Something to beware of when fiddling with SK Maksutovs

[A McEwan]

Hi all,

Slightly esoteric post here. I had to take the focus knob off my Skywatcher 127 Maksutov so that I could measure the shaft, as I'm having a better quality aluminium machined knob made for it. Anyway, the plastic knob attaches to the shaft by means of two small grubb screws. With these undone the knob simply slides off and the shaft is left exposed.

Having done this, I started turning the scope tube around, just to have a peer into the area where the shaft extends from, and whoa - the shaft slid down into the inside of the scope and disappeared!!!

The shaft is not attached to the body of the tube assembly! However, it can't be a wide open space in there, as with some careful manipulation of the telescope tube and some slow and tedious tipping and tilting, I managed to get the shaft to drop through the hole again! Phew - mega relief!

The shaft is very well lubricated and I'm sure that's what saved me from having to dismantle the tube to get it out.

Anyway, I reassembled but was worried that I may have damaged the focus mechanism somehow, so have set it up for some terrestrial viewing. Thankfully, everything seems to work fine. The focus still works, and I inspected the optics just to see if somehow the grease had moved onto the primary anywhere, but it hadn't.

Just thought I'd share this before it happened to anyone else!

[Catanonia]

lucky escape. I hate it when things like that happen

[Space Cowboy]

Thanks i shall take good care next time

[A McEwan]

Yep, always best to really....

[Jaffa007]

Thanks for the head's up!

[calibos]

I'm not quite sure if the previous few posts were puns!! ....or have I just got a filty mind??

[A McEwan]

[Jaffa007]

Have you got your new aluminium focus wheel back yet mate??

Pics??

[philj]

Yup, I noticed the shaft went in a bit when I made an ali focus knob for mine. Another tip, make sure you pull the shaft out as far as it will go then tighten the new ali knob, otherwise you will get axial play in the focus shaft.

Philj

[brianb]

Straightforward rule for working on the focusing mechanism of any scope with a moving primary mirror - the scope must be horizontal & remain so until work is complete.

[A McEwan]

Good advice there, Brian. I shall make sure when I get the knew knob that I keep it so! It will be a while until it arrives though, as the chap at Focusknobs said he would design one based on the measurements and pics I sent him, and to check back in a couple of months - should be just in time for the knext viewing season hopefully!

Knaturally, I will let you all see how it looks and how it functions!

Ant