Sunday, April 20, 2008


More anti-ooze

Inspired by Ed'n'Ian's blog below, I went home and made this. It is a nozzle with an 0.5mm sideways hole intersecting the 0.5mm nozzle hole. Into this goes a length of 0.5mm-diameter piano wire. When you shove it in by hand it stops the polymer flow instantly (even stalling the extruder motor if you leave that running). Pull it back 1mm and the flow restarts equally instantly.

It's really easy to make too:

The trick is to drill the sideways hole using the nozzle hole as a centre before you make the cone. You have to use a woodpecker cycle to clear the swarf and be very gentle to avoid breaking the bit. But if you do, it works fine.

Then you just put the finished part in a drill chuck, use a felt tip to draw a circle round just below where the hole emerges, spin the drill and file the cone up to that circle.

Now to add a solenoid to move it back and forth automatically...

Where did you get the wire?
From Ian...

But I'm pretty sure music shops would have it. Stick your head under the lid of a piano, deploy digital calipers, and go in saying, "E flat" (o.w.e...) :-)
Is this intended to be part of Darwin, or Mendel? I don't see a bit of ooze as a game-breaker, and it seems to me that at this point the goal should be to finalize the existing features, not add new ones. Improvements will of course continue after releasing 1.0, but I think that an official 1.0 release, documented and complete, would be the best thing to grow this project right now. And we've come to the point that we're nearly there - if we can get one or two beta machines printed from a RepRap-like RepStrap functional, it's time to call it good.
If you look at the print quality of my machine here:

compared to the block I printed here:

Then the difference is purely down to ooze so I think it is well worth doing a soon as possible.
Congrats to Adrian, Ed and Ian!

I thought that even if you could stop the ooze, the solution would be expensive or finicky. I'm glad I was wrong.
I agree that we should be getting Darwin out there asap, but it is also vital to blog every idea as soon as we have it for two reasons:

1. Anyone can then decide for themselves if they want to experiment with the idea, and

2. It stops the idea being patented.
The 1.0 machine will get a lot of publicity. The 1.1, 1.2.3 and even the mighty 2.0 machines will not. The public will form their opinions on the basis of what 1.0 can do and those opinions will be hard to change afterwards.

I don't see any particular time-pressure here - IMHO, it's worthwhile to take the time to make it right.
Post a Comment

<< Home

This page is powered by Blogger. Isn't yours?

Subscribe to
Posts [Atom]