Milling aluminum

Discussion about the CNC Shark Pro Plus HD

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Glug
Posts: 31
Joined: Fri Feb 15, 2013 10:10 am

Milling aluminum

Post by Glug »

For those who dare to machine aluminum on your Shark-

I've done a little machining of aluminum on the Shark. The results were mixed - encouraging, but not good. And sometimes frightening. Light cuts, in the .015-.025" range, tend to be the rule to the non-rigid nature of the machine. Sticking with smaller end mills, 3/16 to 1/4, is strongly advised. Solid carbide is a must for stiffness, and also for the typical min router RPMs (my min is 10K). Single flute endmills are risky because the lack of machine stiffness can cause them to auger in. That wicked sharp 5/16" onsrud zero flute designed for aluminum? That is probably a strong no.

When milling aluminum on a mill, the general rule is fewer flutes. 2 or 3 flute end mills are most common, to allow for chip clearance. That works fine in a proper mill that is rigid. But it does result in an interrupted cut and more vibration, and the force vectors are less evenly distributed.

Given the characteristics of the Shark, I wonder if 4 flute end mills would be a better choice. I think the forces would tend to be better distributed and balanced. Most of my small end mills are 2 flute, so I can't try this without ordering more end mills. Since I machine a lot of plastic, I don't bother much with 4 flute mills. Has anyone experimented with higher flute counts in aluminum on the Shark? There is also the question of straighter flute configurations more typical for routing. As unsexy as they appear, it could be they are a better choice.

I am also wondering whether roughing end mills would be advantageous. It is possible that vibration from the uneven profiles might create more problems than they solve. And the complex configurations of good roughing end mills in carbide makes them very expensive, upwards of $40 in 1/4". Their design targets are exactly the opposite of the light skim cuts required on a shark.

James45
Posts: 9
Joined: Thu Feb 07, 2013 4:17 pm
Location: Williamsville,NY

Re: Milling aluminum

Post by James45 »

Single flutes are designed for aluminum to enable large chip loads and to rapidly lift the chip away. If one uses multiple flutes, or resort to small chip loads and or slow feed rates the result will be increased wear on the cutter. Increased heat from friction and as a result the metal "welding"/adhering to the cutter-resulting in increased heat, wear and eventually in a ruined cut. 10,000 rpm may sound slow to you because it is at the bottom of the routers range-but in aluminum, without coolant it is not really a good thing to do. More flutes will make that problem worse. Our machine was meant for basically light cuts in wood and plastic where the cutting conditions are less demanding. I'm speaking from 38 years experience working at GM as a toolmaker, the last 13 running a $200,000 Mazak CNC vertical mill-I don't have all the answers, but I do know what causes failure, bad jobs, etc.

sk8nmike
Posts: 389
Joined: Thu Dec 01, 2011 7:35 am
Location: Carrollton, Tx

Re: Milling aluminum

Post by sk8nmike »

I believe that many people are confused as to just what they have here. The Shark is a Router (Computer Numeric Controlled Router). It has the same capabilities and drawbacks as a handheld router. Not many of you would throw a 1/2" thick plate of Aluminum on your table router and begin grinding away, why do you expect the Shark to do it.

That being said, the Shark will carve soft metals but on it's own terms. Very slow cuts and shallow passes. I've knocked out a few name plates and even a coin but it took 4 times as long as it would have with wood... Slow and Easy.

If you're really into metal work I suggest you get a CNC Mill, that's what they are designed for

Glug
Posts: 31
Joined: Fri Feb 15, 2013 10:10 am

Re: Milling aluminum

Post by Glug »

Thanks. I was more interested in responses from those who do, rather than the naysayers. I've owned a CNC mill for the past 17 years, but it isn't conveniently located.

Aluminum is just another material to be machined.

It may also shock you to know I saw aluminum on my table saw. 3/4" thick plate dry cuts very nice.

