Jump to content


Photo

MI-250 Owners-Should I upgrade these MI-250 parts?

  • Please log in to reply
11 replies to this topic

#1 fetoma

fetoma

    Vanguard

  • *****
  • Posts: 2411
  • Joined: 26 Sep 2006
  • Loc: Southern NJ

Posted 14 January 2013 - 04:24 PM

Hi Group,

Below is a link to a photo of a few parts I am thinking about upgrading. The Az
Adjuster Post, Alt Block, and threaded rods for them. I was thinking about
changing both to 304 stainless steel with 3/8-24 fine threads for everything.
New bronze bushings to accept the larger threaded rods too.

Good idea or just leave it alone?

http://flic.kr/p/dKLNjq

Thanks,
Frank

#2 TxStars

TxStars

    Apollo

  • *****
  • Posts: 1382
  • Joined: 01 Oct 2005
  • Loc: Lost In Space

Posted 14 January 2013 - 08:51 PM

If you have to set-up all the time then the change will make alignment a little easer each time.

#3 David Pavlich

David Pavlich

    Transmographied

  • *****
  • Administrators
  • Posts: 27775
  • Joined: 18 May 2005
  • Loc: Mandeville, LA USA

Posted 14 January 2013 - 10:07 PM

Hey Frank...I was considering the very same modification to my MI250. It's one of the only weak points. The adjustment rods with the USS thread is just not sensitive enough. Replacing them with SAE thread would be a very good upgrade, I would think. The only other less than perfect part of the mount is its inability to go much beyond the meridian. And I have the Maxon motors that stick out further than the stock motors, so I have to watch very carefully.

David

#4 Raginar

Raginar

    Fly Me to the Moon

  • *****
  • Posts: 6138
  • Joined: 19 Oct 2010
  • Loc: Rapid CIty, SD

Posted 14 January 2013 - 11:40 PM

Where do you get the parts to make this happen? Is it an easy order?

David, have you considered Tom Hilton's 'mod' of putting a spacer in for the declination to allow it to skip hitting the motors?

Also, on a side note. You guys have had your mounts for awhile, have you noticed any wear and tear on them? Someone mentioned their fear of getting an 'older' mount like an MI250 was that the gears/worm would start to get 'old'. Are you guys noticing any performance degradation over time?

I'm a few weeks out from finally getting mine setup... I can't wait to try it!

#5 David Pavlich

David Pavlich

    Transmographied

  • *****
  • Administrators
  • Posts: 27775
  • Joined: 18 May 2005
  • Loc: Mandeville, LA USA

Posted 15 January 2013 - 10:22 AM

Where do you get the parts to make this happen? Is it an easy order?

David, have you considered Tom Hilton's 'mod' of putting a spacer in for the declination to allow it to skip hitting the motors?

Also, on a side note. You guys have had your mounts for awhile, have you noticed any wear and tear on them? Someone mentioned their fear of getting an 'older' mount like an MI250 was that the gears/worm would start to get 'old'. Are you guys noticing any performance degradation over time?

I'm a few weeks out from finally getting mine setup... I can't wait to try it!


Hey Chris...I may do the Hilton mod when I take my mount down to do the other mod. My 250 is controlled by SiTech and is set to stop it from hitting the motor. Where I messed up was balancing it some time ago. I let the mount slip and it whacked the motor and cracked the gearbox. :p

As far as the mount wearing out. I suppose it would after a LONG time. Larry built these things like the proverbial brick observatory. One thing I did with mine when I changed over to SiTech was to slow the slews down. Yea, it takes a while to get from one object to another and doing the alignment takes a little longer, but it's a lot less wear on the mount. I wouldn't be concerned about wearing it out. Clean it up once in a while, keep it lubed and you'll have a mount that will probably outlive most of us.

David

#6 fetoma

fetoma

    Vanguard

  • *****
  • Posts: 2411
  • Joined: 26 Sep 2006
  • Loc: Southern NJ

Posted 15 January 2013 - 03:07 PM

Chris,

I will be having them made by a machinist.

#7 Raginar

Raginar

    Fly Me to the Moon

  • *****
  • Posts: 6138
  • Joined: 19 Oct 2010
  • Loc: Rapid CIty, SD

Posted 16 January 2013 - 06:43 AM

Frank,

You willing to have two made? PM me if you would please. I'd love to find someone to make the spacer too. Seems to be the only real issue in the mount is its inability to track to meridian.

Chris

#8 Bowmoreman

Bowmoreman

    Clear enough skies

  • *****
  • Posts: 9162
  • Joined: 11 Sep 2006
  • Loc: Bolton, MA

Posted 17 January 2013 - 01:13 PM

Hey Frank...I was considering the very same modification to my MI250. It's one of the only weak points. The adjustment rods with the USS thread is just not sensitive enough. Replacing them with SAE thread would be a very good upgrade, I would think. The only other less than perfect part of the mount is its inability to go much beyond the meridian. And I have the Maxon motors that stick out further than the stock motors, so I have to watch very carefully.

David


I precisely echo David's posts; *especially* about the Maxxon's (i.e. don't forget to reprogram your safety limits!)...

I would consider the changes you are thinking about if you don't have a permanent setup (i.e. unlike me)... I found the adjustments needed to nail polar were a bit more frustrating than I wanted because of the non-fineness of the adjustments and some "backlash" while doing so... presumably Stainless steel/brass and finer threads would assist there...

#9 Bowmoreman

Bowmoreman

    Clear enough skies

  • *****
  • Posts: 9162
  • Joined: 11 Sep 2006
  • Loc: Bolton, MA

Posted 17 January 2013 - 01:16 PM

I'd be "in" on the spacer as well if someone is driving it... David, what about you?

(you'll find us MI-250'ers are a bit of a "clubby bunch")

;)

#10 David Pavlich

David Pavlich

    Transmographied

  • *****
  • Administrators
  • Posts: 27775
  • Joined: 18 May 2005
  • Loc: Mandeville, LA USA

Posted 17 January 2013 - 06:53 PM

I'd be "in" on the spacer as well if someone is driving it... David, what about you?

(you'll find us MI-250'ers are a bit of a "clubby bunch")

;)


When it gets hot again, I'm going to pull the mount off of the pier and change the Alt and Az adjusters to SAE thread. I'm going to give the spacer thing a look see. It may be a good thing.

David

#11 Raginar

Raginar

    Fly Me to the Moon

  • *****
  • Posts: 6138
  • Joined: 19 Oct 2010
  • Loc: Rapid CIty, SD

Posted 17 January 2013 - 11:16 PM

When I get home, I'll see if I can find a CNC for the spacer too. I wonder if we could find some place online?

#12 Raginar

Raginar

    Fly Me to the Moon

  • *****
  • Posts: 6138
  • Joined: 19 Oct 2010
  • Loc: Rapid CIty, SD

Posted 13 February 2013 - 10:46 PM

I talked with the guy who's been advertising as a machinist over on AM. Are either of you guys interested? He said he could make one or do a run for us. PM me and I can send you the info.

Chris






Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics