Problem with crayford focuser

[dark star]

Hi, I bought a skywatcher low profile focuser to fit to the 14 inch truss dobsonian that I am making (which I have hopefully nearly finished-I will post some pictures when I do).

I have never fitted a focuser before. Obviously I am doing something really  wrong as the focuser keeps falling off the base plate! (fortunatley I am doing this inside where there is carpet for it to fall on, and it didn't have an eyepeice in it!). 

There are 4 grub screws to attach the focuser to the base plate, in the side of the base plate. They seem ridiculosly small to hold the weight of the focuser and eyepiece but reading on line tightening the grub screws seems to be how to fasten it to the base plate.

The problem seems to be that the focuser is not going all the way in to the base plate, there is a tiny gap. There is a flange (if this is the correct word) running round the inside of the focuser where it connnects to the base plate. I have tried twisting and pushing the focuser many times but it will not quite go all the way in. Has anyone had this problem? I am sure I am missing something really simple!

David

[Moonshane]

Try taking the base plate off, fit it to the focuser, then fit as one unit to the ota. Hopefully this will work, maybe the tube wall is stopping it currently?

[dark star]

There isn't a tube as it is a truss dobsonian! I have figured it out and feel really silly! I just needed to use an extremely small allen/hex key to tighten the grubs screws-I was trying to use a little nail which of course didn't work-I couldn't find an allen key small enough. This will teach me to keep all my tools in order so I can find them!

It would be nice if there were instructions as to how to fit the focuser when you buy it!

In my next telescope project (if I ever finish this one!) I may try to make the focuser (if I am feeling brave!) and the base plate as the base plate is curved where as for a truss it would be better if it wasn't. This is because the focuser board is often flat, or in my case the base plate is screwed on to the aluminium square tube that I used in the  secondary cage.

Or maybe I will just make a base plate and buy a focuser.

David

[gooseholla]

My moonlite focuser didn't come with a base plate so I could put in on a flat bit for the truss tube. You sure the skywatcher can't do the same?