“Guide assistant in PHD2 shows a lot of backlash again in the Mach1.”

When I do a calibration with my 1100 with Absolute Encoders I get a text book result. No backlash.

The guiding assistant after a 8 min run a few nights back said I had 248 rms error in backlash.  With encoders I know my backlash is zero. It always asks me to put in backlash compensation. I just disable that function now. As Ray said something isn’t right with PHD2 and that guiding assistant.

Matt

On 27 Nov 2017, at 02:33, ronkramer1957@... [ap-gto] <ap-gto@...> wrote:

Guide assistant in PHD2 shows a lot of backlash again in the Mach1. 

 

Ron,

 

1)      I haven’t been following this thread until now.  So I don’t recall if you have a brand new Mach1 with the “new” adjustable gear assembly or not.  I have an older Mach1 that came from AP with more than one tag on it telling me I needed to, and how to do an initial (and necessary) backlash adjustment.  It was quite simple and quick, but made a lot of difference.  AP felt this backlash adjustment was so important they put at least one tag on the mount, and then enclosed another separate sheet of 8.5” x 11” piece of paper reminding me of the importance of doing this, and how to do it.  The instructions are also in one of the booklets AP included with the mount.

2)      Measuring backlash is also easy and mechanical.  You don’t need software – just a stopwatch.  You can do it with your scope and eyepiece mounted and pointing at a distant fixed terrestrial object.  You move the mount one way until the object is at the extreme edge of the FOV, then move it to the opposite direction to the other extreme edge of the FOV while measuring the seconds it takes to accomplish that.  And then opposite move button again and measure the seconds before the image actually moves.  If you know the speed the mount is moving (published in the AP manuals) and the horizontal or vertical FOV (function of how long it takes the object to move from edge to edge of the FOV), you can calculate the backlash by counting the seconds the mount doesn’t move between direction changes.  This is a direct mechanical/optical/time measurement and there shouldn’t be any software “bugs” or “bad code” involved.

3)      Before jumping to conclusions and assuming your mount is “bad” or a “lemon”, do and read what AP recommends.  These mounts really are head-and-shoulders better than anything coming out of China.  And even more important than that, each and every one is adjusted and calibrated by hand before it’s shipped out.  Nevertheless, you must use common sense and follow AP’s instructions on setup and adjustment – particularly out-of-the-box. 

 

Woody

 

From: ap-gto@... [mailto:ap-gto@...]
Sent: Sunday, November 26, 2017 7:33 AM
To: ap-gto@...
Subject: [ap-gto] What specs should a new Mach1 adhere to?

 

 

I'm so frustrated. Being totally new to this I junked in head first... (had problems using a NEQ6) sold it and jumped in again. Figuring 6,000 would solve my problem.

 

Did I get a lemon? or am I just still a noob that is doing something wrong.  I dumped the NEQ6 due to excessive backlash. Everyone said - well you must have got a bad one.  I pulled it all apart - remeshed gears re-lubed and reduced the backlash by 50% but was still out of control.  Sold it - Mach1 arrives and it's beautiful.

However the proof is in the pudding?

 

Guide assistant in PHD2 shows a lot of backlash again in the Mach1.  Doing a long test it often reports around 1200ms and a (consistent map during backlash testing) where as the NEQ6 was never consistent.

 

Is this normal? did I get a lemon? is there a repair I (or AP) can do?   PHD2 says "set backla! sh in phd2 to 1200ms".  I do and guiding is quite poor. I turn "OFF" backlash compensation and guiding inproves!?!?

 

PHD2 tends to auto adjust the backlash setting and if I set it to 500ms.  When I look later its at 836 oi 1248 or some other auto-set number?  So I find it best to just uncheck  backlash compensation all together.

Is PHD2 the best way to test the mount and BL?  - is there another way?  PEMProv3 have a way?  How do I tell if my mount is bad or needs repair?  I can't believe I got two BAD mounts - whats the odds.

