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Collimation screws

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#1 stargeeser

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Posted 19 March 2015 - 07:23 AM

Does anyone know the type of screw needed in order to replace collimation screws (length, thread type etc.), or where I could find the info? I would like to switch from Phillips head to allen wrench. My C8 is an orange tube that is fastar compatible.

Clear Skies

 



#2 MikeBOKC

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Posted 19 March 2015 - 07:32 AM

I would tend to go in the reverse direction, preferring the Phillips screws. Seems like there would be a greater danger of scratching or otherwise damaging the corrector with a hard to turn Allen wrench.



#3 stargeeser

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Posted 19 March 2015 - 07:42 AM

True but one of the screws stripped ever so slightly and it is now hard to tighten. I need to replace it regardless but I figured the wrench screw would be harder to strip. Maybe I'm wrong but I still need the screw size even to replace it with another Phillips screw. 



#4 T1R2

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Posted 19 March 2015 - 07:45 AM

Bob from "bob's Knobs" should know, if you don't get a answer here shortly, he makes replacement knobs for all kinds of SCT's, give him a call



#5 Jim Davis

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Posted 19 March 2015 - 07:46 AM

Look at the Bob's Knobs web site: http://www.bobsknobs.com/

 

He sells replacement collimation knobs, and has info to identify the type of screws you need for your scope.



#6 JoeR

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Posted 19 March 2015 - 09:02 AM

I stripped my factory screws last year so I replaced then with hex key screws from Home Depot. They work very well and allow a little extra torque to really hold your secondary in place. Bob's knobs are good but is it really a hassle to keep a hex key or screwdriver in your accessory case? I have better piece of mind knowing my collimation will always hold now unless the OTA really gets jolted in transit.



#7 stargeeser

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Posted 19 March 2015 - 11:22 AM

Do you know the length, diameter and thread size that you bought?



#8 HowardK

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Posted 19 March 2015 - 11:28 AM

I would tend to go in the reverse direction, preferring the Phillips screws. Seems like there would be a greater danger of scratching or otherwise damaging the corrector with a hard to turn Allen wrench.

Bad info here in my opinion

 

buy a T handled allen wrench if you find a normal allen wrench "hard to turn"

 

the precision in collimation effected by a set of deep allen headed screws compared to those puny phillips screws really is night and day


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#9 JoeR

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Posted 19 March 2015 - 12:24 PM

Do you know the length, diameter and thread size that you bought?

 

I don't recall I took a screw I removed there and matched it up.



#10 TG

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Posted 19 March 2015 - 12:27 PM

 

I would tend to go in the reverse direction, preferring the Phillips screws. Seems like there would be a greater danger of scratching or otherwise damaging the corrector with a hard to turn Allen wrench.

Bad info here in my opinion

 

buy a T handled allen wrench if you find a normal allen wrench "hard to turn"

 

the precision in collimation effected by a set of deep allen headed screws compared to those puny phillips screws really is night and day

 

 

+1. The primary utility of Philips screws is to limit torque. This can be an issue in plastic secondary cells but with a little care, the precision afforded by a hex key is far more valuable that any over-torquing protection. Also, a small hex key falling on the corrector has a very small chance of damaging it. A substantially larger screwdriver has a proportionally larger change of inflicting lasting damage if dropped onto the corrector.

 

I dislike BK's. They're fine when you're getting the hang of it but afterward, they have neither the precision nor the durability of collimation afforded by hex screws.

 

 

Tanveer

Tanveer.


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#11 stargeeser

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Posted 19 March 2015 - 01:12 PM

Thank u for all the replies but does anyone know the info needed to get these screws at the hardware store? Bobs Knob website doesn't have that infor (it only tells u if they are metric or not)

CS



#12 Jim Davis

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Posted 19 March 2015 - 01:56 PM

My local hardware store has a large selection of screws. They also have a device on the wall with threaded holes to test and identify your screw. Take one to a good hardware store and ask.



#13 dragonslayer1

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Posted 19 March 2015 - 02:00 PM

If I recall correctly, weren't there two different types of screws used depending on which 9.25 you have??
Kasey

#14 RAKing

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Posted 19 March 2015 - 03:03 PM

 

I would tend to go in the reverse direction, preferring the Phillips screws. Seems like there would be a greater danger of scratching or otherwise damaging the corrector with a hard to turn Allen wrench.

Bad info here in my opinion

 

buy a T handled allen wrench if you find a normal allen wrench "hard to turn"

 

the precision in collimation effected by a set of deep allen headed screws compared to those puny phillips screws really is night and day

 

 

Amen to this! :waytogo:

 

With a Phillips head, you have to push against the glass to maintain contact with the screw head. I was always afraid I would push too hard and crack the corrector. :mad:

 

I have replaced all of my collimation screws over the years with stainless allen head bolts and they make life so much easier when I have to collimate. Besides the T-handle, I also have a regular screwdriver handle and both of these will stay in the allen head while I look through the eyepiece. I can then reach out and turn them, usually while I'm watching. No slipping and more precise results for me.

