I'm thinking of removing the drawtube from my ed100 focuser to rub the flat section more smooth with a sharpening stone. Does anyone know if there are any parts that may fall out of place when the tube is withdrawn from the focuser, or is it a simple slide out/slide in operation?
Thanks Mark. Looks simple enough. As soon as I get a new sharpening stone I'll do the job. My focuser is not bad but it struggles to lift the weight of binoviewers.
Job done. The focuser will now wind vertically up with the weight of my binoviewers. I erred on the side of removing too little rather than too much aluminium and the flat section still isn't completely flat but it seems to work well. There isn't anything inside the focuser body to fall out of place; there are two pairs of of rollers mounted towards the top of the focuser(photo shown). After the sharpening stone I used wet & dry sandpaper to remove the scratches left by the stone. I also covered the ends of the focuser with tape as suggested by one place on the internet to keep debris out of the tube.
One thing that concerns me with my 100 ED is the way the diagonal fits onto the draw tube; very little "meat" for the two diagonal screws to grip. Not game to fit the 17T4 to it for fear it might dislodge and make very expensive tinkling sounds on the ground.
I'm using a GSO 2" dielectric diagonal and the original visual back screws seat in the safety groove of the diagonal. I recently bought a mercury systems visual back from Astromart which has 3 set screws and a brass compression ring; it's well made but a little expensive by the time it's shipped out here.
Just a note to anyone considering smoothing out the flat part of the focuser, one thing you could do wrong is to not concentrate on removing aluminium from the ends of the flat section, especially if you get aggressive with the sharpening stone. You don't want to end up with a dip in the middle such that the focuser is tight at the ends of it's range but loose in the middle.
