Haig Mount

[jjjnettie]

I got sick of whinging about having no tracking, so after consulting many designs, I knocked up a Haig Mount this morning.
Took about 3 hours, 1 hr of which was applying layer after layer of shellac before assembling.
I thought I'd stuffed up the camera mount when I used the 16mm spade bit instead of something smaller, but I gasketed it with bits of hose and it's all good.
A couple more things to do to it. Gotta make a timer wheel, make a handle to turn the screw with, mount a finder scope along the hinge and finish off the whole job with an inlay of gold paint on the top. ( Esthetics are everything)
The proof of the pudding will of course be in the images.

[[1ponders]]

:clap: way to go Jeanette. I'm looking forward to see how it works out.

[Dennis]

Wow - that is really neat, a terrific job well done. :thumbsup:

Now, can you explain to me how you took the 1st 2 photos, as the camera is clearly fitted to the mount...? :whistle:

Cheers

Dennis

[erick]

Self-timer plus....ummm....a wormhole in space/time?

[erick]

Looks very impressive, Jeanette.

Thanks to Ken:- http://www.iceinspace.com.au/forum/showthread.php?t=17142 , I'm going to be motorised, so I don't have to build my barndoor tracker. I knew there was a reason that I couldn't find time over Christmas/New Year to build it!

A bit of work to do to set it up - the infamous polar alignment:eek:- then I'll shoot some wide-field.

Looking forward to seeing your results. :)

[jjjnettie]

Very very close Erick,
More of a time warp.
I took the photo with the Digital Powershot, but the camera on the mount is a Canon EOS 50 SLR.
Gotta step back in time to the age of film to fulfill my desire for widefield long exposures.

[erick]

Simple choice for me - I 'ain't got no digital. I'll be relying on my trusty Pentax KX plus slide film.

[acropolite]

Nice work JJJ and with shellac too, most yunguns wouldn't even know what that was. I think it's time you got a shed.....:P

[jjjnettie]

Here's some comparison pics I took with the Powershot.
Canopus came out fab:D , and I think Orion would have been pretty good too if I didn't have my foot resting against the tripod.:doh:

[middy]

With a complex system of mirrors Dennis ...... and a bit of smoke :lol:

That looks fantastic Jeanette!! I was too impatient to bother painting mine. Maybe I'll send it to you and you can paint it for me, yes?? :P

[Dennis]

Hi JJJ

Nice first light images - just watch where you put that foot when you trip the shutter....

I just noticed in your sig that you have a Hama tripod - I picked up a sale item at Photo Continental some time ago; a heavy but very stable model. Easy to adjust although it came without a head and I had to make a 3/8 inch adapter so I could screw various heads onto it.

Cheers

Dennis

[jjjnettie]

The Hama model I have is quite lightweight and not all that stable. I don't use it all that much because I have the Velbon which has a quite luxurious fluid head.

I replaced the drive bolt on the Haig today. There was a bit of a bend in the first one. Added another nut to help guide it as well.
The single hinge has to go. Too much movement. Tomorrow I'll replace it with two smaller brass hinges.
There are other small changes that I need to make before I mount the SLR onto it.
I feel the need for a permenant pier in the paddock.

[Dennis]

Some while ago, I dropped into Capral Aluminium and obtained a 1.5 metre length of 4 inch aluminium pipe with a wall thickness of approx 3mm. Cost me around $45 and I made a pier for the Vixen mount.

The nice thing about aluminium is it is light weight, easy to work with and does not rust.

Good luck with the permanent mount, you’re really motoring along!

Cheers

Dennis

[bojan]

Aluminium does not behave well in concrete (it likes acidic or neutral environment and concrete is very alkaline). Steel pipe is better for permanent setups (it is for ever if nickel plated) and it does not matter if it is heavy. For a permanent site you will want to fill it with concrete anyway.
I was using plastic pipe in the past (filled with concrete and couple of steel rods with threads at the top, to fit the mount) and I was very happy with the setup.
I am planning something like that for my yard in the near future.....

