mark lewis wrote in a message to Roy J. Tellason:

 ml>> i know the files are something.dxf... and i used to look
 ml>> thru them when i'd export them from autocad... in a way, its
 ml>> almost like reading postscript...

 RJT> Hmm.

 ml> yeah... you should have seen me the first time i got postscript
 ml> source from a printer rather than the results of that source...
 ml> postscript really is another language...

Some bits of the linux installation here are .ps files,  and I took a while
when I first started running it to crawl all over *all* of the directories
and "look" at every file on there,  with mc's view function.  Saw
lots of weird stuff...    :-)

 RJT>>  There are also a couple of fairly standardized plotter 
 RJT>> "languages" and some of the software that's out there will no 
 RJT>> doubt provide those as output.  Or a plotter driver will.

 ml>> yup... the thing is that it would be part of the DIY aspect, 
 ml>> wouldn't it? somehow, you'd have to code something that told
 ml>> the system that x=+1 might be to move the x access in the 
 ml>> positive 1 step... its been a while since i dabbled in 
 ml>> engineering areas... i forget, at times, about computers talking 
 ml>> to computers for some of this stuff... it could be as simple as 
 ml>> that x=+1 causing a pulse on one pin of the parallel port and 
 ml>> that pin being cabled to the positive side of the x axis motor...

 RJT> Nah,  I'd think you would want a bit more intelligence in the 
 RJT> thing than that,  but that's not hard to do with even an 8-bit 
 RJT> processor.  Or throw an old MB at it,  with a custom-burned eprom 
 RJT> in there.  But that's probably even more than you'd need.

 ml> well, i didn't say how far +1 would go, either >  working 
 ml> with the scopes and doing a lot of reading, i see that there are 
 ml> motors available where one pulse only moves them some .00002 
 ml> inches or so... something also about halfstepping, too...

And of course gearing and such comes into play...

 ml> there's one guy, mel bartels, who has written software to talk to 
 ml> a two axis setup for telescope movement that uses stepper 
 ml> motors... its freely available, IIRC... a small group is also 
 ml> working on adding a third motor... many telescope mounts are AltAz 
 ml> (altitude and azimuth)... in other words, they rotate about a 
 ml> compass and raise and lower in altitude pointing... these are 
 ml> required to be set up with the azimuth base to be tilted at an 
 ml> angle proportional to your latitude so that when you point the 
 ml> scope at polaris, polaris doesn't move in the visual field... the 
 ml> design with the third motor is what they are calling a AltAltAz 
 ml> setup and basically, IIUC, works like this... you are basically 
 ml> raising and lowering the X (left/right) and Y(front/back) axis' in 
 ml> Z(altitude) and rotating all that around the azimuth... part of 
 ml> the whole thing is what's called (slightly modified) visual field 
 ml> derotation (i added the visual part for better understanding)... 
 ml> basically, as your scope tracks an object or objects in a group, 
 ml> its movement has to be such that an object that is at the bottom 
 ml> midpoint of the visual field will stay in that position all the 
 ml> way across the sky while you are tracking it... without this field 
 ml> derotation, if you start tracking an object on the east horizon 
 ml> and go to the west horizon, the image will be "upside down" when 
 ml> you get to the west horizon...

Gets complicated,  that stuff.   

 ml> i started a discussion about multiple mirror scopes similar to the 
 ml> keck 10meter scope... they have many small mirrors that all work 
 ml> together to form one primary rather than having one huge chunk of 
 ml> glass that weighs several tons... in a multi-primary mirror setup, 
 ml> they have to have three adjustments for each mirror to maintain 
 ml> proper focus of all the images as the scope tracks... this also 
 ml> allows them to use visual feedback into a/the computer to adjust 
 ml> the focus to battle atmospherical abberation to get views as good 
 ml> or better than what hubble can offer of some objects...

Better than hubble?  Interesting!  I didn't think that was possible.  For
what sort of objects would this be the case?

 ml>> i'm getting into some of this type stuff with telescopes and 
 ml>> computer controlled tracking and positioning and such...

Should make for some interesting code to read.

 RJT> Seems to me I remember reading that this was why the Forth 
 RJT> language was first written.  I have an implementation of it
 RJT> here but never did anything with it.

 ml> i've heard several folk say that in the past few weeks... both
 ml> parts >

Heh.

Maybe someday I'll get the book,  and then I'll have a clue as to what to do with it.

 ml>> seems to be very similar... two motors for guidance and there's 
 ml>> also some new stuff working for a third motor in the mix to 
 ml>> eliminate having to align the scope in the traditional ways...

