Automating a 2.1 metre Pulsar Dome. Phase One - Dome Rotation

[Anne S]

Price point unknown at present! I'm hoping to replace my mount shortly. That's more urgent.

 The main problem is my lack of technical knowledge. I'd probably need to buy something, I thought Pulsar only made their drives for the newer dome.

I need to win the lottery then I can get an all in one solution for the new house I'd move to in a part of the country that has more clear skies! Or the South of France.

[skybadger]

As would I,just for the skies of course.

[Nightwatchman]

Thanks Steve, I'll take some photos when assembled in March. Is your T10 belt 16mm wide and the sprocket 40 tooth?

[sloz1664]

On 13/02/2019 at 17:34, Nightwatchman said:

Thanks Steve, I'll take some photos when assembled in March. Is your T10 belt 16mm wide and the sprocket 40 tooth?

Yes  T10 belt 16mm wide and the sprocket 40 tooth. I purchased a second hand 12v car wiper motor with a mounting configuration that suited my Dome. But I had to add a motor controller to reduce the motor speed. You need to slow the motor down, so that the Dome completes a full rotation in around 90 seconds.

Steve

[Nightwatchman]

Thanks for that info.

Graham

 

 

[Mark Henthorne]

Hi Steve,

Having long-admired your efforts and the end result in automating the dome rotation on your observatory, I will shortly be in a postion to replicate this process on my own 2.1 Pulsar.

I have a couple of questions to ask of you please, before I dive in.

Firstly, looking at the shelf construction, did you in any way join together each of the 16 segments to each other or are they simply butted against one another, or was that  achieved solely by glueing the drive belt in place, resulting in one unified piece then? (Supplementary question, was it the shelf parts alone, or the inclusion of the belt that made the dome feel more solid/rigid  to you?)

Secondly, in constructing the shelf and adding the drive belt, this effectively seals off ready access to the support bearing wheels, which should they need cleaning, lubrication, or replacement, poses something of a challenge. I am considering using a holesaw to cut a single hole above the door inside the dome, centred a little higher than axle height, and slightly over the wheel diameter size, so that in theory would facilitate all of the above.  The hole, because it is over the door, should allow access by just myself, with spanners either side on both the inside and outside of the dome. Is this a solution that you have used, or have you elected to take another approach. I really want to get the shelf and drive belt arrangement that you have, but without shutting the door on maintenance of the support bearing rollers. As we all know, these are old obsevatories, and as far as I know, the source of the original bearing wheels is something of an unknown to us all.

Cheers,
Mark

[skybadger]

I can only recommend bil castors as a supplier, I searched for ages for mine and found some at BIL.

[sloz1664]

On 26/08/2022 at 11:22, Mark Henthorne said:

Hi Mark

Sorry for not responding earlier as I grabbed a late Summer break.

On 26/08/2022 at 11:22, Mark Henthorne said:

Having long-admired your efforts and the end result in automating the dome rotation on your observatory, I will shortly be in a postion to replicate this process on my own 2.1 Pulsar.

I have a couple of questions to ask of you please, before I dive in.

Firstly, looking at the shelf construction, did you in any way join together each of the 16 segments to each other or are they simply butted against one another, or was that  achieved solely by glueing the drive belt in place, resulting in one unified piece then? (Supplementary question, was it the shelf parts alone, or the inclusion of the belt that made the dome feel more solid/rigid  to you?)  They were butted against each other. Each piece was clamped in place to it's neighbour and screwed into place with stainless steel screws through the exterior shell of the Dome. I'm sure once all the segments are in place and the drive belt fitted it will be more rigid. I never checked before or after.

Secondly, in constructing the shelf and adding the drive belt, this effectively seals off ready access to the support bearing wheels, which should they need cleaning, lubrication, or replacement, poses something of a challenge. I am considering using a holesaw to cut a single hole above the door inside the dome, centred a little higher than axle height, and slightly over the wheel diameter size, so that in theory would facilitate all of the above.  The hole, because it is over the door, should allow access by just myself, with spanners either side on both the inside and outside of the dome. Is this a solution that you have used, or have you elected to take another approach. I really want to get the shelf and drive belt arrangement that you have, but without shutting the door on maintenance of the support bearing rollers. As we all know, these are old obsevatories, and as far as I know, the source of the original bearing wheels is something of an unknown to us all. As the dome wheels are situated in the centre of each segment I manufactured each segment with a cut-out so I had access to each Bearing wheel (see photo attached)

Before undertaking this project I removed each bearing, in turn, refurbished them and lubricated with silicone grease and all securing bolts replaced with stainless steel replacements.

Cheers,
Steve

 

[Mark Henthorne]

Many thanks for coming back to me Steve, and no apologies needed for any delay. We all have lives and family that demand our time and attention.

I thought that the "cutout" was how you'd achieved this at the outset, but when watching the video, it seemed as though you'd abandoned that approach. Revisiting the video, I can now see that you had indeed followed that, and there is one just visible at the beginning of the video as well as the one towarddso I thought perhaps you'd dowelled them to achieve that. Top tip that, for plainly we are not talking about the inside sections of the dome as presenting an exactly machined surface.  It's tips like these that can make such a difference to the finished job, so again, thanks for coming back to me with the explanation.

Offering something back to the group — For anyone else dealing with the older Pulsar 2.1m observatory, when I acquired mine, one of the aluminium shutter guide rails sheared in the dismantling process, the nuts having effectively "welded" themselves to the rods. This left me with one useable rod and one not (both still have in my possession). Visiting my friendly neighborhood stainless steel fabricators, they manufactured two replacements in stainless steel for me. If you are considering this approach, then as a guide I paid about £100.. If you have found yourself in a similar position, I am happy to send the old rods to you (only one of which is useable) for the cost of the postage, to anyone needing these. Hopefully that can save someone something should they require a replacement.

Cheers,

Mark

[Mark Henthorne]

Oops.... looks like I deleted a few words in my last post concerning the appearance of the first and last pieces of wood with the cutouts to access the dome support wheels.

Also, thanks to Skybadger for the post re BIL castors. I will be taking a close look at them.

Mark