Shopbot for clay etching?

[Ross Kowalski]

I recently did a test using the shopbot for clay etching. I am not sure of the potential for this technique, but here it is.

It went like this.

I turned a 1/2 inch shaft for the back of a standard JAcobs 3/8 drill chuck as a sort of universal shopbot chuck. (believe it or not, it runs true, I checked it with a dial this morning)

I sharpened a piece of heavy misic wire to a fine point.

I scanned in a line drawing, converted it to a vector with a ras/vec program, and made a shopbot toolpath file using Vector. (no Z depth)

I rolled out a clay slab "accuratly" to a quarter inch.

I lowered the Z to what looked like 1/8 into the clay and zeroed the Z.

I set the move speet to 3.5 for the X,Y and 2 for the Z.

Five minutes later it was done.

Results:

Very sucessful plot with even and accurate lines.


Problems:

I had to stop and resume several times as the music wire stylus kept getting covered in dry clay.

[billp]

Ross, Instead of the music wire stylus you might want to consider a Dremel bit I have used for fine line etching in the past. It is their #9909 bit,which is tungsten carbide, and it has a 1/8"shank. I have been able to cut very fine lines with this bit, and since it is made to cut stone, shell, etc. it's tip is scored which might help clear the clay. If you go to http://www.dremel.com you can see a picture of the bit. I pay about 10 bucks for it at my local hobby shop.

[gerald_d]

Ross, how about spraying/misting a little water on the clay surface to keep the stylus clean?

I presume that the stylus is not motorised (stationary) and thus you are not looking for a cutting bit?

If you are looking for solid tungsten wire, look to welding consumable suppliers and ask them for the wire used in a TIG-torch.

[Ross Kowalski]

Some kids did further work on the "clay etching" idea this morning.

I had a student who was using an aluminum template to make multiple tracings onto clay slabs.

This morning we photocopied the template, scanned, ras/vec'ed, sbp'ed it and used the music wire bit to cut "through" the slab. It made excellent time with great accuracy.

The clay was cut almost entirely through with only

a tiny (maybe .0625) web that tore easily when the remaining slab was removed.

[Ross Kowalski]

Reading the comments people added, I realize that there might be some confusion about the state of the clay as we worked on it.

Clay is worked plastic (wet), leather hard (hard enough not to leave a fingerprint, but bendable) and bone dry (like dried mud).

I was using the stylus on plastic or wet clay.

In the next couple of weeks I may have more experimental data as the kids were pretty intrested in this morning's goings on.

[Mayo]

Clay sounds like a great idea to make stuff in.
If it doesn't turn out well, ball it up and re-roll it flat! Try that with wood!

Why the need to use wire to cut into the clay? Why not just use a finishing nail?

Just today I made a re-useable mold out of wood that I was going to pour concrete sand mix into.
If I had a kiln I would try putting clay into it instead of the concrete - but without firing it, the end result would be too fragile.

I'd love to see pictures of how your finished clay items turned out.

[davidallen]

let the slab dry then use a fluted bit. you may be able to use clay at leather hard stage, but the 'chips' will tend to stick. using dry clay, you will make a lot of dust and it will be more prone to cracking. if you don't have a dust collector system with a good filter, you may want to vent directly outside. if surface quality is important, you may want to 'polish' the cut edges with a wet sponge or slip.

if you just want to cut out parts (no etching or relief carving) try using a water jet. you don't need high pressure, just a steady laminar flow. as a base, use a plastic grid (HD sells a 2X4 grid for use with fluorescent light fixtures) with an open fiber overlay. the overlay is needed to keep the water from washing out the bottom of the slab. a fiber batting (used in quilting) can be used if it doesn't collapse under the slab weight. naturally, you'll need to provide a drain.

[Ross Kowalski]

I think the waterjet is a good idea but only for through cutting. I think that a good material for the backing would be the material used in cloor polishing units. It is very open and quite stiff. Hmmm...

Also, thinking of liquid jets, maybe a slip deposition device to extrude or pour a strip of clay slip (the thickness of a frapp or shake. Hmmm...

Here are some pictures I posted to my site.

The image here is a set of sharks one student cut from a slab to make a vessel. I will post a picture of it once it is fired.
http://www.edu-coop.org/images/clay_sharks.jpg

Here is a clay etch with the pin only skimming the surface of the slab to draw the design. Notice the chuck, I turned an old 1/3 hp motor shaft to accept a 3/8 jacobs drill chuck. It is about as universal a chuck as I could come up with.
http://www.edu-coop.org/images/skull.jpg

This is an image where another student cut a box from corian. It was a slow cut, but the cutter looked ok and cut well if a little discolored.
http://www.edu-coop.org/images/corian.jpg

Back to work.

[Ross Kowalski]

I forgot something. In the above post, one of the pictures has the "universal chuck" being used with a piece of music wire.

Yesterday I made a dedicated music wire holder as clay works looks to have staying power.

I will take a picture, but the holder is a 1/2" cylinder about 3" long with a 1/16" hole in the center for the music wire. I drilled and tapped a set screw hole in the side to secure the music wire.

[Ross Kowalski]

Here is an image of a test tile done with the shopbot clay stylus.


http://www.edu-coop.org/images/skuldone.jpg

Ross