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Collimation screws

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#1 James Cunningham

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Posted 15 June 2012 - 09:25 AM

I installed Bob's knobs about 2 years ago. They have worked just fine but you can't turn them precisely enough to get near perfect collimation. I have long since discarded or can't find the original collimation screws. Does anyone know where I can find some. My original were metric with a slotted head (I think). I would love to get some with a hex head. Thanks.
Jim

#2 Peter in Reno

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Posted 15 June 2012 - 09:46 AM

Try www.mcmaster.com . Bring Bob's Knobs to Home Depot to determine the exact size of the screws and threads before ordering screws. Home Depot may have screws but I doubt it. The original screws were Philips head. Hex head screws would work better.

Peter

#3 James Cunningham

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Posted 15 June 2012 - 09:52 AM

Thanks. I also need to know the length of the original screws. I should be able to order a hex head stainless screw that is the right metric size and length as the original.

#4 Bob Griffiths

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Posted 15 June 2012 - 09:53 AM

Super glue a penny on each of the 3 bobs knobs...makes "grabbing them" easier and makes turning one a half a hair much easier..

Those of us with FAT fingers have a hard time knowing if we are actually turning one of the Bobs knows ..with the penny its easy..

Bob G

#5 Peter in Reno

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Posted 15 June 2012 - 09:59 AM

You should be able to know the length of the screws by removing one of Bob's Knobs screws and measure. You are going to remove them anyway so bring it to Home Depot to find out the thread size and diameter. I would order several sets of different lengths. Screws are cheap so you'll have extra parts. McMaster-Carr has very speedy delivery and you should get them in a few days.

Peter

#6 James Cunningham

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Posted 15 June 2012 - 10:00 AM

Wouldn't a dime work better since it has ridges on the outside? Or even a quarter?

#7 Peter in Reno

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Posted 15 June 2012 - 10:03 AM

Be extremely careful when handling super glue. Once it gets on the lens corrector you will never get the glue off. This is assuming gluing while the screws are still on the secondary mirror.

Peter

#8 Larry F

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Posted 15 June 2012 - 01:16 PM

How about emailing Celestron?

How about someone with an 1100 that's in need of collimation simply remove one screw, measure it, post the information, replace the screw and get on with the collimation? I have an 800 and I don't know if the screws are the same, and anyway I'm in good collimation right now, so I can't help. But there's got to be one of you 1100 folks that's going to collimate soon and can help Jimmy out. Taking out one screw doesn't put your secondary at risk of crashing into the primary.

Plus, this reminds you NEVER to throw anything away and label everything and go to Home Depot and get one of those plastic parts suppply drawer thingies to keep all your bits and pieces in.

#9 brianb11213

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Posted 15 June 2012 - 03:57 PM

Wouldn't a dime work better since it has ridges on the outside? Or even a quarter?

Heck, you must be rich. Most of would have difficulty finding even three pennies to rub together. We've spent the rest on scopes ;-)

#10 James Cunningham

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Posted 24 June 2012 - 12:13 PM

Thanks to Bob in Frederick, I superglued a dime on each of Bob's Knobs and the glue held and I was able to get more purchase with the dime. Then I started thinking. Why not super glue the heads off of a hex screw onto the top of the dime. It works! Last night, I was able to turn the collimation screws with the hex key and also can still turn the Bob's Knobs by hand. My only problem is that I used two different size hex heads so I need to keep two different hex keys hand for collimation. That is not a real problem.

#11 gfeulner

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Posted 02 November 2012 - 08:42 PM

This is a GREAT idea! I have to collimate my scope a lot and will give this a try. One thing though. Make sure to use dimes dated after 1965 because the ones prior to that date are 90 percent silver and are worth over $2.00 apiece!!

#12 barbarosa

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Posted 03 November 2012 - 04:25 PM

...use dimes dated after 1964 because the ones prior to that date are 90 percent silver and are worth over $2.00 apiece!!

A small price to pay for a top quality accessory. Go first cabin and get Mercury dimes. Ebay They cost a bit more but you deserve the very best. Get yours on Ebay but tell folks that they came from Arpiffle and van Clef. :shocked:

#13 Bob Griffiths

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Posted 04 November 2012 - 10:25 AM

I used 1943 LEAD Pennies... (The only year that pennies were made of lead !)

I was born in 1943 and have, over the years, pocketed every single one of those pennies that ever passed thru my hands....

You guys can use all the silver coins you want..

Bob G.

#14 mclewis1

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Posted 04 November 2012 - 01:00 PM

Lead, lots of lead in his hands and pockets over the years ... hmmmmm, this is starting to make sense. :silly:

:poke: :roflmao:

Mark

#15 aamilo

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Posted 05 November 2012 - 03:23 PM

I used 1943 LEAD Pennies... (The only year that pennies were made of lead !)


Umm... you mean steel, right? They never made lead pennies.

I can only imagine all the "Lead Poisoning" lawsuits if they had. ;)

#16 faltered

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Posted 06 November 2012 - 04:30 PM

yeah, the 1943 Pennies were made out of steel. A VERY small amount were made out of copper, and were a mistake. And are worth a LOT of money.

#17 barbarosa

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Posted 07 November 2012 - 03:03 PM

Zinc plated steel, sooner or later turning a dull color. Some folks did and do call them lead pennies.

#18 doctomster

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Posted 19 December 2012 - 05:31 PM

the screws are metric M3 .5 x 10mm
Lowes hardware sells the pan head slotted screws.
I was also able to go to specialty fastening shop and get a hex head version which makes for a better choice

#19 KerryR

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Posted 20 December 2012 - 01:45 PM

The tall-headed hex screws with the knurled sides are nice because you can insert an Allen key into them, and the key will stay there if you're gentle. So, you can put one key in each screw and leave them there while you collimate. The length makes teeny adjustments a breeze. If you put a small rubber band around all three, the inward torque will help keep the keys in place even better. It's helpful to affix a small, colorful flag made from colored duct tape or colored electrical tape, so that you can find them should you dislodge one to the ground while collimating.






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