[Coco] [color computer] CNC with a Coco
George's Coco Address
yahoo at dvdplayersonly.com
Sun Jul 22 20:54:56 EDT 2007
----- Original Message -----
From: "Gene Heskett" <gene.heskett at verizon.net>
> I replaced the z axis screw on mine with a 1/2" 10 tpi acme with two nuts
> adjust the backlash. But the head itself rocks a teeny bit on a direction
> reversal, limiting how well I can compensate the backlash in software. If
> always move the z in the same direction during the cut when making 3d
> its well within a thousandth. Do a reverse at the top of a crown and you
> catch a fingernail on the ridge. :(
A couple of months ago, I found an outfit that has a ball-nut and lead
screw at a very affordable price. When I find it again, I'll post it for
you. I think it was a 24 pitch. With a ball nut/screw, your steppers need
some sort of brake to keep it from moving. They are virtually frictionless
and will turn under load. My lathe/mill is so sloppy, it isn't worth the
effort to convert from ACME to Ball.
> But ISTR you are using a Dremel grinder, and its spindle accuracy is so
> there is no real use trying for .001" accuracy.
This Dremel is fairly elegant inasmuch as the chuck is mounted in ball
bearings and driven from the motor through a flexible coupling. However, I'm
thinking of using the dremel to drive a new head via gear or belt reduction
to reduce the speed and increase the torque. This should stop the bits from
glowing a dull red and live longer. 25 thousand RPM is too darned fast.
> As for that lathe, 2 or 3 thou at best, the carriage fits the ways way too
> sloppily. Not to mention the tailstocks height is off about .020" even if
> set for min taper on a long turn supported at both ends. Correcting for
> make life very confusing.
Mine uses a dovetail type of slideways and they totally suck. If I get them
tight enough to reduce the slop, then I can barely move them. There are ball
type slideways but I can't afford that now.
>> Coco lives! PCs die.
> No, PC's running winderz die. Running linux they're fine, cuz they are
> what YOU want them to do, and NOT what Bill might want them to do behind
> back, like phoning home with the contents of the firefox password file,
> including all your bank numbers...
I've replaced a lot of motherboards on my PCs, but only once have I had a
Coco just up and die. I've killed a few of them myself.
When I kill one, it's usually totally shot. Too many parts to change and
another coco is cheaper and easier. I have repaired a coco a few times.
Usually it's a CPU or a PIA. That was back when you could buy them new and
they were expensive. Now, I just will just go out to my storage shed and get
another one. However, I haven't killed a coco in years.....
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