Re: PEMPro vs PHD2 #Guiding

Ray Gralak

Please affirm: PEMPro, while it's doing a PE run,
knows the exact rotational position of the worm any moment,

It is my belief that the worm is simply worn out
Probably not. The worm would not vary between worm cycles. More likely it is a gear mesh and/or differences between worm wheel teeth. If there is dirt, grit, etc., on some teeth that could also cause variations between worm cycles.

-Ray Gralak
Author of PEMPro
Author of APCC (Astro-Physics Command Center):
Author of Astro-Physics V2 ASCOM Driver:

-----Original Message-----
From: [] On Behalf Of CurtisC via
Sent: Monday, September 7, 2020 12:59 PM
Subject: Re: [ap-gto] PEMPro vs PHD2 #Guiding

[Edited Message Follows]

Ray: Thank you for looking at my data.

During the afternoon of Sep 2, prior to the runs I sent to you, I removed the RA box. I thought maybe there was
"gunk" deep in the teeth of the worm. Maybe that was the cause of my bad numbers. So I made a special point of
cleaning out the teeth in the center part of the worm with a toothbrush and paper towels pressed over a fingernail.
I'd already cleaned out the teeth a month ago, but this was a special effort to get to the bottom of it, so to speak. I
then put more lube on the worm and reassembled the motor to the mount. Since I'd spun the worm several times, I
had no choice but to do a PEMPro run. That produced the 6-something curve. I reran the curve late in the
evening, hoping I'd see evidence of a consistent improvement. I don't want to rely on an anomalous one-off curve
to program the mount. The second run gave me the 11-something result. I attribute the "good" curve to new
grease in the teeth of the worm, grease that was redistributed during subsequent imaging with the mount and then
the late PEMPro run (was there more than one? I forget.) Since the evening of Sep 2-3, subsequent remeshings
and PEMPro runs have produced p-to-p in the area of 18 and 19. The curves are smooth. Last night I had 19 p-
to-p. But, with PEC on, the corrected curve was 0.87, which I thought was pretty good. All of this is with
fundamentals 1, 2, and 3 checked.

Thank you again, Ray.

Please affirm: PEMPro, while it's doing a PE run, knows the exact rotational position of the worm any moment,
does it not? When the dots start appearing on the graph, the starting location isn't random. The starting location
and subsequent dots correspond to real, definable positions on the worm. Sometime during the recent weeks, a
consistent broad hump in the middle of the curve was replaced by a consistent broad trough. I attribute this to my
fiddling with the worm.

To continue, during these recent weeks, I've spent a lot of time in the message archives of this forum, looking at
any discussions about Mach1 PE, worms, motor boxes, PEMPro, etc. Naturally, I've paid special attention to any
comments from you and Roland, and the rare comment from George and Howard. I ran into some of my own
posts from 2014, where I was reporting consistent PE of 11-something. That is, the curves produced by this worm
now are worse than they were 6+ years ago.

It is my belief that the worm is simply worn out. Perhaps all of those years between its manufacture and my
relubing the mount took a toll. That is, I'm confident that the worm was spectacular when it left the factory in Mar
2010. The poor results I've been getting since then are due to my own negligence.

I have some outstanding messages to two members of the A-P staff, and one A-P staffer requested some PEMPro
data, which I sent to him. I haven't heard back. But it's vacation time, and now we have the Labor Day weekend.
In the meantime, I decided that as long as the curves are smooth, I'll live with the native PE -- that is, unless
someone can identify a specific, correctable error that I'm making in my procedures. I put my name on the "notify
me" list for the Mach2. When (if!) I get a Mach2, I'll probably send my Mach1 to A-P for refurbishment. That, way,
when I offer it for sale, I can confidently say that it's up-to-spec and has been blessed by A-P.

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