Re: [Emc-users] New Member: Hello

[Gene H. <gen...@ve...>]

On Saturday 26 March 2005 11:04, Carl Helquist wrote:
>Hello All,
>
>Just a quick message to introduce myself to this list's members.
>
>My name is Carl Helquist. I am working on learning how to implement
> EMC. I currently have a spectraLIGHT mill at home and am using a
> Bridgeport CNC I at work. I am also slowly working toward
> converting a Harbor Freight Micro Mill to CNC.

So am I, working on a micro-mill, so welcome to the list Carl.

But so far I'm fighting with the motor driver hardware and haven't=
=20
really gotten around to moving what I know from the testing exersize=
=20
routine into a real, use it with emc, driver.

I thought that the futurlec.com PCI-8255 i.o card at circa $80 for 72=
=20
lines of i/o, and their SMCC-V2 stepper motor driver card at $18,=
=20
might be just what the doctor ordered, but I'm having only moderate=
=20
success in making that motor driver card properly behave, giving a=
=20
sufficiently cool operation that it could be used in continuous=20
service with 1.5 to 2 amp motors without overheating it.

Progress is being made, much redesign and fine tuning of things has=
=20
helped considerably, but the single sample of the 4 I bought at the=
=20
time that I'm playing with now is beginning to show its age & number=
=20
of times under the soldering iron.  Its expendable as long as I learn=
=20
what not to do when I reach for the next one.

Right now I have its chopper frequency reduced from the out of the bo=
x=20
of about 275khz, a full decade above the L298's driver chips real=
=20
capacity, to around 50khz, which is still too high but usable at=20
single amp coil currents.  Running it up to its 2 amp rating would=
=20
cook it in 10 seconds flat though as it comes out of the bag. 29 volt=
=20
supply, 2.7 volt motors in this case.

Herbach & Rademan's Code: TM03MTR4716
Price: $11.95, and:
MFR Japan Servo, DC VOLTS per PHASE 2.7, AMPS per PHASE 0.5, STEP=
=20
ANGLE 1.8=C2=B0, HOLDING TORQUE 50 oz-in, SHAFT SIZE 5/16 dia x 7/8=
=E2=80=9D, NO.=20
OF LEADS 4, MOTOR SIZE 2-1/16 dia x 2", FLANGE SIZE 2-1/4" square,=
=20
CONDITION New.

They don't seem to develop excessive heat until you get up around=
=20
2.5-3 amps, and at 2 amps they certainly have turn the house around=
=20
torque. But I also don't think they will meet the 50 oz/in specs at=
=20
the .5 amp level either.

The SMCC-V2 driver card is a poor, poor design right out of the bag. =
=20
But its cheap, I'm a C.E.T. and I have the time, at least until I=
=20
fall over the last time.  I think, once I get it working, that I=20
might have a friend who is good at backyard pcb making, run me up a=
=20
24 pack of a better design & see if anyone here would be interested=
=20
in a bare board & a parts list that works when populated for just a=
=20
few dollars.

Maybe I should ask the group here at large first, is there any=20
interest in such an offering?

What are you using for motor driver hardware Carl?  Or did you just=
=20
throw large amounts of money in the general direction of something=
=20
commercially made?

I've not found anything thats what I would call affordable when=20
compared to the cost of the basic micro-mill today, at about=20
$279+freight at Harbor Freight according to their last catalog.
One has a natural tendency to not want to throw another $2K-$3K at a=
=20
$300 machine, one with a few warts of its own, particularly in z axis=
=20
drive of the spindle with its full turn + of slop in the front knob=
=20
to actual spindle motion.  Thats a real hoo-doozie there.

Some I see, from my crawling the net, have actually motorized the=
=20
carriage on the post, but that makes for too much give in the x-y=
=20
directions for my taste.

I've also not yet attacked the control of the spindle motor problem=
=20
either.  Hopefully one can get a schematic of the board in that=20
controller and install some opto's in the right placs to do that. =
=20
I've not seen anyone else document that, so when I do attempt that,=
=20
I'll post to the list when its working, and fwd the resultant=20
schematic mods to Paul, or someplace with a handy web page for=20
access.  No use everybody having to reinvent the same wheel.

I can see where this is going to try to keep me out of the bars for a=
t=20
least a year...

Some hints on carving steel, also usable for alu on this machine.

1:  Spend the bucks to get a set of collets, the drill chuck supplied=
=20
is much too flexible for good work as the bits tend to wobble in a 3=
=20
point pattern due to the way the jaws grip the bit.  I got mine from=
=20
the Little Machine Shop, #1752, $49.95.  You'll also need an american=
=20
thread 3/8 x 16 drawbar bolt with those, from the same source, #2034,=
=20
$9.95 so its about $65 total IIRC.  Don't leave home without them.

2:  Dremel sells a 1/8" solid carbide rotary rasp type bit thats=20
worked quite well in steel with a good supply of cutting oil applied=
=20
every few seconds, as does Boschs 1/4" solid carbide, 2 flute upcut=
=20
style router bit.  Both are available at your local Lowes.  I've made=
=20
at least a pound of alu swarf and at least 2x that much in steel with=
=20
the latter bit so far as I'm cutting out motor mounts and such, well=
=20
lubed with cutting oil of course, without any visible dulling so far.=
 =20
Great use for $10 bill and a $20 bill respectively.

> So far I have been=20
> using surplus computers from the University so I am somewhat
> limited in terms of computer speed and hard drive size. I have had
> some successes and still have some failures to figure out.

A well equipt junk box (& being a natural packrat) certainly=20
helps. :-)

>I look forward to communicating on this list.
>
>Carl Helquist
>

--=20
Cheers Carl, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
99.34% setiathome rank, not too shabby for a WV hillbilly
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Copyright 2005 by Maurice Eugene Heskett, all rights reserved.