Portable rotator build

One of these days I will have to start doing portable satellite operations due to loss of horizon at my place of residence. I found this project on the SARCNET website and decided to build it as I have very little experience with mechanical constructions (especially using metals). I never got the sensors to work and so after a year and a half I decided to abandon this design and go for stepper motors instead. Since I already had invested in a lot of materials I decided to use them as much as possible.

Materials used

Bearings

I could have bought these bearings locally, but when doing research on the web I found that Banggood had both the bearings and motors + controllers, so I bought all in one go.

The pillow block bearing with 25mm bore was US$5.09.

The flange bearings, also with 25mm bore were US$6.96 per piece and I ordered three of them.

All of them weren't aligned properly. By putting a rod in them and then using a square I carefully nudged them so the core was perpendicular to the outer rim.

 

DC motors

The DC motors were also bought from Banggood. They're 12V 2RPM Reversible High Torque Turbo Worm Geared DC Motors and they were US$9.87 each. The gears are sweating a little bit of oil, but nothing major. Later I changed to geared stepper motors and they were US$30 per piece, so quite a bit more expensive.

 

Sprockets, chain and chain connectors

These were especially made for me by a local business in the next town of Zhongli. The chain is type 25 and the big sprockets are 25x32 with a 25mm bore, the smaller ones 25*10 with a 6mm bore. I paid NT$200 for the 25*32 sprockets per piece, so US$13.50 in total. The 25*10 sprockets were NT$140 per piece, so US$9.50 in total. Ten feet of type 25 chain was NT$200, so US$6.50. In total, with tax, I paid US$31.00.

 

Aluminum tubing

These were the trickiest parts to get. It was impossible to get 25.0mm tubing of any kind (aluminium, stainless, fiberglass), so in the end I got two 60 cm pieces of 1" alu-tubing with an 8mm inner diameter and 25.4mm outer diameter. With the help of BX2AB I found a metal workshop where they could be machined down to 25.0mm. The added cost of that was staggering: NT$500 per piece of tubing (US$16.50). Luckily I didn't have that much money on me when I collected them and the owner was in a good mood, so I emptied my wallet and only payed NT$600 for both of them (US$20), because that's what I had. Cost of the material: 2x NT$250 (US$16.50 in total). Labor cost: NT$600 (US$20)

 

H-bridges

Banggood had an offer for three LMD18200T H-bridges, which the SARCNET project also uses. I paid US$25.52 for the three and all three didn't work. The quality of the whole assembly also wasn't that great, so I counted it as a loss. Wrote a negative review on the Banggood website, but they ignored it. So I went to al local electronics store and bought an LM298N H-bridge for US$6.30 and it worked flawlessly. Later on I bought a second one from my favourite local Arduino webshop for less than US$2, so in the end I spent far too much on these rather simple circuits. With the stepper motors I had to buy controllers and spend way to much on them, too.

 

Enclosure

This was also a major purchase. Bought from Nonstone in Tainan for NT$1368 or US$45.60. Product number is FT202015, which means a 20x20x15cm IP66 outdoor enclosure. Very heavy, because it is all thick steel and in Taiwanese fashion not 100% perfectly made. They don't have any stock of these enclosures, so it took a three week wait before I got mine deliverer by courier.

 

Page 2: Photos and Videos

Page 3: Arduino Code

Page 4: Code for testing purposes