Would you be interested in buying a Barn door tracker?

[Jasp05 (Aaron)]

Hi guys,

I've recently built my own barn door tracker for some wide field astrophotography use out of some old wood and an arduino.

I'm looking to make another out of acrylic to reduce weight and size, make it more weather proof and this will also allow it to be made with CNC machines to increase precision.

I was wondering if people would be interested If I was to have a few made. (as with most things these days, things are cheaper in bulk).

But I'm just looking to gauge if this is something that some of you would purchase if at the right price point? After everything considered I'm thinking somewhere around $100- $150. (This comes with tracker, motors, electronics etc pre assembled.) Can include a cheap ball head mount in that cost, but I assume most people may have their own to use.

I plan to make it run off 5v, so it will work with the likes of a USB power bank. (It can be adjusted to run off 12v if you prefer, but then you will have to find a way to power it.)

I am going to have one machined up regardless of the feedback here and will post back when that is finished with pics.

But any feedback on whether ppl are interested, thoughts on the above mentioned price (sounds reasonable? or not). I know these are relatively easy and cheap to make at home. but thinking something a bit more precise and reliable may be worth the extra dollars without splashing out for the $400-$500 sky trackers.

[leon]

Great Idea Aaron, although I probably wont need one, I am sure you will have some takers here on IIS.

Leon

[Nikolas (Nik)]

sounds like a plan, got a pic of the one you have made?

[Jasp05 (Aaron)]

Nick, The one I've made is only a quick mock up job out of wood and I'm still to fix the electronics to the platform.

However I may be able to throw up a 3d model of the one I'm looking to produce in a few days.

to give you an idea of size it will be 300mm long (max, could be made shorter) and 150mm wide. and its only 6mm acrylic plastic so all folded up would be 12-20mm high. Which is quite portable.

[leon]

Aaron, although not a Barn Door Tracker as such, and I am not trying to hijack your thread may I show you what I made up with a Curved Bolt arrangement at the correct radius etc, etc, it actually works a treat if lined up South.

Leon

[Jasp05 (Aaron)]

Just wanted to post back with a quick diagram of what I'm thinking it will look like.

Post any comments If you think the mounting design could be changed/simplified. But I would prefer to keep it strong as possible.

[Jasp05 (Aaron)]

Wow Leon. Do you use all that just for your dslr?

I must say though, that I haven't quite worked out how it moves.

the Hinge placement suggests It can't track along that curved threaded rod?

But I'm assuming there is more on top of it that I'm missing...

[bojan]

Originally Posted by Jasp05

...

But I'm assuming there is more on top of it that I'm missing...

It has polar shaft (not visible from that angle)

[JA]

Originally Posted by Jasp05

Wow Leon. Do you use all that just for your dslr?

I must say though, that I haven't quite worked out how it moves.

the Hinge placement suggests It can't track along that curved threaded rod?

But I'm assuming there is more on top of it that I'm missing...

I would say......
The wide triangular end piece connected to the curved threaded rod driven by the red gears/motor IS NOT connected to hinged top plate section at ~30degrees to horizontal, it is instead connected/fixed to the end of the rotating shaft which is housed in bearings fixed to the angled top plate, so that the motor turns the shaft (you can see black end/mounting plate) rather than twists the top angled hinged plate (as it might first appear).

Great Construction BTW Leon

Best
JA

[Stonius (Markus)]

Yup, I'd take one. Was looking at making one, but for that price, it'd be easier to buy yours. Also I like the idea of the arduino control. Easier to update software than hardware from a support point of view.

Cheers
Markus

[leon]

The curved bolt is at a certain measurement to the center polar shaft, when the gears are engaged one gear turns at 1 (one) revolution per minute around the curved bolt which is 5/16" inch in diameter and has a pitch of 24 to the inch.
There is a formula for all of this, which i will try and dig up, it has been quite some time since i made this.

This formula was in a Telescope Magazine from the States many years ago i will try and find that also

Leon

[leon]

Here we go i got this out of a magazine many years ago and it actually works very well.

Formula for building a Camera Clock Drive, using a one revolution per/minute motor and a curved threaded rod with a pitch of 24 to the inch.


Formula

Radius = 1436.5 x ( n / 2 pie t ) where n = 1 and t = 24

Radius = 1436.5 x ( 1 / 2 22 / 7 x 24 )

Radius = 1436.5 x ( 1 / 6.285714 x 24 )

Radius = 1436.5 x ( 1 / 150.85713 )

Radius = 1436.5 x ( 0.0066287 )

Radius = 9.52212 inches, (241.86184 mm)


Motor revolution must be (one) 1 per / minute

Threaded rod pitch in this case is 24, other diameter and pitch can be used

This formula works very well and is accurate to a least 10 minutes plus, of time exposure

[Jasp05 (Aaron)]

That's one of the nice things about having a microcontroller handle the motor RPM.

That formula can be used to calculate the rpm required if you use a radius of "X" with a thread pitch of "Y".

So hopefully I will be able to keep this to a small form factor but retain the accuracy and rigidity of something larger.

Out of curiosity, what kind of mounts do you guys use your existing trackers on??

I had mine on an old EQ1 style mount. which was fine, however It was not very portable. I have a very nice, portable ball head tripod I would like to use. Hence the requirement to keep things small and light.

And just an update, I'm hoping to have my drawings finalised and sent off for laser cutting next week. So all things going to plan should have a prototype to test in the next few weeks.