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Author Topic: Homing to slow  (Read 2747 times)

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Offline bajadave

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Homing to slow
« on: March 21, 2011, 01:34:11 PM »
Why when I ref all home that no matter where my spindle is located that it goes so slow to the home switches... Is there a way to change it so it can home at a normal speed until it gets close to the home switches then start to slow down.. Thanks

Offline Hood

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Re: Homing to slow
« Reply #1 on: March 21, 2011, 02:55:59 PM »
You can set the % of rapid speed that the homing will move at, its done from Config menu then Homing and Limits.
There are ways  to make the homing work as you have described above, it needs you to alter the VB script in the RefAll button but the problem is you can never really be certain your axis is where Mach thinks it is and you may crash your machine as limits are disabled during a homing move.
Hood
Re: Homing to slow
« Reply #2 on: March 21, 2011, 03:25:07 PM »
Ray L. ( I think) had a macro to do exactly what you want.
It homed twice, once at rapid then again slowly for accuracy.
Many just rapid jog near to the switches manually, then run the homing function.

Offline bajadave

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Re: Homing to slow
« Reply #3 on: March 21, 2011, 04:29:16 PM »
Thanks Hood, Ive seen the 20% default for homing.. I'll leave this alone for now... Last thing I need is a crashed Machine before I even Cut anything

Offline bajadave

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Re: Homing to slow
« Reply #4 on: March 21, 2011, 04:29:39 PM »
Thanks Ray

Offline Hood

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Re: Homing to slow
« Reply #5 on: March 21, 2011, 04:36:27 PM »
Regards the crashing, I was referring to the usual way people do the rapid first part of a homing routine, they usually send the machine to a distance just before the machine zero then do the homing from there. Problem with that way is if the axis is not where Mach thinks it to be then it could be crash time
Setting a faster % is not really a dangerous thing if you use NC switches as any problem and homing wont work properly. As to doing a two speed homing like RC mentione, yes that could be done but whether it is actually needed I dont know. I would imagine if you do the homing at a speed, no matter if its 10% or 80% as long as you always use that speed there should be no differences day to day.
Hood
Re: Homing to slow
« Reply #6 on: March 22, 2011, 06:45:26 AM »
i set my % value at 30% which makes it 50% faster with no adverse effects. Or as overloaded said, jog to near the home position then home.

Offline Hood

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Re: Homing to slow
« Reply #7 on: March 22, 2011, 08:01:25 AM »
I home at 5m/min but it is external to Mach in the servo drives but again as long as you always home at a certain speed it should repeat time after time as far as I can see, so fast or slow should make no difference. Obviously if your home switches are exactly at the extent of the travel then you would have to be careful with the travel speed but if you had a small distance (few mm) it should be fine.
Hood