paper I had.

    I'll also try the alignment wizard.
  11. Michael Reed

    Michael Reed Staff Member

    Good to hear David and yes, the lighter silvery parts are the combination of the two chemicals but the dark part is most likely the Silver Nitrate staining the paper slightly.

    This alignment image was generated pretty hastily and is far bigger than necessary for testing only a single set of alignment values. The alignment wizard just makes things a lot quicker and easier - definitely worth a shot even though it's fresh from Rob's brain yesterday.
  12. Have you tried printing a Vernier Scale along the X and Y axes? Print the data scale with Silver Nitrate and the Vernier reference with Ascorbic - also do the reverse for comparison - then read off the misalignment from the most prominent scale overlap line(s).

    ...or is that what your alignment wizard does?
  13. Michael Reed

    Michael Reed Staff Member

    We haven't actually tried that, though it's a good idea.

    Rob's new alignment wizard prints a set of small lines a number of times, each with varying alignment values and then you can choose to generate a new file with finer resolution adjustments in that region. The only reason I think that this might work better is that it helps look at a set of varying thickness lines. But I suppose you could just print a triplicate of the vernier scale... except the resolution of the scale would depend on the thickness of the lines.

    We'll give it a crack and see how it looks.

    We actually played around with making all of this much easier by dying the liquid red and blue in the cartridges but having purpley silver circuits was much less cool than it sounds.

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