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**General Mach Discussion / Feedrate on multi-segment curves**

« **on:**September 21, 2014, 07:14:09 PM »

I'm trying to understand what factors dictate the feed rate when doing curves made from many line segments. For example, if I am pen plotting a circle made from 360 segments, the feed rate will vary according to the diameter of the circle. When the circle is larger, the feed rate is higher, while when it is smaller diameter the feed rate is lower. On a non circular curve where some of the segments are short and others are long, the feed rate will slow down on the short segments. So feed rate seems to be related to the distance being traveled between successive line segments using G1 X Y commands.

I realize there are G codes for dedicated circles, and those don't have the feed rate problem. I'm only using a circle to test with, but my application involves non circular curves that must have a constant feed rate because a heat sealing wheel is being used to make seems. The heat sealer needs to have a specific feed rate, temperature and pressure for optimum sealing. If the feed rate slows down the way it currently does when the line segments of a curve are shorter, the dwell time on the seam will be too high and the film can get melted, whereas if it is too fast then there will not be enough dwell time to make the seal.

I realize there are G codes for dedicated circles, and those don't have the feed rate problem. I'm only using a circle to test with, but my application involves non circular curves that must have a constant feed rate because a heat sealing wheel is being used to make seems. The heat sealer needs to have a specific feed rate, temperature and pressure for optimum sealing. If the feed rate slows down the way it currently does when the line segments of a curve are shorter, the dwell time on the seam will be too high and the film can get melted, whereas if it is too fast then there will not be enough dwell time to make the seal.