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Author Topic: Rapid Feed Rates vs Cutting Feeds  (Read 566 times)

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Rapid Feed Rates vs Cutting Feeds
« on: October 05, 2018, 04:06:21 AM »
Hi all,

This is my first post and I apologise in advance if this topic is general knowledge or has already been covered. I did search the internet trying to solve my issue but couldn't find anything.

I'm aware that in g-code G0 and G1 are for rapid and cutting movements and my code includes these, my problem is that my machine (3 axis router) only ever moves at the Feedrate speed defined in Mach3, I have unchecked the "lock Rapid Feed rate to Feed rate" checkbox in the settings but it does nothing. The slider to the left of the FRO slider has no impact.

My support staff for my machine said this was a Mach3 issue.

Currently I have to manually ramp up the speeds between cuts otherwise it takes so damn long to travel. Someone please help, thank you.

Offline RICH

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Re: Rapid Feed Rates vs Cutting Feeds
« Reply #1 on: October 05, 2018, 08:07:14 AM »
Quote
My support staff for my machine said this was a Mach3 issue.

Show this to your support staff:
The support staff is just lazy and incompetent! They are generating gcode for a controller and they don't know the controller functionality or the default  machine setup?

Just my opinion.............  ;)
RICH

Offline ger21

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Re: Rapid Feed Rates vs Cutting Feeds
« Reply #2 on: October 05, 2018, 08:25:39 AM »
What are your velocity settings in motor tuning, and what is the feedrate in your g-code?
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Rapid Feed Rates vs Cutting Feeds
« Reply #3 on: October 05, 2018, 08:47:14 AM »
Support staff are the guys that made my machine, I use Aspire to generate g-code. My Velocity for X and Y is 6000 in the motor tuning in Mach3 while my feedrate changes depending on the material/bit. Is it a problem with the post processor? I'm using the standard gcode .tap format.

Here's an example:
Code: [Select]
T1M6
G17
G0Z12.000
G0X0.000Y0.000S12000M3
G0X538.500Y298.985Z12.000
G0Z8.000
G1Z-1.000F1200.0
G1Y421.985F3600.0
X661.500
Y298.985
X538.500
G0Z12.000
G0Y1377.797
G0Z8.000
G1Z-1.000F1200.0
G1Y1500.797F3600.0
X661.500
Y1377.797
X538.500
G0Z12.000
G0Z12.000
G0X0.000Y0.000
M30

Offline ger21

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Re: Rapid Feed Rates vs Cutting Feeds
« Reply #4 on: October 05, 2018, 08:49:28 AM »
If Rapid Override is at 100%, then your rapid moves should be moving at the motor tuning speed, or faster (on multi axis moves).
I don't know what else would reduce rapid speeds.
Gerry

2010 Screenset
http://www.thecncwoodworker.com/2010.html

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html
Re: Rapid Feed Rates vs Cutting Feeds
« Reply #5 on: October 05, 2018, 09:04:52 AM »
This is what I'm here to ask for help with.

The max speed of my cnc router running any gcode with Mach3 is limited to the Feedrate which I have to manually tweak. Rapid override does nothing.

I actually didn't even know this was a problem until I had one job that was cutting hardwood relatively slowly and had to traverse the length of the bed (2.5m) a number of times and thought it was weird it wouldn't travel faster when it's not cutting.

Re: Rapid Feed Rates vs Cutting Feeds
« Reply #6 on: October 14, 2018, 08:40:47 AM »
The question is what is the motor tuning speed set to?
Go to Config, motor tuning, and select one axis at a time and see what they are set to.

In your Gcode above your max feed is 3600. If you max motor tuning speed is only 3600, it won't go fast in rapids than in feeds.

Mike
We never have the time or money to do it right the first time, but we somehow manage to do it twice and then spend the money to get it right.
Re: Rapid Feed Rates vs Cutting Feeds
« Reply #7 on: October 14, 2018, 11:13:11 AM »
Your machine may be able to cut at the maximum speed it is mechanically and electrically capable of. In that case a G0 wouldn’t be faster  than G1 unless the selected feed rate is less than maximum.
Re: Rapid Feed Rates vs Cutting Feeds
« Reply #8 on: November 02, 2018, 01:03:45 AM »
Ok guys, I figured out the issue, turns out there's a rapid override control in the settings which was enabled and set to 2000, not sure why but I've ramped it up to the full speed of my motors and everything is now working as expected.