Cutting Aluminum

[dana_swift]

This is my first effort cutting Aluminum, I must say it helped enormously to have this forum to consult before I did anything.

All went very well, here is a video of the work in progress:

http://www.youtube.com/watch?v=CzigLEGIFkM

Here is another couple photos of the effort:


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You can see the red air hose from the compressor blowing a steady stream of air through the brass pipe aimed to provide cooling.

Hold down was simple. I bolted the edges to the c rails in my spoilboard.

Here is a close up:


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The flash caught individual aluminum chips flying out of the cut.

I used 0.050"/pass 0.5ips 10000rpm, 2 flute up-spiral .125 carbide bit.

The material is 0.250" 2024 aluminum.

Coolant was compressed air entering through the brass tube on the right of the tool holder.


The PC router was not struggling so I increased the feed rate to 1ips for part of the cut so I could compare the results. The edge at 0.5ips looked like it had been done on a vertical mill, the 1ips edge looked rough, so I will stick to 0.5ips which seems to be a suggested feed rate.

As soon as the cutting finished I checked the bit with my non-contact thermometer, it read 80 degrees F. So I checked it with my fingers and it was cool to the touch. So mist systems may be only be necessary with aggressive cutting. I was considering a vortex chiller but that seems more than what is required here.

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[scottcox]

Looks like you nailed it on the first try! Nice job.

[carlosgmarroquin]

Dana, One doubt arises.

If you are cutting a whole piece out of the sheet, how are you holding it? Tabs or vacuum.

Thank you.

[gerryv]

Thank you Dana!
This is of great interest to me as I've been struggling with the question of using my Shopbot Buddy router as a milling machine for plastics and aluminum but without the need for HAAS level accuracy and repeatability. This is good news.

[cedarknight]

You should be try to cool the bit with a more direct flow. If you are not going spray fluid on the peice as you are cutting it you might coat with a lube. I use chain lube before I got a spray mist. With the spray mist, it set where the piece is covered with a flim when done on thinner aluminum. You don't need to have the piece drowned for simple cut out. I usually cut at 35 inch per minute. The Porter Cable anywhere from 10,000 to 15,000 RPM. Like the chip size around 1/8" x 3/32". This is usually when I am cutting .080 to .25 aluminum with a 3/16th Osrud bit. #63-614 and 1/16" passes. Could do deeper passes but I don't like to push it, especially when I have small pieces. I also put one to two layer of transfer paper on bottom of sheets and cut down to it. Another reason not to drown it, also help not to lose my vaccum the more I cut. So, I "z" to the table plus the paper. I place a business card under the z-plate and can fine tune when the cut get to the last pass. I found a single flute bit will give a clean cut. Took awhile to get it into my head that more is not always better. Single allows chips to get out the way faster and does not heat up bit and aluminum as much. Use a 1/4" or 3/16" bit when you can, less likly to break. Use 1/8" for detail or to make a finish pass. Just thought I add a little of my experinces. Been routing aluminum regular for about 6 plus years. We make alot of aluminum lighted signs.

[rb99]

"can fine tune when the cut get to the last pass."

Can you please explain how you fine tune it?

Thanks,

RIB

[paco]

I'm surprised you could mill 2000 series aluminum with 2 flutes spiral up (wood?) bit. I haven't had any luck milling anything else than 6000 and 7000 series aluminum on my Bot no matter what tool and at what settings I tried.

I also blow air at the bit/kerf and I use Onsrud 63-600 series (Spiral up single O-flute) exclusively. They give me the best edge quality. I also use 62-600 series for thin aluminum (<0.040") cut in single pass. They help on hold down but they require a smooth ramp in.

When I need accurate result, I cut down to a "last" pass with an allowance (say 0.015") and then I make the final pass spot on the vector. I'm generally within +/-0.005".

[dana_swift]

Carlos- I used tabs. Only a few of them but it worked just fine. I cut through the tabs with a dremmel took holding a 1/16 bit. Then a light filing and it was done.

Gerald- go for it! I have been avoiding aluminum because I did not know what I would be getting myself into. About the only thing I would do different is use dust collection next time. Chips went everywhere.

Paco- This is the only thing I have tried. I looked up 2024 and it is listed as being very machinable. So I gave it a try. It was some drops I picked up from a scrap dealer at a very reasonable price. 2024 is normally pretty expensive stuff.

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[gene]

What is the part you cut used for?

[dana_swift]

Gene- it is a replacement mounting bracket for a TV. It consists of several components that were paneled onto the aluminum sheet. The components were tapped on one side and had clearance holes on the other, then screwed together to make the final assembly. Everything fit like a glove. I tested the hole dimensions, 100% of them could be used as-is no re-drilling was necessary. The bot is just that precise.

This was just a one-time project. The bracket holds the weight of the TV and is hinged so the TV will swing out for rear access.

The aluminum plate has been sitting around for several years waiting for "just the right need". There are enough islands of good material left to make some other projects from the left-overs. So the plate will have more destinations..

What I find so rewarding about owning a shopbot is that when I needed the bracket, it was just a matter of minutes to sketch up what I needed in Aspire, then I could bolt up the aluminum and build something that wasn't even on my mind an hour earlier.

Projects go from concept to done very very quickly now I understand how to build things with the bot.

The biggest problem I had was unbolting and removing my vacuum hold-down with its Trupan spoilboard and switching back to my original MDF spoil-board. That took about 10 minutes. Probably vacuum would have worked nicely, but I did not want the vacuum sucking aluminum bits down into the Trupan where it could scratch future wood projects. I didnt want to re-surface the Trupan yet, but that would have been another solution to the problem.

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[cedarknight]

Fine tune, adjust your cutting depth if it did not cut all the way through or if it cut too deep. You could always do test cuts in area of you sheet you are not using. I'll have to look at the SB software to see if there is any on the fly adjustment. Be a while since I use the software. I don't have a shopbot currently.

[carlosgmarroquin]

thanks for the info.

[donchandler]

I made these for the running boards on my 1949 Ford truck. They are 0.100 6061 aluminum. I used 1/8", 3/16" and 1/4" router bits from Micro 100. I ran at .6 ips and 15000 rpm. Seemed to work good.
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