10inch Newtonian Part 4 - The Cell & Spider

The first cell I made was a bit of a failure as it would not maintain collimation as the telescope rotated as in moved on the GEM from the east to the west and I had to continually adjust the cell. I said "failure" which is a bit harsh as it is simply one was that didn't work and the experience gained was worthwhile. I have a web page detailing this adventure.

The cell depicted here can't be defined as a true floatation cell and I suppose a better term would be mulitpoint cell. Anyway... it works. It maintains collimation and there is no evidence of stress induced into the mirror.

Hole Legend

A= 6 points to aid installing the 20mm silicone pads

B= 2 PSM PFH-M6-30 self clinching studs

C= Clearance holes for the studs

D= Mounts for the duct

E= Mounts for the 50mm fan

Pivot= A small turned part made from 25mm Delrin rod with the centre turned to 6mm.

The small duct is to ensure air from the fan reaches the back of the mirror.

Two 20mm dia red urathane pads make very stiff springs to take up adjustments to the cell.

I have not completed the wiring for the fans which will have high and low settings for each.

The wire spider is made from 0.24mm guitar strings but they sure look much bigger in the photo. The tensioniers are turned from M5 stainless steel cap screws, cross drilled and the square ends filed to fit the retainer which allows 8 step per rev adjustment. The spder is very rigid and maintains collimation well.

Last updated - 18th January 2004

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