RE: [CAD_CAM_EDM_DRO] Re: Xylotex Pwr Sup replacement

Absolutely agree with you but the "feel" that I picked up on Chuck's
original post was that he wanted something fast and also cheap and was not
dis-inclined to roll his own.

Switchers are the way to go if you can get them but for cheap brute force, a
microwave oven xformer is right in the sweet spot.

Dave

> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Danny Miller
> Sent: Sunday, November 13, 2011 2:58 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Re: Xylotex Pwr Sup replacement
>
> I don't recommend this at all. Line-freq transformers and
> rectifiers/caps are just absurdly bad for CNC use.
> I'm not saying it won't work. But the voltage is poorly
> regulated and
> it'll take a large, unnecessary amount of $ to even try to get the
> regulation and safety features "proper". 60Hz requires very large
> filter caps, variations in line voltage cause variations in
> the output,
> and it draws very dirty power on the input with a leading
> current. The
> industry dropped line-freq transformers like 10 years ago for
> this and
> many other reasons.
>
> It's an unjustifiable risk, considering what overvoltage will do to a
> driver.
>
> There's a 48v 7.3A power supply all over eBay for <$40, and they're
> GREAT. Geckodrive recommends a guideline that the supply current be
> rated for 0.6x the sum of the phase currents; this could do
> 4x 3A NEMA23's.
>
> If you require MORE current, you can go totally over-the-top
> with a Sun
> rack supply:
> Sun Sunfire V480 Server 300-1490 Hot swap Power supply 48v 24.5A
> Sun V880 AC Power Supply P/N 300-1353 48v 15.6A
>
> Either one of those can be had for under $40 on eBay. Yup, 1176W of
> top-quality regulated 48v for $33.
>
> Danny
>
> On 11/13/2011 4:35 PM, Dave Halliday wrote:
> > I have mentioned a few times before but a microwave oven
> has an excellent
> > transformer for this purpose.
> >
> > #1) - do not play with it (plug it in) while the high
> voltage winding is
> > still in place. The voltages and currents developed can be
> instantly lethal.
> >
> > #2) - because the high voltage winding is so high (around
> 2,500 volts), the
> > primary and the secondary windings are separate. Most
> transformers have
> > these wound on top of each other. This allows you to
> remove the high
> > voltage winding with a hammer and cold chisel. There will also be a
> > filament winding -- two or three turns of thick wire; this
> can just be
> > unwound.
> >
> > #3) - wind ten turns of insulated wire around where the
> high voltage winding
> > used to be, power it up and measure the resultant voltage
> on your new
> > secondary. Divide by ten and this will be your turns/volt.
> >
> > You can then figure out from there how many turns are needed.
> >
> > The advantage of these is that dead microwave ovens are free and the
> > transformer is good for 500-800 watts continuous power.
> Excellent for
> > projects like this.
> >
> > Dave
> >
> >> -----Original Message-----
> >> From: CAD_CAM_EDM_DRO@yahoogroups.com
> >> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of
> turbulatordude
> >> Sent: Sunday, November 13, 2011 9:08 AM
> >> To: CAD_CAM_EDM_DRO@yahoogroups.com
> >> Subject: [CAD_CAM_EDM_DRO] Re: Xylotex Pwr Sup replacement
> >>
> >> you really need to keep the voltage lower.
> >> remember that the decel of a drive will spike the power
> >> supply. fast decel times can make the voltage jump.
> >>
> >> if you can put your hands on a computer battery back-up, you
> >> can get some high amps from the transformer.
> >>
> >> also, a car charger will have a large transformer.
> >>
> >> you will still need capacitors and diodes to get DC from
> >> these AC units.
> >>
> >> you can lower the amp rating of the drive temporarally while
> >> waiting for the perfect fix.
> >>
> >> all electronics offers power supplies that are DC, you should
> >> be able to get one in a few days.
> >>
> >> Dave
> >>
> >> --- In CAD_CAM_EDM_DRO@yahoogroups.com,
> "ebiz_59"<chuckm@...> wrote:
> >>> Murphy bit the Xylotex box on our minimill tonight. It
> >> appears as though the 24V 6A power supply gave up the ghost -
> >> just when we were FINALLY making our first part for our FTC robot.
> >>> So I need some ideas for replacing this power supply
> >> quickly. I think I saw a 30V power supply on an HP printer
> >> the other day, but I'm thinking it was only a couple amps.
> >> And I think I might have a 15-20V 4ish amp laptop supply
> lying around.
> >>> Any other thots? And what are the odds that the Xylotex
> >> drives are OK if this power supply board is only putting out
> >> like 1.5V? Should I be looking for another set of stepper
> >> drivers too?
> >>> Ugh! Chuck
> >>>
> >>
> >>
> >>
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> > http://www.metalworking.com/news_servers.html
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> > 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........
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> 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
>
> Yahoo! Groups Links
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>
>