How to cut sheet metal?

[coolhammerman]

OK, so I'm brand new and this may be a really stupid question. I just got my ShopBot and haven't even cut anything yet. I make folk art signs from plywood, vine, bottle caps, roofing nails, wire and 26 ga galvanized sheet metal cutoffs used to make fireplace chimney pans for homes in the Atlanta area. Right now I do it the old fashioned way with bandsaws. I will use the ShopBot to cut the plywood and anticipate no problems. I need help with the sheet metal parts.

I have been cutting the sheet metal parts out with a 14" band saw and a 1/4" metal cutting blade dry, no coolant. I actually stack three (sometimes 4) layers and cut with no problems. The sheet metal is painted black on one side and gray on the other.


Other than plasma, can anyone suggest how I might cut out the sheet metal parts with a router bit? One layer at a time would be fine.

Here is a link to the signs. You can easily see the parts which are made from sheet metal. In this case, feathers. You can click the image to enlarge for detail.
Cigar Store Indian (https://www.wildandwoody.com/catalog.product.asp?catalog%5Fid=ProductCatalog&pa rent%5Fcategory%5Fid=MountainLake&category%5Fid=Mo untainLake&product%5Fid=LAK04455L%20%20)

Or, more signs here (http://www.wildandwoody.com) WildandWoody.com.

Thanks in advance.

The Coolhammerman, or
Georgia Ron Brown

[odulfst]

Maybe if you glue the sheet metal to a piece of plywood the bot will be able to cut it. Hard pary will be getting it back off.

[odulfst]

Maybe if you glue the sheet metal to a piece of plywood the bot will be able to cut it. Hard part will be getting it back off.

[coolhammerman]

Thanks Tony.
I won't actually be able to try this until early in Sept due to other scheduling conflicts. But, here is the best suggestion so far. The material comes in 9" x 36" pieces. I am going to try using a TIN coated centercutting double end mill. The shaft is 3/8". I will try one with a cutter diameter of 1/8" and a larger one 3/16". No coolant. This is 26 ga sheet metal so is relatively thin.

I will make a holding jig which will hold the raw metal by the edges and use the tabing feature. Time will tell if I'm on the right track or not. I'll keep you posted.

The other Ron Brown.

[coolhammerman]

PS
I don't have to get 100% efficiency from the material since it is scrap to begin with. I am able to get it free for the taking, for now at least. Of course I don't want to waste it unnecessarrily, but at this price I can afford to allow for a 1" border all around.

The Other Ron Brown

[frank_hav]

Ron,

I cut sheet metal on both my router and my milling machine. GOOD!!! Sticky tape from 3M(MSC) will hold it down. Also you should use a down cut mill if possible, it will help force the part down. Also you need to set the feed down as low as you can go and then sneak up. The same is said for the RPM. Watch the chipload, you should try to get around .003-.005, this is hard to due with the minimum feed rates on the Bot.

[coolhammerman]

Frank:
Thanks for the info. Although I have been a woodworker for 35+ years, I had to learn many new techniques to make the folk art signs in a production environment. I use conventional tools in unconventional ways. I expect the same will hold with my Bot.

Thanks,
The Other Ron Brown