Tuesday, December 7, 2010

Parts is parts

As noted in past blogs, I have the four main components of the telescope.

I have the primary and secondary, mirrors, the focuser and the telescope tube. Now the task is to put them all together to be a telescope.

My first challenge was to build the mirror cell. The mirror cell holds the primary mirror and holds it in position at the base of the telescope tube. The cell is comprised of two components: the mirror carrier and the back plate. The mirror cell has two functions. The main function is to hold the mirror steady at the back of the telescope tube and the other is to offer fine adjustments to the orientation of the mirror in relation to the secondary mirror. I made the mirror cell of maple ply as it is very hard but light. I decided oak was too heavy.


The mirror bed is 5/8" maple plywood and the retaining plate is 3/4" I made a retaining ring out of 3/8" thick Plexiglas. The retaining ring holds the mirror cell assembly to the tube with three bolts. Two bolts can be seen.

The mirror is held on to the carrier with three metal pressure plates. I will be changing this so as to allow a centering adjustment.


The Plexiglas ring can be seen in this picture as well as the fine adjustment screws and springs.




This is the assembly attached to the tube. The three hex socket bolts adjust the mirror level aspect to align with the secondary mirror. Aligning the primary mirror with the secondary mirror and the focuser is call collimation. The two mirrors must aligned perpendicular to each other in order for the image to be nice and crisp.


The next component is the assembly that holds the secondary mirror at the opposite end of the tube. The component is called the spider. You can see why in this picture. The spider holds the secondary mirror suspended above the primary mirror.



Three hex socket screws similar to the adjusting screws of the mirror cell help with the fine adjustment of the secondary mirror.

The secondary mirror is much smaller than the primary and its job is to direct the rays of light towards the side of the telescope tube assembly and through the focuser and onto the eyepiece lens. The angle of the secondary mirror can be seen in this picture.





This view shows the adjustment screws.













The spider is attached to the open end of the telescope tube as shown in the picture. The spider is made of 1/8" threaded rod and 1-1/2" pvc pipe..










The tube body is allowed to rotate up and down, latitude. A plywood frame with 3" pvc "axels" rest on the telescope base. Teflon pads allow easy and smooth rotation.
















The telescope also needs to rotate right and left, azimuth.




The telescope on its base.

















Much tweaking will be made in order to get the telescope to work just right.

I've been able to see Jupiter and the Orion nebula with this scope, but I need to make some modifications and adjustments to get it to work smooth and provide sharp, clear images.

The primary modifications I need to make are the altitude and the azimuth, up and down and left to right, rotations to be nice and smooth with no jumping or jerking.

I am also making some modifications to a web cam so I can capture images through the telscope onto my lap top. This will be the next challenge.

Thanks for reading and I hope to have some nice images soon.

2 comments:

Leonor Marquez said...

Hi! I´m Leonor from México City, I just want to say that I admire the work you´ve been dooing, actually you´re inspiring me to build one telescope for my husband who loves the night sky, so if you have any other tip, i´ll be wainting for it.

Thank you! ;)

Newcoach said...

HI Leonor. I am sorry I took so long to respond. I have been busy with so many things.

If you have already built or bought your husband a telescope already I would like to read about it and how he is enjoying it.

If I could give you one bit of advice it would be to get the best quality primary mirror (the one at the bottom) that you can afford. The quality of the mirror will give the telescope quality. and don't bother with anything smaller than an 8 inch reflector telescope. Anything smaller and you will see very little.