Cutting 24 Gauge (G90) Galvanized Steel

[BruceH]

I'm working with steel for the first time, and I have a new bit to try out on it.

Bit: Amana 51593 Spiral Multi-Helix Square Bottom 1/4 Dia x 5/8 x 1/4 Shank Solid Carbide AlTiN Coated End Mill

Material: 24 Gauge Galvanized Steel, G90, .024"
Unfortunately, I don't know anything about the steel itself. As far as I can tell, the G90 spec just refers to the thickness of the zinc coating. It's definitely ferrous, but I that's all the info I have. Amana's feed/speed guide (http://www.amanatool.com/media/custom/upload/File-1419875251.pdf) doesn't list by gauge, and it doesn't mention galvanized sheet metal or any term that I know how to associate with what I have.

I'm going to start testing under the assumption that it's a harder steel that it probably is, but I would appreciate any tips or pointers you fine folks might offer.

Thanks!

[steve_g]

I’m curious… Do folks with shears, plasma cutters, nibblers and Cold cut saws try to cut wood with them?
SG

[Brady Watson]

It's pretty nasty stuff to cut & the biggest challenge is keeping it held down. A single flute spiral downcut would be my starting point.

Search for my Vacuum Film Technique on here...a pressure foot may also be beneficial, but steel chips will embed into the plastic shoe pretty easily - making for scratches.

-B

[JimmyD]

I’m curious… Do folks with shears, plasma cutters, nibblers and Cold cut saws try to cut wood with them?
SG


Steve, as a matter of fact I do cut wood on my metal lathe and knee mill. I also cut aluminum on my table saw. They're all tools with cutting surfaces. I take care of my tools and don't abuse them.

I haven't cut any wood on my plasma table, yet.:cool:

Jim

[steve_g]

Jim…
I was thinking last night, after I left my somewhat snarky reply, that I cut many more materials today then I did 50 years ago and think nothing of it! We have bits and blades designed to cut composites, plastics, nonferrous metals and even soft stone and glass.
So… My previous post should be modified to say:
Bruce…
Let me know how it works out, and post pictures!
SG:o

[BruceH]

Success ...in failing in spectacularly!

I spent way more time that usual with a new bit and material, researching feeds and speeds, ramps, depths, etc. I did a series of 5" circle test cuts. The first test left a hot spot on the table where the cut started, so I increased the ramp length and feed. The second test kicked the piece out, so I added tabs I could snip out. The third test went fine, so I loaded up the main cut and sure enough... immediate failure. Sparks flew, the metal wrapped up around the bit and wadded up under the spindle before I could slam the emergency stop. It took me a while to coax the metal out from under the gantry. The bit chipped a tooth, but I don't think there was any damage to the ShopBot, fortunately. I'm still not clear on exactly what went wrong. Best I can figure, I should probably have glued or screwed the metal down instead of relying on the vacuum, and the bit WAS an upcut, so that couldn't have helped. Spot on there, Brady.

Jim, I'm thick skinned enough, and aware of my inexperience enough, to be able to appreciate snark from the veterans. Some of the best points are delivered in zingers. No need to hold back on my account, but I also appreciate your follow-up, sir. I'll take all the advice I can get!

[Brady Watson]

The Vac Film Technique = masking tape on the back of the metal. Carpet tape on the back of the masking tape. Stick both to a piece of coroplast or other cheap substrate that can be sucked down by the vacuum.

What you are doing is really dangerous...shrapnel isn't fun at all. Make sure you cover your eyeballs and wear a sweatshort or something to protect your innards and dirty belows. :eek:

-B

[rb99]

In the 1990's I used to cut 22/24 gauge for channel letters. I bought an oil mister. I used screws to hold down the sheet, and as the letters cut I would put screws with washers in the cut path to hold the letters down. Tabbing was not used. I can't remember what bit. It worked great.

The mister is this one: http://www.fogbuster.com/index.html