Engraving 26 gauge copper

[rtaulbee]

Hello Everyone,
Let me start by saying that I don't yet have a shop bot, but am leaning in that direction.

I am wondering if a shop bot can be used to engrave and cut out sections of 26 gauge copper.

A couple of questions:

1) Has anyone used the shop bot for engraving thin metal stock such as 26 gauge copper or brass?

2) Have you done drag type (spindle off) engraving?

3) I am also wondering how to best hold the material for cutting out sections after engraving. I have read suggestions ranging from two sided tape to hot melt glue, but am concerned about bending the material when I remove or clean it. I was also thinking of sandwiching the material between two sacrificial pieces of mdf for the cut-out operations.

Any thoughts or suggestions would be greatly appreciated.

[gerald_d]

Ron, I have a vague memory of working thin copper sheet while it was stuck to "pitch" (tar/bitumen) when I was at school. Pitch behaves like hot melt glue, plus final traces can be removed with a solvent like gasoline.

[gerald_d]

Ron, you could also do repoussage work by cutting a die into hardwood, laying the copper over and then using a rubber hammer to beat the pattern down into the die. Alternatively, lay a sheet of rubber on top and use a press to get a uniform pressure over a larger surface. Example (http://www.sml.lr.tudelft.nl/research/r_pr_rubber.html)

Thicker sheets need explosives (http://www.miller-company.com/illustration.html) . . . . .

[ron brown]

Extreemly thick metal can be formed by hand with the proper technique. I can think of several ways to form metal of about any thickness. Each method would depend on knowledge, tools and time available.

[gerald_d]

Ron, I was looking for a link to some explosive thing I read about years ago. Some artists were trooping into an old quarry, setting up a slab of concrete/stone/whatever, laying some junk on this (keys, kitchen utensils, shoes, etc), putting a sheet of copper over it with a few sticks of dynamite on top. Half the fun was finding the sheet afterwards.....

Anyway, what I was trying to say between the lines, is that the SB may be useful for making simple dies, and that you don't have to worry about matching male/female dies. (instead of using the SB to form the copper directly)

[rtaulbee]

Gerald - I wasn't looking so much to form the copper or brass, but to engrave or etch it using using either a v cutting tool (spindle on), or a drag type (spindle off). Some engraving machines use a non-rotating stylus to engrave soft metals.

What I am aiming for is a flat piece of copper or brass with areas cut out completely, and the areas that are left have some engraving, say a scroll pattern or something. I am hoping to use finished piece as part of a frame and panel door. The copper piece would be placed over the wood of the panel, the wood showing through where sections of the copper were cut out.

I guess this type of copper or brass piece would be mass produced as a stamping, but I am more concerned about very small quantities, and many different styles.

Thanks

[gerald_d]

If you are talking of artistic work (lots of freestyle curves) in very small quantities, then I have serious doubts that the SB will work for you.

[ajsaward@infionline.net]

Ron, I own an engraving company. We have many ways of engraving metal. We usually run .020 brass or .025 aluminum. We do work with copper in .020 thickness. While I have used our shopbot to do large panels, I think you will find that a non-rotating cutter, be it steel or diamond tipped (like most award-style engravers) leaves such a fine line that it might not be very visual. You could run your designs with a lined fill, but the run-time would be very long. We have cut designs out by holding the sheet with vacuum tables consisting of zones.

[rtaulbee]

Gerald - Why do you doubt the ability of SB to do freestyle curves? Is there anything about the new SB (rumored ball screws and servos) that would address freestyle curves?

John - I need a little more education if you have the time. What is a lined fill?

Thanks for your time - Ron

[gerald_d]

Ron, you have to program these curves before you even walk over to the SB. If you are already very proficient in doing your artwork on a CAD system that produces DXF files, then the SB will complement your work. But, if you still have to learn how to do CAD, and how to make a free-style curve in dxf format, then having a SB will slow you down.

[rtaulbee]

Gerald - Thats good to hear...I have been supporting a high end cad system (SDRC I-deas/UGS)for some time. I thought it was a limitation of the machine. For me, CAD/CAM is not a problem, I would just like to fully understand the capabilities of the machine. If you look at the following page, the images between the shield and the pumpkin are the closest example of what I would like to be able to do in thin metal sheets.
http://www.shopbottools.com/megaart.htm

By the way, I have seen a couple of negative threads lately, and let me just say that anyone with a brain is not influenced by an anonymous poster. I was quite impressed to see that most of the response was from people willing to A) sign their posts, and B)take time out and offer the gentleman various forms of help.

[gerald_d]

The machine is lot dumber than most of the aspirant SB'ers want to believe. The "wizardry" is all in the programming. And I am very happy to hear that have CAD /CAM background.

The machine's parameters are published in terms of speed and force, you mount your own tool entirely at your discretion. That can be a scriber, laser, router, monkey wrench, whatever. The motors will move your tool as fast as you want to, to the right place, but not to the right force (there are no force sensors - only distance sensors).

For free-style curves, the issue is not ball-screws, motor quality, or anything to do with the machine's mechanical construction. The snag is, how do you define the curve in the programming? Splines, parabolas, ellipses, even circles, are tricky things to cut with machines that only have straight rails (x,y,z). This is true for all CNC machines, not only the SB.

The negative threads you talk of, fall into two main categories:
- People not appreciating the amount of software and programming needed to make the dumb machine perform its magic
- People wondering why they don't get the same performance with their under $10 000 DIY-assembled-machine as their neighbour who has a $40 000 factory_technician_assembled machine.

Anyway, understand the mechanical limits, and do some programming before you commit yourself to a purchase. You can test your programming with the preview facilities of the SB software that you can download now already.

[ron brown]

Ron,

I see the problem of holding the small matal pieces as "interesting". Copper is so much fun to deal with... And, 26 guage is not thick enough to have a lot of "structure" on its' own.

The ShopBot has the accuracy and ability to do the work. Tooling, setup and the ability of the operator are the main limitations of a ShopBot - IMO.

Ron