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DIY DRO for lathe or mill
AdeV:
Usually, the "zero offset" is done using a tool library, are you thinking along the lines that having changed tool, you'd go into "offset mode", touch off the tool, then back to "normal mode" and the machine carries on as before? Or would you prefer to say "I've put in tool #73" and the machine knows the offset already, because you already programmed it?
Regarding fractions - I agree that, on a metal machine, fractions are probably not that useful. Could be handy for woodworkers though? I can also see it being useful if you've got, say, a bolt pattern to drill & the dimensions are given in inch fractional... Rounding shouldn't be too big an issue on one micron scales, and if you're working to the nearest 1/4", what's the odd tenth between friends? :)
BillTodd:
Fractional inches are not uncommon, hardinge parts are often multiples 1/64 , just like metric parts tend to stick to integer mm. A fractional display avoids the need for decimal conversion.
efrench:
The rose engine is a little different than a lathe in that the headstock can move side to side as well as along the Z axis. The cross slide also floats on the bed, so it can be set at any angle to or distance from the headstock. There's no concept of touching off (but I'll have to think about that a bit more to see if it's practical).
One of the recurring tasks is to cut a tenon on the end of the workpiece in order to machine the inside of a lid. After starting to cut the tenon, it would be nice to be able to measure the diameter, then set zero based on that measurement.
I think that if you allow data entry in fractions, then the actual decimal values should be displayed. How will you decide what the smallest fraction denominator will be?
My rose engine project uses stepper motors for the spindle as well as for the X, Z, and B axes. I'm using a Teensy 3.5 (Arduino compatible) and a Nextion touch screen.
BillTodd:
--- Quote ---I think that if you allow data entry in fractions, then the actual decimal values should be displayed. How will you decide what the smallest fraction denominator will be?
--- End quote ---
You don't need to decide , the fraction is a simple division function. Data entry in fractions is common in CAD/CAM (as is unit specific entry - solidworks will allow you to enter 1/27" while working in metric or even 1/4mm if you so wish )
On my analogue 'inch' meters, the option is set as part of the VB object's display parameters , I chose 1/64 as it is about the smallest division in common use .
As I said above I found it very useful and would include it in another DRO .(see video below)
https://drive.google.com/open?id=1mp6jvlf6PH_2U3VWnIHgY3bB39XeZ_37
djc:
A couple of things:
Presumably you are aware of how you can use native AVR assembly instructions as well as AVR C within the Arduino environment. This can considerably speed things up as the Arduino programming language has a lot of overhead built in (canonical example, how to toggle a pin).
If you know the pulse speed it can reliably read, monitor it and it it is exceeded by 10%, flash something up on screen to warn that there is a possibility of position loss (like the temperature light in your car: your engine will not blow up the minute it lights up, but Bad Things will happen if you ignore it).
On your reversing sensor, I maybe question why you would not want to look at the DRO. I certainly do not want my lathe beeping at me. The trouble with a digital count down is you have no sense of how fast it is progressing. If you could replicate on screen the analogue clock gauge we have on the carriage, that would be a winner. You can see how fast the hand is sweeping and how close it is to zero. Bigger the better on screen.
What of ability to move between machines?
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