Dear Gene
Thankyou for your kind note. The pont about
microswitches is well taken, tho I personally have had no trouble. But
when I have a moment I'll set up a test jig using a micrometer spindle,
see what I find, and let you know. I think some of the variability might
be due to slop in the mounting. Anway, I'll try various things (e.g.
putting a microswitch having only a small plastic acuator usually driven
by a spring lever in a 0-1" mic and see what happens. I think the dvice
from MAXNC is just a set of mechanichal contacts, and if so perhaps I
could make a simple prototype. I have had one in mind using an opto
interrupter, and if that proves twichy, I did when a young impoverished
student make a mechanical test gage with a gain of about 30 that let me
center work in a 4 jaw chuck to better than .001 inches. That with an
ordinary optical interrupter might come close to .0001 in. There is
somewhere in my library a design for such a lever device. I'll see iv I
can find it. Somebody who might be interested is Guy Lautard who lives
not far from Vancouver. Ahh, I've found him <[EMAIL PROTECTED]> I
think. If I'm wrong, and find out, I'll tell you who you should e-mail to.
Sincerely
John Gabriel
Gene Heskett wrote:
> On Wednesday 25 April 2007, John R. Gabriel wrote:
>> I have such a probe sold by MAXNC for a rather expensive price. Having
>> seen it, I think one could be made based on 4 micro switches arranged
>> round a 1/4" ball end of a probe in gimbals or on small springs at its
>> midpoint and a 1/16 or 1/32 ball on the lower end.
>
> The repeatability of a microswitch scares me, its terrible.
>
>> If the object being probed were metallic, a simple electrical contact
>> could be used.
>
> But that needs clean metal.
>
>> An alternative, but also expensive, would be the very useful
>> CNC camera from Atto Research, advertised on EBay. For the Homebrew
>> enthusiast there are video cameras from $40.00 up, which might be usable
>> if fitted with an extension tube, or with an inexpensive microcope
>> objective to provide a much enlarged image , and correspondingly small
>> depth of field. For the dyed in the wool homebrew enthusiast All
>> Electronics have CCD sensors and circuit boards, descibed as video
>> cameras w/o lenses for under $ 3.00 each. If these contain the scan
>> electronics, and I had spare time, I would ask the vendor for a price
>> break on Qty 100 and go into business buying suitable lenses (Edmund
>> Scientific) and making video cameras for CNC. I think finished cameras
>> would show a profit around two or three hundred dollars each, and parts
>> kits somewhat less.
>>
>> Because deteriorating vision (I am 75 years old, and lost the sight
>> of one eye in an accident a couple of years ago) compel me to automate
>> my small machine shop, Gene Haskett's letter has suggested yet another
>> product I have not considered making besides the DIY CNC kits for SIEG
>> minimills and lathes, and larger tools from Grizzly and ENCO that I will
>> need and expect to manufacture, but have not considered making.
>>
>> Thankyou Gene for a good idea.
>
> You're most welcome John, but you have to realize you just knocked me off my
> perch in this group, I thought at 72 I was the oldest old fart here. :)
>
> But, just to put that in perspective for both of us, I was out to see Doc
> Blake 2 weeks ago as I pick up scraps I can use from his shop floor from time
> to time. It was about 7pm and he hadn't quit for the day yet, so I asked him
> when he was going to retire as I know he has a few years on me, but give him
> a chair at a pickin session and he can still start a fire on the fretboard of
> a banjo or mandolin doing real justice to some bluegrass at least as good as
> you'll hear on Mountain Stage, the radio program on NPR. He could sit in
> with Ricky Skaggs and be right at home anytime. Anyway he said he was too
> young to retire, he was only 78. And he said it with a straight face.
> Knowing Doc, he will probably fall over while tending his power hacksaw,
> making parts to fix a broken well tender rig. He and his son turn away work
> all the time.
>
>> Sincerely
>> John Gabriel
>
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