What is the difference between wood working and metal working routers?

I am about to order the steppers needed to drive my 4 x 4 EVO, my very first router.

I don't want to waste money over-designing or overbuilding the machine but at the same time, i do not want to build a machine that I will outgrow in a few months of use or damage making demands its not up to.

On the basis of my limited experience, the EVO is primarily a woodworking machine and it is listed in the Wood Working Forum.

Does that characterization change to Metal Working simply by going to more powerful steppers and a 3 HP router?

I'd like the option of machining parts from 6000 series alloy.

What size steppers should I buy now in anticipation of metal working?

Thanks

L. J.

What do you consider metalworking?

Generally, routers are for wood and plastics, and mills are for metals.
You can cut some non ferrous metals with a router, but the cutting forces are much higher than when cutting wood.

Cutting any type of steel is out of the question with a router.

As far as stepper choice, what your cutting really has no influence on stepper selection.

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Originally Posted by ger21

What do you consider metalworking?

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6000 series aluminum plate, 1/8 to 1/4-inch thick.

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Originally Posted by ger21

As far as stepper choice, what your cutting really has no influence on stepper selection.

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Am I to assume then that the bigger steppers are chosen to manage the mass of the gantry or the larger, heavier routers?

I have about one thousand hours on a manual feed "J" Head Bridgeport so I know speed, feed rates and material are what drive the rate at which you can feed the cutter. I'm new to CNC routers and do not wish to assume anything.

thanks!

L.J.

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Originally Posted by LaughingJaguar

6000 series aluminum plate, 1/8 to 1/4-inch thick.

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A wood router (I'm assuming you mean a hand held one?) will handle that fine so long as your not too aggressive, but personally I far prefer a spindle and VFD over any form of hobby type automated router anytime. They generally have a better tolerance and are designed for a harder workload, longer.

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Originally Posted by LaughingJaguar

Am I to assume then that the bigger steppers are chosen to manage the mass of the gantry or the larger, heavier routers?

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Both and more. But bigger isn't always better for CNC, you should work out what kind of load you'll have and go from there. Others I'm sure will chime in here with more info.

cheers,
Ian

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Originally Posted by LaughingJaguar

6000 series aluminum plate, 1/8 to 1/4-inch thick.

Am I to assume then that the bigger steppers are chosen to manage the mass of the gantry or the larger, heavier routers?

I have about one thousand hours on a manual feed "J" Head Bridgeport so I know speed, feed rates and material are what drive the rate at which you can feed the cutter. I'm new to CNC routers and do not wish to assume anything.

thanks!

L.J.

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I routinely cut 1/4" plate on my router, and have cut up to 1" plate. Like the others mentioned, the forces involved with cutting aluminum are exponentially more than wood, and requires a much rmore ridgid frame, more powerful spindle, and I would say some form of commercial precision linear guides to get a decent surface finish. Spindles have more heavier duty bearings than routers. Another thing to consider is some 6000 series aluminum may be difficult to machine on a router, which typically have higher RPMs, probably 3-4 times the speed of a Bridgeport. There are specialized bits made specifically for milling aluminum on CNC routers. Mist coolant and or air blast would be a plus.

In the stepper world, oversizing for a particular appication could mean slower perfomance, excessive "cogging", potential resonance problems... and it's probably a waste of resources that can go to upgraded frame components, linear motion, screws, electronics... Ideally you'd want to size the steppers "just right" with a little bit of overhead. There's not much documentation on this, but the GeckoDrive website has good resources and formulae that can be used to determine the proper stepper size (or if you should be considering servos for your application).

As to feeds and speeds, you can approximately determine them by getting the chipload information from the tool manufacturer. The feedrate is directly proportional to the spindle speed. So with the faster spindle speeds, you would need a higher feedrate to maintain a decent chipload, and then adjust your depth of cut to your machine's ridgidity and spindle HP. More than wood, aluminum will "telegraph" any and every bump, imperfection, backlash, deflection, and slop in your machine...

In the commercial world, most all heavy-duty metalcutting CNC gantry routers use cast iron in their construction. Most commercial woodworking CNC gantry routers use steel tube and even aluminum components. While they can also cut aluminum, they are not intended for doing so on a production scale and their spindles are not designed as such or have as much power.

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Originally Posted by louieatienza

In the commercial world, most all heavy-duty metal-cutting CNC gantry routers use cast iron in their construction. Most commercial woodworking CNC gantry routers use steel tube and even aluminum components. While they can also cut aluminum, they are not intended for doing so on a production scale and their spindles are not designed as such or have as much power.

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The hardest material I expect to cut will be red oak and most of the time The machine will see Baltic birch or apple ply.

Your response took a lot of time and effort.

I appreciate that a lot

Thanks.

L.J.

Back to your first question, most people building that size machine use a Gecko G540 and 380oz steppers. They give you the most power for the price.

The best thing you can do is see what everyone on Joe's forum is using for similar machines.

After all was said and done, it appears unlikely i will build the EVO.

i'm seriously attracted to the Kronus Robotics KRMx02 CNC Router.

It is a proven design.

I'll buy the builders guide and see what power he uses.

Thanks

L.J.

Old thread but wondering on the differences between metalworking and woodworking CNC machines.

To me, the difference really comes down to chip removal. With wood you can have a dust collector which should suffice in terms of both chips and fine dust collection. With metalworking machines you can't do anything unless you have high pressure liquid coolant which basically means the design of the machine must be such that it must accommodate for coolant flying everywhere.

The beefed up spindle goes without saying.

Am I on the right track?

The main difference between a woodworking machine and a metalworking machine is rigidity - everything else is secondary. There are mills without flood cooling or chip collection; but I have yet to see a (working) metalworking mill made of PVC sheets or aluminum profile.