Restoration - mirror cell advice please

[DanDare]

Hi all,

Having cleaned up and de-rusted the mirror cell and base plate I have decided that its good enough to re-use, (I'll paint it up in due course). When I removed the mirror these floating supports were just loose under the mirror:

(click to enlarge)

I found some pieces of sprung wire and I's sure that these hold the supports in place, one looks like it clips to the outside of the cell and one to the inside thus holding the support in place, does this sound right?I think when all are in place it would have looked much as it does in the preceding photo.

For a more details view:

(click to enlarge)

I'm just not sure what purpose the drilled holes are for in the following photo, or are these just red herrings?

(click to enlarge)

Any thought you might have would be most welcome.

Thanks

Roy

[barkis]

Hi there Dan,

I too had a nine point cell to support my 12" Newt mirror.

It consisted of three triangular plates just like yours. I had a recess at the geometric centre of each plate, and a corresponding one in the base of the cell. A ball bearing fitted between the two recesses so that the plates could tilt easily back and forth. To keep them from rotating out of alignment, I had drilled a small hole between the apex of each plate, and the recess. I drilled the mirror base of sufficient size to press in a Groverlock pin, so that it protruded through each plate. Just be sure the pins are not too long so that they might contact the base of the mirror.

I also countersunk the apex point of each plate, and stuck a ball bearing in the hole tacked with grease to prevent the ball s falling out when lowering the mirror onto the three support plates.

So, what you finish up with, is the mirror sitting on nine balls, and the three triangular plates sitting on a ball each underneath, with a locating pin protruding through each plate at it's apex, to prevent rotation. You don't need the springs.

I hope this helps . It certainly worked well for me.

Remember to make the holes where the pins come through, large enough to prevent the plate locking up. In other words plenty of leg room.

Ron.

[DanDare]

Thanks Ron, that's given me something to think about, I could probably adapt the three small holes (indicated in the last photo) for the ball bearings. As it was, it appears that the plates just sat on the (slightly squared off) machine screw heads with the springs holding them in place.

Cheers

Roy