Hello Guest it is July 20, 2019, 01:56:20 AM

Author Topic: What's the best way to determine motor velocity?  (Read 13000 times)

0 Members and 1 Guest are viewing this topic.

What's the best way to determine motor velocity?
« on: April 19, 2006, 01:17:58 AM »
Just kinda curious what your take on this is?

When I tune my motors on the config screen, I get then going till they start missing steps (around 130 in/min), then back it off untill they run without missing (120 in/min).

This works fine assuming I don't Feed Rate Overide more than about 120%.  If I go above this FRO then I miss steps.

So what's best, tune your motors to a velocity that takes into account a max FRO of 290% (which would then cause everything to run super slow at 'normal feed rates).  Or just forget about FRO's above a certain ceiling level?  Is there a way to set the max FRO someplace?

Thanks,
Sid
Re: What's the best way to determine motor velocity?
« Reply #1 on: April 19, 2006, 08:09:13 AM »
If it was me I would have it set to 100IPM for the max rate...
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: What's the best way to determine motor velocity?
« Reply #2 on: April 19, 2006, 08:29:49 AM »
Hey Brian!  ok 100 IPM but then if I use a FRO ove say 200% that will cause the motors to miss steps.  So, how to prevent this?  Is there a way to set a limit to the max FRO or is it something that just has to be remembered manually?

Thanks,
Sid
Re: What's the best way to determine motor velocity?
« Reply #3 on: April 19, 2006, 10:40:20 AM »
correct me if i am wrong,
but i think that if you tune your motors for 100 ipm in the motor tuning dialog, then that would be the max speed for that motor, you wont be able to go over that speed even if you have a F4000 on your gcode, or yo have a F100, and feed rate override to 300%, the speed should be limited to the 100 imp that you set on the tuning dialog.
Hope this helps
Fernando
Re: What's the best way to determine motor velocity?
« Reply #4 on: April 19, 2006, 10:51:11 AM »
Fernando,

Thanks for your reply!

One one think that this is the case, but it does not seem to be true.  I could be mistaken but it seems to me that I iif I set the motors to 100 IPM in the tuning screen, I can make the motors move faster (& miss steps) than 100 IPM by runing a program using an FRO of F200. 

That's why I asked the original question because it seems this is either a bug or I am doing something wrong (which wouldn't be the 1st time  ::) )

Perhaps most 'seasoned professional CNC-ers, don't even bother with FRO above 100%.  But if that's the case why even have that as a feature?
Sid

Re: What's the best way to determine motor velocity?
« Reply #5 on: April 19, 2006, 09:30:12 PM »
I have (in the past) redone the buttions for the FRO... I have made buttons that will not go past 125% because I program with the right rate and don't ever need more than 125%... If you would like I can give you a hand with that.
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: What's the best way to determine motor velocity?
« Reply #6 on: April 20, 2006, 01:08:37 AM »
DUDE!!!  Now were cookin' with Gas!  Yeah, I would like to create some kind of limit to the amount of FRO.  Lemme play with the machine a little and let you know what my max is.  Thanks Brian!

Regards,
Sid
Re: What's the best way to determine motor velocity?
« Reply #7 on: April 22, 2006, 02:22:03 AM »
I have a Dream....

Hey Brian,

After messing around a bit, I was able to determine my max velocity before missing steps but, there is another consideration. 

I cut different types of materials, sometime wood, sometimes foam, sometimes casting resin.  Each of these materials will use different feed rates and, of course, only allow for a certain FRO before things get 'hairball'.

That being said, is there a way to create some kind of a user definable "Max FRO" input box someplace (maybe on the settings page)?  Then if someone was runing the program and they tried to run the FRO up, they could not go past the Max FRO?  (kind of like those stupid govenors they put in all the rental trucks)

The absolute best would be if somehow, someway you could use a Gcode to set this limit and could write that limit/Gcode into each program.  I know that this idea is probably not realistic but hey, I said it was a dream.

Lemme know what you think we can do?

Thanks,
Sid
Re: What's the best way to determine motor velocity?
« Reply #8 on: April 22, 2006, 08:04:04 AM »
it is all doable ;) Now we just need a programer...

I will see if i have time in the next few days
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com

Offline DAlgie

*
  •  304 304
    • View Profile
    • Algie Composite Aircraft
Re: What's the best way to determine motor velocity?
« Reply #9 on: April 22, 2006, 10:51:49 AM »
I use Surfcam for program generation, in this, and I'm sure all CAM programs, you set the material to be cut when you generate the Gcode. You can play with the material specs to make it automatically generate the feeds and speeds you want. Example, for aluminium, it will generate a fast spindle rpm and feedrate, with hard steels a slow rpm and feedrate, and you adjust these to suit your particular machine. Unless you machine very simple parts, you need CAM, might as well use this feature as well.