Help with secondary mirror fix

[johninderby]

Well sorted now. 👍🏻👍🏻👍🏻

Strange that Bresser fits a steel washer on the 10” and doesn’t fit one to the 8”. 🤔

Lack of washers is a common problem on many dobs though. 

[Pixies]

12 minutes ago, John said:

That does look better.

With the milk carton washer modification, I think the optimum benefits are gained from having the collimation screw tips bearing directly onto the washer / washers. This PDF file from long time SGL member @Moonshane explains:

Collimation of Newtonian Telescopes-1.pdf 392.22 kB · 3 downloads

And discussed here:

 

Thanks. I tried it that way first, but the screws went straight through the plastic before I had even tightened them up. Obviously the ends are VERY sharp. I didn't bother trying to file them down as they are being replaced shortly. I've also seen some other posts describing having the plastic washer between metal washer and holder, so gave it a go, and it feels great.

I'll see how it goes when I have the new screws. I might change things round then.

[John]

8 hours ago, Pixies said:

Thanks. I tried it that way first, but the screws went straight through the plastic before I had even tightened them up. Obviously the ends are VERY sharp. I didn't bother trying to file them down as they are being replaced shortly. I've also seen some other posts describing having the plastic washer between metal washer and holder, so gave it a go, and it feels great.

I'll see how it goes when I have the new screws. I might change things round then.

You don't need much tension on the screws.

 

[johninderby]

3 minutes ago, John said:

You don't need much tension on the screws.

 

Which is why I prefer thumb screws. 🙂

Easy to overtighten with a screwdriver. 🙁

Edited May 22, 2020 by johninderby

[Pixies]

8 minutes ago, johninderby said:

Which is why I prefer thumb screws. 🙂

Easy to overtighten with a screwdriver. 🙁

Tell me about it! At least there's less chance of doing any damage now.

Shame you can't get M4 nylon-tipped set screws long enough for this.

[John]

5 hours ago, johninderby said:

....Easy to overtighten with a screwdriver. 🙁

I think it's easy to overtighten if you don't realise that they don't need to be tight !

They are adjustment screws not locking screws.

 

[johninderby]

Finger tight is good enough. 👍🏻

[johninderby]

The TS secondary holders look a bit interesting but not cheap.

[Captain Scarlet]

4 minutes ago, johninderby said:

The TS secondary holders look a bit interesting but not cheap.

sprung, which is good too