Bob's Knobs

[Hayduke27]

Hi all!

I bought a set of Bob's Knobs for my Celestron NexStar C8 based upon many recommendations I had read.  They have shown up, and the threads on the Bob's Knobs seem to be wider than the threads on the original collimation screws.  They don't really want to screw into the scope easily, and I certainly don't want to force anything.  Does anybody have experience with this?  Should these work for my telescope? The set I bought had the following description:

 

Bob's Knobs Celestron 8" SCT f/10 Collimation Knobs fit Celestron 8" (20cm) f/10 post-1980 SCT with factory silver or Allen Phillips collimation screws, with or without Fastar secondary with silver collimation screws (NexStar 8, Ultima 2000, C8 black, or gray, etc). Please note that this includes post-2000 orange tube but does not fit pre-1980 orange tube or majority of scopes with black Phillips factory collimation screws. 

Has anybody else had trouble with these?

Thanks for any help!

[barkis]

Check here to see If you ordered the correct ones.

 

http://www.bobsknobs.com/SCT/page26/C8.html

[HunterHarling]

" with silver collimation screws "

The nexstar has black screws and the ones you got are for silver screws. You need the ones for faster compatible scopes with black screws.

Hope this helps

[L8-Nite]

Have a close look at the photo here, anything look familiar ?  

Consider taking one of "your" collimation screws to a local Hardware Store and ask an assistant to match the threads to some stainless socket head cap screws. Then get the plastic thumb screw caps to match, and either ask the assistant to squeeze them on in a vice, or do it your self. The cost, probably less than ( $ 2.oo ) two dollars.

Don't do it, but if you were to break off the head of one of those that was sent to you, you're likely to find that there's no difference.

 

[Dave In Vermont]

Be sure to swap out the screws for the Bob's Knobs (or equivalent) one-at-a-time. Do NOT remove the screws all-at-once. You'd risk dropping your secondary inside the scope.

Practice Zen -

Dave

[Mr Spock]

If it's Fastar then take the Faster assembly out to replace the screws. You have to collimate anyway when fitting screws so why not make things easy That's how I did my C9.25.

[Hayduke27]

Just as an FYI to anybody that might wonder what happened, I was informed by the seller that some runs of C8s had different threading on the collimation screws than others, and the ones I received DO fit some C8's, but he said without seeing my scope there was no way to get me exactly the right size.  Anyway, I am returning the knobs and I think I will just make a trip down the to hardware store.  Thanks for the advice everyone!

[ejp1684]

Once I managed to work out the size of the screws on my Evo 8, I bought three (with the heads on them) on ebay for just a couple of quid. They work perfectly.

Eric.