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Electronic Leadscrew for the New Lathe
vtsteam:
I've got a running experimental system with a toy encoder/gearhead motor w/IR detector combo feeding an Arduino, doing the dividing function, with step and direction output to a stepper drver and a stepper motor running at the divided rate. :ddb:
It all works at the relatively low data rate that the toy encoder is putting out. The real encoder hasn't arrived yet, but it's really great to see it all running together as imagined now!
I used Arduino's Wiring language just to work out the connections and timing, but I'm in the process of writing FORTH code for it, which will make future extensibility easier -- at least for me.
spuddevans:
--- Quote from: vtsteam on April 12, 2015, 09:09:02 PM ---I've got a running experimental system with a toy encoder/gearhead motor w/IR detector combo feeding an Arduino, doing the dividing function, with step and direction output to a stepper drver and a stepper motor running at the divided rate. :ddb:
--- End quote ---
It's always a good feeling to get a test system up and going, well done :clap: :clap:
Are you going to have a LCD readout of the pitch/TPI?
I was wanting to have one on mine, but then realised the PIC that I've ordered haven't enough ROM (or I haven't pruned my code down enough) for the menu structure that I was thinking of, hence I changed plan to use BCD thumbwheels as setting/display means.
Tim
vtsteam:
Tim, I don't know yet. It makes sense to do that, but the retro part of me wants to have a knob selector or lever selector and no display, or a hidden set of switches or something on the new lathe. Just an aesthetics thing. I'd like it to look like a manual lathe -- and function like one, actually.
On the other hand a display would allow me to do lots more in the future re. expansion of capabilities without adding too many knobs and levers! I keep thinking of writing my own simple CNC manual control stuff for a lathe instead of using the heavy CNC hitters and mega computing setups. After saying I just wanted to replace change gears, it gets tempting to go further. :palm: But I noticed I've stopped building my lathe, and that's no good. I think I'll put off getting too ambitious electronically at this stage, get the electronic change gears working, and finish the lathe. I can always come back to the fancier programming stuff after.
I might play with a display, maybe just to learn how it works. But I don't know if updating a display will hurt the gear routine throughput -- another consideration. I'm not using interrupts yet, just a simple input polling loop -- I'll have to see what is needed for speed when the "real" encoder gets here.
I'll have a very short video of the toy encoder setup shortly -- as soon as Vimeo gets done re-encoding it.
vtsteam:
Just a quick test.
First button runs the DC toy motor turning the encoder. The arduino translates that to step pulses at any preset ratio and sends to the stepper controller.
Second button reverses the stepper (leadscrew) direction.
Third button is an emergency stop/limit switch input.
spuddevans:
I'm impressed with the video, that looks a good rate of RPM on the encoder.
--- Quote from: vtsteam on April 13, 2015, 10:21:18 AM ---But I don't know if updating a display will hurt the gear routine throughput -- another consideration.
--- End quote ---
When I was looking at having a LCD for mine I was worried about that too, so I came up with the thought of using a toggle switch for "Set" or "Run". then the program would regularly poll the switch and only update the display or change parameters when set to "Set".
Another thought was to use the Quad Encoder instead of buttons to change parameters (obviously without the lathe running!!) saves having a plethora of buttons, just one "Set"/"Run" switch and the display.
Tim
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