Sheet metal milling

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tburzio
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Sheet metal milling

Post by tburzio »

Hi!

I'm cutting sheet metal (24 gauge steel) with a 1/8" end mill. The fixture is masonite under the sheet metal, screwed to the table top at the diagonals. There's a plunge cut, then sideways, which does work. I'm getting a lot of burrs that have to be filed off the resulting piece. Any quick tips for a newbie on ideas how to reduce the amount of burrs? Slower, faster? Slow the feed rate?
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Harold_V
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Re: Sheet metal milling

Post by Harold_V »

tburzio wrote:Hi!

I'm cutting sheet metal (24 gauge steel) with a 1/8" end mill. The fixture is masonite under the sheet metal, screwed to the table top at the diagonals. There's a plunge cut, then sideways, which does work. I'm getting a lot of burrs that have to be filed off the resulting piece. Any quick tips for a newbie on ideas how to reduce the amount of burrs? Slower, faster? Slow the feed rate?
Hard to suggest going faster or slower when you haven't provided the speed at which you're operating now.

If possible, stay away from the finish dimension. Rough first, then climb mill, taking the cut to size. That will eliminate the burr almost 100%. If it does not, you should investigate the end mill in use.

Finish pass should be light, but heavy enough to remove the rough cut with 100% cleanup. I expect .010" may work well enough. You may benefit by using a few finger clamps at strategic points.

Use the shortest end mill you can, which will limit deflection. Don't be afraid to run it fast. It most likely will tolerate 3,000 rpm without issues. Slow down if the chip comes off yellow or more.

Harold
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Mike Walsh
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Re: Sheet metal milling

Post by Mike Walsh »

Could also try a downward spiral endmill - this will prevent the workpiece from being pulled off the worksurface - against the mill. You'd have better results, most likely. Don't know about burrs, but when I was working at an electronics mfr on co-op, we had to deburr our sheet metal/sheet aluminum workpieces, so it may just be part of the game.

Mike
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Bill Shields
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Re: Sheet metal milling

Post by Bill Shields »

You can also sandwich the 'good' metal between (top and bottom) two pieces of 'junk' metal strips.

Holding things down nice and tight will prevent the burr from the center piece.

Yes, it is a lot of work, but if you object to de-burring, you may have little choice.
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10 Wheeler Rob
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Re: Sheet metal milling

Post by 10 Wheeler Rob »

If the sheet metal is aluminum, a wood router bit with vertical flutes has worked for me. And sandwiching between layers of masonite or thin ply wood helps too.

Rob
tburzio
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Re: Sheet metal milling

Post by tburzio »

Well, heck. I got a different mill with more turns per inch, leaving the speed the same and making the speed of the cut slower, and it caught on FIRE!!! Got it out, but the bit broke. Oh well, back to the original one! :mrgreen:
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Bill Shields
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Re: Sheet metal milling

Post by Bill Shields »

The TOOL caught fire, or the wood under the sheet-metal?

There is a good reason to use WATER SOLUBLE coolant on things.

Makes the wood a bit tougher to ignite.

You should see a Titanium chip fire in a machine....POOF - like puff the magic dragon, and your machine is GONE without a Haylon system.
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tburzio
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Location: San Diego

Re: Sheet metal milling

Post by tburzio »

Bill Shields wrote:The TOOL caught fire, or the wood under the sheet-metal?
the tool was fine until it broke by getting wedged. The hardboard caught, plus the metal was burned back quite a bit. Oh well. May have to go to a job shop to have the parts cut on a laser...
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