Re: OK, I've got a detent encoder... What now?

Hi Marcus,

I think someone expressed a desire to have the jog handle be essentially
absolute. So that he could dial in a move, and get there! And my
handwheel is graduated 50 divisions, so 50 or 100 steps would fit. This
would involve using a DRO chip, to better keep track of the actual
encoder position (as my program ignores encoder steps, unless in
"Pendant jog" mode). Sounds useful!

Alan KM6VV


Marcus & Eva wrote:

>
> Hi Fred:
> Are you SURE it has to be a number like 100 detents per turn??
> I've used commercial controls with manual pulse generators for a while now,
> and I can't ever remember counting either turns or clicks of the handwheel.
> What I care about, is that each click gives me an even decimal increment
> that I can control.
> The reason for this is as follows:
> When I am jogging up to the edge of a job, I eyeball it at 0.01" per click
> until I'm close to my gauge block size (I use a 3/4" dia pin in the collet,
> and a 0.125 gauge block as a feeler gauge for setting up).
> Then I switch to 0.0001" per click and run the pin up until I can just push
> the gauge block into the gap.
> For this operation I don't care a hoot what the graduations are, so long as
> I have a coarse one for rough positioning, and a fine one for twiddling in
> the last tenths.
> I have another application though, for which the even graduations matter.
> Sometimes I'm too lazy to program a drilling job, and I use the CNC as if it
> were a DRO equipped manual mill.
> I build molds for a living, and there's lots of holes in lots of plates.
> I plan the holes to be on even decimal centers as often as I can.
> When I'm moving from hole to hole, it's nice to be able to set a coarse
> increment, and have each step move an even decimal fraction of the hole
> spacing.
> I still don't count clicks; what I do is look at the job until I'm close and
> then look at the readout to click it into position.
> It's really nice if the movement occurs in even chunks so I don't have to
> switch between coarse and fine on the pulse generator all the time.
> As an example, suppose I want to move between holes that are 5.000" apart.
> My first hole happens to be at X0 Y0.
> I bomb along to the second hole by eyeball using the 0.01" per click
> function, looking at the job and the drill until my drill point is close.
> Then I transfer my attention to the readout and keep clicking until the
> number says 5.000
> I don't care if it took 3 clicks or 4; what I care about, is that when I got
> close, it had moved say 4.9600, and not say 4.9612.
> That way, I'm not constantly swiching from 0.01 per click to 0.0001 per
> click to dial in the holes.
> Notice I haven't ever bothered to count the turns or the clicks; I don't
> care a fig whether it goes 96 clicks per turn or 100, so long as each click
> moves me EXACTLY 0.0100".
> So, after all this lengthy dissertation...have I overlooked something that
> makes a 100 division encoder mandatory???
> All you commercial CNC drivers.... more thoughts anyone?? Are you guys doing
> it differently??
>
> Cheers
>
> Marcus
>
> >
> > Spehro, this is just about right for the application, except, it MUST
> > be 10 or 20 or 50 or 100 detents. One full revolution is important
> > and 18 does not convert to any useful scaled units. Is this a $20
> > part or a $100 part? Is it available in one of the listed scalable
> > numbers?
> >
> > Best Regards,
> >
> > Fred Smith
> > IMService