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Offline CDyckes

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Feed rate override
« on: May 12, 2007, 03:41:21 PM »
There used to be a way of overiding the 300% max limit on feedrate override for those who wanted to take the risk (as a config file setting) .  I can't find this anywhere. Does it still exist as I often do want to bump the speeds way up if I've poorly coded a job with say Lazycam?

Thx

Colin

Colin
Re: Feed rate override
« Reply #1 on: May 12, 2007, 09:33:24 PM »
We have changed it to only go to 250% :(
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Re: Feed rate override
« Reply #2 on: May 12, 2007, 10:17:15 PM »
Way back I had the same feeling regarding being able to increase the F.R.  But some of the other dudes here kinda turned me around and said, you should really not get in the habit of increasing your feed rate but DECREASING to fit the job.

In other words, your motors are tuned too low.  Increase your max velocity and start runing all your jobs at 50%.  That way when you need to go faster you will never chance missing steps and always have headroom to go MUCH faster with never needing to go much past 100%.  Make sense???

HTH,
Sid

Offline CDyckes

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Re: Feed rate override
« Reply #3 on: May 13, 2007, 06:43:01 AM »
Consensus from the 'big boys' was just that, but Art implemented an override in the config file for those of us with small hobby machines who wanted it to have our own specified max override.

250% is even worse :(

PLEASE can we have an XML entry to override it by editing the XML manally as before?

Colin
Colin
Re: Feed rate override
« Reply #4 on: May 14, 2007, 09:27:10 AM »
Could you program your code for a fast a bit faster :)

The more you up your FRO the more likely you are to have an axis fault :( So it would be good practice to start making your Feed rate a bit higher
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Offline CDyckes

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Re: Feed rate override
« Reply #5 on: May 14, 2007, 10:20:14 AM »
Are we talking at cross purposes, or am I missing something?

Doesn't the FRO just adjust the feed rates as set in the g-code file? I didn't think it had any affect on the defined acceleration or maximum motor speed so can't see why it would cause an axis fault.

All I'm looking for is the ability to compensate for the fact that say I've made a stupid error in the g-code file from Lazycam which was maybe last used to cut a piece of carbon steel at maybe 5mm/min and am actually cutting MDF (or doing an 'aircut') on this job so just want it to cut 10 times faster.

Art did make this manual adjustment of percentage override available before. I was hoping it could be done again on a 'manual XML edit' basis as I can't see any downside.

Colin
Colin
Re: Feed rate override
« Reply #6 on: May 14, 2007, 10:38:23 AM »
In Quantum you would be corect :)
In Mach3 when you change the FRO you are changing time... so when you make a second shorter you are changing anything that uses time... for example Velocity will be twice as fast if you make a second happen in .5 sec. This will also change the Accel :( If you use the No FRO onQ that is telling mach 3 not to change time but to change time but to change how the TC's (Move vector in the buffer) are calculated and will take longer for the FRO to take effect..

that is a bit deep but it shows the problem :)

Hope it helps
Brian
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Offline CDyckes

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Re: Feed rate override
« Reply #7 on: May 14, 2007, 11:15:27 AM »
It was the "No FRO onQ" override that I remember possibly being the default in days of old as it did take until the next g-code item or so for the FRO to take effect.

I assume the new 250% will still apply if I set "No FRO onQ" :(   Hope I don't need to resort to binary patching :(

Colin
Colin
Re: Feed rate override
« Reply #8 on: May 14, 2007, 05:03:36 PM »
The NoFRO on Q is the new one :)

and the override will work both ways...
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