Greg - To Gene - and list
If the RPi can use SPI over a 250mm length cable at rated speed then it is a
great option.
No? How about a 150mm cable?
If the signal can't get off the host PCB and to the target PCB reliably then
the whole issue is a non starter moot point.
Maybe if there was an off the shelf adapter PCB to rig a hat sandwich. For 90%
of users PCB level mods are beyond what they signed on for.
SPI is faster than needed which is nice to have extra available free time in
the loop.
But MACH 3, other than smooth stepper users was almost all para port. LCNC
proved it could drive parallel ports just fine. Higher level controls Like Pico
Systems and Mesa ECP/EPP based FPGA cards have proven that an ECP/EPP
connection is plenty effective speed wise.
For my mill retrofit I went with a small pile of Mesa cards starting with a
5i25/7i77 with several additional SSerial cards added to the mix (mega
overkill, and probably not really needed)
I still have a 7i43 I bought way back, and I have a lathe conversion that has
been on a back burner for a few years. I was thinking of driving the 7i43 with
a new/old stock DM510 I have had on the shelf NIB long enough that any warranty
has long expired. Sadly the DM510 is actually less powerful than the RPi, only
thing in the DM510 favor is I can stuff it with 4gb ram.
I have renewed my interest in the Pi because I'm looking at some simple
applications which using the Pi as the front end driving an Arduino with GRBL
is plenty. One application is a powered feed with auto reset for my horizontal
bandsaw, a second axis could be used to auto feed the stock for the next cut
using a vise clamped/unclamped sensor switch to inhibit/resume. Another RPi +
Arduino GRBL is a stand alone programmable 4th axis indexer for manual milling
- plus having connectors that would allow bypassing the Pi/GRBL and driving the
stepper (with encoder feedback) from LCNC.
Another project that is just on the wish list at this point is a 5 axis tool
grinder, but it might become 8-9 axis if I include programmable form wheel
dressing. (bring Whiskey and Asprin)
Currently all conversions are on hold as I am trying to make space to shoehorn
in the machinery I purchased from my Uncles Estate. I have a Okuma LK 350mm
lathe, Bridgeport, another horizontal bandsaw and a Harig 6x18 Surface grinder.
Been so much rain the soil is too soft for the forklifts to unload. So delivery
keeps getting pushed back. Thankfully I'm not backlogged currently because
after the machines are in, then I have to go back to the old site and remove
the wiring and phase converter and install the outlets at my shop.
Greg
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