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it's too late I know, but Rother Valley Optics sell Bob knobs.

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Non of the retailers had them to fit the US Orion's for some reason. One of them told me I could only get them from the US.

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What's so special about these knobs? Are they a metric thread? You can buy a set (4 or 5) of cap head bolts, length and thread of your choice for just over a pound on Ebay? Same thing?!

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Am new to Newts so don't know, can only go on what I was told/read. Leaving that aside, if they're standard threads, with standard ends/chamfers, then why do so many even bother buying Bobs Knobs at all? Why do they exist?

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That's almost $70 CAD for 3 screws, I would cry in the fetal position, an abomination!

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Posted (edited)

Hi .Yes I think there way overpriced. I bought a pack of 10 stainless steel knurled knobs from ebay for £8:50.and made my own .as I had some 5mm threaded bar in my workshop.easy .

Edited by fiestazetecmk2
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Lessons to be learned from this discussion is it is vital to do your homework before buying from the US. I have bought loads of gear over the years from Astro dealers in the States but only if it saves me money.

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There's a lot to be said for buying things off the shelf. A lot of people don't want to fiddle about making their own :wink2:

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Posted (edited)
6 hours ago, Markinaboat said:

Am new to Newts so don't know, can only go on what I was told/read. Leaving that aside, if they're standard threads, with standard ends/chamfers, then why do so many even bother buying Bobs Knobs at all? Why do they exist?

I have them on an SCT. They exist because it means you don't have to use a metal hex key near the corrector plate when making adjustments to collimation. If you are using a large aperture SCT then you cannot make adjustments at the same time as looking through the eyepiece. The thinking is if you let the hex key fall, quite possible on account of its small size, then it could damage the glass on the plate. Also, if using the knobs then it is more convenient than faffing about, in the dark, with a hex key.

Whether it is possible to achieve very small tweaks with a hex key, rather than the knobs, to enable more precise collimation, is another discussion. From my experience the hex key is the winner.

Edited by Cleetus

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There's Alot to be said for saving yourself money and being able to make your own thing also. 

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2 hours ago, Mr Spock said:

There's a lot to be said for buying things off the shelf. A lot of people don't want to fiddle about making their own :wink2:

I have bought everything from AliExpress as off the shelf parts. Complete kit (10 M5 knobs, 5 M4 knobs, 20 bellville washers to replace o-rings) was about $12 with some spares left. 

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3 hours ago, Cleetus said:

Lessons to be learned from this discussion is it is vital to do your homework before buying from the US. I have bought loads of gear over the years from Astro dealers in the States but only if it saves me money.

Absolutely! However, I could not get the information I needed quickly enough and wanted to use my new (to me) scope whilst I had the time. Perhaps if I'd bought via ebay, it would have stated there and then what the additional costs would be..

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56 minutes ago, pregulla said:

I have bought everything from AliExpress as off the shelf parts. Complete kit (10 M5 knobs, 5 M4 knobs, 20 bellville washers to replace o-rings) was about $12 with some spares left. 

Just to add, if I hadn't already mentioned, that I was led to believe that the knurled thumbscrews were sized so as to fit the relatively close centres of the three holes. Anyway, I'll be re-collimating the secondary again without the fiddling that I experienced with the allen key and my arthritic left hand!

Thanks to all here for your input

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I used pc screws off ebay £4 the second time I  needed secondary   Screws first time I used bobs knobs never again couldn’t justify the price for what they are . 

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Actually most if not all other countries postal services change handling fees for goods clearing customs so it’s not just the UK. In Italy for instance think it’s about £11.00. Anyway it’s way less than the handling fees charged by couriers.

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When I bought BK's from the USA - from Bob direct - about five years ago they just dropped through my letterbox like any other letter.  They came in a jiffy like envelope.  No charges or payments required.  Are the Post Office or HMRC being stricter now?

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21 hours ago, bottletopburly said:

I used pc screws off ebay £4 the second time I  needed secondary   Screws first time I used bobs knobs never again couldn’t justify the price for what they are . 

I agree.  That said, Bob has done his research into this and developed his website - from which we can grab info (or use other posts from folks who used his website to get the info) -   so needs to charge.

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25 minutes ago, kirkster501 said:

I agree.  That said, Bob has done his research into this and developed his website - from which we can grab info (or use other posts from folks who used his website to get the info) -   so needs to charge.

Oh no doubt on that ?

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4 minutes ago, kirkster501 said:

I agree.  That said, Bob has done his research into this and developed his website - from which we can grab info (or use other posts from folks who used his website to get the info) -   so needs to charge.

Just to add my 2p, I don't think in this case Bob's Knobs has had to do a lot of unique research to come to the conclusion that you can replace these grub screws with knurled screws. It's not like the only source of the information must have been from Bob's hard work and that we are stealing his IP...   given the ingenuity on regular display within the DIY astronomy arena I suspect we'd be doing a simple mod such as this anyway.

I'm not saying that Bob's Knobs isn't offering a product that has value, and has put work into marketing that product, and I am definitely not criticising Bob Knobs. 'He' is offering a service, and a lot of people want to buy something off the shelf that they know is the optimum size and will just work.

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