Gina's Mini Widefield Imaging Observatory

[Gina]

Been thinking about the east end of the roof - the part that has to be open as it moves over the imaging rig and mount.  My main obsy has a hinged flap that folds down inside and fits against a ledge inside the roof with draught excluder seals but I don't think this is practical in my diminuitive WF imaging station.  As an alternative I have been considering a sliding panel. 

I'm just wondering though if all this is getting just rather too complicated.  I favour the KISS principle where possible   I'm wondering if a simple, lift off, framed plywood top covered with some tarpaulin material would work.  It could be fastened down with hasps (or whatever they call them).

[Tinker1947]

There are the plastic sheds with a slide off roof, this would cut down on loads of DIY hours, not sure of the cost of the sheds though.....

[Gina]

Yes, I've looked at those and rejected them I'm afraid but thank you for the suggestion.

Very expensive and unsuitable anyway.  I've scoured the net for suitable plastic enclosures or covers without success unfortunately

[Tinker1947]

How about a shed style Obby, open a door and fold the shed down hinged at the bottom, when set upright the door act to strengthen the structure for when its windy......just big enough to clear the scope.....

[Gina]

Yes, that's a possibility.  Though with the high winds we get here I think I favour a good solid box for the base well anchored to the ground.  A movable roof structure that more than covers the top and hinged further down is another idea.

[Gina]

I've just cut two of the wooden uprights and after sorting out the timber finding where the extension lead got to, connecting up the mitre saw, wagling the wood into position and cutting it to length, I'm out of breath!   I think my age is beginning to show    I certainly wouldn't be up mto building a full sized observatory these days...

The top of the roof will be around five feet off the ground and not the easiest thing for one to lift off even with handles so maybe a roll off roof is not such a bad idea

[Tinker1947]

I tried the hinged roof, it worked buy was a real pain getting up and over to hang down the side, i ended up with a slide off roof, made from 2" X 1" with thin ply glued (PVA) to the frame this is help in place by to lumps of timber so from the inside i under the clamps lift to roof to clear the pieces of timber and it slides down and hangs along the front on  angled piece of timber, putting it back i lift it up and slide it along the edge of the end walls untill the top end drops into place, weight is next to nothing pick it up with one hand...thats how i got over the normal high walls for the better viewing position.....

The Hinge type,,,

The slide off system, the 2 pices on wood on the end wall, it drops over them to stop sliding down..

[Gina]

I can understand that - even the shallow drop down flap in my main obsy is no lightweight.

[Gina]

I was looking for something else and came across two posts about 75mm square and around the right length and also two more longer ones.  Square corner posts will be easier to use than the 80mm x 36mm timber I cut for the job   The latter will come in handy for the cross members.

With corner posts of 75mm square I could buy 4 spikes for hammering into the ground and use those to give both support and ground anchorage rather than hammering those galvanised iron pipes into the ground.  There were several things wrong with the galvanised pipes.  Too long and difficult to hammer into the ground (really wants a post hammer) plus not so easy to attach anything to.  The post spikes will also hold the posts sideways whereas the concrete blocks wouldn't.

[Gina]

Just ordered a set of 4 galvanised fence post spikes from Amazon - should come in a couple of days.  Have to say, I'm much happier with this approach

[Tinker1947]

My posts went straight in the ground in holes then in filled with pea shingle. but the soil here is very soft so a 4' deep 9" round hole takes about 10 minutes, if your ground isn't soft then the spikes might be better, just a thought on getting the spikes straight drill a hole with a largish masonry bit first...

[kirkster501]

What visualisation software are you using Gina please to create the drawings you show on this thread (and others)?

Steve

[Gina]

What visualisation software are you using Gina please to create the drawings you show on this thread (and others)?

Steve

Google SketchUp and Windows Snipping Tool to cut screen areas out for the screenshots.

