Re: Lost steps

Dave,
Thanks much for the try but you are talking way beyond my knowledge.
That is part of my problem, I have tackled a project way beyond
anything that I know about.
I have some machining knowledge, most of which I learned about over
40
years ago. I bought a Shoptask that already had three stepper motors
and began to learn about CNC, which I'd never heard of before buying
the machine.
By reading this and other sites I got the idea I could make mine a
CNC
machine for small dollars. I built some "Hi-FI" kits back in the
70's,
and thought, how tough can it be. I now know! Maybe impossible for me.

Jerry




--- In CAD_CAM_EDM_DRO@egroups.com, dave engvall <dengvall@n...>
wrote:

> Been following this thread and some interesting ( and good ) ideas

have been advanced but I'll throw out one more. When in doubt

> drop back to basics. This assumes you have a few chips to play with

or a computer with some parallel bits to play with.

> Make a set of drivers so each bit switches a stepper coil off or

on.
Set up a bit sequence to step the motor either forward or

> back. ie. some of this was shown in the discussion on the 5 phase

states.

>
> Use the computer to step thru the sequence. Try different step

rates, and supply voltage, dropping resistors in series with each

> winding. Since this in independent of the orginal setup, except for

power supply it may give you some hint of what is picking on

> you. Best of luck.
>
> Dave
>
> Ozzie@h... wrote:
>
> > Okay we have some discussion of wire sizes, power supply,

decoupling

> > caps!
> > The main power supply is two transformers, 10A each in parallel,
> > feeding to a rectifier and then a big capacitors, all supplied by
> > Camtronics, with knowledge of what I was building.The wires

supplying

> > motor voltage to the boards is 18 Ga stranded wire, +and-. It's

not

> > shielded.There are two capacitors right at this power connection

on

> > the board.
> >
> > The motor wires coming from the board to the connectors in the

back

> > of
> > the case are 16Ga stranded, now home shielded with foil.
> >
> > The signal wires from the DB25 junction board are 22Ga stranded,

home

> > shielded with foil. The shielding is wrapped with some bare wire

and

> > then grounded to the chassis.
> >
> > The 5V power supply is built as instructions given to me by Dan

via

> > e-mail. The main power supply run through a resistor, a 5V

regulator,

> > and two capacitors. The 5V then goes to the boards through 18Ga
> > wires.
> >
> > All of this is redundently grounded to the chassis/case. The power
> > cord is grounde, the rectifiers are grounded, the 37 Volts is
> > grounded, the 5Volts is grounded, and each board is grounded on

all 4

> > corners to the ground trace which also grounds both power

supplies.

> >
> > The fan runs on the transformer AC, and those wires are now home
> > shielded.
> >
> > The driver side of the DB25 cable has all unused wires grounded

and

> > the port end I don't know about, but it is a very standard port

card,

> > screwed to the housing/case in the normal manner. It is a

commercial

> > cable and the pin housings show continuity to each other
> >
> > I don't understand decoupling caps, please explain.
> >
> > Hope we're getting somewhere!
> >
> > Jerry
> >
> > n CAD_CAM_EDM_DRO@egroups.com, ptengin@a... wrote:
> > > In a message dated 08/21/2000 1:17:08 PM Hawaiian Standard Time,
> > > jmelson@a... writes:
> > >
> > > << Ah, HA! Now, you are getting somewhere. Clearly, it is some
> > sort of
> > > interference
> > > problem, radiation from the motor wires and other things are
> > > contaminating
> > > the step and/or direction inputs to the driver. >>
> > >
> > >
> > > I had similar problems on mine. I installed decoupling caps and
> > went
> > to
> > > twisted pairs of 20 or 22 ga wire for the signal, no shield. The
> > problem went
> > > away!! I don't recall the value of the decoupling caps but they
> > must
> > be small
> > > as larger caps did manage to dampen the pulse when observed on a
> > scope.
> > > Perhaps Jon would have the value off the top of his head. I'd

have

> > to drive
> > > out to my dad's place to look/see. Good luck
> > >
> > > Peter
> > > THRD, Inc.
> >
> >
> >
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