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Message |
    
Gerald_D
Registered
Username: Gerald_d
Post Number: 335
Registered: 11-2005
| | Posted on Saturday, October 28, 2006 - 07:53 am: | 
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This is probably the part of the MechMate that needs the least discussion - get Geckodrives! 
The G202 is the right one for now. It is 15 year old proven technology, but still up there with the best.
You need 4 of these G202's for a MechMate
(March 2007 - G203 drives are becoming a reliable option - see post lower down)
(If you are using an already packaged control box, then you don't need to buy drivers...) |
Gerald_D
Registered
Username: Gerald_d
Post Number: 336
Registered: 11-2005
| | Posted on Saturday, October 28, 2006 - 12:18 pm: |
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GeckoDrive will soon launch a newer version of the G202, which will be known as the G203 "Vampire". These are the features:
1. Short-circuit protection
2. Reverse polarity protection
3. Over-temperature protection
4. Over-voltage protection
5. DISABLE input is optoisolated
6. STEP, DIRECTION and DISABLE are COMMON ground
7. STEP, DIRECTION and DISABLE work with 2.5V, 3.3V and 5V logic
8. STEP, DIRECTION and DISABLE need only 2.5mA
9. STEP pulse frequency to 350 kHz
10. No funny DIRECTION to STEP pulse timing. 200nS setup/hold times
11. 0 to 7A phase current
12. 18 to 80VDC supply voltage
13. Recirculate mode while stopped for reduced motor heating
14. No user jumpers or settings inside
15. Top settable ADJUST trimpot
16. Green POWER LED, red ERROR LED
17. Internal socketed power fuse
18. Crystal-controlled 19.531 kHz switching frequency
19. No external 470uF/100VDC capacitor needed
20. Power-on reset
Snag is, the G203 is a totally clean sheet design with zero exposure to the real world yet. The G202 has evolved and is fully debugged. The people living close to GeckoDrive can "experiment" with the G203, but I suggest to stick to the G202 if you live more than a 1000 miles from California. Geckodrive will not be withdrawing the G202 from the market until there is a natural swing away from it. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 356
Registered: 11-2005
| | Posted on Wednesday, November 01, 2006 - 07:30 am: |
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The press release by Mariss last night:....
Good evening! The G203V drive gets introduced for sale tomorrow.
The G203V is our first attempt at a truly bullet-proof drive. Short
it, run it without a heatsink, overvoltage it, miss-wire motors,
reverse power supply polarity; throw everything at it save dunk it in
saltwater or fill it with metal chips. The worst consequence it will
suffer is to replace an internal socketed 20-cent fuse.
The "V" in G203V stands for "Vampire" as in cannot be killed. It
incorporates everything we have learned in the last 6 years about how
good drives wind up dead.
New features have been added and many annoyances have been removed.
The G203V does'nt need external capacitors, the ADJUST tripot is now
top-adjustable, the motor stays very cool when stopped, there are no
jumper settings at all, The DISABLE input is optoisolated, the STEP
and DIRECTION inputs are common-ground, it works with 3.3V logic (no
breakout board needed), no "funny" G2xx timing restrictions, power LED
and error LED indicators and more.
All the good things have been kept. 33A at 100VDC MOSFETs and 100VDC
tested power section, same package size (G201 package) and the same
terminal pin-out, the same mounting-hole pattern.
What this means to you if you are a reseller is drive-related service
calls, support and drive replacement should drop to nil. The worst
case customer service response will be "sort out the problem and
(maybe) replace the fuse". The G203V is targeted at never having to
replacing the drive.
Caution: The G203V is an entirely new clean-sheet design. Circuitwise
the G203V shares absolutely nothing with its predecessors. As such it
has absolutely no history. The older G2xx drives have a 20-year design
history where every vice has been bred out of them. They simply have
no uncovered bad behaviors or surprises left.
The G203V is completely new. I will not feel comfortable with this new
design until there are at least 6 months and 5,000 user's experience
under our belts.
Pricing is $147 singles, $114 at 1K quantity. See the files section
for the preliminary user's manual.
