RE: [CAD_CAM_EDM_DRO] Why is my feedrate slow with stepper motor

I'd like to point out one additional cause of low maximum speeds, even with
the chopper motor controllers - any "add on" software such as some versions
of EMM386 that steal time during the PC's 18.2 millisecond clock interrupt.

I encountered one situation with a low end (Zenith Z-Star EX - 486DX2-50
processor, 8 mbytes ram running Novell DOS-7) where Novell's EMM386 memory
manager stole enough time during the clock interrupt to make the step pulse
train to the motor drivers unsteady enough that the motors would stall out.
By eliminating the driver, I was able to increase my max speed from about
900 steps/second to 4000 steps/second.

I agree with Jan, that your immediate problem is most likely the use of 12
volts to power the circuit and also with his comments regarding the chopper
drivers. I chose the other "vendor" for my machine - Camtronics, and bought
Dan's 2 amp kit. It does require assembly (Gecko's are prepackaged modules)
but it worked the first time and I'm happy with the results.

-- Carol & Jerry Jankura
Strongsville, Ohio
So many toys, so little time....


|-----Original Message-----
|From: JanRwl@... [mailto:JanRwl@...]
|Sent: Saturday, March 23, 2002 12:29 AM
|To: CAD_CAM_EDM_DRO@yahoogroups.com
|Subject: Re: [CAD_CAM_EDM_DRO] Why is my feedrate slow with stepper
|motor
|
|
|In a message dated 22-Mar-02 22:06:14 Central Standard Time,
|rnichol1@... writes:
|
|
|> Is this normal for stepper motors? I'm thinking of designing a
|> current limiting or chopper(?) circuit but do not know electronics.
|>
|> I'm guessing others have been here already. Will a chopper circuit
|> work? could the k-cam software be part of the problem (I get
|> a "stop" for one cycle every rev that gets more pronounced with speed
|> rate)
|>
|> Any comments / advice?
|
|
|Roger: This is what it's all about! A properly designed stepper-motor
|driver of either the "old" L/R type, or the new ("only kind to
|even consider
|these days!") "bipolar chopper drive" usually takes-in at least 24
|VDC, and
|feeds the motor with "constant current" (well, ideally, anyway).
|12 VDC is
|way-low!
|
|Why re-invent the wheel? A couple of guys on this group manufacture/sell
|bipolar-chopper drives, and MY choice is Mariss' Gecko Drive G210.
| It does
|what you want, AND will keep the speed "up", if your DC supply is
|at least 24
|volts. Maybe on up to 80! Mariss might comment. HIS advice is gospel!
|
|Jan Rowland
|
|
|[Non-text portions of this message have been removed]
|
|
|Addresses:
|FAQ: http://www.ktmarketing.com/faq.html
|FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
|
|OFF Topic POSTS: General Machining
|If you wish to post on unlimited OT subjects goto:
|aol://5863:126/rec.crafts.metalworking or go thru Google.com to
|reach it if you have trouble.
|http://www.metalworking.com/news_servers.html
|
|http://www.jobshophomeshop@yahoogroups.com I consider this as a
|sister site to the CCED group, as many of the same memembers are
|there, for OT subjects, that are not allowed on the CCED list.
|
|
|
|Post messages: CAD_CAM_EDM_DRO@yahoogroups.com
|Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
|Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
|List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...
|Moderator: jmelson@... timg@... [Moderator]
|URL to this page: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
|bill,
|List Mom
|List Owner
|
|
|
|Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
|
|
|
|
|