Bob's Knobs

[ScubaMike]

These are the only thing I have bought that didn't fully install or use with the C9.25 scope.

Installed two of them on and realised that they gave absolutely nothing unless you have fingers like needles to get them round the ridiculously small heads. No room between the edge of the "knobs" and the edge of the plasic surround. Unable to reach round and adjust them as they are so awkward.

Couldn't recommend them to anyone.

Removed them and replaced with decent stainless steel hex headed bolts for 1% of the cost. I can put an allen key into the bolt head and it doesn't slip like the original screws, and gives me some leverage so that I can make small adjustments

I suggest you visit your local hardware shop, get something useful, and save yourself £20 or so.

[angusb1]

I got some with my new R200SS the other day. I thought the ones for adjusting the primary were better than the originals but the secondary ones were no better than the grub screws that they replaced and meant that I couldn't put the cover over them so I went back to the grubs.

[smudgeball]

Interesting comment, mine were delivered a couple of weeks back and worked fine.

But I have a baby SCT in comparison to yours

Neil

[wrinkly]

Installed on a Newtonian secondary and found them useful despite bananas instead of fingers. Expensive, yes but at least you don't need one of those easy to lose small hexagonal keys.

[johninderby]

Bob's Knobs work perfectly on my C8. Easy to grip the knobs.

John

[tony4563]

Expensive for what they are, but I think they are great

[Merlin66]

In my recent review I mentioned my initial problem with the "standard" knobs for the C11 Fastar version.....Bob came back immediately with a couple of improved suggestions....they now work an absolute treat!!

http://stargazerslounge.com/supplier-reviews/97438-bobs-knobs.html

Which version of scope do you have?

[Charon]

Wish I had read this thread 30 mins ago as I have just ordered a set for my CPC800, ho hum.

[Mr Spock]

I was considering these for my C9.25. Hmm, I have some long M3 bolts around the house somewhere... maybe I should give them a go first.

[ScubaMike]

@Merlin,

I have the C9.25 (non-fastar) looks very much like John's image above.

I found it virtually impossible to grip the knobs due to the recessed part of the secondary holder they go into.

The ones on your scope look much easier to use though.

[Merlin66]

Bob can supply longer knobs....will give much more clearance BUT you need to check whether or not the cover will still fit the scope....that's the limiting factor.

[beetlejuice]

I have Bob's knobs on my C9.25 and C6 - the covers still fit perfectly. Just make sure you order the correct version for your scope.

[Hypernova]

Instead of shelling out £14 or so for Bob's Knobs I instead bought a pack of 10 hand knobs with an M4 thread from eBay and fitted them to the secondary on my 8" newtonian. They were 25mm long which were the longest I could find and they just about reached. Because the rear of the secondary was pitted by the grub screws I placed a large washer there for the knobs to push against so they didn't sink into the holes and muck up the collimation.

Maybe now I should consider upgrading the primary collimation screws to ones that don't require tools to adjust. The primary is most likely to be knocked out of alignment and I'd rather not have to mess about with screwdrivers and allen keys.

[ScubaMike]

Bob can supply longer knobs....will give much more clearance BUT you need to check whether or not the cover will still fit the scope....that's the limiting factor.

That would be an issue as I store my C9.25 in the garage, so it needs to be protected from dust. I believe the longer ones prevent the front cover fitting.

I have Bob's knobs on my C9.25 and C6 - the covers still fit perfectly. Just make sure you order the correct version for your scope.

The knobs did fit perfectly, I did order the right ones, the cover did fit back. I have not suggested that the cover didn't fit back with them installed. Merlin suggested that the cover might not fit with the longer ones that are available.

I just thought they were a waste of time & money as they were not easy to adjust. (see original posting?)

If you find them easy you must be much more dextrerous than I, and have much thinner fingers.

[gfletcher]

What is the thread size on the secondary adjustment screws ?

Graham

[Merlin66]

Just a note of caution:

If you DIY the secondary adjusting screws on an SCT you need to use a suitable spacer tube to "lift" the head of the knob to a workable position AND ensure the engagement of the screw in the secondary body doesn't interfer with the internals....you can gauge the "operating" length from the existing, original screws.

[Macavity]

I was quite happy with my Bob's Knobs for the secondary of my TS 8"/F4 Newt. In truth, I couldn't find an EASY UK source of 30mm M4 knurled screws. And I want to "chop a bit off" them, round their ends, add (as above) a washer behind the mirror to reduce friction etc.

It is less clear whether I will use them on the primary cell. I want to investigate how the adjustment on that works or doesn't (at least not very well!). <G> I sense I need a set of decent SPRINGS, rather than a change of knobs, too? I hate screwing things blindly / tightly into holes, in close proximity to a chunk of rather expensive thick glass!

[Mr Spock]

My scope is so well collimated at the moment I don't feel like disturbing it! I'll probably get a set of Bob's Knobs for when I do need to adjust.

[Mkofski]

The Bob's Knobe I have for my Celestar C8 fit and work great! It will be the first purchase I make for any new scope. The orange cap on the secondary doesn't attach after installing them, but that is just cosmetic so who cars?

[Charon]

My set of bobs knobs were delivered and they fit my CPC800 a treat, it will make re collimating so much easier.