 

The newer Celestrons use 3mm X 12mm screws. I do not know if the earlier orange versions used metric or standard sizes.

 

Cheers,

 

Ron


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#15 MikeBOKC

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Posted 19 March 2015 - 06:43 PM

Maybe it's just the arthritis in my hands, but I feel awkward using an Allen wrench and prefer the standard screwdriver I guess it is a matter of taste Luckily SCTs don't need collimation very otten whatever tools one uses.



#16 HowardK

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Posted 20 March 2015 - 05:28 AM

Maybe it's just the arthritis in my hands, but I feel awkward using an Allen wrench and prefer the standard screwdriver I guess it is a matter of taste Luckily SCTs don't need collimation very otten whatever tools one uses.

T handled allen wrench



#17 nemo129

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Posted 20 March 2015 - 05:37 AM

From Bob's page:

Special Note: The Celestron SCT uses either standard 6-32 or metric M3 collimation screws.

 

I think you just need to examine the examples of the secondary holder to figure out the metric/standard question.

 

If unsure of length, take one out of your OTA and measure it. Maybe take that one to the hardware store, just in case! ;)


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#18 John O'Grady

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Posted 20 March 2015 - 07:43 PM

Here's one link I found useful: 

 

http://www.celestron...escopes (SCTs)?

 

This should be the information you're after.  If in doubt, you should consider contacting celestron support. 

 

Regards,

John



#19 stargeeser

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Posted 23 March 2015 - 01:53 PM

Thx for the info I just got the screws from home depot. They didn't have button head screws so I bought the cap head screws (I think that's what they're called). I will hold them until the scope loses collimation. For now the scope is spot on so why touch it. At least I'll have the screw when needed and wont lose a night of observing when it does happen.



#20 WesC

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Posted 24 March 2015 - 07:32 PM

Here's what I used to replace the collimation screws on my Edge 11... they work great, are cheap, and if you strip one you have a lot more!

 

http://www.mcmaster....274a106/=wgdsnw



#21 stargeeser

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Posted 24 March 2015 - 10:13 PM

Those are exactly what I got (though they were not that cheap. Mine were 3 for a buck) Glad to hear that they work.

Clear Skies



#22 Jeffmar

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Posted 31 March 2015 - 08:09 PM

Thank u for all the replies but does anyone know the info needed to get these screws at the hardware store? Bobs Knob website doesn't have that infor (it only tells u if they are metric or not)

CS

 

I have three SCT's and have replaced all the collimation screws with Bob's Knobs. I tried several years to find easier ways of collimating my scopes. I even glued shortened 90 degree hex wrenches into the screws. It was better than stock but not ideal. When I finally got around to trying Bob's Knobs on my first SCT I found it was many times easier to collimate my scope. 

My newest scope, which is a celestron edge, had phillips head screws. They were almost a disaster for me. I nearly stripped the heads trying to collimate my new scope. I was not sure which knobs to order so I emailed Bob. He replied in less than 24 hours. I am not trying to sound like an ad for these little knob things but they are soooo much better than having to use screwdrivers or hex wrenches to collimate my scopes. Good luck in your project.



#23 BILJ

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Posted 03 January 2016 - 11:26 PM

I just got my first telescope, a Celestron C8-XLT on AVX mount.  It has the black metric philips screws. I wanted to replace them before my first collimation attempt (wish me luck).  I have a GoldFocus mask I plan to use for collimation which makes it hard to use thumbscrews, and the makers of the mask recommend a T-handle hex driver for more torque and finer control. 
I bought a pack of 3 hex socket cap screws at Home Depot for $0.45 and they fit nicely.  They are M3 with 0.5 threads and have a 2.5mm hex socket.  I got 10mm long screws because they didn't have them in 12mm (which other posters have used).   Regarding the length, even at 10mm these are longer than the original philips screws.  I've attached a picture of original screw next to with the ones from Home Depot and a picture of the package.

To adjust them, I've ordered a Klein Tools JTH6M25BE 2.5mm Hex Key with Ball-End Journeyman T-Handle ($4.22 on Amazon).  Until it arrives, I'm using a regular allen wrench (L-shaped).  While traditional allen keys are clumsy, the T-handle looks ergonomic and should give me fine control.

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#24 Itz marcus

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Posted 03 January 2016 - 11:47 PM

Hi,
I think that the edge scopes use 12mm screws the regular ones use 8mm. I switched mine with the hex head but at m3 .5 8mm. So these are too long and I wouldn't use them.
Clear skies
Itz

#25 BILJ

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Posted 04 January 2016 - 12:14 AM

Thanks Itz.  I only replaced 1 screw so far and it seemed ok but can't really tell if it's causing a problem inside (pressing on something) or not.  I'll play it safe and get the 8mm screws: http://www.homedepot...03178/204808022




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