Dual Head Design issues

Discussion in 'Guides, Mods, and Upgrades' started by Julian64, Oct 2, 2016.

  1. Julian64

    Julian64 Active Member

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    So I am in the first few weeks of using my big box dual. Flawlessly printed about ten objects. If I had my time all over again I possibly would have bought the single rather than dual head, but most of the time if I buy a design that doesn't work well I have fun upgrading it.

    The problem is that the big box dual design isn't a really good platform as it stands. Trying to fix the two heads to be identical height and in line is virtually impossible. If the two heads are even a single layer thickness different in height then the lower one will remove the layer deposited by the higher one.

    Moreover the only adjustment you have are at 180 degrees from each other so you can go up and down but have no adjustment for side to side. Inevitably there is side to side movement. So you end up after a lot of work with two wonky eye'd nozzles but at identical height.

    Now if this was actually the case I could live with it, but it isn't. The bodies fit into a printed hole and are pushed against an oring. Compression of the oring gives a degree of adjustment defined by the two grubs screws either side. Problem is that after the shunting of a print there is significant movement in this arrangement. It isn't a system stable against the vibration of the print. So much so that my dial gauge has read nearly 150 microns height change after a two hour print. So in order to print dual head I am having to adjust nozzle heights on every print, which then means I am having to feed in offsets in Y on every print as well.

    I can see why most people seem to leave comments that they are only using one head of their dual head printer.

    So the reason for this wordy post is to ask if anyone has removed the rubber oring an replace with something much tougher or got rid of the oring completely.

    Lastly and god forbid but has anyone actually glued/fixed/shimmed their bodies rather than use the adjustments.
     
    Ephemeris likes this.
  2. Ephemeris

    Ephemeris Well-Known Member

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    I have to agree the o-ring compliance mount with the set screws positioned where you can't readily access them is a bit of a kludge. We were warned the dual setup was experimental, but I too was disappointed with it. Chase's dual Direct Titan is a huge step in the right direction.

    http://www.thingiverse.com/thing:1554356

    In Chase's design height is adjusted by two screws ON TOP of the x-carriage plus the extruder assemblies can be removed from the carriage without tools. It also restores full access to the original x build volume which the dual lost. The down side is you have to replace the X and Y carriages with Chase's design. Once you do that though, all the chassis can be removed without taking out the carriage rods (ie. the bearings stay in place and you pop the carriages off for maintenance.
     
  3. Julian64

    Julian64 Active Member

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    Yep I looked at chases design but am a little worried about the amount of weight that is putting on the rods. I also looked ta the thread where it seems BB is looking into two relatively independent heads and currently am wondering whether to wait or try chases.

    Meanwhile I have a metal working CNC machine in the other corner of my room which makes lovely aluminium objects and wondered just how light and stiff I could make a skeleton of aluminium that does the job, never to have to move the nozzles once set. . Probably pie in the sky as I'm sure chase spent months on his design and better minds than mine and all that.
     

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