Barn Door Tracker

I am making this thread at the request of a few UK members of this forum.

I mainly do landscape photography but recently have found myself looking at more and more astronomy and celestial images so I decided I would like to have a go myself. From the research I have done I have found that it can be quite expensive so I decided I would have a go at making my own barn door Tracker. If it works and I find I like astrophotgraphy then I will probably invest in proper gear designed for the purpose.

I decided to follow Gary Seroniks plans here:
http://www.garyseronik​.com/?q=node/52

So I won't go into great detail about the basics. All I will say is that I made it with a few hand tools I had around the house and a lot of patience. I have no work shop, garage or work bench.
My main problem was sourcing materials in the UK. Most of which I sourced on ebay and local DIY stores such as B&Q, after some research.

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I initially decided with a 12V DC motor and purchased one from Amazon along with a PWM controller board from ebay. I then did some research and found that these motors can lose power as the batteries die, which is not good as you must have a constant of 1 RPM at the drive rod, so I decided to look for another option. By the way none of these items have arrived yet 1 month after purchase :roll eyes:
I came across a thread on this forum by 967Stuart where he was looking at using a stepper motor and Arduino UNO controller. Thanks for the help Stu.
After some research I decided to follow suit and ordered a 5V stepper and Arduino from ebay:
http://www.ebay.co.uk …_trksid=p3984.m​1497.l2648
http://www.ebay.co.uk …_trksid=p3984.m​1497.l2648

My initial concerns with this combination were:
a) would the motor be powerful enough due to it's small size and
b) I know nothing about programming and the Arduino requires some code uploading to drive the motor at the correct RPM.

More on these later….

Now the brass rod.
I was concerned that I wouldn't be able to source the correct size here in the UK as Gary Seronik states he used 10-32 thread brass rod. I couldn't find anywhere that supplied this in the UK. Again I did some research and found that M5 metric is the same. So I ordered 2 x 500mm lengths from ebay.
The bending of the rod was quite easy and I did this by hand using a full 500mm length before cutting it to the required length..

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The gears

I searched quite a bit on the internet and found the following company that supplied them:
http://www.bearingshop​uk.co.uk/delrin-3262-c.asp

I ordered a 1 mod 16 and 64 tooth delrin gears.

I had to do the same as Gary Seronik with the large 64 tooth gear. That is file the hole to make the blind well nut fit into it. I used a small file set purchased from B&Q to do this, cost around £7.00. With a bit of patience I managed to get a really tight fit. The plastic is harder than it looks and it took some effort to file it to the required bore.

Whilst waiting for items to be delivered I decided to do a partial assembly.
The holes for the brass rod to go through on the plywood are measured from the centre of the hinges and this is a critical measurement.
Note on the pictures that the 64 tooth gear is slightly bigger than the base so anyone making one of these may want to make the base slightly larger. The crucial point is the positioning of the hole for the brass rod to go through.

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The 5V stepper motor and Arduino arrived so I decided to attach the motor to the base.
THis is where I had the most difficulty. The drive shaft on the motor isn't long enough to reach through the ½ inch plywood and the 16 tooth gear isn't long enough to fit over the drive shaft so I decided to cut a ¼ inch recess in the plywood to fit the motor into. Like I said previously I have no workshop or bench so I did this with a 10mm wood bit marked with a piece of tape on the bit to give me the depth. Once I had drilled this out I then used a small swiss army knife to clean the recess out. This is where I drew first blood and sliced the end of my finger open

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The 5v Stepper motor comes with it's own drive board which has to be connected to the Arduino to receive the required signals to drive the motor. I checked the power supply fitting on both the motor and Arduino and then ordered the appropriate 9V battery cases and fittings from ebay. The Arduino fitting sourced without problem but the motor board I had to order the fitting for the board and a separate 9V battery case then connect the two together.

IMAGE LINK: http://www.flickr.com/​photos/k3na1/122065321​03/

Now for the fun part, programming the Arduino. I spent about 2 weeks researching this and still not sure how or what I did but I got it working perfectly. The motor has to turn at 4RPM to make the drive bolt on the brass rod turn at 1RPM through the gears.
It is quite easy to upload a program to the Arduino using the usb cable supplied with it.
To do so you need the Arduino IDE software readily available on the Arduino site. At first I just tinkered with various programs that I downloaded from the web. There are loads out there with a lot of tutorials.
I just wanted to get the hang of using and changing the motor parameters. Arduino programs are known as sketches.
Next I downloaded quite a few motor sketches and then tried to change them for my requirements.
I eventually found one, which after changing a few things in the sketch, worked perfectly.
From what I have learned about the programming and the bits to change in the sketch I found that the parts to change in the sketch just didn't make sense and the motor wouldn't turn at the required speed. I eventually got there by trial and error and it works perfect at the required speeds.
I then tested the motor and gears attached to the tracker using the stop watch on my laptop and the larger gear turns at exactly 1RPM.
I have this code available if anyone requires it.

Next I assembled everything. I already have a Manfrotto 405 pro geared head with a spare plate that I attached to the underside of the tracker. I already had a spare Giottos ball head that I attached to the top of the tracker. I then carried out some more testing and and the motor worked flawlessly, turning at the correct 4RPM.

IMAGE LINK: http://www.flickr.com/​photos/k3na1/122063005​75/

The next step was to test the tracker under load. I attached my Canon 5D3 and 24-40 L lens, quite a heavy combination. Once again everything was perfect. This is when I thought the stepper motor would struggle.

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Now to tidy things up. I ordered a small plastic project box from ebay and set about installing the motor drive board and Arduino into it.

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I wanted the project box to be completely plug and play so to speak with no wires dangling out of it. To do this I had to cut the wires from the motor as the motor plugs directly into the driver board that is supplied with it. I purchased a 5 pin male/female chassis mount plug to do this. A bit of soldering is required to do this. I used a portable gas soldering iron with a fine tip to do this. This is something I had in my toolbox.

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This image shows the project box with the Arduino power supply and the motor cables with plug attached to the box. I have also shown the soldering iron I used. You can see the power supply for the motor driver board in the picture. I have ordered the same type of connection as the 9V Arduino power supply. Both male and female plugs. I am waiting for them to be delivered. More cutting of wires and soldering to carry out. Once this is carried out the project box should be completely plug and play. I intend to attach it to the underside of the tracker using velcro strips.

IMAGE LINK: http://www.flickr.com/​photos/k3na1/123840581​55/

Whilst waiting for bits and pieces to be delivered I purchased a celestrion red dot Star finder and attached it to the top of the tracker, parallel to the hinges. I then aligned this with the hinges as per instructions that came with the finder. I used jupiter to do this, so now the red dot should be aligned with the tracker hinges.

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I have since tested the tracker with my 5D3 and sigma 120-400 lens on, as this is my heaviest combination. Everything works as it should and the motor turns at 4RPM constantly, giving 1RPM at the drive bolt on the brass rod. I must say I had my doubts about this motor as it is so small. The proof in the pudding will be field tests I suppose.

That's all I can say for now, I am still waiting for a few bits just to tidy things up.
If anyone has any questions or needs more information then please don't hesitate to ask.

All I need now are some clear skies and see if I have the astro bug.
Not hopeful on the clear skies at the moment as the UK is being battered by one storm after another.