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Small Allen Wrench for Adjustment of Laser Collimators

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#1 patindaytona

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Posted 07 December 2019 - 08:51 AM

A laser collimator came with my telescope, but I can't adjust it. I bought a whole set of allen wrenches hoping the smallest one in it, which was very very small would fit it. It's still to big.

Looks like I can't even find an allen wrench anywhere to adjust it now. Anyone have similar experience with this?



#2 zakry3323

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Posted 07 December 2019 - 09:21 AM

What telescope? 



#3 patindaytona

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Posted 07 December 2019 - 09:37 AM

What telescope? 

I bought the Orion Skyquest xt12i used and a Meade Laser Collimator came with it.



#4 SloMoe

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Posted 07 December 2019 - 09:52 AM

2mm most likely,



#5 mashirts

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Posted 07 December 2019 - 10:05 AM

.7 to 3mm set on ebay. I searched ebay "micro Allen wrench". Then chose "nearest first" to bring up non-chinese shipping. Google search should bring up something on amazon, but I prefer ebay.

https://www.ebay.com/p/2127543633

#6 mich_al

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Posted 07 December 2019 - 10:08 AM

Had a similar issue, turned out it had been partially filled with goop and was really larger than expected.


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#7 skytele

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Posted 07 December 2019 - 10:10 AM

My Zhumell Collimator uses a 1.5mm Hex Key. Available individually at hardware stores that have boxed assortments of set screws and cost .37 cents each. I would also pick up a 2mm which comes in handy for other items.

In my area, ACE has these individually.

Edited by skytele, 07 December 2019 - 10:41 AM.


#8 patindaytona

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Posted 07 December 2019 - 10:32 AM

My Zhumell Collimator uses a 1.5mm Hex Key. Available individually at hardware stores that have boxed assortments of set screws and cost .37 cents each. I would also pick up a 2mm which comes in handy for other items.

I went to Home Depot. I have to buy the whole set. I already had all those though. The smallest in the set was still to big, so now i have alot of allen wrenches.  Maybe like ACE Hardware...



#9 Dynan

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Posted 07 December 2019 - 10:49 AM

Not sure this applies, but I carry a complete set of metric and SAE allens. Metric goes down to 1.5mm, SAE down to .050"

 

I am sometimes surprised that a foreign scope or item may use SAE. Try both. Nothing I have run across has stumped those two kits.



#10 patindaytona

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Posted 07 December 2019 - 10:59 AM

.7 to 3mm set on ebay. I searched ebay "micro Allen wrench". Then chose "nearest first" to bring up non-chinese shipping. Google search should bring up something on amazon, but I prefer ebay.

https://www.ebay.com/p/2127543633

yea, that looks more like the right sizes. Thanks Mashirts!



#11 B 26354

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Posted 07 December 2019 - 11:11 AM

https://www.wihatool...ric-5-piece-set

 

https://www.wihatool...nch-5-piece-set

 

These are super-high quality and high precision.


Edited by B 26354, 07 December 2019 - 11:14 AM.

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#12 SloMoe

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Posted 07 December 2019 - 12:17 PM

What I did to set the collimation of my laser was to first have a dedicated 1.25" to 2" eyepiece adapter, in other words an adapter you leave on the laser, I replaced the thumb screw with a socket set screw so I wouldn't be tempted to change it.

 

Then I placed the set up into my scopes focuser and slowly rotated it around and around, stopping every revolution to make an adjustment to the laser until when I rotated the laser & adapter the laser dot on the mirror was centered in the mirrors center spot/mark.

 

Then I removed the set up and set it aside for a bit to take a break from all that tweeking,,,,,,about an hour and a half's worth, then I put the set up back into the focuser to check that it still hit the center and when rotated it didn't walk around in the center spot of the mirror when I rotated it. 

 

Now I can set my laser set up in the focuser draw tube anytime and know it's accurate.

 

So does all that effort for accuracy need to be done?

 

No,,,,,,,,,

 

I use the Barlow'd laser collimation technique, Olof Carlin developed it, for that technique to work all the laser has to do is bounce back a shadow of the center mark to be seen on a screen, just because the laser is so accurate doesn't mean the rotation or the tilt of the secondary is precise, it's close but for precision you need to see the center mark reflected back and forth between two mirrors, the primary mirror and the draw tube eyepiece holder.

 

An Auto-Collimater is the second mirror, with a hole in the center and one to the side so it gets complicated to explain but imagine standing between two mirrors and looking to either side and only seeing one image, you.

If either mirror is off then you'll see a million you's like in a fun house mirror set up.

 

Now bouncing the reflection back & forth requires the a third mirror in the path to turn the reflection 90° out to the eyepiece in the end of the draw tube, where the Auto-Collimater now is placed.

 

So the third mirror needs to be accurately tilted and rotated to center the reflections path, that's your secondary mirror.

 

So now we eliminate the "You" standing there and to see an image stack on both mirrors of a center spot of your primary we put a third mirror with a hole in it so you can see the center spot image, as you tweek either of the main mirrors involved that stack will shift to a set of center spots, as you adjust the mirrors to see only one spot you're collimated.

That's what an Auto-Collimater does, it's the third mirror with a hole in it.

 

So when I go out and set up for viewing, first I adjust or tweek my secondary so the laser dot hits the primary mirror center spot, then I set my Barlow into the eyepiece holder then the laser, I adjust the primary so I see the reflection of the ceter spot pretty well centered on the screen, I remove the Barlow & laser and drop in the AC, now I tweek just a bit more and I have a stack of center spots,,,,,, about 5min if I take my time.

 

All the laser has to do is be accurately aligned to is to be able to illuminate the center spot on your primary mirror thru a Barlow.

When you drop the laser into a Barlow it defrac's the beam into a wider beam, 

 

I hope this helps explain why I'm not too worried about collimating my laser, even tho I spent a great deal of time doing it I learned that I didn't need to, but the lesson learned was well worth the time.

 

Here's a link to Catseye, go there and read.

All the credit for what I know about it goes to many that have helped me here on CN.

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