James45
Posts: 9
Joined: Thu Feb 07, 2013 4:17 pm
Location: Williamsville,NY

Re: Milling aluminum

Post by James45 »

Sometimes the naysayers are the ones pointing out the king has no clothes on. And sometimes it is because the majority of folks in our forum are unfamiliar with materials other then wood-leading them to believe the machine is capable of more then the intended design/function. Your right-it is just another material. So by that argument lets cut some granite, glass, Waspalloy or titanium. At some point it becomes a futile undertaking. And "amazed" by cutting stock on the table saw---no. We use a hand held circular saw to cut 2" thick 6061 aluminum plate into manageable pieces. But that has nothing to do with the Sharks intended function or limits. Could have just as easily jumped on the bandwagon and patted you on the back to "go for it"-what good would it have done others? I don't believe in treating people like mushrooms.

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Consultingwoodworker
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Joined: Fri Jul 02, 2010 7:37 am
Location: Nashville area
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Re: Milling aluminum

Post by Consultingwoodworker »

When I was selling and servicing MultiCam CNCs back in the early 2000s, they offered an optional mister for cutting aluminum. It used vegetable oil to lubricate the cutter with a fine oil mist rather than a flood system. It worked well.

I have cut aluminum on the table saw and chop saw, and yes, I have even routed it with a hand router and turned it on a woodworking lathe with carbide tipped hand tools.

As stated above, light cuts and lots of care. And pretty much all of these operations were done by hand. The human body, especially a skilled machine operator, is capable of remarkable sensitivity, feeling the resistance of the cutting tools and continuously adjusting feed rates and pressures to make the cut. Very few machines are even remotely capable of this. Any CNC, once started on a cut at 30 ipm is going to try and achieve the 30 ipm no matter what. It is a very different process.

Ralph

sk8nmike
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Joined: Thu Dec 01, 2011 7:35 am
Location: Carrollton, Tx

Re: Milling aluminum

Post by sk8nmike »

Glug wrote:
It may also shock you to know I saw aluminum on my table saw. 3/4" thick plate dry cuts very nice.
And what is your saw blade good for after a foot or so of that 3/4" plate? Hammer and chisel will work too, but a band saw with a metal cutting blade or a plasma cutter are much better choices. Right tool for the right job.. Yes the Shark will cut soft metals,,,,But if you're really into metal work invest in a mill you'll' be happier in the long run.

Want in on a little trick?? Your shark control panel does nothing more then tell 3 resolvers which way and how far to turn. Most mills have 3 hand wheels, up and down, left and right front to back, XYZ.

LeeWills
Posts: 40
Joined: Sun Oct 27, 2013 5:05 pm

Re: Milling aluminum

Post by LeeWills »

sk8nmike wrote:
Glug wrote:
It may also shock you to know I saw aluminum on my table saw. 3/4" thick plate dry cuts very nice.
And what is your saw blade good for after a foot or so of that 3/4" plate? Hammer and chisel will work too, but a band saw with a metal cutting blade or a plasma cutter are much better choices. Right tool for the right job.. Yes the Shark will cut soft metals,,,,But if you're really into metal work invest in a mill you'll' be happier in the long run.

Want in on a little trick?? Your shark control panel does nothing more then tell 3 resolvers which way and how far to turn. Most mills have 3 hand wheels, up and down, left and right front to back, XYZ.
I too have cut aluminium on my table saw.
I did, however, invest in an aluminium blade and even so, the blade didn't last that long.
Just long enough to cut the parts I wanted it to and no more.
Regards
LW
If you can't blind someone with science, Confound then with B***S***

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Consultingwoodworker
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Re: Milling aluminum

Post by Consultingwoodworker »

Below is an interesting video I found. It is an industrial-level CNC milling machine cuting 6062 aluminum sheet. This is the manufacturer's video, so I'm guessing they know how best to operate their system.
As you can see in the video, the feed rate is VERY low, and this with the cutter using an oil mist system as I mentioned above. [urlhttp://www.youtube.com/watch?v=jMZQ02waPNU][/url]

Ralph

sk8nmike
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Joined: Thu Dec 01, 2011 7:35 am
Location: Carrollton, Tx

Re: Milling aluminum

Post by sk8nmike »

Looks like the bit it spinning at less than 8K rpm too.

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