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  #31  
Old Tue 10 June 2008, 13:40
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Doug, what's your power supply voltage, and any comment on the motor temps.? (The amount of work that the motors do is not a major factor in their heating - just standing idle often gets them the warmest)
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  #32  
Old Tue 10 June 2008, 14:04
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Gerald,
It might be interesting to know if the guys are running with the current setback feature of the geckos enabled? Dont they have a setback current when the motor is not moving for a period to reduce heating? I think Art changed this to help his setup at one time.
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  #33  
Old Tue 10 June 2008, 14:33
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
The guys with G203's don't have that option. But that issue is not going to help me decide what wiring option and voltage to select for the PK296A2A-SG7.2 motors that I must start working with soon. Still looking for anecdotal evidence of what guys are seeing with this particular motors and what wiring/voltages they have.
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  #34  
Old Tue 10 June 2008, 22:04
dmoore
Just call me:
 
Bipolar Wiring

PK296A2A-SG7.2 motors

53.8v at Gecko input

33K Resistor on Geckos

After cutting 90% of 4'x8' MDF sheet down .05" with 1" surfacing bit at ~60 IPM the temps were:

Both X's: 115-120F
Y and Z's: 92-94F

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  #35  
Old Tue 10 June 2008, 22:17
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Quote:
Originally Posted by Gerald D View Post
Doug, what's your power supply voltage, and any comment on the motor temps.?
I built a 35V PS. I haven't touched the motors so I can't answer your question. It's late now and I'm just reading this post but tomorrow, I'll come home from work and turn the machine on and since idling will still make it heat up, I'll let her sit for a while. Then I'll give you a report tomorrow evening. Unless you tell me you want me to do something different like cut or jog.
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  #36  
Old Tue 10 June 2008, 23:12
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
The greatest heat with the Gecko G203v would probably be obtained when an axis is moving very slowly.

Here is the quote from the G203v data sheet:

"AUTO CURRENT REDUCTION: The G203V reduces motor phase current to 71% of the set current value 1 second after the last step pulse is sent. The G203V also changes to a special recirculating current mode to nearly eliminate motor heating."
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  #37  
Old Wed 11 June 2008, 00:02
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Mike, I don't know if you are running the motors on a test bench or on a router table......do you have a preference for either half or full coil for routine and diverse router work?

Doug, if it is not too much trouble, could you drop the y-motor away from the rack, set a very slow (crawl) move speed, and then rig something to hold the cursor key down on your keyboard while you go and have a nap on the sofa?

Thanks everyone for the contributions so far.
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  #38  
Old Wed 11 June 2008, 00:04
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by Richards View Post
The G203V reduces motor phase current to 71% of the set current value 1 second after the last step pulse is sent. The G203V also changes to a special recirculating current mode to nearly eliminate motor heating.
If memory serves me right, the first G203V's dropped the current to 50% - I think Art had some of those.
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  #39  
Old Wed 11 June 2008, 04:35
smreish
Just call me: Sean - #5, 28, 58 and others
 
Orlando, Florida
United States of America
So,
I did a little test yesterday.
I turned on the table 1st thing, and let it sit IDLE the entire day.
Just luke warm motor's at the end of the day (8 hrs later).
Recirculation (or whatever technology is used) seems to work just fine with my G203's
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  #40  
Old Wed 11 June 2008, 06:26
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
OK, now it's starting to make some sense.

Last evening while setting up the Shuttle Pro, the motors were left on not moving or moving very slow for a couple of hours. The warmest motors were the X axis and it was "luke warm" (very little heat).

I should have a new temperature gun today.
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  #41  
Old Wed 11 June 2008, 07:28
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Gerald,

Will do. Is an hour long enough?
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  #42  
Old Wed 11 June 2008, 07:36
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Gerald,

I prefer half-coil connection. That costs me about 30% of the full-coil torque, but it gives me much higher speed. Assuming that the motor is the PK296A2A-SG7.2, the gear box could never deliver all of the torque that the motor generates but the gear box can deliver the speed (up to 500 RPM, which would be about 40 inches per second - which would be impossible, given the mass of the various axes).


My work is almost 100% cutting cabinet sized parts from MDF. I can use all the speed that a motor can give me. On the other hand, if I were doing 3D or work that required slow speeds (1 to 2 inches per second), wiring the motor full-coil would be more practical.
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  #43  
Old Wed 11 June 2008, 08:09
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Thanks Mike, my reasoning is that the very slow CNC work (like 3D) will not require the high torque that full coil will provide. I will pursue the half coil configuration, and a supply voltage that gets the motors nicely "hot" but not quite toast. . . .

Thanks Doug, an hour should do.
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  #44  
Old Wed 11 June 2008, 18:29
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Gerald,

I hope you don't mind but I stopped the test after 30 minutes. I set the motor for about 10 RPM and forgot about it for the first 15 minutes. After that point, I kept checking the motor and the temperature didn't change between 15 minutes and 30 minutes. It was warm but I could have easily kept my hand on it forever. Nowhere near as warm as a fresh mug of coffee which is too hot for me to keep my hand on. Maybe as warm as a ceramic mug of coffee that was poured 5 to 10 minutes ago.

