[Coco] [coco] Coco CNC

George Ramsower georgeramsower at gmail.com
Wed Feb 13 20:10:28 EST 2008

From: "Gene Heskett"

> On Wednesday 13 February 2008, George Ramsower wrote:
>>I have that lead screw nut fitted to the slide now..
>>It's fun to watch this thing work, especially knowing a Coco is operating
>>it. So far accuracy on the Z axis is dead on and side milling is within 
>>inches. Not too bad for a dremmel.
> Looking good George.  Are you going to need to deepen the other end of the
> groove too, to clear the screw as it protrudes from the nut?

 The groove is done and no further action is necessary. The end block on 
that slide needed a groove also, and room for the coupling from the stepper. 
I did that this afternoon on my manual lathe. I also made the coupler on 
that manual machine. Damned Chinese. When I drilled the 1/4 inch hole for 
the stepper shaft, the hole was .013 oversized and the shaft was .002 
undersized. So I dug around to find a small enough 1/4 inch drill bit that 
would make that hole. Got it within .003. Close enough!
 Right now, I'm brain working on mounting the stepper to the end block on 
that slide. Once done, I can put it back together and do the 
drilling(actually just making the pilot holes) for the working work surface. 
I figure I can mark the slide for the holes, and then use double sided tape 
to temporarily stick the working table to the slide and use the same routing 
to mark the hole positions on that, then take the slide and table back out 
to the shop for drilling a tapping. Should be error free this way.
 Can't beat automation for precision!!

> I am getting closer to having the 4th axis working on my mill, a motorized 
> 4"
> rotary table.  For a drive coupling, I re-used the coupling I originally 
> made
> for the first rebuild of the z axis, but had to bore half of it out to 
> 10mm
> from 8mm, which turned out to be fun.  I'd made those originally out of 
> some
> sort of worn out mine shafting I'd found at the scrap metals place & 
> bought a
> few feet of, and had fun making in them in the first place cuz it was such

 Most of my raw material comes from scrap yard/recycling centers. Pay by the 
pound stuff. I go in with a back pack, gather up anything that looks good 
and stuff that back pack until I had enough or couldn't find anymore good 
"stuff". Then go to the scales and check it out.
 For larger items, I will take my truck.
 All the roller bearings in my mill came from old VCRs. The steel bars the 
bearings ride on came from old dot matrix printers. The angle iron is from 
bed frames and the steppers, if I remember correctly, came from an old IBM 
hard disk >14" < and one came from a laser disk player.
 The transistor arrays to drive the steppers, I think, came from that laser 
disk or perhaps some other device that used steppers.

> hard steel.  I pretty well wrecked a drill bit that was about 9.5mm but it
> did go thru, but when I hit it with a small carbide tipped boring bar to
> finish up the fit, the bar just slid off, so I wound up making a strap 
> bolted
> to one of my quick change tool holders with a tab sticking out with a 1/2"
> hole in it, put the hand piece of a flexible cable for a Dremel through 
> the
> hole, and mounted a 1/8" diameter diamond coated ball burr from one of 
> those
> ten dollar kits, and made about 20 passes through it to center up the hole
> and enlarge it to fit the 10mm shaft.  Dremel set for about 5 thou, lathe 
> at
> 50 rpm with its slowest gear feed.  Very very slow, but it worked.
> The last time I dealt with steel this hard was when drilling and tapping 
> my
> P17 Eddystone Enfield action for a scope 45 years ago, where we had to 
> spot
> the top of it with a grinder before a carbide tap drill for 6-48 screws 
> could
> touch it, and the carbide tap had to be sharpened about every turn.  I 
> still
> have whats left of both of them!

 That's the very reason I obtained a new drill press. Those bed frame rails 
are hard as heck. My old drill press would only go down to 650 RPM. A 1/2 
drill bit would smoke once it got into it. My new drill press is a floor 
model with something like fifteen speeds. It will go down to 300 RPM whis is 
just right for 1/2 drills.
 Any bigger than that, I'm sure I can bore it out on my lathe, if I fit it 
in there.

 Did you know that T-Posts, bed frame rails and something else(can't 
remember) are made from extrusions of old railroad rails? Yep! Saw it on 
"How It's Made" a couple of months ago.

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