 

I just don't know where to turn and well - 6K + APCC at 500 and Pempro at 150 - it's getting rather pricey.

What should the mount do for it's 6K price tag?   And how to test it for that?  I'd like to be sure if it's the mount or me. (likely me).

 

 

 

 

Ron

If you scroll down to the Mach 1 section on

http://www.astro-physics.com/index.htm?tech_support/tech_support

you will find backlash mitigation instructions tp which Woody refers.

Bryan

---In ap-gto@..., wrote :

Woody - thanks will do.  I didn't get a tag and extra sheet? (that I remember) it's like a kid on Christmas when they arrive and well paper is flying everywhere never to be seen again.

I will do a mesh on my dec - though I don't think it needs it - it can't hurt?

I didn't think my RA needed it - but I recently swapped scopes and after mounting the 127mm I could wiggle it with a clicking noise. I felt it was the cheap rings on the ES scope...

and tried to track it down. I could hear the click in the RA gearbox.  Luckily I had just read about the adjustment the night before.  So I loosened the 2 screws and with a little thumb

pressure laid the two gears (how ever they are configured in there) together more. Tightened.   That took the tiny bit of slop, wiggle and the click out of the RA access. 

(not sure if I'm getting better because of it) but I feel better.  I don't feel any slop in the DEC, but I'll do the same to check. 

I do love it - I just wish I could run a over all test and be sure it's doing well.  I have to say that the pointing is amazing.  Dead center... my camera is in for warranty repair and I wanted to play 

with the mount so I told it - point at the sun.  I ran sharpcap (since SGP can't handle sun exposures) and bam... dead center in my 80mm and guide camera.  Ohhh that ASI290mm is a low

res offering. I'd really hate to use it for imaging.

I'll tweak the dec mesh - just to be sure. 

Bryan- thanks for the link, I will check it out in a sec.  I'm awaiting a camera repair - so I just come out to the dome to tweak and play with the toyz.  Tweaked my dome rotator - and then I looked for slop in the DEC.  I had already removed a good it in the RA.  I didn't feel any in the dec last time - I DID THIS TIME.  I remeshed and now I don't feel any. 

I think that's what the link will say - but I'll go check it out.  It's SO EASY to work on this mount - Love it.

I suspect that should help in several ways. 

On Mon, Nov 27, 2017 at 7:07 PM, bryancashion@... [ap-gto] <ap-gto@...> wrote:

 

Ron

If you scroll down to the Mach 1 section on

http://www.astro-physics.com/index.htm?tech_support/tech_support

you will find backlash mitigation instructions tp which Woody refers.

Bryan

---In ap-gto@..., wrote :

Woody - thanks will do.  I didn't get a tag and extra sheet? (that I remember) it's like a kid on Christmas when they arrive and well paper is flying everywhere never to be seen again.

I will do a mesh on my dec - though I don't think it needs it - it can't hurt?

I didn't think my RA needed it - but I recently swapped scopes and after mounting the 127mm I could wiggle it with a clicking noise. I felt it was the cheap rings on the ES scope...

and tried to track it down. I could hear the click in the RA gearbox.  Luckily I had just read about the adjustment the night before.  So I loosened the 2 screws and with a little thumb

pressure laid the two gears (how ever they are configured in there) together more. Tightened.   That took the tiny bit of slop, wiggle and the click out of the RA access. 

(not sure if I'm getting better because of it) but I feel better.  I don't feel any slop in the DEC, but I'll do the same to check. 

I do love it - I just wish I could run a over all test and be sure it's doing well.  I have to say that the pointing is amazing.  Dead center... my camera is in for warranty repair and I wanted to play 

with the mount so I told it - point at the sun.  I ran sharpcap (since SGP can't handle sun exposures) and bam... dead center in my 80mm and guide camera.  Ohhh that ASI290mm is a low

res offering. I'd really hate to use it for imaging.

I'll tweak the dec mesh - just to be sure.