If you need me to go for a full hour or run it at a slower RPM or any other test, please let me know.
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  #45  
Old Wed 11 June 2008, 22:07
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Thanks a lot Doug! If the temperature stabilised within 30 minutes, then the test was long enough. What was the approx ambient temperature in your workshop at the time of the test?
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  #46  
Old Thu 12 June 2008, 09:58
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
It was in the mid 80s in my garage. Sorry but I don't know what that is in Celsius.
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  #47  
Old Thu 12 June 2008, 10:00
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
85F is about 29C
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  #48  
Old Thu 12 June 2008, 11:29
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Doug,

Have to give you a hard time on that last unacceptable answer.

Your a MechMate builder of international means.

http://www.onlineconversion.com/temperature.htm
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  #49  
Old Thu 12 June 2008, 12:37
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Greg,

I know. I know. Pretty lame excuse on my part but I figured that Gerald had the conversion equation in his head.

PS. Thanks Heath.
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  #50  
Old Thu 12 June 2008, 12:55
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Doug,
I still prefer F Measurements for hot weather but like C measurements when talking about cold weather.
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  #51  
Old Thu 12 June 2008, 14:08
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Connected a motor/gecko/supply together tonight and left it switched on, non-moving, unipolar/half-coil/39V supply for 2 hours. . . .

Well, if I did not measure the slight rise in temp, I would have sworn it did not heat up at all. The increase in temp was only 5.2C [9.6F]

Now I must find a simple way to feed steps to the gecko to dupe its current reduction mode . . . . .
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  #52  
Old Thu 12 June 2008, 22:56
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Another Data Point

Conducted this test tonight,

Motor - PK296A1A-SG7.2 (unipolar/half-coil 7.7mH, 88.8Volt "capable")
PS - 70 V
Gecko Drivers - G203V (current limit resistors 12.8k for 1.5Amp?)
Condition - No motor moving.
Time - 2 hours
Ambient Temperature - 90 deg F

Increase in Temperature,
X motor - 6 deg F
A motor - 6 deg F
Y motor - 1 deg F
Z motor - 7 deg F

All four G203V's showed no increase. Actually, the temperature decreased as the ambient temperature decreased.

Conducted a second test on the Z motor. I operated the Z motor up and down at 200 ipm for 5 minutes. The increase in temperature was an additional 6 deg F for a total (1 hour, 5 min) of 12 deg F.
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  #53  
Old Fri 13 June 2008, 00:02
Kobus_Joubert
Just call me: Kobus #6
 
Dalview
South Africa
Send a message via Yahoo to Kobus_Joubert Send a message via Skype™ to Kobus_Joubert
Did some testing on my setup:
4 x Geckos G 202's ...with 100k resistors...between 4 - 5 Amp
4 x MotionKing 34HS9801
42 volt AC transformer
Set X-axis (+slave) on SLOWWWWWW rev's
Set Y and Z on a nice Fast pace.
Stuck some tape on keyboard and waited

Observed the following after about 30 minutes:
the Y + Z motors were hotter than the X- motors. All four nice and hot...could keep my hand on it without any problem.
What I did notice.....not measured.. is that the Gecko's on the X-motors were or felt hotter than the Y + Z Gecko's.
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  #54  
Old Fri 13 June 2008, 00:26
dmoore
Just call me:
 
Quote:
Originally Posted by Gerald D View Post
Now I must find a simply way to feed steps to the gecko to dupe its current reduction mode . . . . .
Run a job in Mach3?
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  #55  
Old Fri 13 June 2008, 01:06
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
This test is at my home workbench - no Mach3 there.....yet
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  #56  
Old Fri 13 June 2008, 03:27
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Greg, even though your motor is the A1A version, your measured results agree with mine.....While the geckos are idle in current reduction mode, the heat rise is minimal (below 10 F).

I have a feeling we can set these Oriental Motors quite a lot higher than the cheaper motors (our money must have bought us something extra?). Greg, your options are limited by the A1A version - you have about the best you can do with the voltage. But, is your current set resistor on the gecko at 13kiloOhm, verified by measurement?
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  #57  
Old Fri 13 June 2008, 03:35
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Kobus, you bordered on an interesting test . . . . .
If you had set all 4 motors for a low speed, then you should have blown your main power supply! The calc for power supply size assumes that only some motors are drawing peak power, not all of them.

Well, glad to hear that the MotionKings are staying cool enough. That passes their first test. Watching your tests with those "cheap" motors keenly!
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  #58  
Old Fri 13 June 2008, 07:32
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Gerald,

I'll check resistance tonight.

Watching this thread with interest. May already be "upgrading" to A2A version.
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  #59  
Old Fri 13 June 2008, 09:11
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Greg, nobody is yet saying that the A2A is performing better than your A1A. The jury is still out. (Suspect there is not much difference except that the A2A gives you the option of going bipolar with the G203)
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  #60  
Old Fri 13 June 2008, 15:41
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Greg,

I have a PK299-02, which has inductance similar to the PK296A1A-SGxx motor. In half-coil mode, the PK299-02 is very impressive. The problem with that motor is that when connected full-coil, the Gecko G20x drives cannot handle enough voltage to take full advantage of the stepper motor. I would not feel handicapped using the PK296A1A-SGxx motor, when wired half-coil. In theory, the A2A motor would perform a faster, but I doubt that you would be able to tell much difference - if both motors were connected to the proper voltage power supply.
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