 RJT> I never got into any of that.  I expect that there would be
 RJT> some stuff in common,  though.

 ml> yes, all it is is simple motor control... the differences are only
 ml> in the orientation of the motor axis and what is being moved by the
 ml> motor... 

 ml>>> in any case, the CAM platform was fixed in place and you 
 ml>>> anchored the flat material to be engraved... the engraving
 ml>>> stuff was basically little more than the (old style?) "moving 
 ml>>> cross" flatbed plotter movement with a dremel type
tool attached 
 ml>>> to a z-axis for automatic height adjustment and precision 
 ml>>> control instead of the pen-up and pen-down type stuff...

 RJT>> Y'know,  I have a dremel tool and the thought never occurred to
 RJT>> me that it might be a thing to use for this.  

 ml>> it might... though i've burnt up a few simply by using them
 ml>> for too long in a session...

 RJT> Mine does get pretty hot.  Maybe applying somewhat less power to 
 RJT> it would help.

 ml> i dunno how to do that with the units i've burnt out... they were
 ml> simply plugged into the 110VAC outlet and used...

I've plugged mine into a variac already.  Haven't tried it with a dimmer
yet,  though I have a box with a dimmer handy...  One way or the other
should work.

 RJT>> Mine is an older model for which the common accessories are no
 RJT>> longer available,  and i was lucky to be able to find collets 
 RJT>> for it,  all four of them.  But somebody pointed me to a source 
 RJT>> where I could buy a "drill press" setup for it that
was made by a
 RJT>> third party.  Perhaps something like that would be useful,  
 RJT>> adaptable to this sort of thing.

 ml>> cool...

 RJT> The unit was available at Lowe's,  if you have one of them around 
 RJT> you somewhere.  I never did look at it too closely, just went in 
 RJT> and asked the guy if I could bring my dremel in and see if that'd 
 RJT> work with it and he said yeah...

 ml> yeah, we have a lowe's superstore here... i know several of the 
 ml> guys there... most times you can/will find friendly assistance like
 ml> that...

I never did go back and get it,  either.  Yet.  :-)



 RJT> Sounds time-consuming.  Unless you had software that could
 RJT> cope with a number of different-sized cutters.

 ml> oh yeah... one of the settings was what diameter the cutting bit
 ml> was... this so that you could use it to remove "large" areas of
 ml> material without leaving any "lines" or
"ridges"... oh! and
 ml> speaking of that, i just remembered that some of these setups also
 ml> have two axis tiling of the Z axis... like a gearshift in a car..
 ml> tilt forward, back, left and right... thinking of how an airplane
 ml> moves in 3 dimensions...

 ml> so, there's X,Y positioning over material, z positioning for depth,
 ml> and then tilting forward/backward on another axis and tilting
 ml> left/right on a fifth axis... mmmmmmm...

This just got a whole lot more complicated.    Now to figure out
some simple way to implement it...



 ml>> the economy is so bad in this area that if you hear about
 ml>> any type of job opening, you'd best be there waiting in line
 ml>> like folk do for concert tickets...

 RJT> Where are you,  anyway?

 ml> central carolina... middle of no where and about an hour from
 ml> everywhere... hate the traffic in the city, hate the long drive
 ml> both ways, definitely don't want the stress, and surely don't want
 ml> to go postal on anyone due to any combination of those factors...

I was just saying elsewhere that I'd like to be a whole lot more rural than
I am now,  but you gotta go where the work is,  I guess...  Of course, 
there's always the prospect of retirement.  I know a guy a couple years
younger than I am who's managed it.  Also had a heart transplant,  so if
that's what it takes I guess I can hang in there,  but he was doing okay
before that came along.  Probably would've retired before me anyhow...



 ml>> too bad its against the neighborhood charter to have a yardsale

 RJT> I wouldn't pick a neighborhood like that.

 ml> we did because of the privacy and such... lots are 5 acres or 
 ml> larger... plenty of trees, peace and quiet... no cars racing up and
 ml> down the road and no kids yelling and such all the time...

Hmm.

 ml>> and i'm not toting it all to the truck to move to some place 
 ml>> where i have to rent a booth and such...

 RJT> A hamefest might work.

 ml> what i was thinking... my problem is finding out about them and
 ml> then getting there...

Yep,  always something.

 ml>> i do know that i've carried over 1500 pounds of stuff out... the 
 ml>> recycler has to weight the truck going in and coming out...

 RJT> Heh.  If I were getting into that much weight I'd load my truck 
 RJT> up and go down to the place that buys scrap metal. Which might 
 RJT> just barely pay for the gas it takes to get there and back.    
 RJT> If my truck were showing a current inspection sticker...

 ml> yah, that too >

Like I was saying,  always something...

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