Help with Royal Astro reflector please.

[4333bw (Brad)]

I have just purchased a Royal Astro 100mm f10 reflector on a wooden tripod. The telescope is well abused with very dirty mirrors. Both end plates are pop-rivetted to the tube which causes me some concern. The tube is about 955mm from end to end. Has this been shortened? The telescope won't come to focus on the moon with the 6mm eyepiece but does with the 12mm eyepiece. To remove the mirror I can drill out the rivets but if I replace them with bolts and nuts the nuts appear to just tighten against the inside of the tube, is this normal? I would need long arms to hold the nuts to tighten them.
I did take some photos but attaching them seems to be beyond my abilities.
This is my first reflector so any help would be greatly appreciated. Brad.

[mura_gadi (Steve)]

https://www.cloudynights.com/topic/6...-newt-rebuild/

FL is measured to focal plane, which includes the 1/2 tube span from the 2ndary mirror and focuser height/focuser plate/tube thickness etc from the tube. The focal plane will sit slightly outside of the focuser, that's where you spend your time trying to get the ep's to sit for focus.

If the mirrors are filthy you may only be magnifying dust at the higher power?

[4333bw (Brad)]

Thanks Steve, I was hoping someone out there had the same telescope and could tell me if a bit had been hacked off each end of the tube, the pop rivets just done seem to be right. Brad.

[4333bw (Brad)]

Steve, that link seems to show the same telescope and should be helpful, thankyou. Brad.

[OzEclipse (Joe Cali)]

You can buy a cheap pop rivet gut and rivets for about $20 or maybe less. Given the handful of rivets you will need to replace, you don't need an expensive high quality gun. When you need to clean the mirror again in future, you'll have the gun at hand.
Joe

[4333bw (Brad)]

Thanks Joe, That's probably the easiest solution. I just don't like the pop rivets, they don't look right. Brad.

[OzEclipse (Joe Cali)]

Brad,

Find a scrap of sheet metal and drill a few holes in it and have a practice until you are confident with the way the rivets work.

There are various another products that can also solve your problem. There are nuts that can be crimped into sheet metal with a rivet gun, others that just get hammered into the sheet.

This might work for you depending upon the clearances between tube and cell. I'm not sure because although I know the type of reflector you are talking about, I am not familiar with the cell arrangement.

https://tinyurl.com/2r7crw5s


Joe

[mura_gadi (Steve)]

At some stage you'll want to pop the mirror out from the cell. There is a post for making a small 3 prong template to help lift the mirror out in "Projects and articles".

If you want to restore the scope, you will need to get pop rivets and be a little restricted on how you can get things done overall. If you want to get the scope back to functional you have a little more freedom.

Using scrap material to try before hand is a great way to learn and build confidence.

[raymo]

Use short mush head self tapping screws, then you can easily remove the mirror whenever you feel the need. If the end cover is riveted on with no screws protruding from the end of the scope, you may find that there is no
collimation adjustment possible for the primary mirror. Many years ago quite
a few Newts had the primary mirror glued to the rear cover. A very occassional tweak of the secondary was all that was needed.
raymo

[4333bw (Brad)]

Thankyou Joe Steve and Raymo, I guess I'll just have to drill out the pop rivets and see what goes on inside the tube. The Rivnuts sound like a good idea if there is room and there is certainly some good info in the 'Projects and articles'. Thanks for the help. Brad.