Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: jguillen on April 04, 2006, 10:39:04 PM

Title: wrong feed rates at the machine
Post by: jguillen on April 04, 2006, 10:39:04 PM
Hello All,

Somebody please help. I am fairly new to Mach3 and I am usinig it to control a mill/drill converion. Everything is working fine except for the actual feed rates of the machine. If I write the following code,  G1  f10  X10    Mach3 will move the table  and will display a feed rate of 10 inches/min. The problem is that the actual feed rate is half that.( It actualy takes 2 min to travel the 10 inches.).

Title: Re: wrong feed rates at the machine
Post by: Brian Barker on April 05, 2006, 10:15:56 AM
Is it moving 2" when you tell it to? or is it moving 1" if you tell it to move 2"?
Title: Re: wrong feed rates at the machine
Post by: fer_mayrl on April 05, 2006, 11:01:54 AM
Another thing, if you have a VERY VERY VERY low acceleration rate, it might take longer to reach the 10 inches in one minute
Title: Re: wrong feed rates at the machine
Post by: jguillen on April 05, 2006, 11:11:45 AM
If I tell it to  move 2" it moves 2", If I tell it to  make a 3" diameter circle it makes a 3" diameter circle. The problem is that if I tell it to make that circle in 1 minute it takes about 2 minutes.  Both the X and Y axis are set at 180 ipm with an  acceleration of 3"/sec^2.
Title: Re: wrong feed rates at the machine
Post by: fer_mayrl on April 05, 2006, 11:14:15 AM
Do you have constant velocity (CV) turned on? or are you working on exact stop mode?
Title: Re: wrong feed rates at the machine
Post by: jguillen on April 05, 2006, 11:34:21 AM
I am not sure, I will have to check later. Which mode should I be in? What does each mode do?

Thanks.
Title: Re: wrong feed rates at the machine
Post by: fer_mayrl on April 05, 2006, 11:41:19 AM
constant velocity, as the name implies, moves the tool at a constant velocity, with means that it looks ahead some moves to plan the current move´s speed, think of it as if you draw a curve which is drawn in small straight segments, the tool would move in one seamless stroke along the curve. If you have exact stop turned on, then the tool would accelerate, reach the max speed, and deaccelerate on each one of those segments, which would make the cutting process take longer if you have a small acceleration value.
To sum up, CV just makes things faster but the down side is that some corners might get rounded because the machine cannot ake a tight turn and keep constant velocity.
exact stop takes longer but follows the true shape you are trying to cut.
hope this helps
Fernando
Title: Re: wrong feed rates at the machine
Post by: Brian Barker on April 05, 2006, 12:07:54 PM
If I tell it to  move 2" it moves 2", If I tell it to  make a 3" diameter circle it makes a 3" diameter circle. The problem is that if I tell it to make that circle in 1 minute it takes about 2 minutes.  Both the X and Y axis are set at 180 ipm with an  acceleration of 3"/sec^2.