[jjjnettie]

I was thinking of using hardwood because we have some in the shed.

[bojan]

Jjjnettie,
That may be OK for temporary permanent site :-)
You just drop the hardwood pier into the hole 30cm deep in the ground filled with concrete.
But you should expect it to change with time, it could twist and/or split... But for the type of setup you are using now it might be OK.
Just be sure to use old hardwood (already properly dried and completely dead and stable) and always keep it dry under the cover.
However, I would consider steel or plastic pipe filled with concrete, it is not complicated at all to do and you will be certain it won't move.

[Dennis]

Whooops – thanks for that!

I should really have written that I made a transportable pier, with 3 bolt on legs, although I have since considered a permanent pier in the back garden. Glad I didn’t now.:whistle:

Just out of curiosity, over what time period would a catastrophic failure be expected to occur? Say 12 months, 3 years, 5 years or greater?

Thanks!

Dennis

[bojan]

Couple of years maybe or faster, I think it depends on many factors... but I know for certain that aluminium is never used with concrete.
Non-protected aluminium left outside in the rain will "rust" in a matter of month or two (I was watching parts of the old washing machine that I stored in the backyard before disposing them off, very quickly the shimne was gone and was replaced with white powder-like substance (Al hydroxide)

[Dennis]

Wow - now that is agressive.:scared:

Thanks

Dennis

[bojan]

Most likely the residuals of detergent helped the process a lot ...
Of course, if aluminium was anodized, nothing would happen (in that time period)

[jjjnettie]

Got a quote yesterday for a steel pier.

50x50 3mm box section @1500mm
Cut to 26.7 degrees (gotta check that) on the top
A 60x100mm plate welded on the top
Section of whitworth bolt fixed into the top plate
Total Cost approx $25

Am digging the hole today while the ground is wet. How deep should I go?

[bojan]

Like for planting a tree: ~40-50cm deep, I would say, ~30-40cm in dia or square should be more than enough for your purpose.
You may need 2 or 3 packs of premixed concrete (Bunnings).
Do not drop the steel pipe all the way, allow ~15 cm of concrete on the bottom. All depends on how much of pier you want to have above the ground.
I think this will be useful for something bigger in the future too :-)
Good luck,
Bojan

[Dennis]

Hi JJJ

I know it may be a little rich, a city boy telling a country girl what to do, but try to get the altitude and azimuth aligned as accurately as you can. I assume the top plate is not adjustable, so you can always insert shims between the top plate and tracker base to touch up the alignment.

Somewhere, I once read (for heavy supports) have approx 1/3 of the post below ground.

Nice to have some wet soil to dig into eh.

Cheers

Dennis

[jjjnettie]

I'll be very careful with the alignment, there's no allowances for error at all. I guess I'll have to sort out some framework to support it, unless I want to hang on to it until the concrete dries.
That first 15cm of concrete, should it be put in a few hours before to make it firmer for support, but mushy enough to push through it a bit? (know what I mean?)

[bojan]

Yes I guess that will be fine...
You can even drop in some chunks of old concrete in it, or bricks or stones if you can find them to support the pier (and so you will need less fresh mixture for the rest of the job). The concrete sold in packs at Bunnings to be used for fencing etc could be very fast-setting (couple of minutes only, you just put the mix in your hole, then the pier goes in then you you pour water and thats it, after 5-10 minutes it is set enough so you can remove the support. Of course, the full grip will be achieved after couple of days and couple of buckets of water. Wet soil will also help a lot.
It may be a good idea also to weld couple of bits of steel rods and to drill couple of holes on the part of the pier that goes in the concrete, so that concrete grabs the whole structure more firmly.

