Hi All
I am trying to make a simple plywood mirror cell for a 14.5" mirror (dobsonian). It didn't seem too hard but my first attempt has resulted in a wobbly mess (better than jelly but not much).....So does anyone have and links to good mirror cell design or photos of their own ATM cells?? Is velcro OK to attach the mirror to the cell?
thanks Phill
I built a metal version of the one he uses on his 10 inch. The thing I like about it is there are only two collimation knobs. Primary collimation is very quick.
I posted this on another "cell" site. It is very simple. This one is for a 6 point floatation (10") It is a circle with three spoke/attachment lugs, held together with pop rivets. Works beautifully - the mirror is stuck to the six points. The cross members (upon which the mirror is stuck) are riveted loose so they free to reach equilibrium. To rivet "free" place a spacer between the spoke and the cross piece, rivet and then remove the spacer.
Is velcro OK to attach the mirror to the cell?
thanks Phill
For years , I've used nothing but a ring of 1" Velcro squares at the 60% zone to attach my 14" to its cell ( a 1/2" ply triangle with spring loaded bolts at the corners). No clips , no astigmatism , holds collimation really well.
Removed it recently for realuminising, and it took about 5 minutes sustained pressure with a piece of 1/8" ply between the mirror and back plate to break the velcro grip of all that velcro. I'm certainly not worried about the mirror falling off.
I used Marks suggestion and havn't had a problem with it
I do have some pics here but they seem to of gone off to davey jones locker in that I can't seem to find them.
my cell is overly complicated in its build as you can see, but that hex
shape is just a ring of sorts at the 60% zone to which i attached some heavy duty velcro from bunnings.
I do have 3 rubber edge clips but they barely touch the mirror
the velcro does the job , I often transport my mirror box on its side without any problems and have had it fall forward on the lawn once or twice without anything moving .
Velcro ..!! Awesome .. I was looking for a mirror securing method for my 10" on my Simplified 6 point Suspension Cell and there it is. Was going to use nylon washers and RTV Silastic but I think I'd trust the Velcro more and it still can move enough.
6 Point Cell pics down bottom of this thread. http://www.iceinspace.com.au/forum/s...ad.php?t=62220
Hi All
thanks for the responses, very interesting. So the mirror is ONLY supported by the 2cm velcro circle at 60% of the mirror diameter??
I'll post some pictures soon (don't look if your offended by bad carpentry)
thanks again
I'm not familiar with your cell design as I can see it there ?
So it floats on a two way load of silicon, pivot ,and on the mirror back?
I'm not sure If replaceing just those 6 points with velcro will work well enough or whether the two differant approaches will be compatable
Yes Phil a continuous ring of velcro at the 60% zone, mine are a little bigger than an inch square .
Design is my own, 6 point measurements are from GUIPLOP but I've simplified the attachment hardware. I realise it is not functional in the purest requirement of 6 point suspension but still reckon it is better than the 3 point spot fix design.
Using neoprene rollers instead of springs and pivots for support of both the mirror suport base and the balance arms has eliminated all sideways movement in the cell and yet collimation adjustment is easy and mirror should sit quite unstressed on the aluminium bar supports. I could actually use strips of Velcro along the whole bar length ( 90mm each) if I wanted to be more secure although my 6 pads would be 25 mm square as you are using so I don't see a problem. There will also be some side retention brackets added for my peace of mind. Rear fan blows directly at the mirror rear as well.
The bars won't be siliconed into the support base until the mirror is attached so it all starts off as a neutral balanced system. I'll do a diagram if you like showing how my thinking has worked on this one.
For such a small mirror , I wouldn't bother with flotation bars, just make sure you have a nice flat plate and mount the six pads on it or better still a ring of pads. Plop actually comes up with a better RMS wavefront with a continuous support ring than half a dozen points.
For such a small mirror , I wouldn't bother with flotation bars, just make sure you have a nice flat plate and mount the six pads on it or better still a ring of pads. Plop actually comes up with a better RMS wavefront with a continuous support ring than half a dozen points.
The way my old eyes are RMS values mean nothing anyway. This is as much an exercise in design and construction as a telescope build. It HAS to be better than my cheap chinese 114 and I can rebuild it later if it has major flaws. Easy enough to build another cell, I've already got some more ideas I want to try.
>Phizzy: Nice Work !! Very professional indeed. I'm taking note of your design for future reference. <see above>
Hi Phil, I have been reading your progress and I like the end result. What a beaut cell, mate
There is an alternative to Velco, called Dual Lock. I used it for years in the broadcasting industry to attach cameras to the bonnets, roofs, rear spoilers etc.of racing cars, including Group A touring cars (as they were known back then), 500cc motorbikes, jockey's helmets, you name it. The cameras never, ever moved.
This may also be an alternative for securing mirrors to cells (and other handy uses in the hobby) . Just throwing it out there in case some creative ATM'er wants an alternative.
Hi all,
thanks for all the mirror cell ideas, photos and links. The super velcro looks great. I've now moved onto the secondary holder...I am making a wire spider but have had alot of wire breakage while trying string the secondary holder (Using wire from a hardware store). So, yesterday, I bought some guitar strings and today I'll give that a go.
.....So does anyone have and links to good mirror cell design or photos of their own ATM cells?? Is velcro OK to attach the mirror to the cell?
This is as much an exercise in design and construction as a telescope build. It HAS to be better than my cheap chinese 114 and I can rebuild it later if it has major flaws. Easy enough to build another cell, I've already got some more ideas I want to try.
. The super velcro looks great. I've now moved onto the secondary holder...I am making a wire spider but have had alot of wire breakage while trying string the secondary holder (Using wire from a hardware store). So, yesterday, I bought some guitar strings and today I'll give that a go. 
