Rob`s Obsy Build

[r3i]

I used one of those blue caravan type hook ups when I used to have a garden pier - it worked quite nicely, running an extension cable back into the house.

Are you fitting any lighting into the observatory?

[red dwalf]

I am indeed Mike, what I was intending to do is use the plug in clip on lights that I use for the tent at starpartys, then I can easily move it around if needed.

[red dwalf]

yesterday i finaly managed to get external power cable fitted to the obsy, very simple design and the cheapest option.

bought some 14 meter, 16amp, ip44 arctic cable from Toolstaion at a very reasonable price of £16,50 and a industrial ip44 socket for £5.20. seems to work a treat, fired up the mount last night and the laptop and i`m using a clip on light fitted with a red bulb that simply plugs into a mains socket rather than having a fused spur for the lighting circuit.

very simple and cheap and it works fine.

here`s a picture of the cable pluged into the mains in the garage.

one of the cable going to the obsy outdoor socket.

and one of the outside socket screwed to the cladding, cable exit goes through the back of the socket instead of out the top.

[r3i]

yesterday i finaly managed to get external power cable fitted to the obsy, very simple design and the cheapest option.

Looks simple and effective. Have you got RCD protection on the ring main that you're plugging into?

[red dwalf]

indeed yes, this was a concern of mine, but the circuit is protected with a RCD unit and a very qiuck to trip MCB switch.

having talked with a electician at work and asking about the best way to run power to the obsy without major works, he surgested this system as long as i don`t over do the amps i`ll be fine. 13 amp maximum on this circuit and about 3000 watts.

properly the biggest amp draw will be the desktop computer, not 100% certain what the amp rate on one of these is.

[yesyes]

I've got one of those energy monitors that show current electricity consumption for the house. That shows that our 2 computers running use about 350 - 400W together. They are fairly powerful machines (one quad core and one 6 core) with lower end graphics cards (we're not gamers) ;-)

So you could budget for about 200W for one PC, that's under 1 Amp.

The biggest wattage I would expect in a warm room would be a heater.

[r3i]

indeed yes, this was a concern of mine, but the circuit is protected with a RCD unit and a very qiuck to trip MCB switch.

having talked with a electician at work and asking about the best way to run power to the obsy without major works, he surgested this system as long as i don`t over do the amps i`ll be fine. 13 amp maximum on this circuit and about 3000 watts.

properly the biggest amp draw will be the desktop computer, not 100% certain what the amp rate on one of these is.

Great - Sounds like you have it all covered - just didn't want you disappearing in a puff of smoke

[r3i]

The biggest wattage I would expect in a warm room would be a heater.

Indeed - I've got one of those long tubular heaters to go into my obs, which is rated at about 200W. I guess though that it won't chuck out a lot of heat and perhaps will only serve to keep condensation at bay. Anyone else use one of these in their obs and can comment on if they're useful or not?

[red dwalf]

I've got one of those energy monitors that show current electricity consumption for the house. That shows that our 2 computers running use about 350 - 400W together. They are fairly powerful machines (one quad core and one 6 core) with lower end graphics cards (we're not gamers) ;-)

So you could budget for about 200W for one PC, that's under 1 Amp.

The biggest wattage I would expect in a warm room would be a heater.

thanks for that, i thought that the desktop might be alittle more than that so it`s nice to know, it`s a older machine, pentium 4 i think, but runs fairly quickly as it has 2gb of ram, but it has a nice "N" wireless adapter card so works a treat wirelessly in the garden.

come to think of it i`ve got one of those energy units somewhere, british gas sent me one ages ago, i`ll dig it out

[Gina]

I've go a fan heater in my warm room I think that goes up to 2 or 3 KW but I have it plugged into the ring main with 13A fuse and no problem. RCD garage unit in obsy to run power and lighting.

[sloz1664]

3KW at 240 volts takes 12.5 amps, which would take all of your 13amp supply. I suggest you get a heater no more than 1KW (just to be on the safe side).

You shouldn't need any more for a small warm room.

cheers

Steve

[red dwalf]

thank you Steve for the advice

[yesyes]

I used to have a 500W fan heater in my shed/workshop that was roughly the same size as my warm room is going to be. It got the room warm enough in about 10 minutes. So I'd think even 500W would be enough...

[3ggman]

Very nice build Rob.

[red dwalf]

hi all,

been happily using the observatory for a few weeks now so not been doing alot to the build, now have managed to sort out the height needed for the pier so this week have been putting together the parts need for the pier build, managed to source so 6mm steel plate from a fellow astronomer so cut out 2 10" square "ish" plates for the mount to sit on, drilling holes in 6mm stell was a pain untill a neighbour offered to do it using his pillar drill, a must if your contemplating doing your own, saves alot of trouble and the holes line up nicely.

anyway here`s a few pictures of the parts and build of the pier so far.

drilled out top plate for the puck.

altair astro puck fitted

8" plastic pipe which will be filled with concrete

threaded rod which will be put into the concrete filled pipe and hold down the plates

here`s a few of the almost finished pier mount, apart from painting it

[jambouk]

That looks the business Rob.

Did you do some tests with the ota to see how big the plate could be before it might interfere with the ota when it's pointing at the zenith or thereabouts?

Also, i've been looking at various piers lately, and any rigid system is only as solid as its weakest point; how thick are the four bolts which separate the two steel plates? Would there be any advantages (or disadvantages) in using bolts twice as thick?

I am looking forward to the next invite over

James

[jambouk]

Sorry, and another question, the threaded rod which is buried in the concrete, does this just go through the lower plate, or through both plates, or through both plates and up into the mount?

