Return to the Cloudy Nights Telescope Reviews home pageAstronomics discounts for Cloudy Nights members
· Get a Cloudy Nights T-Shirt · Submit a Review / Article

Click here if you are having trouble logging into the forums

Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu… uh, User

Equipment Discussions >> Mounts

Pages: 1
BruceGFL
member


Reged: 04/07/08

CG5 mountng knob/bolt replacement ?
      #5766291 - 03/30/13 08:33 AM

Good Day All, I have an older CG5 mount with the accessory tray nearer the bottom and the Celestron non-computer driven equatorial mount. This morning I discovered the grasping handle of the knob in pieces lying in the tray, shattered from age I guess. Would a new part from Celestron fit and be of the same screw pitch?

http://www.celestron.com/astronomy/celestron-knob-3-8-16-x-1-quot-four-prong....

Thanks for any and all help


Post Extras: Print Post   Remind Me!   Notify Moderator  
jbalsam
sage
*****

Reged: 07/06/12

Loc: Darnestown, MD
Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5766498 - 03/30/13 10:53 AM

Hey Bruce. Do you have a thread-checker? If so, measure the threads and let me know what they are. I'll measure the threads on my CGE bolts (the one you linked to) and let you know if they are the same.

Post Extras: Print Post   Remind Me!   Notify Moderator  
Geo.
Carpal Tunnel
*****

Reged: 10/01/08

Loc: Upstate NY
Re: CG5 mountng knob/bolt replacement ? new [Re: jbalsam]
      #5767462 - 03/30/13 07:54 PM

Not sure what you mean by the grasping handle of what. The CG-5 is principally metric. The parts that have plastic hand wheels are the dovetail saddle clamping bolt. That's M8x 1.25. The tripod hub retaining bolt - M10x 1.5 and the Az fine adjustment screws, think these are M5 or M6. The 3/8-16tpi is the bolt that secures a fork mounted scope to the equatorial wedge. The holes in the fork base are 3/8-16.

Try here: http://tinyurl.com/cogz7jn


Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: Geo.]
      #5771392 - 04/01/13 06:13 PM

JBalsam, apologies but I do not have a thread checker. Thanks for the offer though.

Geo. To be more specific, I meant the grasping knob which fits around the center mounting bolt. This bolt comes up through the center of the tripod and secures the equatorial mount to it. It looks like a tooth gear with 4 projections or teeth for grasping. Apparently the bolt head was press fitted into this plastic knob to make it easier to spin without using a wrench. Sorry if I'm making this more confusing. With what was left in the accessory tray, it must have looked like the one in the Celestron link above. The now revealed bolt head is definitely 9/16th. Hope this helps.
Thanks Everyone !


Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5771534 - 04/01/13 07:36 PM Attachment (8 downloads)

I've just realized a photo is worth those 1000 words so here is a the bolt and the center hole it comes up through to secure the equatorial mount to the tripod. Actually now that I have measured it, I was wrong is guessing that part in the above Celestron link is it.
But imagine this bolt with that 4 tooth plastic handle pressed over the bolt head and you have it. Any ideas??
And should this bolt be smooth in the middle as it is. I purchased this mount and tripod second hand so I do not have any manuals.

Edited by BruceGFL (04/01/13 07:39 PM)


Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5771544 - 04/01/13 07:40 PM Attachment (10 downloads)

Apologies but I do not know how to add multiple photos so the next two will come separately.

Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5771546 - 04/01/13 07:41 PM Attachment (9 downloads)

One more

Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5771555 - 04/01/13 07:44 PM Attachment (11 downloads)

And

Post Extras: Print Post   Remind Me!   Notify Moderator  
Skrenlin
member


Reged: 12/13/10

Loc: North Chicagoland area
Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5771565 - 04/01/13 07:47 PM

That's the bolt (that used to have a hand-nut on it) that screws the mount down onto the tripod? I'd take it to your hardware store. There are plastic finger knobs made now that are press fit on to most bolt sizes.

Post Extras: Print Post   Remind Me!   Notify Moderator  
skywolf856
sage


Reged: 01/25/08

Loc: SE Michigan
Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5771610 - 04/01/13 08:07 PM

That looks like a home made captive screw.
The threads are filed down in the center to allow screwing thru a tapped hole then attaching to another thread above that while the body of the filed down screw passed through the first threaded hole without binding.


Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: skywolf856]
      #5771668 - 04/01/13 08:43 PM

Hi Skrenlin, you are correct. That is the bolt which had the four tab spinning plastic knob pressed on to the top. Which is now shattered, a problem I have not idea how it happened.

Skywolf, yes, where it passed through the tripod top plate is threaded along with that silvery part on the equatorial mount. So you think it should be smooth in the middle for snugging up?


Post Extras: Print Post   Remind Me!   Notify Moderator  
Agatha
Pooh-Bah


Reged: 06/04/12

Loc: Coulee Region, Wisconsin
Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5771741 - 04/01/13 09:36 PM

Bruce,

I agree with Skywolf 856, it looks like a homemade bolt for the purpose. That's just fine. Yes, it is normal for the middle part to be smooth. It allows you to push it up to the mount base and then start threading/tightening it. I'm assuming that there is a washer or spacer of some sort for the bolt near the head end.

Best, Linda B.


Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: Agatha]
      #5772151 - 04/02/13 04:26 AM

Linda,
Yes there is a washer at the bolt hear, I appreciate your input.


Best Regards, Bruce


Post Extras: Print Post   Remind Me!   Notify Moderator  
BruceGFL
member


Reged: 04/07/08

Re: CG5 mountng knob/bolt replacement ? new [Re: Agatha]
      #5772152 - 04/02/13 04:27 AM

Linda,
Yes there is a washer at the bolt head, I appreciate your input.


Best Regards, Bruce


Post Extras: Print Post   Remind Me!   Notify Moderator  
Geo.
Carpal Tunnel
*****

Reged: 10/01/08

Loc: Upstate NY
Re: CG5 mountng knob/bolt replacement ? new [Re: BruceGFL]
      #5773719 - 04/02/13 07:07 PM

That's not homemade that's China made! They take a standard 10-1.5 metric bolt and machine off some threads. Generally when this happens to me I find a short piece of 1/4" steel rod and braise it to the top of the bolt to replace the plastic. Overtime plastic looses its plasticizers, get brittle and fails. Off gassing plasticizers are give you that "new car smell."

Bronze is forever.


Post Extras: Print Post   Remind Me!   Notify Moderator  
Pages: 1


Extra information
8 registered and 31 anonymous users are browsing this forum.

Moderator:  Dave M, richard7, bilgebay, iceblaze 

Print Thread

Forum Permissions
      You cannot start new topics
      You cannot reply to topics
      HTML is disabled
      UBBCode is enabled


Thread views: 530

Jump to

CN Forums Home


Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics