Four hours of wading through the knee deep dirty waters on the streets of Calcutta on a certain fateful rainy day and hundreds of electronics shops later I finally found the four potentiometers needed for our feedback master slave servomechanism.It was that very thing that had forced us to postpone our dates.
It was time to get back to durgapur and begin the design of the shafts,the joints and start construction as soon as possible.The parts were ready to be put together and the joints had to be manufactured.We made yet another mistake,underestimating the importance of the joints and its capability to withstand the weight of the links,the gearboxes,the end effector,the headers ,the screws.the potentiometers and everything put together.It was of prime importance that we minimise any sort of vibrational movement and bending of the plastic headers.The joints were bending after we had assembled it initially, the screws were unable to hold up the headers properly.It needed more clamping force.
Two days went by without much work.It was back to the drawing board job.
3 rd October the joint problem was solved.A shaft having gear tooth profiles at one end of it was machined from a brass shaft and inserted into the header hole of the headers by applying pressure(read hammering).It did its job well enough.
One headache was finally out of the way.The slave was ready and the potentiometers and the links and the headers and the gear boxes fitted in just fine and the joints were strong enough this time to hold the entire setup in an upright manner.Bending was minimised to the extent that was desirable and extra nuts were put at the ends of the links to make the movement of the links possible with minimum slipping.
The chassis was now a piece of cake to make as we had the materials and it had no such component that could cause much headache and it was completed without any fret.
5 th October----We were nearing completion and it seemed that it would take another two days to complete(yet another mistake).Having worked for 2 days on the trot on soldering the resistors,diodes,etc to the veroboard (and I had to "un"solder and "re"solder it a couple of times) it was finally ready for testing.Last moment checks were still to be made and we had to be sure that the components were soldered properly and the connections were made correctly.The transistors were particularly menacing in this respect and we had to download the data sheets of the transistors and check them out.
9 th October----The circuits were complete ,the connections were left to be made,the mounting was not complete and z-brackets(4) needed to be machined into place.Most of the work was done but it still was unfinished,it was still bits and pieces left to be put together.
10th October---Came back to Calcutta today.The autumn weather and the festive mood of the city was refreshing.Our little piece of creation could wait a few weeks i guess...................
