Re: Mach1 (spring loaded vers) has gear slop?

Roland Christen

So my question is there another method or documentation of what I might do to take that play out of the RA mesh?
There is no reason to take out any play in RA. That axis is always running in one direction and is never reversed, so play or backlash is not an issue. It doesn't come into play at all during tracking or guiding. Leave it be.

Run Guiding Assistant and look at the natural star motion when the mount is not being guided. It will tell you instantly what the stars are doing, how much they are moving due to atmospheric motion. If you get 1 arc sec RMS of natural star motion (scintillation) then no amount of guiding will get you less error. I recently checked my skies here in Northern Illinois when it was clear on Saturday. Stars were moving around so much (probably jet Steam) that i had 0.8 arc sec RMS values of just scintillation. I could not get better then that all night long with any guide settings. It's just the way things are in spring time around here.


-----Original Message-----
From: Ron Kramer <ronkramer1957@...>
To: main <>
Sent: Mon, Apr 6, 2020 5:41 pm
Subject: [ap-gto] Mach1 (spring loaded vers) has gear slop?

I was having superb performance over the last year. Total RMS guiding down around .24 - .32
I had some time away while swapping scopes from V1 RASA 11 to a V2 RASA 11. (very similar) V2 seems heavier. I rebalanced.
My guiding is now at best  .99 and averages around 1.50.  Good enough for decent stars at my image scale but it makes me concerned. The corrections are very abrupt. I've used PHD2 for 3 years and know it quite well for tuning. I can't seem to get it to smooth out.
I believe there was a PHD2 update during this  (good to bad shift). so it's hard to know if it's the mount or phd2. 
With that said - I feel there is a good bit of play in the RA mesh. I have taken the slop out before using the 'thumb pressure" tuning trick.  That isn't working this time.  I move the weights/top of teh scope a good bit that I think is the culprit. 
I opened the RA end of the box where the 3 gears are. (the middle gear turns freely easily). But it too seems to have some slop. ?  Meaning I can wiggle the middle gear1 bit (1/16th?) inch or could say 1.5-2mm or so before it contacts the other gears to make them move.
So my question is there another method or documentation of what I might do to take that play out of the RA mesh? 
I have seen the instructions for (old-style - no spring-loaded vers) which doesn't apply to me I don't believe. As noted above, the thumb/finger pressure on the release lever doesn't seem to work this time. Could this mean a new gear is needed in the box?  What else could I try?

Ron in Grand Rapids, MI

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