[Dennis]

I've never done what you are doing JJJ, but I do recall seeing on Backyard Blitz that the guys compacted some gravel (approx 10cms) at the bottom of the post hole to allow for water drainage, and then they poured the cement mix all at once, after having nailed some support struts to the post after first getting it nice and vertical.

I think they drove some wooden pegs into the ground to fix the support struts to, which were at right angles so the post was vertical in both planes.

They also used the rapid setting stuff as they had to do the job over 2 days.

Where the post exits the concrete above ground, they also sloped the concrete away from the posts, so water would not pool on top of the concrete (if it were level or flat).

Cheers

Dennis

[jjjnettie]

We've got the quick set post hole mix.
Pouring the concrete will be the easy bit, it's getting the prep correct so it stays polar aligned that concerns me most.
Fun project though.

[bojan]

Waiting for pictures taken with the new setup :-)

[jjjnettie]

You must have blinked and missed them Mr Bojan.
I've posted some test shots on the first page of this thread. Taken with the Canon Powershot using 12x zoom.
One of Canopus and one of Orion. 15 seconds each, without tracking and then with tracking.

[bojan]

Oh OK :-)
But what I meant was pics from the new pier :-)

[bojan]

Double arm drive is here:
http://www.astunit.com/tonkinsastro/atm/projects/scotch.htm


But, there is no need for double arm... if the tracking speed is variable (see below)
http://www.keteu.org/~haunma/proj/barndoor/

[erick]

I was going to build an isosceles design - seemed pretty simple to allow a nut to swivel and the drive point will automatically swivel. Glad to see the error of that is substantialy less than that of the tangential drive. But that's on hold until I try out my second-hand RA-driven Meade mount.

[bojan]

If you bend the threaded rod, the error is even smaller.
http://www.tucsonastronomy.org/barndoor.html

The wheel can be driven with the stepper motor, of course.

[bojan]

Threaded rod M10x1.5, bend to radius 342.834 mm will require rate of 1 turn /min.
If it is driven by stepper of 200 steps/rev, the rate will be 3.3333 steps/sec, quite reasonable speed.
This can be increased by additional gear reduction.

[jjjnettie]

I've countersunk a hole in the top board for the head of my drive to slot into so it doesnt' move. This should allow me to shoot for at least 20 min before any errors start to happen.
Come winter time, 20min is a long time to sit perfectly still and carefully turn a handle. Brrrrr

[bojan]

That is what stepper motors are for :-)

[jjjnettie]

LOL
If I motorised, it might as well be with a little ED80 on an EQ. Sweet.

[bojan]

Well... Not so long ago the wall clocks powered from mains were popular.
The axis that drives the minute arm is just what you need here... There was enough torque available to move the Haig mount timing wheel, if everythig was smooth enough.
Also, sync motors from washing machine programmators (or mechanical timers) were suitable for the purpose ( I was using such motor for this purpose a long time ago - it had output speed exactly 1rev per minute.... unfortunately it was lost during some unfortunate events in the past).
The output speed of those timer motors with gearboxes of course depends on the model... but then, if you have such a motor, you can always adjust the rest of the design of the Haig mount :-)
If I find something suitable I will let you know.
To start thinking about it have a look at the link:
http://www.globalspec.com/FeaturedProducts/Detail/Hansen/AC_Timing_Motors/201/0

The amateur astronomy is supposed to be a pleasure, and not torture.....

[bojan]

I found this on ebay..
http://cgi.ebay.com/5-Small-AC-Timing-Motors-1RMP-120VAC-60HZ-NEW-NEW_W0QQitemZ120088295925QQihZ002QQ categoryZ78206QQcmdZViewItem
They are designed for 60 Hz, so the speed here in Australia would be 20% lower. But it only means that the Haig mount arm must be 20% shorter.
120V AC power supply voltage is easily dealt with by 5kOhm, 2W resistor in series with the motor.
B

[jjjnettie]

I downloaded some formulas to use for this.
One fellow made his mount small enough to slip into his camera bag!