If the first option, is there just one bolt which holds the lower plate to the pier? And does then a second bolt go through the top plate and puck and into the mount?

If the middle option, how do you then bolt the mount to the puck?

If the last option, how do you turn the bolt to screw it into the mount if it's fixed in concrete?

Thinking about it, i think it must be the first option.

Janes

[r3i]

Also, i've been looking at various piers lately, and any rigid system is only as solid as its weakest point; how thick are the four bolts which separate the two steel plates? Would there be any advantages (or disadvantages) in using bolts twice as thick?

Looking good Rob, but have to echo James' comments on the bolts between the pier plates. They do look a little thin and long in the photos - can you detect any twisting between the plates if you apply some force on the mount? If so it might be worth using thicker bolts and/or can you reduce the distance between the plates?

[red dwalf]

i echo your thoughts and concerns, and i have done alot of thinking about what i need to secure it properly.

firstly the bottom plate is secured to the pier with a 1/2 inch threaded bolt, which is thicker than the the original bolt that secures the mount to the skywatcher tripod, i did want to use 3 bolts but my problem was that i need to polar align and therefore need to rotate the mount and plates, but the bottom plate will be sitting on 8 inches width of concrete so when bolted down i don`t expect and problems, i`m also thinking of putting some thinish rubber matting between the pier top and the bottom plate.

the reason i`ve left the bolts long between the two plates is that i wasn`t certain of the room i`d need to get my hand between the two plates to be able to but the bolt in that screws from the bottom of the top plate to the underside of the mount to secure it to the puck.

when fitted i will reduce the overall length to the minimum.

the threaded rods are 10mm thick, i was thinking bigger might be better and thinking of using 16mm but 10 mm was what i had lying around the garage and to be honest as it`s a short length it`s very robust and doesn`t flex or anything plus if there are any problems i could always drill out the holes and install bigger threaded rods without too much extra work involved.

having never done this kind of thing before it`s all a work in progress but having put it all together it does feel very sturdy at the moment.

[r3i]

did want to use 3 bolts but my problem was that i need to polar align and therefore need to rotate the mount,

If the amount of azimuth adjustment on the HEQ5 is as generous as it is on the NEQ6, I wouldn't worry too much about getting a very accurate alignment of the pier plate - as long as it's roughly north you should have plenty of azimuth adjustment on the mount to get it spot on. See how much of an angle of adjustment you have to play with on the HEQ5 and it may give you the confidence to use more anchors into the concrete.

the reason i`ve left the bolts long between the two plates is that i wasn`t certain of the room i`d need to get my hand between the two plates to be able to but the bolt in that screws from the bottom of the top plate to the underside of the mount to secure it to the puck.

Could you do what I did, i.e. fit the mount to the top plate first before plonking the top plate onto the 4 threaded studs. Then you can use as short a bolt as you like and reduce the gap between the top and bottom plates.

[ianaiken]

One of the problems I have with polar alignment is that the mount sticks due to the way it is bolted to the plate. If I loosen it too much then I get movement which knocks out the alignment. If I tighten too much then I cannot adjust it using Azimuth. What are you using to bolt the mount to the plate and any ideas on what may help it move more once fastened?

[r3i]

One of the problems I have with polar alignment is that the mount sticks due to the way it is bolted to the plate. If I loosen it too much then I get movement which knocks out the alignment. If I tighten too much then I cannot adjust it using Azimuth. What are you using to bolt the mount to the plate and any ideas on what may help it move more once fastened?

I use one of these to bolt my mount to the plate: http://www.trend-uk.com/en/UK/product/KB25_M_12/4/213/lever_male_m12x50_adjustable_1_off_.html. Once tightened, I remove the lever part (it's just attached using a hex bolt), which reduces considerably the gap needed between the top and bottom plates.

As for getting the tightness just right, well that was a case of trial and error in order to get the right balance between the tightness of the lever bolt and the ability to still make adjustments to the azimuth position.

[red dwalf]

thanks for the help guys, i`ve a shortened bolt that bolts under the top plate and into the mount base big washer and secures it very nicely, i`ve also done alittle giggling of the support bolts and now the plates are 50mm apart and don`t move at all, so far ! fingers crossed.

i really did think of putting more bolts into the bottom plate to secure it to the pier but i was adviced by a friend that as the plate is supported by the 8" diameter pier which will be leveled with concrete and fingers crossed again that when the 1/2 inch nut is tightened onto the plate it should be fine.

here`s a few more pictures of the reduced height.

[r3i]

thanks for the help guys, i`ve a shortened bolt that bolts under the top plate and into the mount base big washer and secures it very nicely, i`ve also done alittle giggling of the support bolts and now the plates are 50mm apart and don`t move at all, so far ! fingers crossed.

i really did think of putting more bolts into the bottom plate to secure it to the pier but i was adviced by a friend that as the plate is supported by the 8" diameter pier which will be leveled with concrete and fingers crossed again that when the 1/2 inch nut is tightened onto the plate it should be fine.

here`s a few more pictures of the reduced height.

Looks much better with a narrower gap between the plates and sounds as if it is solid. One possible issue with just a single bolt into the concrete is that you will have a pivot that the plate could theoretically rotate around. Whether this is a real issue in practice is another matter of course, but even just a second bolt into the concrete should stop that.

[jambouk]

Yes, it looks much more stable now the gap between the two plates is reduced.

I also agree that holding the lower plate down wqith just one bolt in the centre would theoretically allow rotational movement of the wheol assembly above. Two or ideally three would prevent this but I appreciate this has added costs and hassle.

Is the concrete poured yet?

James