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Longer print bed? Is this possible?

Discussion in 'Mods and Upgrades' started by Erik Kasparian, Feb 13, 2015.

  1. Erik Kasparian

    Erik Kasparian New Member

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    We received a Robo3D R1 a few weeks ago and we do like it very much. So far the only issue (which is currently being resolved with Robo's support team) was that the wire going to the heatbed broke and shorted out and damaged some of the electronics which happened on the 4th print in the middle of a 16 hour print....

    Other than that it is a great printer.

    We were just wondering if there was anything major that we would have to do in order to make the be twice as long as it currently is....? I don't think that there should be much to change in the firmware (maybe changing or updating the auto level probing positions?) Also we are contemplating doing this without the heated bed, but maybe adding a heating function later on?

    Regards,
    Erik
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    You would need to replace the Y drive belt, plate/rods, but I see no reason it is not feasible.
     
  3. Erik Kasparian

    Erik Kasparian New Member

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    For the firmware if i wanted to make an "accurate auto level" for the extended print bed would i just change the Y dimensions to go from end to end of the new print bed size???? So changing the back probe position to say 480 (since we are looking to double the length of the bed)

    Also does anyone know how the positions are set for the auto level grid? it doesn't seem very self explanitory since i would figure it to be x,y coordinates. I just can't seem to visualize what the following code says since i am thinking in x,y system not basic point system..... *needing to take a step back from it*


    Code:
    #define AUTO_BED_LEVELING_GRID
      // with AUTO_BED_LEVELING_GRID, the bed is sampled in a
      // AUTO_BED_LEVELING_GRID_POINTSxAUTO_BED_LEVELING_GRID_POINTS grid
      // and least squares solution is calculated
      // Note: this feature occupies 10'206 byte
      #ifdef AUTO_BED_LEVELING_GRID
    
        // set the rectangle in which to probe
        #define LEFT_PROBE_BED_POSITION 15
        #define RIGHT_PROBE_BED_POSITION 200
        #define BACK_PROBE_BED_POSITION 240
        #define FRONT_PROBE_BED_POSITION 20
    
         // set the number of grid points per dimension
         // I wouldn't see a reason to go above 3 (=9 probing points on the bed)
        #define AUTO_BED_LEVELING_GRID_POINTS 3
     
  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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  5. Montravont

    Montravont Active Member

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    From looking at the code you posted & the known dimensions of the bed, it looks like those are actually coordinates. It's used to define the rectangle that the auto-level system works within, not the actual probe points.
    Probe Left: 15 tells the system that the furthest left it should probe is 15 on the X
    Probe Right: 200 tells the system that the further right it should probe is 200 on the X
    Probe back: 240 tell it that the furthest back it should move the bed to probe is back to 240 on the Y
    Probe front: 20 tells it that the furthest forward it should move the bed to probe is 20 on the Y

    Then you set the number of probe points and it calculates the best positions within the defined rectangle to probe.
     
  6. Erik Kasparian

    Erik Kasparian New Member

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    THANKS!!!!

    Now I'm looking into good bed materials for that length that won't warp too much :p

    Mainly we are going to print with PLA but we are looking into t-glase as well for future prints
     
  7. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Well, if you increase the size of the bed dramatically, you will probably need larger bed heaters (assuming you use them).
     
  8. Erik Kasparian

    Erik Kasparian New Member

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    Could we just run two silicone heat mats? Rather than trying to find 1 large one, just run two of the them? I see that the ramps 1.4 is setup for dual extruder but I didn't know if you could do a single extruder and 2 heat beds????
     
  9. David Sparrow

    David Sparrow Member

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    You would also need a heavier duty power supply. The 12 rail used to power the heat pad is near maximum capacity and you are talking about doubling consumption with two heat pads.
     
    2 people like this.
  10. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    24v upgrade like @Mike Kelly did would be a better solution. Faster heat and enough power to cover it.
     
  11. Stephen Capistron

    Stephen Capistron Active Member

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    A SSR would probably be a good idea.
     
  12. Erik Kasparian

    Erik Kasparian New Member

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    Does the firmware support 2 heatbeds to be controlled simultaneously? or would i just treat heatbed 2 as an extruder and make my start and stop code start the "heatbed" and shutoff the heatbed in the 2nd extruders spot?
     
  13. Ben R

    Ben R Active Member

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    Other than physics getting in the way, it could theoretically support any finite build size yea?
     
  14. Mike Kelly

    Mike Kelly Volunteer

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    You could run 2 heaters in parallel. You'd need to remove the polyfuse and put in like a 30A fuse or something. There's around 15A of current remaining on the power supply.

    The firmware doesn't really support 2 bed heater controls.
     
  15. Erik Kasparian

    Erik Kasparian New Member

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    So I could just use an off board control to control the two of them. Are there any unused pins on the RAMPS that I can access via the GCODE commands to allow me to switch between the two heatbeds or allow both to be on at the same time based off of what command i setup in the GCODE that way if i need to i can disable one or both of the heatbeds????

    Currently i will be upgrading to a 24V power supply and use a 12V 15A step down for the RAMPS and hotend. With two SSR 25DD relays to control each of the heatbeds. I have an Odroid-C1 setup on it for remote operations already, so if need be i can write a couple of scripts to have it control the heat bed, but i would rather the ramps if there are open pins and i can map GCODE commands that are open or free to use.
     

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