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Offline mikee

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motor temp
« on: July 02, 2011, 12:15:57 AM »
   hey everone  first cnc   24X 74in build your own cnc
y axis motor is alot warmer then z or x motors 
 homing and ran  first simple program or g codes  2 D 6in  circle air cut no tool  feeds and speeds  are way slow
 like gear oil in winter slow    had cnc turned on 1.5 hr   i cannot tell you exact temp at this time  motors seem to run ok         
 is it normal for one motor to run warmer than the other  is there normal opeating temp 
please advise
    mikee
not much land dam few cattle co. 

Offline RICH

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Re: motor temp
« Reply #1 on: July 02, 2011, 08:17:18 AM »
Quote
is it normal for one motor to run warmer than the other  is there normal opeating temp


Each motor temperature could be different ie; depends on the driver amp setting / wiring method for a motor, just how much work it is doing, and also the ambient temperature.
Max motor temp is based on the winding insulation and the manufacturer states what that is or recommends the max amp at a voltage.
My general rule of thumb for steppers ..... if it's too hot to hold your hand on a motor after running for some time ( which would be around 140 degrees F) change you drive amp setting.
You can get burnt at 140F.  A stepper can start to behave rather wierd if it gets too hot.
As far as time goes , I have left mine engaged for say 12 hours and they didn't get hot, i have run steppers for 6 hours constant and they were at around 130 deg F with no problems, yet
I have also run them for about 1 hour and they started missing steps, sounding differently, etc.  Different steppers ....different temperatures.
Since i have a number of different machines which all use the same controller / drivers  a switch box is used allowing me to choose a resistor which changes the driver amp setting.

If you look at a motor curve, which shows torque to rpm at some voltage, the ideal would be to have the amp setting such that you get the max power  ( speed x torque ) from the motor.
Above and below that power point is something only you can determine based on desired motor application.

Quote
feeds and speeds  are way slow

Not considering the mechanical side of your system.........
The feedrate is limited by your max velocity which will llimit your rapid move. The motor rpm can be limited by the amp or voltage being supplied.
 An extreme example of this is a low amp setting and the motor won't even turn when pulsed.

Hope the above is helpfull,
RICH
 


 

Offline mikee

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Re: motor temp
« Reply #2 on: July 02, 2011, 06:03:52 PM »
  thank you rich
  i have my motor drivers set to 1/16  at 36v  1.5 amps . 
   (velocity)  Setting
port pins. motor tuning.motor movement profile, velocity slider. is this where i would set the velocity  ???
 if possible   i am not  wanting to start guessing on setting's for the material  i m wanting to  cut  (exotic hard woods) and MDF .
  is there  a good starting point on settings for speed and feeds
 
i have a 2 1/4 hp porta cable  variable speed router 10.000 to 23.000 rpm  i have a 3/8 dia 2 flute router bit .
 
for my first  cnc cut i was thinking of 6 in circle cut at  0.0100 depth

in the tool properties # 5 calculate speeds  and feeds  when i right click on this it dosent seem to change anything. 
i can see  that i am jumping around guessing at this.     
i keep on thinking  surface speeds  for some reason . 
ok im going to change velocity  
if i am skipping steps  please get me going in the right direction  this is hard for me to understand i cannot tell you how many times i have read manual 
thank you  ;D
mikee

 
 
     

Offline RICH

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Re: motor temp
« Reply #3 on: July 03, 2011, 06:29:37 AM »
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is this where i would set the velocity
 
Yes, it's somewhat trial and error, you set the velocity for say 10ipm, try, and then keep doubling it until you find where it skips.
At that point reduce max velocity by about 30 to 40 %. Now try different acceleration values ie; if max was 50ipm try 5 for accel and then increase until you find where it skips reduce that by say 30%. The 30% below the max leaves some head room for machining etc. Experience on what you are doing will  find what you need to refine the settings to.

Quote
good starting point on settings for speed and feeds
I don't do any cnc woodworking, but, setting a feed rate at the equivalent of what you would do manually with a router for desired result would be a good starting point.
 Some of the exotic hardwoods sort of machine like  metal....and don't cut the rock in Ebony ....... ;D
Surely the router folks in here can give you better guidance.

RICH

Offline ger21

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Re: motor temp
« Reply #4 on: July 03, 2011, 07:47:41 AM »
1.5 amps sounds like some very low powered motors. Do you have one of those inexpensive Chinese packages with big motors? If so, you might not be able to get a lot of speed out of it.
How are you driving the machine? Acme screws, or rack and pinion? Ballscrews?

I cut MDF at 125-150ipm, and around 12,000-14,000 rpm. This is limited by the speed of my machine.
My day job is programming a large industrial router, which can cut MDF in one pass at 1000ipm, and 16,000 rpm with a 1/2" bit.

You should be able to cut hardwoods at similar feedrates to MDF. You may be able to slow the rpm down a bit, but it depends on the quality of the cut. Higher rpm's can give better quality cuts, but will shorten bit life, as more heat ids generated at the cutting edge.
Gerry

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

JointCAM Dovetail and Box Joint software
http://www.g-forcecnc.com/jointcam.html

Offline mikee

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Re: motor temp
« Reply #5 on: July 03, 2011, 07:28:32 PM »
 hey rich Gerry
 Gerry this is what i have build your own cnc black toe 2ft x 8 ft x and y chain drive #25 chain 9 tooth sprocket's 1/4 pitch steppers set at 1/16 1.5 amp's 36 DCV  all the same on z axis except acme 10tpi with 5 starts
 i tuned motors i have normal toggle controls  speeds   any speed a person wanted my next posting i will say what i have motors set to  
  when running g code I'm very slow even when i use override the feed on mach3 s i not sure what to do now
i found how to set motor profile in the manual that i have read 20 times and over look 20 times (sorry rich)  i am a slow learner
I did set motor velocity and accell 
 installed Multie leads for pyrometer on all motor's as soon as i can get my feed rate to what i think would be normal operating speed i will know if i really have problem with motor getting too hot .
 i was worried motors being wired incorrectly i have check my wiring it is  Good i didn't want to burn a motor up
i have normal toggle speeds
 still to slow running g codes  
i will reread what you guys have suggested and the manual again
I'm not sure what i have over looked or done wrong?  on   if i need to fix this by tuning the motors again  or if it is me not setting the feed rate properly
 before when Y axis  motor getting warmer than the other motors i had to put my hand on motor to feel if it was turning
when running g codes the cnc is not running to the motor profile's
this is where i am reading in the manual 5.5.2 to 5.5.4
 thank you  
mikee

Offline mikee

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Re: motor temp
« Reply #6 on: July 03, 2011, 11:53:37 PM »
 got it guys at least some of it
  in the mach 3 addons in the tool  properties select surface speed  i was right clicking carbide  by doing so i  auto sets surface speed no matter how many IPM you put  in
 other part not fixed  how many ways is there to set feed rate
 motors are not running warm now   i did my fist cut  the circle  little flat on both sides   (my new  next problem)   
 i learned today
 motor profile  150 IPM
thank you rich and jerry 
i could  not of done it with out you guys
mikee
not much land dam few cattle co.

Offline mikee

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Re: motor temp
« Reply #7 on: July 04, 2011, 12:59:31 AM »
gerry i liked how you zero everythime   how hard would that be on my cnc