Weight of SCT primary mirrors??

[Merlin66]

Anyone know the weight of say the 8", 10" 12" etc Meade SCT primary mirrors?
I've got a 12" which has some, not a lot of mirror flop, but just enough to move a star of my 20 micron slit in the spectro.
The usual solution ( see MAPUG for details) is to put a locking screw into the the rear cell. I don't think this is great. BTW the latest GPS versions have a locking collar which "grabs" the central baffle to reduce clearance and hence flop, but again, I don't think it's great.....
What we need is "Harry's Mirror Mat", can be fitted to any Meade ( don't know about Celestron yet) and will 100% support the mirror, anywhere in its travel up and down the baffle WITHOUT flop!!!!!!!!
I'm putting together a pneumatic tube/ring about 2" wide which will support the back of the mirror near the edge. Needs about 1.5psi ( a hand air camera release will do) to support what I think is about 30Lbs for a 12" mirror.
The air supply tube, about 4mm diameter can be routed throught the locking screw hole in the rear cell, so no additional machining required.
To prevent over pressure a poppet valve will be set to limit the pressure ( to suit the mirror weight) so that it's safe.
" Harry's Mirror Mat", coming to a SCT near you.
To finalise my design, it would be good to know the various mirror weight to set the pressure range.
Any comments, development $$$, donations????

[trent_julie]

Hi,
I would like to revive an old thread, was there any progress on the Happy mirror mat? Seeking a solution to c9.25 flop

Cheers,

Trent

[Merlin66]

Trent,
That is an OLD thread.
For other reasons I moved from the Meade to the Celestron.
As I’ve mentioned in other threads, the focus arrangement is completely different- more robust and repeatable.
On the C9.25 and the C11 I found adding the Feathertouch 10:1 micro focuser a great help.
Also run the focuser through full travel (about 30 turns) a couple of times to re-spread the grease on the baffle.

[trent_julie]

Thanks Ken,
I have got myself a moonlight, so as I understand it - move the mirror to end stops and the flop will stop? Thanks for the reply to an otherwise old thread.

Trent

[Merlin66]

Yes and no....
The focus threaded rod on the Celestron is fixed to the “sled” on which the mirror is mounted.
This means that when the threaded rod is held securely (by the focuser) the sled and hence the mirror cannot move forward and backword
However, there is still some residual slop caused by the operating gap between the sled and the baffle it runs on. This slop cannot be removed (or the sled would bind on the baffle and jam up.) it can be minimized by Re-spreading the grease in the gap between the sled and the baffle.
Hope that helps.

[trent_julie]

Thanks again