erick
11-03-2011, 05:41 PM
Well, based on my experience, Peter Read of SDM Telescopes must rank up at the top!
When it was constructed, we decided that my SDM#039 would be parked vertically, with a Telegizmos cover over it. I have been worried about it if the wind gets up and on my trip to Fowlers Gap earlier this year, I started tying it down to some tent pegs. The wind always came from much the same direction so I would tie it with two ropes coming from around the UTA with about 90 deg between them.
Had a bit of wind at Snake Valley early Monday morning as I packed up for the night, so I did the same. Well, unfortunately, the wind made a significant change of direction during the day and when I went out mid-afternoon, my scope was no longer standing vertically, but was having a little lie-down. YIKES! This does not look good!
First observation under the end of the cover shows the rocker box up-ended 45 deg, with the mirror box completely out of the rocker box and resting on the rocker box end on one of the primary collimation bolts. A look under the cover showed the alt encoder arm pointing a funny direction and bare wires showing on the cable. I could see the primary mirror and it appeared to be in one piece, hanging in its cable sling.
With Nick and Andrew's help, I lifted the mirror box/trusses/UTA upright and stood it to one side. I expected to hear the tinkle of glass and to see bits of finderscope and secondary mirror fall out, but no. So far, so good.
Examined the rocker box. Only two problems observed. One, a "ding" in the edge of the rocker box which didn't correspond readily to a collimation bolt location. It looks like the mirror box and upper assembly hit the ground, then bounced to a new location, stopping snagged on the rocker box. Second, the plug from the alt encoder arm was still in its socket, but the cable was completely ripped out.
We lifted the cover off the mirror box/trusses/UTA. Where is all the damage?? I cannot see anything? This cannot be right? In fact, after a full check, the only problem was that three little teflon pads that I had placed between the ends of the secondary collimation screws and the secondary mirror holder had come completely out and were lying at the bottom of the plastic container that I have around the secondary mirror during storage. For that to have happened, the secondary mirror holder must have bounced quite violently on its central mounting bolt! The alt encoder arm wasn't bent. The trusses didn't appear to be bent. The UTA must have landed on one of the upper catches, but no apparent damage to it. The focusser operated smoothly. The finderscope was still in place and the view through it was fine.
To cut a long story short, Doug had the crimping tool and spare plug, so I could replace the alt encoder plug. I put the teflon pads back in place. I went over everything and could see no problems.
Recollimated and I was away, for a successful nights viewing. All electricals, mechanics and opticals were working as expected. I guess that a few inches of grass and soft ground helped. If I'd been on a concrete surface?
:prey2::prey2::prey2::prey2: Peter Read! What a marvellous scope.
But I have just manufactured a bracket to lock my "tube unit" closer to horizontal. Now to see if my Telegizmos cover will fit this new orientation.
I can breath again and my heart resume beating!
When it was constructed, we decided that my SDM#039 would be parked vertically, with a Telegizmos cover over it. I have been worried about it if the wind gets up and on my trip to Fowlers Gap earlier this year, I started tying it down to some tent pegs. The wind always came from much the same direction so I would tie it with two ropes coming from around the UTA with about 90 deg between them.
Had a bit of wind at Snake Valley early Monday morning as I packed up for the night, so I did the same. Well, unfortunately, the wind made a significant change of direction during the day and when I went out mid-afternoon, my scope was no longer standing vertically, but was having a little lie-down. YIKES! This does not look good!
First observation under the end of the cover shows the rocker box up-ended 45 deg, with the mirror box completely out of the rocker box and resting on the rocker box end on one of the primary collimation bolts. A look under the cover showed the alt encoder arm pointing a funny direction and bare wires showing on the cable. I could see the primary mirror and it appeared to be in one piece, hanging in its cable sling.
With Nick and Andrew's help, I lifted the mirror box/trusses/UTA upright and stood it to one side. I expected to hear the tinkle of glass and to see bits of finderscope and secondary mirror fall out, but no. So far, so good.
Examined the rocker box. Only two problems observed. One, a "ding" in the edge of the rocker box which didn't correspond readily to a collimation bolt location. It looks like the mirror box and upper assembly hit the ground, then bounced to a new location, stopping snagged on the rocker box. Second, the plug from the alt encoder arm was still in its socket, but the cable was completely ripped out.
We lifted the cover off the mirror box/trusses/UTA. Where is all the damage?? I cannot see anything? This cannot be right? In fact, after a full check, the only problem was that three little teflon pads that I had placed between the ends of the secondary collimation screws and the secondary mirror holder had come completely out and were lying at the bottom of the plastic container that I have around the secondary mirror during storage. For that to have happened, the secondary mirror holder must have bounced quite violently on its central mounting bolt! The alt encoder arm wasn't bent. The trusses didn't appear to be bent. The UTA must have landed on one of the upper catches, but no apparent damage to it. The focusser operated smoothly. The finderscope was still in place and the view through it was fine.
To cut a long story short, Doug had the crimping tool and spare plug, so I could replace the alt encoder plug. I put the teflon pads back in place. I went over everything and could see no problems.
Recollimated and I was away, for a successful nights viewing. All electricals, mechanics and opticals were working as expected. I guess that a few inches of grass and soft ground helped. If I'd been on a concrete surface?
:prey2::prey2::prey2::prey2: Peter Read! What a marvellous scope.
But I have just manufactured a bracket to lock my "tube unit" closer to horizontal. Now to see if my Telegizmos cover will fit this new orientation.
I can breath again and my heart resume beating!