https://www.amazon.com/Laser-Center-Edge-Finder-polarizer/dp/B00WVG4DF4
I bought one of these a few years ago when they were somewhat less
expensive. The polarizer helps the beam considerably. I think one can
get something on the order of 0.01" repeatability using your eye. A
sensor and a pin hole should do better. There just ain't no free lunch.
Dave
On 3/22/20 11:09 AM, Gene Heskett wrote:
On Sunday 22 March 2020 12:57:34 Leonardo Marsaglia wrote:
You would have to turn the coolant off to measure, but have a look
at laser triangulation distance sensors:
https://www.micro-epsilon.co.uk/news/2018/2018-05-15-optoNCDT-1750LL
/ (specifically mentions grinding wheels)
Thanks for the link Andy. But these I assume measure distance,
reflecting the beam against a surface and then receiving it and
measuring the time elapsed between the two events am I right?
I was thinking in something more like two IR barriers transversally
crossed by the wheel. The problem is, this is just an idea it came to
me because geometrically ,for me, this is the simplest way I came up
with to measure the wheel radius only depending on the accuracy of the
ballscrew and the motor driving it. But I don't really know if one can
achieve good levels of repeatability with such a setup.
That would be quite a heavy reponsibility on the ability to repeatedly
dial in half of the beam blocked. I measured the bed wear of mt lathe
with a 38 cartridge bore siting leser and an ir cell fixed to the point
of a dead center in the tailstock, with the laser moditied for power
thru a contact on the other end of a 18" tail sticking out of the back
of the spindle and a cutoff blade raised high enough to block it fully.
Fist adjusting thetail stock to center the beam on it photocell. Then
mount the cutoff tool and advanced it in front of the receiver cell
until half the beam was being cut off by the cutoff blade. Touched off
x at 0.0000 at that point, jogged z a short distance each way to check
for torque on the carriage, found under a thou, the jogged toward the
spindle and recorded both z and the x jog offset. Every inch of travel.
pretty close to a straight line for almost 20" of Z but then the bed
wear closer to the spindle started to show so I wound up at he spindle
pretty close to zero. Then I picked out the peaks and composed a
settings table for a lincurve from that, inserted the lincurves output
thru h offset to modify the x to keep its =- a thou or better over the z
range checked. Taint perfect but it plenty close enough for the girls
I've gone with. Ranges up to 8 thou if disabled. Using the method I've
described I that methods accuracy budget would show that friction in the
home switch would account for the huge majority of the errors, and I
found those to be repeatable to .0002". or better. More than enough to
measure thermal effects.
El dom., 22 mar. 2020 a las 13:52, Leonardo Marsaglia (<
ldmarsag...@gmail.com>) escribió:
You only need one beam. I would use the first beam interruption as a
second home switch of sorts, setting that with the home_offset when
you install a new wheel. The established home offset then becomes
your new wheel reference. This should then be considered a fixed
reference and a suitable distance from the work to prevent
accidental contact during setup.
I was thinking about using the two beams that are transversally
cut by the well because that way I can measure the length of a
circular portion and have an exact measure of the radius
independently of the home distance or the part diameter being known.
The only thing that would matter with this approach would be to know
exact distance between one beam and the other and they off course
must be perfectly perpendicular to the wheel axis of movement.
And obviously Leonardo, make a youtube video and tell us about it
when
its working. :)
Be sure I'll let you guys know as soon as I do something. In fact,
I can't wait to see and show you the mazak turning with LCNC. After
that, I hope I can start converting the grinder as soon as poosible!
El dom., 22 mar. 2020 a las 10:41, Thaddeus Waldner
(<thadw...@gmail.com>)
escribió:
The most
primitive idea I have is to measure the wheel before placing it
into the machine and then keep track of its diameter as it gets
dressed. But sometimes we have to adjust the offset of the
dressing tool because a diamond just detaches from the tool and
then you need to correct for
that
difference.
I don’t know what the dressing system looks like, but if it’s
motorized in both axis( cut depth and motion across the wheel) then
why don’t you touch off the dressing point? You could do an initial
homing when machine starts, and again after each dressing
operation. Use the info to determine dressing point depth of cut
and also to infer actual wheel diameter. You could also use it to
catch the event of a diamond point being knocked loose, and alarm
the operator.
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
Cheers, Gene Heskett
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
