Friday, 14 January 2011

X-Axis & Extruder Carriage



I decided to redesign this area of Huxley, as i felt that all those bearings and RP parts was a bit over the top.

X-axis (http://www.thingiverse.com/thing:4831)

I took inspiration for the Prusa Mendel, but tried to make the part simpler and slightly more attractive!
 


The axis is now made up of only 3 pieces: Idler side, motor side & the extruder carriage. I have not used any bushings or bearings for the idler or motor side; drilling the abs hole out slightly larger than 6mm allowed the silver steel z-axis rod to slide through easily without any play. As the axis is moved only a small amount by a lead screw the torque is high enough to overcome the increased friction, and there was no chance of an increase of heat. 


Extruder Carriage (http://www.thingiverse.com/thing:5421)

I wanted to make a very low profile carriage so I could allow for a concurrent second extruder in the future, which could be used to extrude support material. I used the same PTFE bushings as I did with the y-axis. These were turned on a lathe from 16mm bar stock (M6 hole and 10mm long) and push fitted into the printed carriage. 



From thingiverse:

‘Insert a M6 nut into the slot to allow a M6 bolt (or grub screw) to lock the thermal barrier in place (If you have a shallow M6 hole on the thermal barrier then the bolt can locate the extruder head in place... will hopefully save recalibrating when the extruder gets fiddled with!)

Finally use a short bolt (M6x15) to self tap into the side of the carriage to allow the timing belt to be attached.

Bushings:

Machine/acquire some 16mm round PTFE into 4x10mm lengths with a 6mm drill (or use US drill size C for a really nice fit). Then simply push them into the recesses with a small drop of glue (be sure to use a length of M6 silver steel to keep the bushings aligned)’

Posted by Strelly at 11:56

2 comments:

  1. Ivor O'Shea15 February 2011 at 04:11

    Hi there,
    It's coming along well for you. I like that X-axis arrangment. Would you consider a single long 'joiner nut' instead of the spring set-up on the vertial (Z axis)? I've read that some have not found the spring/nut arrangment that effective or necessary. There's no real back-lash concerns in the Z direction, and a lightly greased long-nut will sit well. Also, since it's lifting most of the time, you could close in the top of the hex-hole, only allowing the threaded rod through, then the nut would simply slot in from beneath,and not need fixing.
    Anyway... there are many options. Best of luck with it.
    No.6

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  2. Strelly15 February 2011 at 05:55

    You are correct! I played with using a spring initially, but I found it to only added friction! Instead I used the same setup, but without the spring, which is working very well.

    If i was to design the part again I would take your recommendation and constrain the leadscrew at the top.. eliminating the need for the upper nut.

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