Sunday, September 4, 2011

Improving my extruder...

I build my first extruder using an old stepper motor (old 5.25" floppy drive), and some salvaged printer cogs. It 'worked' but proved to be a bit weak, struggling a little if I tried to increase print speed. The under-powered stepper and poor cog ratios lead to stepper skipping. You'll see it here in an early photo. The good thing was it worked well enough to print new cogs, which you can see in the second photo...
Old exturder. I've replaced the cogs but retained the motor. The motor is compact if a little 'vintage'! :)

New extruder cogs (from Gregs extruder http://www.thingiverse.com/thing:6713 ).
What else have I changed?
Cut a new MDF x-carriage which receives the extruder easily, allowing removal for maintenance or swap-out.
I printed PLA bushings before I dismantled the old extruder, and bolted those to the new x-carriage. I chose these ones (http://www.thingiverse.com/thing:8282) with the bolt holes. I wanted to compare the PLA bushings to the steel bushings I had been using.
I rotated the extruder through 90 degrees, to give a narrower width and hence greater x-travel.
I cut a new hobbed bolt, this one an M8. The old one was in a 6mm bar. This fits the new large cog nicely and grips the filament a lot better.
I built new belt clamps and a fan mounting bracket. Some photos  below...
Rear view. The belt travels through the bridge in the clamps and under the motor.
Side view.

Front view.

Side view, showing cooling fan and it's new mounting bracket. (other experimental small fans since removed).
It's all still a bit 'rough and ready' but it works, and works better than the previous version of my extruder.

So.. why didn't I just print a new x-carriage while I had the original extruder working? Well, my design has the x-rods at 60mm between centers instead of the usual 50mm so I would have had to modify a drawing, and I'm just not up-to-speed on that end of things yet. If I were to change my x-rods to 50mm I'd need to print new x-mounts, z-motor-mounts... and so on, and with my printer so slow it would have been Christmas before it would finish!

It's  chichen 'n' egg as to what I do first or next to improve the speed and accuracy of my printer. Once I get it printing consistently at a moderate speed then I can get it to print a whole new printer rather than swapping out any more parts on itself!

Oh... finally for now, to make life easier the one accessory I really needed was a spooler, so I knocked one together from some scrap wood and a pair of 608 bearings. Works a treat!


Thanks for viewing!
NumberSix

2 comments:

  1. Hey NumberSix,

    Nice work - it'll be interesting to see how much faster you can push out plastic with this new configuration.
    A dumb question for you... whats the purpose of the metal strip which is clamped down with an oak block and a wingnut... a spacer or something more interesting?

    All the best,

    Alan.

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  2. Hi Alan,
    The aluminium strip you spotted in the picture is just a spacer. It's funny what people observe, especially once they have built their own machines! :) I've tidied it up since.
    NumberSix

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