how to calculate the torque for my CNC project ?

Hello,
Im new and I would make a large CNC machine for my final project career.
the working area for the CNC is about 1.5 meters x 2.5 meters, and I wondering how is the correct way to calculate the enought torque to work in wooden, aluminium or metal for this CNC maching.

at the moment I supose that I need consideer:

- weight of the X axys structure
- torque needs to milling the material
- torque of the motor in Z

but I wondering if exist an "academic" way to do it. just to not mistake in the choosen of the motors.

sorry for my english, I hope can be understable.

Thanks

There is an academic way and its probably worthy of a final year project on its own.
This may get you started www.machinedesign.com/motors-drives/arti...rs-for-linear-motion
but we did find an error in their methodology so don't just use it without confirming the maths at every step.

yes, its my first attempt with cutting cnc machine, previosuly i have working in 3d printed machine project with optimal results.

anyway, if you can share the title of the book, I'll appreciate.

thanks

thanks for the link rodw, I will study and share any issue about the design process.

Yaskawa makes an app called sigmaselect. You enter in all the parameters of your machine and it will tell you what motors you need. It's meant for their motors of course, but the data can be applied to most others.

To get an idea of the force you need to input for cutting various materials, try one of the calculators online. Kennametal has a good generic one. Material doesnt really matter much, pick aluminium and punch in the heaviest cut your spindle can manage. It will give you the tangential force on the machine, which you would enter into the yaskawa calculator as a load. You may want to add 50-100% as a buffer for safety.

As a basic guide to start, a large but light weight router with a low pitch screw, direct drive needs something in the 400-750w range. Higher pitch screws, faster acceleration, rack and pinion, larger diametre screws or heavier machines may need bigger motors. Gear and belt reductions may let you get away with much smaller motors.

If you intend to use steppers, the same rules apply, but you need to pay attention to the torque at speed at the voltage you are using. Bigger doesn't always end up better when you want to go faster. 10000oz-in doesn't help you if it drops off at 400rpm and you need to go 2000.

ihavenofish wrote:

Yaskawa makes an app called sigmaselect. You enter in all the parameters of your machine and it will tell you what motors you need. It's meant for their motors of course, but the data can be applied to most others.

To get an idea of the force you need to input for cutting various materials, try one of the calculators online. Kennametal has a good generic one. Material doesnt really matter much, pick aluminium and punch in the heaviest cut your spindle can manage. It will give you the tangential force on the machine, which you would enter into the yaskawa calculator as a load. You may want to add 50-100% as a buffer for safety.

As a basic guide to start, a large but light weight router with a low pitch screw, direct drive needs something in the 400-750w range. Higher pitch screws, faster acceleration, rack and pinion, larger diametre screws or heavier machines may need bigger motors. Gear and belt reductions may let you get away with much smaller motors.

If you intend to use steppers, the same rules apply, but you need to pay attention to the torque at speed at the voltage you are using. Bigger doesn't always end up better when you want to go faster. 10000oz-in doesn't help you if it drops off at 400rpm and you need to go 2000.

a direct drive motors must be used with some kind of encoder to control the turns ? anyway I always thought in stepper motors, like NEMA 23 or 34, I just want to be sure to use the correct one.
Anyway, the main project is thinking to work just with wooden, but its important for me give support to use in metal sheets, like aluminuim too.