Centre Spotting Discussions - Page 2

netwolf · #21 14-09-2005, 07:34 PM

Thanks iceman, i feel better now. I was not to phased by the hole because it looks like it was ment to be there. The ding was alarming. But i gues this is going to happen sooner or later. I am going to take photos of the whole process when i center spot my mirror. So i will take a shot of it the hole then also.

Does anyone know if Trannsperency's can cause harm to the mirror. I dont intent to let it touch but i am not sure i can stop it from touching. I hope to have it taped to the edge so its stretched over the mirror.

netwolf · #22 14-09-2005, 07:37 PM

Thanks Starkler, i will check that out, i think you are right on the money with the stapple. Has anyone modified these bearings or replaced them with something else?

Can anyone also reccomend a Texta i should get for this?

RAJAH235 · #23 14-09-2005, 11:22 PM

I used a permanent marker. It's in the 'blind' spot along with the reinforcing ring.
The teflon pads are a must. Do not replace with anything but teflon.
The transparency will not damage the mirror, but if poss., get someone to hold it for the second it takes you to 'make your mark'!
ps. If people are having trouble with the balance of their tubes, experiment with the position of the alt teflon pads. Move them up in the 'D' to tighten, & down the 'D' to free up the movement. (about 1/4" to 1/2" is all you need). You might just be able to get rid of your dreaded 'Springs'!
HTH.

L.

netwolf · #24 15-09-2005, 12:22 AM

Thanks Rajah. I have seen posts from people recommending non-perminent ones so you can wipe them off later if need arise. I also considerd looking at the Catseye (http://www.catseyecollimation.com/) type method were you make get the binder reinforcers. But a bit of tape over the cross hole in the transperency, attach the non adhesive side of the reinforcer rings to the tape and then remove the adhesive covering. Press down the transperency remove tape and presto ring on mirror. But this method as simple as a marker.

One thing i had a problem with making the template was deciding on the Cross hair size. Am not sure what the smalles shadowed area is. I made the bold cross with a 10-12mm diameter. Not sure if this is within the shadow area of the secondary. Idealy I wanted this to be about 5mm less than the smallest secondary shadow for a 6".

Does anyone know what the shadow diameter would be for the various GSO dobs?

square_peg114GT · #25 15-09-2005, 09:25 AM

Quote:

Originally Posted by netwolf

One thing i had a problem with making the template was deciding on the Cross hair size. Am not sure what the smalles shadowed area is. I made the bold cross with a 10-12mm diameter. Not sure if this is within the shadow area of the secondary. Idealy I wanted this to be about 5mm less than the smallest secondary shadow for a 6".

Does anyone know what the shadow diameter would be for the various GSO dobs?

Should be the same as the secondary's diameter. As seen from infinity (where astronomical objects are) the 4 feet of tube you've got are insignificant. Secondary on a 6" GSO is 1-5/16".

slice of heaven · #26 15-09-2005, 10:07 AM

Quote:

Originally Posted by RAJAH235

ps. If people are having trouble with the balance of their tubes, experiment with the position of the alt teflon pads. Move them up in the 'D' to tighten, & down the 'D' to free up the movement. (about 1/4" to 1/2" is all you need). You might just be able to get rid of your dreaded 'Springs'!
HTH.

L.

Tried this option Laurie but the alt bearing surface is too slippery to make repositioning the pads worthwhile. I dare say the choice of surface is because of the pressure the springs apply.
There are ways to modify the alt bearing though to make the springs redundant.

janoskiss (Steve H) · #27 15-09-2005, 10:28 AM

Laser collimator?

slice of heaven · #28 15-09-2005, 10:57 AM

Quote:

Originally Posted by janoskiss

Laser collimator?

I was thinking the same

Seems the 'Title' is a bit off topic

iceman (Mike) · #29 15-09-2005, 11:00 AM

I've split the thread, the centre spot discussions are now in this thread.

netwolf · #30 15-09-2005, 11:37 AM

thanks iceman

netwolf · #31 15-09-2005, 07:21 PM

I went into Bintel today and bought a 2" GSO Barlow and 1.25" Orion Combination Cheshiere/Sgiht tube. Mike was very helpfull and gave me some advise on center spoting. Another gentelmen there i forget his name now (with specs and a pony tail) said the best way wos some brown paper, a compas and a texta. He gave me a print out that comes with the laser collimator that had some similar instructions on it. They guys at Bintel are very helpful and friendly and they know there stuff. Also they gave me a discount, not that i asked but i did mention iceinspace and thanked them for there sposorship of the comp.

So I am all set .. 1 Center Spot DIY coming up soon, I hope.

iceman (Mike) · #32 15-09-2005, 07:46 PM

Quote:

So I am all set .. 1 Center Spot DIY coming up soon, I hope

Excellent work, don't forget to take pictures and document as you go!

Quote:

Also they gave me a discount, not that i asked but i did mention iceinspace and thanked them for there sposorship of the comp

Nice one! They are good blokes.

netwolf · #33 17-09-2005, 05:14 PM

where can i get these reinforcement rings, if thats what they are called?

asimov (John) · #34 17-09-2005, 05:53 PM

At the news agency.