skybadger

Mike

I'm not actually doing anything about the shutter at the moment.  There is an Irish amateur astronomer who has a first model Pulsar 2.7m dome like mine.  He started from scratch and used Exploradome parts that he bought in the US and brought back to Ireland. 

Unlike me, and more conventionally, he has the Velleman card mounted on the wall of the dome so did not need a wireless, battery operated, system for rotation.  This is a link that shows something about it.  https://www.irishastronomy.org/kunena?view=topic&catid=22&id=95329#96208 

Exploradome have changed their system for the lower shutter to one that uses a pair of electro-hydraulic rams.  I did not have much joy getting a price from them but it does appear that they can still supply, on request, the old-style lower shutter part.  They use very expensive (but apparently very good) motors,  the cost now even higher with the very weak £. 

It does not look impossible though to have someone skilled to replicate the actual metal hardware.  For the upper shutter you will see that Michael used parts from Exploradome's rotation system.  The acorn gear and trackway are available separately from other US sellers and are not very expensive.  On how it all works and how he did it Michael is very approachable. 

Michael has however told me that he really doesn't use the automation of his shutter. The main reason is that he finds the weather where he is too unpredictable to rely on it closing quickly enough, even with a weather station.  As our weather in Scotland is probably no better my thinking was that spending a lot of time and money on the shutter, and then not using the automation would be a waste.  To me the manual system is easy and likely quicker than any sensible motor system.  Rotation is of course different, not having to go out to nudge the dome around during an imaging session is much more useful and I think being able to slew to new targets from indoors will be too.  I don't though have a method to automate flats which remains one of the limitations to my automation.

Before Michael told me that about the shutter I spent quite a while looking at the option of using rams for the lower section of it.  I could not find a position for the bottom of the rams that did not involve having a pretty massive framework projecting into the dome.  I didn't try to take advice on that but there are a lot of bright people on this forum so one of them might have the expertise to advise on that sort of solution.

Sorry not to have an actual solution for you.

Peter