Mark & Juanita said:

Sorry, you missed the thread a couple weeks ago in which we were
discussing adapting a DRO to a planer. Here's a link to one source:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=41939&item=3843610 956&rd=1

Yea, I missed that one. Sometimes I'm here every day, and then months
laspes before I return. Life's kinda like that - a roller coaster
ride that alternates between boredom and exitement; busy and slack.

I hadn't thought using a quill DRO. There is one drawback - if the
thing loses it's zero setting when powered off, you would have to
recalibrate it every time you use it - not something I would want to
do. I'm not certain how you would calibrate a DRO quill meter on a
planer, 'cause they don't allow a "zero" setting. Most start at about
3/16" or so. I wouldn't want to do math to arrive at the actual
measurement - just another source of stupid errors. ;-)

I'm still trying to find something not on e-bay

I've bought stuff from eBay and never been screwed. But keep in mind
that this is probably a cheap, Chinese, blister packaged device...

Rockler sells that digital router depth measuring device, but I'm not
certain of the "zero" method on it either, and it's around $100.

scribble, scribble... optical slot wheel, infra-red opto-coupler,
PIC microcontroller to convert ticks to fractional inches, backup
power supply to hold settings while planer unplugged, 1 line x 25 LCD
panel and language interface... scribble, scribble...

I'd look at something pre-built first. Just need to find one from
somewhere other than e-bay.

It's definitely cheaper and easier to use pre-manufactured stuff. In
fact, after looking at Mouser and DigiKey for laser diodes, I found
that I could buy the whole level and gut it for considerably less.

But when I can't find anything else to do the job, I design something
like this:

http://www.thevideodoc.com/preefs5.htm

When I get the time, I may invest some time into this project as well.
I have to finish roofing and siding the garage first, so it could be
December before I get around to it. But it is definitely something I
could "get in to."

Ciao,

Greg G.