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  • Reonarudo 01:17 on 12/02/2011 Permalink | Reply
    Tags: , , fail, , , ,   

    Trying to fix precision… 

    Hello,

    This time I’m just trying to fix the machine so it can output properly the models.

    If you have read the previous post you know that I’m having problems with circles. From what I have read on the net the problem is called backlash. Other people had the same problem in the past. One of the solutions is to tight the belts but if you have read the previous posts you know I already did this and when I rotate the gear manually the carriage responds accordingly.

    So to start I got someway to debug the thing several concentrical circles:

    And it came out like this:

    Ok this definitely shows the problem with circles…

    I lubricated the bearings and the X axis smooth rods to diminish the friction as suggested by nophead in the reprap forum.

    The result didn’t change at all. This can be because the problem in on the Y axis or it is something else on the X axis like the gears not fitting properly with the belt. I haven’t replaced the old gears that are glued with hot glue yet  so if the problem is from this I have a good solution now that I have replacements.

    This was the result of the lubricated X axis on a red tape.

    In this picture is clearly visible that circles are broken in the top  suggesting that there is at least one problem in the X axis and that I will probably have to change the gear that I’m using or increase the motor current.

    I tried everything and printed several tests none of them produced any diferences in the result.

    And now after a day of tests I present all my tests results and an acceptable end result (nº 15). :)

    Conclusion: The X axis is pretty sensible and the Y axis belt has its teeth against bearings and that causes variations in tension while printing it should be revised. For the X axis I basically remount it having attention to every little detail and check if the Z axis is correct and not interfering with the X axis. So after all this testing it is time to re etch the circuit…

    So it was a good improvement and the circuit was almost usable, but I guess my mendel X axis isn’t good enough. Maybe someone out there in the community can shed some ideas how to improve this because I’m out of them. :(

    I’d probably only get better results with a completely new X axis and for that to happen I have to receive my hot-ends first…

     

    • Ken Jenkins 20:46 on 08/06/2012 Permalink | Reply

      I read a write up on what you are doing over on hack-a-day. I’m interested in the process. I have a commercial laser system so that part of it and the “motion control issues” are not a problem. I’m not exactly clear about the process you are using. ie. are you “getting rid of the non-trace copper by oblating it with the laser” or are you “getting rid of the black paint in the non-trace area so that the etchant can eat the copper in a second step.” Thanks. Very interesting approach.

      • Reonarudo 21:43 on 08/06/2012 Permalink | Reply

        Exactly. The laser oblates the paint where I want the etchant to reach, it is faster if you only oblate the outline of the traces.

  • Reonarudo 05:45 on 31/01/2011 Permalink | Reply
    Tags: , fail, , , ,   

    The rise and fall of an Extruder and its replacement… 

    So after doing some experiments with the laser and the Reprap mendel I posted the video to YouTube to share with some friends that are into 3D Printing and such. Eventually Casainho found the video and asked for some explanations of what was happening. I promptly explained to him my setup and he told me about his project of etching PCBs with a laser and Reprap. So I agreed to make some experiments for him since he didn’t have access to the equipment necessary to replicate my setup.

    One of the goals was to get 0.25mm tracks for some solder mounted chips so I tried several laser focus distances until I got one that looked really precise and made this:

    It wasn’t perfect but it was a good start.

    I tried a lasing some permanent pen ink on a PCB but didn’t get any results.

    After that I tried paper again this time I changed the speed os the laser passes and got really nice results:

    After theses tests I got the parts for my extruder and halted immediately the laser tests to build it.

    I had to drill 2 extra holes on it so I could fit the PEEK block on it since it was smaller.

    Yet one thing was missing the aluminium block, the power resistor that would heat the hot end and the thermistor. I was so nervous and wanted to print so badly that I used some nicrome wire that I had and a rather large 100k thermistor that I had around and started the machine to maque some prints. The first thing to do was to choose what to print. But that one was easy, it would be some gears since mine where slipping and where hot glued to gain some friction to the motor. After that I just had to wait for the thing to heat up and start printing.

    That was when something strange started to happen and the demise that was upon me started to reveal it self. First I was using PLA and was sure that the temperature reading was between 180ºC and 200ºC (don’t EVER trust big thermistor readings) but the plastic came out full of bubbles and it was making smoke rings (yea WTF…) some one on the IRC channel told me I had my Temperature to high, but for me that was preposterous my readings at the time where at 170ºC. I checked if it was jammed or something like that but it didn’t seem so.

    Hot end eminent failure…

    At that time the harm was done and I only found out the full extent of the damages after I disassembled the extruder and inspected the hot end. The PEEK partially melted. the plastic was flowing between the PTFE and the metal and they where really tight everything when bananas… I tried to fix it somehow with PTFE tape but it didn’t work, even after I gor the block the resistor and the thermistor it didn’t work. It starteed extruding correctly for 3 seconds then stopped, I pulled the filament out tried again and it was the same thing over an hour… My first big Reprap failure…

    So after my demised I rendered myself to laser engraving…

    At least until my replacements arrive.

     

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