maybe a dumb question

[F3RR3T]

ok i am wanting to build a cnc router for cutting mdf and light aluminum.

my question is if i build a smaller machine out of mdf (12"x28" cutting size) out of mdf. will it be able to cut 3/4 aluminum if i do 1/32 passes?

the only reason for the small mdf machine is to make the actual machine.

also my gantry consist of .75 inch main supports on each side and my gantry beam is a 4x6 inch 1/4 inch wall beam. cutting table size will be 6'x10'.

if i use a good quality spindle and cutter i should be able to cut steel correct?

[dertsap]

Originally Posted by F3RR3T if i use a good quality spindle and cutter i should be able to cut steel correct?

could be done if you use steel channel , linear rails and bearing blocks , ball screws and a quality high torque low speed spindle

[YZF]

I'm not an expert and this is just my opinion

1/32" of an inch cuts in aluminum sounds too heavy. I think steel is out of the question. In theory lighter and lighter cuts and smaller tools can reduce the cutting forces but in practice there's only so far you can go before your tool will just bounce of the surface you're cutting. Even if you can cut the finish and tool life will suffer. The accuracy will also be questionable.

A lot depends on the exact construction, the rails etc. Metal working machine are usually massive pieces of steel (steel is about x100 stiffer than MDF).

With very careful construction you may be able to cut aluminum using very light cuts, I think steel is not possible, never built an MDF machine myself though...

[F3RR3T]

Originally Posted by YZF I'm not an expert and this is just my opinion 1/32" of an inch cuts in aluminum sounds too heavy. I think steel is out of the question. In theory lighter and lighter cuts and smaller tools can reduce the cutting forces but in practice there's only so far you can go before your tool will just bounce of the surface you're cutting. Even if you can cut the finish and tool life will suffer. The accuracy will also be questionable. A lot depends on the exact construction, the rails etc. Metal working machine are usually massive pieces of steel (steel is about x100 stiffer than MDF). With very careful construction you may be able to cut aluminum using very light cuts, I think steel is not possible, never built an MDF machine myself though...

im not cutting steel with the mdf machine.

heres how my build process is going.

i will build the mdf machine with the same servos and controls i will be useing on my main machine to save cost.

the only reason for the mdf machine is to cut out a few pieces of 3/4 aluminum for the main machine. once those are done the mini mdf one is getting trashed.

once my main machine is finished (all the gantry and axis parts are 3/4 aluminum. the frame to support the machine is 1.5 square tubing (maybe 80/20)

i have a 3.5hp water cooled spindle i will be using on my machine. and will frequently machine mdf and sometimes aluminum. i am just curious if i can cut steel with a 3.5hp spindle (1/4 inch plate i dont have access to a water jet and i need to cut some pieces out for a custom bumper.

all linear motion will be rack and pinion most likely belt driven

[YZF]

Originally Posted by F3RR3T im not cutting steel with the mdf machine. heres how my build process is going. i will build the mdf machine with the same servos and controls i will be useing on my main machine to save cost. the only reason for the mdf machine is to cut out a few pieces of 3/4 aluminum for the main machine. once those are done the mini mdf one is getting trashed. once my main machine is finished (all the gantry and axis parts are 3/4 aluminum. the frame to support the machine is 1.5 square tubing (maybe 80/20) i have a 3.5hp water cooled spindle i will be using on my machine. and will frequently machine mdf and sometimes aluminum. i am just curious if i can cut steel with a 3.5hp spindle (1/4 inch plate i dont have access to a water jet and i need to cut some pieces out for a custom bumper. all linear motion will be rack and pinion most likely belt driven

You should probably ask about steel in the metal working forum. I think that horse-power is not going to be an issue, stiffness is. You will also use much lower RPM when you're cutting steel so your spindle needs to be able to put out enough torque at those lower RPM's, usually that requires some sort of gearing.

I think your plan is good assuming the accuracy you want in your aluminum cuts is not too demanding and that you are careful to get your mini machine as rigid as you can... Good luck.

[F3RR3T]

Originally Posted by YZF You should probably ask about steel in the metal working forum. I think that horse-power is not going to be an issue, stiffness is. You will also use much lower RPM when you're cutting steel so your spindle needs to be able to put out enough torque at those lower RPM's, usually that requires some sort of gearing. I think your plan is good assuming the accuracy you want in your aluminum cuts is not too demanding and that you are careful to get your mini machine as rigid as you can... Good luck.

nothing im doing in the aluminum is super critical at all. just some material removal and some non critical mounting points

[ahren]

If you are considering building out of aluminum extrusion, why not build the whole thing out of it? What parts do you need to cut?

Ahren
www.cncrouterparts.com

[F3RR3T]

Originally Posted by ahren If you are considering building out of aluminum extrusion, why not build the whole thing out of it? What parts do you need to cut? Ahren www.cncrouterparts.com

i can get steel and aluminum cheaper than the i can get the 80/20. there is only going to be 1 piece of 80/20 about3 feet long that will be used with a handheld router as a jig to cut 45's