Re: [CAD_CAM_EDM_DRO] Re: Check my math and reasoning....

Brady,

If that is the case than 70 volts may be OK. Typically when using Gecko
drives I look at the 20 to 25 tune. Sometimes if necessary the 5 to 20 rule.

I like to run my stepper motors at a voltage that is about 20 times the name
plate voltage. At least it seems to work for me. With Gecko drives you do
need to keep it below the 80 volt maximum. I like to keep it below 70 volts.

If the voltage is going to be the same for both the servo and stepper
motors, than one supply most would likely be OK.


Bob Campbell
Bob@...
www.campbelldesigns.com
Breakout board
THC board sets
CNC router plans
Stepper Motors
VisualMill Basic

----- Original Message -----
From: "braidmeister" <braidmeister@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, June 27, 2005 6:13 PM
Subject: [CAD_CAM_EDM_DRO] Re: Check my math and reasoning....


>I have no idea as the nameplate on the Sigma stepper is buried (only
> shows wiring schematic). I was told by a very reputable source on
> driving steppers that the Nema42 motors need the higher voltage &
> that this would push the torque curve up a little higher than stock
> configuration. The original supply, I believe is 60v for these
> steppers...I sincerely doubt that an increase of 10v would have any
> negative effect.
>
> -Brady
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Robert Campbell" <bob@c...>
> wrote:
>> Brady,
>>
>> Just one more question. What is the name plate voltage on your
> stepper
>> motors?
>>
>> Bob Campbell
>> Bob@c...
>> www.campbelldesigns.com
>> Breakout board
>> THC board sets
>> CNC router plans
>> Stepper Motors
>> VisualMill Basic
>> ----- Original Message -----
>> From: "braidmeister" <braidmeister@y...>
>> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
>> Sent: Monday, June 27, 2005 5:28 PM
>> Subject: [CAD_CAM_EDM_DRO] Re: Check my math and reasoning....
>>
>>
>> > Thanks Bob. What would be the result of running the larger
> ampacity
>> > supply (@70v) over one that had less amps for the steppers?
>> >
>> > Drives will be 202s for the steppers and 320/340s for the
>> > servos...same 70v requirements just different ampacities.
>> >
>> > -Brady
>> >
>> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Robert Campbell"
> <bob@c...>
>> > wrote:
>> >> Brady,
>> >>
>> >> You need to separate the calculations for stepper motors and
> servo
>> > motors.
>> >>
>> >> I would suggest that you build two power supplies. One for the
>> > stepper
>> >> motors and one for the servo motors.
>> >>
>> >> One of the limiting voltage factors will be the drivers that you
>> > are going
>> >> to use. The Gecko drives have an 80 volt limit. I would keep it
> at
>> > about 70
>> >> volts.
>> >>
>> >> I would recommend that you look for 100 volt capacitors. You can
>> > always hook
>> >> them in parallel to get more capacitance.
>> >>
>> >> Bob Campbell
>> >> Bob@c...
>> >> www.campbelldesigns.com
>> >> Breakout board
>> >> THC board sets
>> >> CNC router plans
>> >> Stepper Motors
>> >> VisualMill Basic
>> >> ----- Original Message -----
>> >> From: "braidmeister" <braidmeister@y...>
>> >> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
>> >> Sent: Monday, June 27, 2005 5:04 PM
>> >> Subject: [CAD_CAM_EDM_DRO] Check my math and reasoning....
>> >>
>> >>
>> >> > OK gang,
>> >> > I am trying to piece together my power supply and have a few
>> >> > questions regarding the rated voltage for a capacitor. I am
>> > finding
>> >> > that most use 50v caps and they are cheap and available...I am
>> >> > wondering at this point if I am missing something...here's
> where
>> > I am
>> >> > and where I want to go with the PS:
>> >> >
>> >> > I am running Sigma N42 motors on the Bridgeport and the manual
>> > says
>> >> > that they are 6.8A. I would like to build a power supply with
>> > enough
>> >> > juice to power these 3 steppers AND an 11A Servo for the 4th
> axis
>> >> > down the road. I will eventually need to run 4 of these 11A
>> > servos @
>> >> > 70v ~ so I am thinking why not just build one supply and be
> done
>> > with
>> >> > it?
>> >> >
>> >> > Right now I have 2 50v (what decal says on each...but
> advertised
>> > as
>> >> > 55v when I bought them) 800VA torid transformers. I bought 2 at
>> > the
>> >> > time so that I would have enough amperage to run the 4 servos.
> Now
>> >> > comes the question of capacitors...I need caps are rated by
>> > voltage
>> >> > after being rectified, right?...In this case at least 80v...not
>> > 50v,
>> >> > right??? I searched around on here and didn't see any
> reference to
>> >> > this.
>> >> >
>> >> > So...If my math is correct, I will need (using the servo motor
>> > draw
>> >> > as a guideline) Assuming 50v rectified to 70v by the 2 torids:
>> >> >
>> >> > 44Amps * 67% (from Campbell's pdf) = 29.5A
>> >> >
>> >> > C= (80,000 * I) / V)
>> >> > (80000 * 29.5) / 70 = 33691 uF
>> >> >
>> >> > Could I get away with 3 P10653-ND from DigiKey? They are 12,000
>> > uF @
>> >> > 100v +/-20%.
>> >> >
>> >> > Did I do my math right...or am I missing something???
>> >> >
>> >> > Thanks!!!
>> >> > -Brady
>> >> >
>> >> >
>> >> >
>> >> >
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>> > http://groups.yahoo.com/group/jobshophomeshop I consider this
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> there, for
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> [Moderators]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> 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://groups.yahoo.com/group/jobshophomeshop I consider this to be a
> sister site to the CCED group, as many of the same members are there, for
> OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
> DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> bill
> List Mom
> List Owner
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>
> Yahoo! Groups Links
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