Co-Polywire extrusion

Hello,
due to much dreaming about my reprap that is currently parts scattered though the mailing system and at home depot. I have been thinkering about other extrusion heads specifically heads that could be used to make electrical connections. My current thought pattern had resulted in manufacuting a new 3mm filliment that would consist of a metal probably copper thin wire centered in the 3mm filliment. The wire would have to be sufficiently thin enough to fit through the extruder outlet (head). The extruder would have to be modified in at least the following ways. The extruder head would need cutters and actuation to cut the wire after extrusion. This should be relatively easy with small gage wire (by small gage I mean size not number). The harder part would be the extrusion rate problem due to the polymer melting and extruding faster i.e more length of melt filiment out than unmelted filiment in and therefore metal in. It may be possible just to have a small 3mm going to 2.75mm reduction head vs the reduction that is currently present.
Thoughts comments and criticism is greatly appreciated.

Oh BTW I have access to equipment to make such filiments from bulk plastics and such.

Peace

The spoolhead extruder seems a better approach if it works; embedding wire in 3mm thermoplastic seems tricky mechanically, prone to error, limiting in application, and expensive?

- how do you push filament at 1/30 rate (for .5mm extrusion), yet push embedded wire out 30x faster?
- how do you get the wire to go thru the hole as opposed to just curly up and making a nice fuzzy metalic plug inside the extruder head?

Thanks for the link to the spoolhead extruder I had not seen that before I have only been working looking through the site for about a week.
To answer your questions

how do you push filament at 1/30 rate (for .5mm extrusion), yet push embedded wire out 30x faster?

You cannot it is rather imposible to push the filament faster than the extrusion hence my comment about needing either a smaller reduction or smaller starting filiment as to not have this incongruity.

- how do you get the wire to go thru the hole as opposed to just curly up and making a nice fuzzy metalic plug inside the extruder head?

This would rely on surface tension between the metal wire and the extruded filament. I have done this in our research lab pulling glass coated metal wires where the surface tension keeps the glass (600C melting point) on the metal wire and the metal wire centered in the glass filiment. I am assuming (though it is not proven) that I can do this with a polymer the same as with the glass.

embedding wire in 3mm thermoplastic seems tricky mechanically, prone to error, limiting in application, and expensive
I already have a setup to do this it is in my lab to produce glass coated metal fibers but i dont see any caleability problems and transitioning from glass to polymer should be easy just reduction in heat required.

After seeing the spool head I am now thinking of modifying that to run slightly polymer coated metal wire where the polymer is just a few microns thick on the metal and add a small heater so that the fiber coming out of the extruder will stick to the polymer part.

Just more food for thought

jabberwocky Wrote:
-------------------------------------------------------
> After seeing the spool head I am now thinking of
> modifying that to run slightly polymer coated
> metal wire where the polymer is just a few microns
> thick on the metal and add a small heater so that
> the fiber coming out of the extruder will stick to
> the polymer part.

Sounds like a better plan; though, I still feel mechanics may get in the way of a melt chamber + wire + thermoplast; using a spoolhead printer + heat + coated wire may work out better.

How would one go about making thermoplast coated wire feedstock inexpensively, I.E, would someone with minimal tools at home be able to do so, or do you need specialized equipment?

And welcome aboard! If you feel something might work, give it a try and post your results.

The coated wire setup is what I would call specialized but all of the parts probably cost less than 200$ if you are thrifty and are available between ebay, mcmaster, and home depot.
The setup i have for glass melting uses a platum resistivly heated crucible that necks down to 3-5mm in diameter this can run up to 1100C this is expensive but unnecessary for polymer work. for polymer we can just use aluminum or steel and resistive heaters attached. Basic setup needs a melt chamber (resistively heated) A metal wire feed spool. And a takeup reel run by a servo or variable RMP motor. The speed of the takeup wheel mostly determines the thickness of the pulled filament or coated filament. The metal fiber is fed through the melt and grabed after the nossle it is then pulled by hand and attached to the takeup reel the takeup reel is usually running during this process at low RPM. The takeup reel speed is then adjusted to a set parameter and the finished product is cooled between the melt chamber and the takeup reel.

A picture is a little easier to show the concept but I think I described it well.

This is a small modification to industrial technology for making fiberoptic cables. In my oppinion glass is just like high temp polymers the processing can usually be used for both.


At my company I do a lot of Repurposing old industrial equipment for material science purposes so we spend a decent amount of time scouring used equipment sites and re-engineering the equipment to do something it was never meant to do in the first place.

I plan to start posting results on some of the things I try but first I need to finish the base reprap robot and get my feet wet.
Thanks for the welcome.

Hey,

Glad to see that other people are thinking about this idea too! It means we're on the right track. One of the questions I'm often asked is "why would you want a wire extruder?"

The SpoolHead design is still very much in its early evolution - please share your ideas if you can! There's this forum
[dev.forums.reprap.org]

And also the wiki discussion page

Jacob