I actually tried this technique previously using the ats675s but I
couldn't get a satisfactory quadrature output, my gear teeth produced more
like a 25-30% on time and 70% off, so clocking the two sensors for real
quadrature was problematic and didn't really provide the result I was
looking for, plus it put my sensors inside a pretty greasy/oily gearbox
which didn't make adjusting things appealing or convenient. A single
ATS601 was used with a small dimple in the gear face to pickup an index
pulse, that did work pretty well.
I'm not trying to mount at the top of the spindle but need to leave room
for drawbar equipment. I guess I could mount a small toothed pulley/belt
and bring something out the side to a traditional rotary encoder, but
theres not a lot of mounting area, seems inconvnient, ugly, etc. With
something lower profile like the AEDR lineup it might be do-able directly
under the drawbar equipment.
Another alternative I do have is to pick up off a shaft stub that comes
out the back of the Z column with a traditional rotary encoder, some lathe
work and a mounting bracket. But that shaft is 2 gear pairs away from the
spindle so there seems to be about a degree or so of backlash in the
interface between it in the spindle, I haven't measured an exact amount
yet. My guess is this won't be the worlds biggest issue, but doesn't sound
ideal. I don't plan on doing much rigid tapping, but I can imagine some
scenarios where having better spindle position information would be useful.
Dave
On Thu, 01 Nov 2018 12:36:04 -0400, Jon Elson <[email protected]>
wrote:
On 11/01/2018 03:09 AM, Chris Albertson wrote:
You don't want to block the hole in the spindle so you are looking for
an
encoder with a large hole though it? Is that right?
If the spindle is belt or gear driven you could place the sensor on the
gear or pulley that drives the spindle. You could also place a timing
belt puley on the spindle then drive the encoder with a 1:1 belt drive.
1:1 drive would allow using a 3 channel encoder
Yes, see :
http://pico-systems.com/bridge_spindle.html
I did this a number of years ago on my Bridgeport mill, but it could be
done on a lathe as well.
These sensors are ideal for this purpose, as they have logic to detect
the PASSING of the gear tooth, not just the presence/absence of a tooth.
Jon
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