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When you read the title it's rather easy to make the wrong assumption about the term "Dolly".
However the Oxford Dictionary clearly defines it as
https://en.oxforddictionaries.com/definition/dolly
And just to be clear this is related to the small platform ....
BACKGROUND
I had a conversation with one of the guys at work who also dabbles in photography.
He asked if I'd seen any of the moving shots that were not a video, but a series of still shots but they moved the camera.
Intrigued, I started looking and discovered that there was a large number of interesting builds.
Some were extremely amatuer IMO and there were comments about the need to tweak it each time it got used.
Many of the drive systems worked only in ideal conditions, and couldn't do vertical or steep movement.
Eventually I ran across this video.
It had all the criteria and showed a very simple and portable unit.
The next bit of useful information was this discussion
Timescapes - Digital Timelapse Discussion - View topic - MX2-IGUS slider
So there it was, Dynamic Perception had it all ....
KITSETS
Obviously the next thing was to have a look at their kitset and see how much it was.
Freighting stuff from the states is fine, unless they start using Fed-Ex or UPS and then it all gets very expensive.
At this point I hadn't quite decided what length the slider rail had to be, but I was tending towards 2m (78.75 inches), and sending this across the world wasn't going to be cheap.
So I brought the kitset and motor from them, and they were very helpful.
The conversation with Jay was that they were spending a lot of time supporting people with little or no electronics experience.
Their profit on the components part was minimal and the support time was far exceeding that, so they were discontinuing the kit.
They did however fully support Open Source and have published everything, and the Arduino code. WELL DONE.!
So if you want some great gear, you might want to look at these guys www.dynamicperception.com
SLIDER RAIL
Having sorted out the controlling part, it became a choice of what to use as the slider rail.
I'd seen some really dodgy examples often involving skatebard wheels, etc.
This one is a three part device and they write about it here.
https://hurleydolly.wordpress.com/
It's based on an aluminium extension ladder.
Not sure where this one came from
I saw lots of versions and most needed tweaking once you got there.
I kept coming back to the IGUS extrusion and the advantage of this system is that it was locked onto the rail, came with the carriage that ran on the rail which had plastic replaceable drylin glides.
As luck would have it a NZ company was a distributor and I ended up paying NZ$250 +GST and freight for a 1.5m (59 inches) length.
They even drilled and taped the tripod mount holes as part of the price. 
MOTOR
There are lots of options when it comes to motors, and I'd decided to circumvent all the issues and buy the one Dynamic Perception supply.
This was a Dayton gearmotor (12v 8rpm). The gearbox is metal and I've seen similar ones used in other places.
https://electricmotorwarehouse.com/dc-gear-motor/
One big advantage is they are low current draw, so your 12v battery is going to last for a long time.
Dynamic Perception have changed to a quick change style motor and gearbox, and it offers a size advantage due to the planetry drive style.
Once the motor/gearbox was sorted, the next task was the drive system.
CNC router, and 3D printers have made it much easier to find affordable T5 drive belts, and so a length and pulley was ordered.
The plate dimensions are here (if anyone is interested)
The idlers are common bearings (624zz), but I added a plastic washer to ensure the belt couldn't slip off.
As you can see there is 180 degree contact around the drive wheel, which ensures multiple teeth share the load.
This is using a different drive wheel and belt than some of the other images .We finally sourced something that would fit the gearbox shaft size without having to drill it out.
The pictures above show the belt fixing and the controls.
Obviously a cover would be useful to protect against the elements.
SOFTWARE
When I first started on this I thought the software would be a breeze.
Move the motor, take the picture, move again, etc.
Little did I know how many settings that Dynamic Perception included in their product.
There is a means of calibrating the distance, which changes with the motor rpm and the size of the drive pulley.
You can even calibrate the speed horizontally, at 45 deg and 90 deg angle
You can control the ramp up and ramp down speed to help stabilise the rig when you're moving a large camera.
The manual gives all the options and I'd never of thought of half of them.
The code is attached as it's too much to post as I've done for other posts.
All I can say is thank you to Dynamic Perception and their belief in Open Source .
SHIELD
So the issue with a lack of support was cured by making some boards.
I used Hackvana and added TheShed logo to differentiate and ensure that support questions didn't go back to Dynamic.
VIDEO
Obviously this has been optimised for here, but gives an idea.
It used 157 images to make up the video, and looking back the movement between shots could have been a little smaller.
Above shows the camera and rail to create the video (I even had to steal my daughters camera to take it)
Hopefully you've enjoyed this example of how versitile the Arduino can be.
It also shows that while the board and software were off the shelf, there is still other parts of a project you can be involved in.
Mark
edit an image escaped and some letters got confused where they should be.
 | Original-English.pdf |
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