Charles Hopkins <chopkins@mip.net> wrote

Peter I could not get through with your e-mail so I will just post here.

<<I used 1 ½" belts geared 1.5 to 1>>
When you say 1 ½" belts do you mean belts with the notches on one side so
there is no slipping? (I think car timing belts are like this.) Here is a
picture of what I am thinking of http://sme.asiaep.com/b1.jpg

I used 8 mm HTS belts which are rounded tooth rather than what is in the
above picture. It is my understanding that the HTS is easier to obtain
zero lash. I used the 8 mm because it is very much over kill and thought
it might almost last forever. With this thought I first paired the
sprockets and measured the actual center to center distances for each set.
I then built my drives with this dimension and no adjustment. I placed an
outboard support bearing to help rigidity and for the last 5 years my
theory has proved to be sound. The belt size is the same as the primary
belt on my Harley Davidson. This certainly must be over kill !!
<<I use an indicator to locate a reference point>>
What sort of indicator? (I have a feeling this is a software indicator that
is a feature of the Ah-ha software.)

Nothing trick here. I use the limit switches just as a safety in case I
program a wrong number. I can do all kinds of dumb programming.
I set absolute machine zero to match the job. That is for normal vise work
the left rear corner of the job. The machine is now set to the job, but
there is no way to easily come back to this point incase of a failure. We
will say a power failure just as an example. This doesn't make me look
bad. I could just setup again, but that usually involves removing the part
or tool. Instead, just for reference, I set magnetic base indicators on the
ways and zero them at an out of the way point. This point is also where I
will tool or part changes. With this said, I just look at the indicators
before I start the next tool or part. If they read zero, all is well. If
they are not zeroed there is a problem. Although there is rarely a
problem, the indicators will tell this before a second part is involved.
In the case of a power failure, the indicators are a known distance from
the absolute zero. When I power up in the morning the indicators tell me
I still have good position. Also when I exit the Ah-ha program, to do a
file transfer, the position does not have to lock in exactly the same when
the motors are powered up. These very small changes don't amount to much,
but a power blink or brown out will make the indicators worth all the
trouble. I have plans to mount encoders to the motors and let software do
the reading. I think with the Ah-ha system the position reading will be
done by a second CPU. The EMC control for my new project Bridgeport will
be able to do this with one CPU. It is also still in the development
stages. On big jobs the indicators are hard to place. The encoders won't
get knocked off or pushed out of the way by a wrong jog move. Hey hey, I
am letting my mistakes show.
I don't quite follow you on this stuff. I think if I understand the
indicator stuff you were talking about better I will understand what your
are talking about here.

I am happy to share experiences and ideas anytime.
Charles Hopkins