I would like to be able to adjust the feed rate throught the duration of a cut.  I have been playing around with some of the sample G-Code files included with Mach3 and attemtping to adjust the Feed rates and I have noticed that sometimes the feed rate changes and sometimes the command is just ignored.

I am under the impression (perhaps incorrectly) that F command can be used with G1 & G3 and NOT G0.  Is this true?
 
Is there a specific protocol/syntax for using the F command? 

Does the F command need to precede or follow the X, Y Z commands (my guess answer to this is that it SHOULD work in either position but WHEN the FRO takes place will differ depending on the placement of the F command-right?).

the 'F' command is global i.e. it could be put on the first line of the program and all following feed lines G01,G02,G03 ETC.  would work to this feed rate until another 'F' command it read.

so if you entered G01 X2. F.01 the X axis would move at this rate.  If the next line was Z-.25 this would feed at .01 too unless you told it to feed at a different rate.

G00 is a rapid move and as such takes no notice of the global feed rate.

I hope this helps

Graham

Yes, That Helps!  Thanks Graham!

For the most part that is kinda what I thought and what I am doing.

Any ideas why some of the F commands are being ignored?

Sid

If you have a G00 in the program it will run at Rapid until a g1,2,3 is reached