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Re: librecad



Gene Heskett <gheskett@shentel.net> writes:

> On Friday 07 December 2018 19:54:56 John Hasler wrote:
>
>> Joe writes:
>> > ...he's still on wheezy.
>>
>> I wrote:
>> > That is easily fixed.
>>
>> Gene writes:
>> > Not until an rtai patched kernel is available for the newer stuffs.
>>
>> Why would you run your CAD software on your machine controller?
>
> Why not John? With 6 machines here running 32 bit wheezy, one running 
> jessie on an R-PI-3B, and one running armbian stretch on a arm64, all 
> but the arm64 actually running a machine or the card firmware updater, 
> the only one w/o enough iron to run cad stuff is the pi.
>
> This machine, with its comfy chair, can run anything installed on the 
> other 6 machines via ssh -Y logins, and all are or can be mounted over 
> an sshfs facility for moving files around. Samba/cifs has turned into a 
> headache precisely because of all the windows crap that been 
> incorporated in the last years since Andrew T. got a helper.
>
> NFS, any version is at best a chain with broken links, whereas sshfs Just 
> Works.
>
> The machine that will carve the back panel is the best simulator ever for 
> code that will be run on it, simply by turning off all motor power, I 
> can run gcode on it, with the gui exported to this machine and its comfy 
> chair. This allows me to exercise the code, making sure it does exactly 
> what I had in mind, without carving up a hundred bucks worth of raw 
> material and putting more wear on a cutting tool.
>
> alu is the hardest stuff to cut in terms of tool wear there is, only 
> partially mitigated by a mister directed fog of sealing oil directed at 
> the back of the cutting tool so the alu is sealed away from the air, 
> majorly sealing the just cut surface.
>
> 99% of the heat you get from machining alu is not the cutting tool 
> friction, but the burning of the alu as it forms a new layer of alu 
> oxide in the thousandth of a second after the passing cutting edge of 
> the tool has exposed the alu to the airborn oxygen. That alox layer is 
> the 2nd hardest substance we have, 2nd to diamond, and asking the tool 
> to cut thru it with every passing cutting edge is pure hell even on 
> silicon carbide tooling. At $10 to $50 a tool.
>
> CAD/CAM may be able to do it faster, but they do not yield editable 
> gcode. This file I am working with, if exported as gcode from freecad, 
> would be 5 to 20 megabytes because the cad/cam programs have no clue 
> about the use of loops and conditionals. I am doing all this, with one 
> hole of unk size to cut yet, with 199 LOC. 50+ is comments, keeping 
> track of what I'm doing.  And I can fix it with the same editor I used 
> to write it. geany.
>
> Biggest problem ATM is I'm one eyed, haven't let the left eye settle long 
> enough after the surgery Tuesday to be able to write a prescription and 
> get the correct lens in the frame, so its empty on that side. Since I'm 
> partial to hard coated Transitions lenses (special order, takes 7 to 9 
> days in this neck of the woods), that will be 2 more weeks till I've got 
> two medium good eyes again.
>
> Other than that, whats not to like, John?

First, because if you *really* need real time response, you shouldn't be
running anything else that might be computationally intensive.  I'm
happy to believe the developers of RTAI are competent, even excellent,
programmers.  All the same, if I want real time levels of predictable
response I don't want to put anything that might decide to be
computationally intensive on the same machine.

Second, because you're forcing yourself to look for workarounds due to
the decision to use an obsolete (as in, not even in LTS since last May)
distribution.  As we've seen in this thread.


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