[Gina]

New base design using 75mm square corner posts held in fence post spikes driven into the ground (not shown).  The eastern ends of the ROR rails are held in a 100mm x 20mm cross piece with 1" holes cut out.  The other ends will be held by pipes driven into the ground with 3D printed plastic couplings at the junctions.  The places where the rails pass over the western corner posts will be supported by 3D printed plastic spacers.  The plastic pieces are not shown in this sketch.

Maybe I should explain that the three base blocks - two heavy concrete blocks and one stone paving slab support the feet of the SW pillar mount.  The only part of this shown in the sketch is the central tube.  For clarity and because I can't be bothered to "sketch" them

[Gina]

Here's a photo of the ROR Rail Couplings.  1" OD running rails to 1.5" OD upright pipes.

[Gina]

The fence post spikes came this afternoon and I've hammered two into the ground and the third placed in position ready.  These weren't exactly as illustrated but they'll do.  They're supposed to be galvanised but being painted, I have my doubts.  They're also supposed to have clamps to hold the posts but these haven't - just two holes on opposite sides.  They also don't appear as strong as some I've seen but I'm not using them for a 6' fence so they should be quite strong enough.

I'll post a photo as soon as the uploader starts working again

[Gina]

[Gina]

Here I have put two posts in their sockets and clamped a piece across the top to check how things will fit together.

[Gina]

The NW spike stopped going any further into the ground than as shown in the photos attached but as it's very firm and actually not far off right for one of the posts I've got, it'll do.  There's lots of stones in the soil here, some pretty big and I guess I caught one   I was lucky with the first two   Fingers crossed for the last one

[Gina]

Fourth and final ground spike hammered in and post placed in it.  The far (south side) posts want cutting off a bit and then I'll cut and fit the cross pieces.

[Gina]

Maybe due to the rain soaking into the ground, I was able to hammer the spikes that were partly out of the ground, all the way in.  A much neater result

I have also cut to length and screwed on the top cross members as the following photos show.  I have placed a roof running rail in rough position (it won't be this long in the final design).  Finally, I've attached a sketch showing how the roof position works out with this arrangement.

[Gina]

With the base made (apart from the weatherboarding) and the NEQ6 mount in position, the way the parts fit together can be seen.  The weights have to clear the north side rail as the mount goes through its movements and the imaging rig has to clear the south side fixed parts.  Plus the south rail has to clear the PA scope dome.  The result is that the south side rail will be higher than the north side.  This can be seen in the photos above.

I have been working in SketchUp to design the fitting of the rails and various parts of the roof.  The result so far is shown in these screenshots.  The rails are held in holes at the end and rest in semi-circular notches where they extend beyond the base.  I have not included the west end of the roof or the east end flap (or slide) as these would have obscured the bits I wanted to show.  I also haven't modelled the mount but that's because it's too difficult

East end.

West end.

[Gina]

Now we come to the wheels and how these are attached to the roof.

Firstly the wheels...  These I designed in SketchUp and 3D printed in clear ABS plastic.  They have a semi-circular groove to fit the aluminium tubing I'm using for rails.  They have a 12mm clearance hole designed to run on the plain part of stainless steel bolts.  While not in the same class as a ball bearing, these have quite low friction for plain bearings.

Next comes the mountings.  The sketch below shows one idea I have for mounting onto the sloping part of the roof.  I've shown the ABS in green and the SS bolt in grey.  This is only a rough sketch to show the idea and not to scale (unlike the models of the obsy box and roof above which are to scale).

[Gina]

That wheel mounting above won't fit with the present design.  There isn't room between roof and rail unless I can lower the rail a bit without catching the mount PA dome.  I'll have to wait until daylight and dry weather to check. 

Here's the problem.  This sketch shows a template of the wheel cross-section resting on the rail and actually interfering with the plywood panel of the roof.  I pushed the wooden batten back to show where the wheel would go.  A possible (but not nice) alternative would be to mount the wheel at an angle and make other changes to suit.

[tekkydave]

How far (angular) would you have to tilt the wheel axis so it clears the obstruction. A small tilt of a few degrees may be ok but any more you might have issues. Did you realise how much use you would get from your 3D printer when you first bought it?