I propose that in a multiple spool/pinch wheel design-> in order to facilitate "multi-head" printing: the "new" wire could be adhered to the "current" wire by means of an adhesive such as superglue and a crimping clamp. The "current" wire would then feed both wires past the adhesive crimping clamp, grab the "old" wire, and cut it at a point past the grabber, but prior to the bond.
The "new" wire can be then towed to the pinch rollers by the "current wire."
In practice: it is most likely more practical to have multiple "spool heads" which contain pinch rollers and the spool of wire as a complete independent assembly, separate from the stepper driver, and which can be changed out by the means of a "tool changer."
>> There are three proposed methods for this as well: Using superglue, using UV-curing resin, or using heat.
A fourth option may exist as a viable alternative - use mechanical means to secure the wire.
Print a layer or two with a linear recess with a small complete or segmented overhang, then press the wire into the recess, snapping it past the overhangs. The recess should be as close or slightly larger than the wire diameter, and the overhangs just slightly less... in cross sectional ASCII art:
O <- mechanical pressure forcing the wire past the overhangs. __ __ (_) <- surface created with a small recess allowing the wire to snap into it.
- Interesting method! This could work well for larger diameter wires than what we're considering at the moment (<0.5mm), but I don't think our resolution or accuracy are good enough for doing that on the small scales we're starting out with.
We are planning to use similar mechanical methods to help position the wire though; for example, we'll print guides on the inner radius of corners and such, so that the wire's tension doesn't pull it out of place.
By the way, can I ask who wrote the above idea? :)
--Jbayless 19:31, 28 January 2010 (UTC)
I also mentioned in the forum the idea of 'zigzagging' thru pre-printed small overhangs. new ASCII art image:
< <-. | \ > <-+-- tiny overhangs to prevent the wire from moving laterally | < | <- wire
I'm not sure how you would secure the initial bit of wire.. perhaps wrapping a small amount around a post that would be snipped by the operator when attaching external wiring. The idea would be that you would advance the wire enough, then switch to printing plastic on top of that wire to firmly secure it. With two print heads, one wire head, and one plastic extruder, and the ability to retake up slack given from the wire tool, you could possibly calculate points that would allow you to more firmly secure wiring by wrapping it around a temporary post, extruding extra plastic on top of the just layed wire, then returning to the wire wrap tool which unwraps the temporary end back off the post.
Hi Guys, As I talked about on the forums, you could extrude the metal thread from an extruder orifice to 'lubricate it' with thermoplastic and at the same time keep it a the right temperature in order to fuse with the material below it. The fact that there will be thermoplasts around the wire will really help bonding with the rest. Stopping the regular extrusion would allow you to keep a part of the wire bare (for galvanic connections). It could be functional for conductors, but keep in mind that structurally the parts could also greatly benefit from composites (like anchored mortar). The extruder tip might degrade from the wire, so I'm not sure whether it would be useful as a normal extrusion head too. Otherwise it would be promising to combine the two.
Also, for some wire material, fusing it through induction heating could be an option. And for the nichrome, a current could be applied to heat it up.
... i saw in past some methods of feeding wire-wraps along paths and edges, where on a thermoplast sheet were many prefabbed short columns, the wire was feeded between or around a column and then a heated stamp pressed on the column, so the tip melted and fixed the wire beneath the collar ...
That's very interesting! We're already planning to pre-print short columns/ guide curves along the inside of turns, to improve accuracy. Melting them onto the wire would be very helpful I bet.
--Jbayless 17:53, 1 February 2010 (UTC)
... maybe another idea: - fab or mould a sheet with a grid-array of holes ... then insert only there some plastic-pins, where you want to feed wires ... or fab some clips/pin-modules with the right grid-dimensions for adding all sorts of electronic or mechanical components by simply clicking in the holes.
Then you'll have some versatile module like a bread-board for electronics or mechanical construction ...
How about heating the wire so it melts the plastic just a little, similar to how each plastic layer bonds to the previous? Then you could embed it in the surface, and hopefully the plastic will grab it firmly enough to stop it curling up as the head moves away.
... i think this is not so good as the wires would be of different lengths => diferent currents for the same temperature - and the temperature profile along the wire wouldn't be uniform too - as the local heating per current is highly depending of contact to the plastic surface, what's nearly impossible to guarantee over the complete length.
Maybe better try with strictly local heating per hot stamps, induction, light (if the wire is dark and the plastic white) or laser ...