Instructables
Picture of Bicycle Frame Polar Tracker
What better to make out of an old boy's BMX bike frame than an equatorial style tracking mount that can be used for solar energy to get nearly 50% more power out of a couple PV panels! Most solar trackers are either big expensive things, or so small and flimsy as to be completely impractical. I wanted to come up with something in between. And just for fun I wanted to make it a true equatorial tracking mount instead of an Altitude-Azimuth style mount. The concept is simple enough: use the handle bar as the control arm for the main polar axis with the front forks, the bike frame is turned upside down, and then tilted up to get the correct polar angle for the latitude, then a frame that mounts on top of the forks and pivots on the original axle bolt locations provides declination adjustment and support for the PV panel. There's a little bit of work to be done on the forks and the frame to accommodate the linear actuators that will move the tracker, but it can all be done with basic MIG skills on most steel frames. Nobody could guess what I was building when I made it at TechShop (www.techshop.ws) using just MIG1, Ironworker, and basic metal shop class skills and tools. Final control is provided by a Home CSP Mega Tracker dual-axis digital controller.
 
Remove these adsRemove these ads by Signing Up

Step 1: The Frame

Picture of The Frame
Picking a good frame is important. This boy's BMX frame has a few features that make it ideal:
 - the seat tube and fork tubes are nearly parallel
- the seat to crank distance is short which helps actuator clearance
- the fork tubes are round and easy to cut and splice

The frame is prepared by stripping everything else off except for the seat because we'll use some of the hardware from the bottom of the seat later on. This would also be a really good time to sandblast if desired and really clean everything. Lubricate the fork bearings now as well if needed.

Glimm6 months ago
Tracker could be simpler: A housing with a slight aligned over a photocell switched, turning off a small motor that turns the whole unit once the sun passes through the slit to hit the switch for the motor. you would want the direction of rotation to match the sun moving in your sky.
Glimm Glimm6 months ago
*slit aligned*
rhino1 year ago
Bravo! I wish I was smart like you. Here in Arizona everyone should have solar!
kmpres1 year ago
Brilliant!  I love the McGiver-esque application using everyday parts.  Can you post some pictures with the PV panels mounted and your device in various positions?  Also, how stable is the thing with the panels mounted? Can it sustain much wind without having the base tied down?  How much greater is the watt/hrs obtained than the same panels on a typical stationary mount?

Thanks!
schmitta1 year ago
NICE!
KEUrban1 year ago
Any ideas how you'd modify this to do celestial tracking for astrophotography?
Yes, find tracking trajectory of the heavenly body you wish to observe and plug it into the servos.

I didn't check how many axis this (the project says plainer so I am thinking 2 axis) is so if the comet is 3 and this is 2 axis understand it will travel across the photo.
HomeCSP (author)  KEUrban1 year ago
Thanks for the comment. I understand the temptation. I've got a little 4" scope I may try to mount on it just to play with. I think It would be OK for wide field visual observing, but not planetary/photographic.
The first change would be to replace the R.A. actuator with a clock drive mechanism because the linear actuator movements are too crude for photography. The second problem is because it uses a control arm (instead of a gear/slew ring) the rate of rotation varies relative to the actuator motion. This is most pronounced at the extremes of movement. A speed controlled DC brushless motor would probably be the best, you'd have to come up with your own controller most likely.
The third problem is that telescopes are usually counterbalanced to help provide consistent tracking rates, and this design doesn't really have that, so your motor feedback would have to help you control the speed..
rimar20001 year ago
Clever idea!
nkapon1 year ago
SUPERB!!!