1
G-Code, CAD, and CAM discussions / Question about G1 speed
« on: May 28, 2007, 08:47:34 AM »
I am familiar with the G1 command, where the 'f' value sets a speed in units/minute. I am about to bring on a fourth axis, a 6" rotary table, and am wondering how the speed gets calculated if I have a G1 command that has both a rectangular coordinate move (x,y, or z) as well as a rotational move (a, b, or c)? My x,y,z is in inches and I assume the a,b,c is in degrees.
So at some point the CNC software has to calculate a vector length, based on the current position and the desired final position. Then, with a given speed rate, it gets the movement done in (length divided by speed) minutes. But if there's a combination of linear and rotational movements, I am not ure how it will calculate the vector length. For this purpose, does it treat one degree of riotation the same as one inch of linear movement? Would a one degree rotation and a one inch movement of the z-axis equal a vector length of 1.4142 "units"? To get that I took the square root of 1 squared plus 1 squared, or the square root of 2.
I ask this because I usually use a speed of 3 to 5 units per minute when doing linear stuff. But if a complete revolution is going to be considered 360 units, then the speed will need to be significantly faster. I'd still want the z-axis to descend at about 5 units per minute and for it to finish a one inch boring depth therefore in 12 seconds (0.2 minutes). So the table would need to revolve completely in that same one 12 seconds, or 30 units per second or 1800 units per minute. This is where my confusion comes from. Is the speed rate then the square root of (1800^2 + 5^2)
Any help is appreciated!!!
So at some point the CNC software has to calculate a vector length, based on the current position and the desired final position. Then, with a given speed rate, it gets the movement done in (length divided by speed) minutes. But if there's a combination of linear and rotational movements, I am not ure how it will calculate the vector length. For this purpose, does it treat one degree of riotation the same as one inch of linear movement? Would a one degree rotation and a one inch movement of the z-axis equal a vector length of 1.4142 "units"? To get that I took the square root of 1 squared plus 1 squared, or the square root of 2.
I ask this because I usually use a speed of 3 to 5 units per minute when doing linear stuff. But if a complete revolution is going to be considered 360 units, then the speed will need to be significantly faster. I'd still want the z-axis to descend at about 5 units per minute and for it to finish a one inch boring depth therefore in 12 seconds (0.2 minutes). So the table would need to revolve completely in that same one 12 seconds, or 30 units per second or 1800 units per minute. This is where my confusion comes from. Is the speed rate then the square root of (1800^2 + 5^2)
Any help is appreciated!!!