Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Sheldon Dingwall on September 12, 2008, 07:55:44 PM
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This wasn't a problem until I upgraded Mach to the latest.
When jogging in 3 axis most of the time the head travels at move speed now. Not always though, usually at the start of a file when the machine rapids to the first position it will go at normal speed, but during a file, when it rapids from one location to the next it moves at cutting speed if it's a 3 axis move. 2 axis rapids work as they should.
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The axis with the SLOWEST max speed set in motor tuning will dictate the rapid move speed when that axis is involved.
May be your trouble.....maybe not.
Just a guess,
RC
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If the move you are making is all written on one line - e.g. G0 X10 Y20 Z2, then the computer works out the relative speeds of the axis so they all arrive together - as though it were a cutting move, so therefore in the above, if you take the rapid as the axis with the longest travel, Y, X will move at 1.2 Y speed and Z will move at 1/10 Y speed.
If you put the moves on separate lines, they will move at whatever the rapid speed is for that axis.
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I haven't had time to follow up on this.
It appears that the angle the z travels at in relation to the horizontal plane determines if the head moves at jog speed or move speed.
In other words as long as the z is traveling at a very low angle let's say less than 10 degrees, then the head will move at full jog speed. If the angle is greater then the head will move at cutting speed. This hasn't caused any accidents yet, but a few surprises when you're expecting the tool to "move" to the next cutting location and it rapids there.
There must be a setting to adjust this angle somewhere. Thanks
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Bump
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What is the version you have, you say the latest but is that the development only or the release candidate? The development version was a test for comp code so best to stick with the release candidate.
Hood
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Version 2.63
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Can you try and explain exactly what is happening and what you think should be happening. You say the head moves, are you meaning the Z axis? You are saying full jog, are you meaning rapid?
Sorry for the questions I am just trying to get a clear picture of what your problem is.
Hood
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Sorry.
Maybe if I use an example instead.
X0.000 Y0.000 Z0.000
G0 X100.000 Z-10
This results in a rapid move that's too slow
vs.
X0.000 Y0.000 Z0.000
G0 X101.000 Z-10.000
This results in normal rapid speeds. The difference in distance is 1 mm in the X direction. The difference in rapid speed is 200% or so.
Changing the Z feedrate changes the "hinge point" between normal rapid speed and the really slow rapid speed, but it doesn't smooth it out. It's either full rapid speed, or really slow. In the previous version rapids were always fast.
I'll try updating to version 3 and see if that helps.
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Ok know exactly what you are meaning now (takes a while for things to get through the thick skull :) )
If you attach your xml I will see if I can replicate it here.
Hood
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Thanks Hood.
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Seems to be working fine here but it is just in simulation. I notice you have a kernel speed of 25KHz but the X and Y are just tuned slightly too fast so possibly try 35KHz and see if that helps.
Hood
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Thanks Hood, I'll give that a try. It might help solve another issue I'm having.