Mariss |
Dan Mauch
Registered
Username: Dmauch
Post Number: 1
Registered: 11-2006
| | Posted on Friday, November 17, 2006 - 04:13 pm: |
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I have been testing some of the first batch of the G203. They are awesome. There is only one problem with them. That is he uses a new disable function. I use this for manually position my machine. The issue that Mariss said he will address is that once you disable the outputs it take about 1-2 seconds for this to occur. At the speeds you use for routers this can be quite a problem. The other issue is that if a motor does cause a reset then only that axis is affected. I have suggested that he change the design so that if one driver faults they all fault. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 466
Registered: 11-2005
| | Posted on Friday, November 17, 2006 - 05:11 pm: |
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Welcome to this forum Dan. So, my opening line at the top of this thread "The G202 is the right one for now" still holds true
I don't envisage a router user wanting to disable the drives (to make motors freewheel) while anything is moving - so the fact that a router may move faster than other CNC machines doesn't seem to apply. |
Dirk Hazeleger
Registered
Username: Dirk
Post Number: 47
Registered: 12-2005
| | Posted on Saturday, November 18, 2006 - 02:38 am: |
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Hey Dan
What do you see as the performance difference between a 203 and a 202. It sounds like you can get higher rpm out of the steppers. Is this true?
Any idea as to why?
Dirk |
Gerald_D
Registered
Username: Gerald_d
Post Number: 587
Registered: 11-2005
| | Posted on Tuesday, December 05, 2006 - 10:23 am: |
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Sales of the G203V have been suspended for a while because there are bugs to iron out. The next update is due out on 22 December.
The tried and tested option is still the G202. It is suggested that you only consider the G203V if you are near to the GeckoDrive offices and that returns for updating are viable. |
Gerald_D
Registered
Username: Gerald_d
Post Number: 712
Registered: 11-2005
| | Posted on Monday, January 15, 2007 - 08:00 am: |
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Something mentioned by Gecko on their forum last night:
"........all our step motor drives morph from a
sine/cosine reference to a full-step (quadrature) reference at higher
speeds.
Microstepping has a huge benefit below 2 revs/sec. It makes the motor
move smoothly without resonances and other bad bad motor behavior.
Microstepping loses all benefit above that speed and becomes a net
deficit above 4 revs/sec. It's an "area under the curve" thing; the
sine function has pi/4 (78%) the area a square-wave has. That means
only 78% of the potential torque a full-step drive has.
Secondly, persisting with a sine reference generates aliasing
frequencies between the drive's 20kHz switching rate and the step pule
frequency that pump the motor into parametric resonance (mid-band
resonance).
So what do we do? We morph the reference from sine/cosine to a
full-step quadrature square-wave reference beginning at 4 and
finishing at 6 revs/sec. The result is the motor delivers every last
Watt of its potential performance to the load.
The motor 'thinks' it's being driven by a full-step drive above 4
revs/sec but it still takes 10 step pulses from your controller to
generate a full-step (1.8-degree motion) from the motor.
The anti-resonance (mid-band or parametric resonance)damping circuit
insures the the motor will not waste its available torque resonating
above that speed (4 revs / sec). It effectively adds about 80 degrees
of phase lead to the system loop.
End result? Your motor delivers all its potential to the load. Nothing
is wasted; stratigies that add performance at low speeds
(microstepping) get switched-out when they become a hurt instead of a
help. Other circuits prevent the motor from doing wastefull things
(mid-band compensation). Your motor delivers all it has to give.
Other circuits manage motor heating when it is stopped and resting.
More than any other motor type, step motor performance depends on the
drive running it. A crap drive gives crap results on a step motor. The
same motor driven with a good drive tames all the motor's vices and
makes it sing. It is a motor on steroids when driven with a good drive." |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1107
Registered: 11-2005
| | Posted on Monday, March 05, 2007 - 12:44 pm: |
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Revision 5 of the G203V has just been launched. Apparently the teething problems are ironed out now.
From the Geckodrive company, one could use either the G201, G202 or G203V drives. With the door of the control box closed, I don't think that anyone will be able to tell which drives are in the box when the MechMate is cutting away.....
The G201 needs an external capacitor and a fuse. $114
The G202 needs an external fuse only, but it is wider. $134
The G203 needs nil external components and is back to the narrow footprint. $147
The internal fuse of the G203V is unknown out here. You might also have difficulties in locating an exact replacement. Explore the option of buying spare fuses with your G203. |
James Webster
Registered
Username: Wti
Post Number: 24
Registered: 02-2007
| | Posted on Monday, March 05, 2007 - 07:36 pm: |
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The internal fuse of the G203V is a 5A axial fuse (it looks like a green resistor, not glass). It is made by LittelFuse part #0251005.MXL . $.43 USD each:
http://www.mouser.com/search/ProductDetail.aspx?R=0251005.MXLvirtualkey57610000v irtualkey576-0251005.MXL |
Gerald_D
Registered
Username: Gerald_d
Post Number: 1110
Registered: 11-2005
| | Posted on Monday, March 05, 2007 - 07:50 pm: |
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Mariss on his Yahoo forum this morning said he could supply a spare fuse with a G203V at cost ($.22).
I can find similar looking fuses here in S.Africa, but not the Littelfuse version. Don't know if these will fit the socket when crunch time comes. |
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