RE: [CAD_CAM_EDM_DRO] Re: Stepper Motor Driver

taig and sherline both sell regularly for 2k or better
for a cnc rig. taig is used in a number of serious
settings for small parts.
taig is quite a beast for a desktop- i realllly like
it.
though i had my issues with sherline (for crap z axis)
it also will produce good parts within its limits.
but hey- the day is coming when some ppl will be
wanting to measure feed and speeds in microns! the
nano age!
and the cool thing that happens as you get smaller -
radii approach zero, wear becomes negligible, tiny
forces produce proportionately outrageous performance
-
like a bug that can lift 1000 times his weight cuz
it's just how it is on that scale of things.
i was thinking just now - if i were a gem carver, i'd
be all about 'if you can't get spindle speed of
50krpm- what good is it' cuz when you are using
cutters with diameter of .05 - you need the rpms to
get any meaningful tooth travel.
in the end - it's what you get out of the whole thing.
i think it's just plain fun! but then i'm some kind of
freak...i'd rather make it than buy it. whenever i do
buy anything, it comes out of the box and first thing
it's in pieces to see what i can hack to improve it.
oh- i have a friend who wants to make a machine
exactly like yours - i'll send him to your site.
meanwhile, i really crave to make a bunch of what i
consider tiny mills - laptop size - there's a niche
for that - jewellers, i think, primarily. and small
injection molds and stuff... i have a dream of a stack
of rack mount lappie mills. my robotic slaves chirring
and giggling out parts while i sip coffee and gaze on
approvingly...lol
nice job you did on your machine. show and tell was
always the best part of school.
sure is great to see ppl doing this - a person who's
only interest is TV and only skill is 'air guitar'
just can't inspire me.

--- Paul Kelly <tech@...> wrote:

> I guess so. We just regard anything smaller than the
> tools we have as mickey
> mouse, the next size up as "serious" and anything
> bigger as excessive. We do
> this irrespective of the size of our machines...
>
> How much does an NC taig mill cost? Gotta be around
> US$500....
> (ie, I must be right about something!)
> PK
>
> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf
> Of juan gelt
> Sent: Sunday, 2 October 2005 10:54 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: RE: [CAD_CAM_EDM_DRO] Re: Stepper Motor
> Driver
>
> lol - a topic ppl love to debate - mostly cuz it's
> quite subjective - observe how the context has been
> dropped...lol-
> the question of 'goodness' ALways presupposes an
> anwer
> to the questions: good to whom? and for what
> purpose?
>
> what you are calling tiny is not necessarily what
> someone else thinks of as tiny.
> the taig mill and sherline - with tens of thousands
> of
> happy users - can hold .001 or so, run forever on
> screws & brass nuts (cheap replacement if/when
> needed)
> and perform admirably for the uses to which they are
> put. my backlash can be tightened to .001 noooo
> problem.
> for me - 1 meter a minute is about 10 times faster
> than i'd ever dream of running it in metal - but You
> are doing wood- and a router is barely getting
> started
> at that speed...
> so, for My uses, ball screws and microstepping ARE
> wasteful expense. the parts that come off my machine
> are within tolerance.
> for Your purposes - you Do need faster and therefore
> acceleration is an issue, etc...
> Blue will be able to get excellent results cheaply
> that suits the purpose he described using his motors
> and cheap ass stepper controllers, brass nuts and
> ready-thread. i see nothing in his requirements that
> dictates a need for ballscrews or microstepping at
> all.
>
> see your 2cents and raise you a penny...lol
>
> --- Paul Kelly <tech@...> wrote:
>
> > I'll chip in my 2c worth.
> > Many people start off thinking they will build the
> > cheapest cnc machine ever
> > and that all this fussing about ballscrews,
> bipolar
> > chopper drives,
> > acceleration curves etc.. is either a pretentious
> > waste of money or a means
> > of generating speeds that they don't require. I
> know
> > I started this way. 7
> > Versions of stepper drives and at least 2 rebuilds
> > of the drive screws
> > later, I feel I am now closer to the "truth".
> Making
> > a machine you are happy
> > with on a hobby budget just isn't possible. Yes
> you
> > can experience the
> > thrill of generating motion, but important issues
> > like backlash,
> > repeatability and wear will end your project.
> > On a small project budget of say US$500 you could
> > make a TINY machine that
> > would last, maybe, and I'm talking 50um and 1m/min
> > here.
> > The technology to make a useful cnc machine is
> > reasonably advanced (in terms
> > of power and precision) and, by hobby standards,
> is
> > expensive.
> > I bet there are a lot more wood framed nc routers
> > sitting in the junk box at
> > the moment than there are cutting swarf.
> >
> > The thing is, don't be discouraged by this! Set
> > yourself some and ask for
> > help (which you have done, congratulations on
> that.
> > If only I...), when you
> > have a good idea what you want to do, cost it,
> again
> > with help. Then start
> > work.
> >
> > Now, to avoid this looking like a condescending
> > newsgroup post:
> >
> > Having stuffed up a small mill and completed a
> lathe
> > conversion I'm building
> > a tiny router/mill
> > http://www.rcmodels.net/cnc/hobby/cnc.html
> >
> > I've had the laser cutting done.
> > I have built a 3 axis drive board with some
> > additional opto isolated io
> > based on he allegro 3977 chip.
> > I built a second for a buddy who is scratch
> building
> > an NC pcb drill (he
> > felt he could do it better and cheaper, but that's
> > for another post :-)..
> >
> > I also have some other uni and bipolar drive
> > circuits for higher currents.
> >
> > I'm happy to share any of this.
> >
> > PK
> >
> >
> > -----Original Message-----
> > From: CAD_CAM_EDM_DRO@yahoogroups.com
> > [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf
> > Of turbulatordude
> > Sent: Sunday, 2 October 2005 8:06 AM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Subject: [CAD_CAM_EDM_DRO] Re: Stepper Motor
> Driver
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson
> > <elson@p...> wrote:
> > > Blue wrote:
> > >
> > > >Hi,
> > > >
> > > >I was going to use this driver with 50oz motors
> > of 1 amp using a power
> > > >supply of about 20 volts. The machine would be
> > quite small for
> > > >drilling/routing circuit boards.
> > > >
> > > >
> > > Well, you would need to add resistors. A 1
> > Amp/winding motor would not
> > > have a 20 Ohm winding resistance, or it would go
> > up in flames.
> > > So, you would need to add 2 resistors of about
> 19
> > Ohms (assuming the
> > > motor drops about 1 V at 1 A) at 360 W. Each
> > motor/drive combination
> > > would need 720 W from the power supply, so a
> > 3-axis system would draw
> > > over 2 KW!
> > >
> > > >Speed is not really an issue but I wouldn't
> want
> > o wait all day for
> > it to
> > > >finish a job. I thiught it was a cheap
> > alternative to proper drivers.
> > > >
> > > >
> > > Well, you will get your 50 Oz-In when standing
> > still, but at 60 RPM, you
> > > might have only 5 usable Oz-In, because of R/L
> and
> > resonance problems.
> > > The performance of such a drive is going to be
> so
> > abysmally below a
> > > good bipolar microstepping drive that it is
> almost
> > impossible for
> > someone
> > > who has not seen it with their own eyes to
> > believe.
> > >
> > > The IRFZ44 transistors are not properly driven
> to
> > saturation by a 5 V
> > > power supply, which is what the logic supply
> > voltage is. The logic
> > signals
> > > are not opto-coupled, which may cause noise
> > problems in a multi-axis
> > > system. There is no provision to control the
> > inductive energy when one
> > > of the transistors is turned off, which may
> cause
>

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