any formular for torque calculate?

[szcharle]

Now I am in the period of select which mill i want to buy, mill like EMCO Fb-2 clone, and RF45 etc.
and I want to convert it to CNC, and I hope i can use 2 phase stepper motor only (due to easy to get, cheap to drive,I can diy the driver )
I read a book ,it have some simple formular , but i think that calculate is not very nicety.
does any free software or tell me such formular that can calculate the torque needed for motor?

[NC Cams]

sure: by DEFININITION,

HP = (Torque x RPM)/5252

where:

hp = horsepower

torque is in ft/lb

and RPM is revs/min.

without 2 you can NOT figure out the third.

stall torque is not the same as continuous torque nor is it same a "max torque".

Ok max but at "max what"?

RPM, max current w/o demag, max continuous current, max light of the moon, max what???

Unless you have the torque vs rpm curve, your guess is as good as ANY as to what the third is or wher it was rated.

By the way, unless you know the power factor

1 mechanical HP is NOT 100% equal to 745.7 watts if power factor is only 80%

Be careful of the numbers game and "game" is being charitable when it comes to rating game.

[Al_The_Man]

does any free software or tell me such formular that can calculate the torque needed for motor?

Here http://www.danahermotion.com/design_...p#motioneering
Al.

[Mariss Freimanis]

If you are a machinist, a good place to start is your experience with a manual handcrank-wheel machine. Measure the diameter of the handcrank wheel. Ask yourself what is the maximum force you would put on the handle. Multiply that force by the radius of the wheel to calculate the torque you need.

I gather from your post you are not a native English speaker and therefore you probably use metric units. I apologize because the conversion to Newton-meters escapes me right now but maybe you can calculate that from the following:

Most handcranks are about 50mm to 75mm in radius and most people say they apply no more than 5Kg of force to the handle. I leave it up to you to multiply the both togeter and convert it to Newton-meters for torque.

Mariss

[szcharle]

thanks all,thanks for you reply!
and Mariss, you are very careful! yes ,i am not a native english speaker, I am a Chinese at China.

and about convert between Metric-Inch
it's 1Nm=8.85 InLb=141.60 OzIn
calculate the normal torque for most handcranks then is about
5kg*50mm*0.001*9.81(g)=2.4525Nm=347 OzIn
5kg*75mm*0.001*9.81(g)=3.6788Nm=521 OzIn
so ,from experence, we can say the max torque needed for XYZ axis handcranks is between range 347to521 OzIn.

and from the freeware that links from AI. i will calculate later, use a normal mill as a model and paste result here
also, the formular that I read from a China's Design CNC Mill books(related with work force, HP of main axis Motor,etc) i will paste at here later when i have free time.