Subject: cyberlab cnc fiasco

From: David Allen <[email-masked]>
Date: 25 Jan 1995 23:11:51 GMT

ok, I give up.  I bought a tabletop cnc system from u.s. cyberlab because
it was cheap, and boy is it cheap.  after re-drilling over half the 
mounting holes in order to align the components and substituting my
own connectors because the supplied ones wouldn't, it's still giving me
problems.  may someone out there can help.

the problem seems to be the mounting hole in one of the threaded 
shafts.  the system drives a mounting block, containing a nut, via a 
threaded shaft which is turned by a stepper motor.  the motor shaft 
is inserted into an axial hole in the threaded shaft and held in place 
with a set screw.  the motor is mounted on the face near the shaft 
with the opposite end floating free.  the mechanical connection 
and alignment between the motor and drive shafts is solid, which may 
be causing the problem.  when driving the platform and it's in the 
middle of the threaded rod, the free end of the motor wobbles, the 
platform raises and lowers about 1/16", and the drive noise from 
the motor seems to vary in direct relation to the rotary position 
of the threaded shaft.  at either end of travel, the motor occasionally
binds and loses position.  it's almost like the hole in the threaded rod
was drilled non-parallel to the axis and the system is trying to 
torque the block around (like I feel I've been).  

aside from having the drive rods re-milled (which would double the cost
of the system) is there a good way to connect the shafts to permit some 
sort of axial compliance.  I've thought about a universal joint of some
type but can't find one the right size in either Berg or Small Parts.

any suggestions?

da

---

From: [email-masked] (Peter L. McCann)
Date: 27 Jan 1995 04:33:20 GMT

As for the small universal joint I've got a miniture set of
socket wrenches (sorry don't know where I got it) but one of the
attachments that came with the kit was a universal joint. So
check with tool supply companies.

Pete

BTW. I lost my access back in october, but i'm back now. 
I have built a semi moble robot using one of the old moble
radio shack robots (They're selling them again YEA!) and have
hooked it up to a radio shack model 100 laptop. I'm still working
out the BASIC programming bugs , and a glitch in my circuit
but its getting there.

---

From: [email-masked] (bruce burden)
Date: 27 Jan 1995 18:46:24 GMT

Peter L. McCann ([email-masked]) wrote:
: As for the small universal joint I've got a miniture set of
: socket wrenches (sorry don't know where I got it) but one of the
: attachments that came with the kit was a universal joint. So
: check with tool supply companies.

	Small Parts Inc.
	13980 N.W. 58th Ct.
	P.O. Box 4650
	Miami Lakes, Fl. 33014-0650
	305-557-8222

     Offers universals with bores down to 1/8", od is 0.28", length is
     1.05". I have dealt with them, and found them to carry some 
     useful items.

								Bruce

--
-----------------------------------------------------------------------------
  Bruce Burden            [email-masked]		Austin, Tx.

"I like bad!"
        -Thuganlitha
        The Power and the Prophet