plating as a building resource?

I got this off the blog, and figured I'd post it too.

Soi Sentinel said...
> Now if it was only possible to use electroplating
> to grow larger, non-symmetrical metal parts

I said...

Why not?
Plate it indiscriminately, then cut off what you didn't want to add. Use wax or oil as a final application to prevent the part from growing any more in that place.

Plate for a moment, cut for a moment, plate for a moment, cut for a moment. Would probably be best to have the solution added and subtracted by a syringe so you don't have to keep moving the structure up and down.

Possibly 3 "heads", 4 counting the plating system.
One to machine off the excess. One to apply wax to prevent the thing from growing on the bottom, or in, side, (the current applicator head should be fine,) also to act as filler for the next head. One to apply solder to give a base to plate against to allow for overhangs.

I see no reason it should be a hurdle.

11:08 PM
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Sean said...

...However...
You need to wash off the millings, or, should they make contact with the metal, they'll grow.

Since the printer would be working "blind", from what should be there, it'd cause surfaces to grow bumps, which would cause problems quickly, both in that it wouldn't stay smooth, and in that it'd eventually interfere with the wax applicator head.

Probably use a strong vaccum system to vaccum up the millings as they're cut, but it needs to leave as little dust as possible.

Otherwise, the whole surface would need to be swept between each plating stage. This might actually be easier to implement and maintain, with fewer fails.

11:19 PM
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If you are just going to mill a board, why bother plating them? Just start with copper clad.

I'm not talking circuit boards.

I'm talking about maybe reprapping in copper.
Plate a "layer" of copper.
cut out everything in that layer, that isn't supposed to be there for that height.
Fill with wax, to both prevent the holes from just filling back up with copper, and to support later layers.
paint with solder, or conductive paint, wherever you have plastic on the current level, but will want metal on the next level.
possibly mill again, to clean up the paint lines, if they're not generally to suitable tolerances.
Repeat.

Basically, a hybrid of additive and subtractive machining, but one that might allow for metal parts to be "grown" at room temperature, without expensive, non-duplicable, sintering tricks, such as lasers.

Why not deposit the wax before adding a layer by electroplating? Adding an additional tool to deposit "seed" material to increase the cathode size might be necessary. A problem which would occur is the cathode would become rounded and probably deposit un-uniformly.

Use the same applicator head you'd use for overhangs. Probably a conductive paint head, possibly a solder head, (except it'd have fits with the solder.

Also, mill each stage smooth to "straighten out" the plating process. You could either mill only the areas that are "set", or you could simply mill the entire layer. Anything that goes above the current level gets cut off before growing the next level.

Since the tailings can be thrown back into the anode, and the leftover wax melted down after that to reclaim it, even the milling step wouldn't waste much more than time.

Really, since you'd be doing it in turns, which is "first" becomes a moot point.

Actually, you have a point about applying wax before milling. If the last stage of plating is always suitable unfinished, provided it went down on a milled face, then you could apply wax, then mill, to both smooth the plating, and to trim the wax, since it'd probably be at a fairly gross resolution, compared to what could be done with a milling head.

I still think you'd be able to get better resolutions if you trimmed between add stages. That holds true for plastic fabrication, too.

I once saw a film of someone electroplating something using a conductive paintbrush dipped in copper sulfate solution. Maybe something similar could be built as a replacement for the plastic extruder head. The machine could then paint on fine layers of metal wherever it was desired.

A toy designer once told me how molds for vinyl doll heads were made from wax sculptures. The wax model is painted with silver-iodide, making the surface conductive. Then the whole thing is electroplated for a week. Similarly, you would start your object by having your prototyper paint the footprint of the object on to a surface with conductive paint.

I have already placed an order for copper powder at 45 micrometer grain size.
When i get it, hopefully in the next 2 weeks, i will do some resin mixes with different weight % of copper and read the conductivity.

I don't have copper sulfate at home now to do the plating tests, i hope i can get some small quantities somewhere....

Does anybody know how ultrasound vats work? to mix the liquid permanently, some kind of ultrasound generator mixing the liquid constantly up would be a nifty solution!

You can buy copper sulfate as a fungicide at farm supply stores, and at larger hardware stores. Its mostly used in farm ponds.

I did copper plating as a science fair project in junior high, and didnt bother to mix at all, I just used a saturated solution. If mixing becomes an issue the sulfate isnt going to hurt a simple aquarium pump.

I used a car battery and it took about 5 minutes to get a good solid coating. If you have a battery charger that should work as well.

Mike

The thoughts and ideas expressed in this post do not reflect those of my employer and are intended only as communications between individuals. Any attempts at implement are at your own risk

Edited 1 time(s). Last edit at 09/12/2007 09:19PM by ohiomike.