JOURNEY OF A MECHANICAL SPIDER

First of all………….let me think how & what I actually did.
Yeh…. I got all of it, Let me take a deeeeep breath( My First Blog… OMG !!)

It all goes back to 2013 when I was in Hyderabad thinking about my Major project with my room-mate while preparing for GATE 2014 from ACE. I came to know about this MECHANICAL SPIDER while surfing internet, some guys posted their experience on this project they really looked Professional using AUTO-CAD, CATIA VS, taking their professor’s help & advice, using M/C which I never used.
Form that moment I decided to take Mechanical spider as my Major project.

So the overall plan was to make something which walks like spider based on KLANN mechanism but not to copy any website's video directly.

Our whole analysis was based on Trial & Error method apart from the one’s where the analysis is done completely in SOLIDWORKS, CATIA before implementing it in practical, so the cost of our project increased slightly RS.5300 (don’t laugh huh..)

The other group members are my friends who always supported me ( even when some time talked about the stupidest/idiotic ideas they ever heard).

On the first day the stupidest thing that I ever did is to take sun-mica as material ( plz don’t laugh), even convinced all of us for it. Me and Roshan searched whole city for a 1sq.m sun-mica. Carpenters, hardware’s , wholesaler no one is willing to give a piece out of their set(coz it would ruin the whole set & the cost of each set is more than Rs. 500) , at last we found one for Rs 50 with the tool to cut it.

The moment I started to cut everybody was staring at me as if something went wrong they would taunt me for that my whole life. I accept, I accept, I accept that it was ‘THE’ most ~~silly~~ hilarious idea anyone would ever thought of.
Then I had to come back where I started, everyone was suggesting ALUMINIUM so we bought 1meter AL strip which cost us almost Rs.250.

The most difficult thing is to make the leg to follow desired path, in order to do that I took some help form a website( http://www.mekanizmalar.com/mechanicalspider.html ) which shows the output motion of leg by feeding the length of various links in it. Finally we got the link lengths for smooth motion (without any jerk). Then we made a sample of leg by cardboard to check the motion.

So finally we cut the strip in desired shape and size using SAW (blade) and draw all the points where we have to make holes on it.

After cutting and drawing we went to a small but resource full Engineering workshop owned by a punjabi -_- near sulabh’s residence. Actually I never went to that workshop coz u know Punjabi repels Punjabi so I prefer to stay outside and let others do the talking. For each leg nearly 14 holes had to made ( 3 on frame, 11 on links) and each 3mm hole cost us Rs.2 , I thought we should buy a drill machine but who would listen to me expect Babu ( talking to Babu is like talking to a wall) , it costs slightly more than Rs.700 .

The Positions of Links used in leg is same as that of the video & it follows KLANN MECHANISM which is not possible for me to change, so we all ( me, roshan, sulabh) had a GROUP DISSUSION of an hour which was very useful as well all come up with different ideas for the FRAME ,length & angles of LINKS which holds the legs, in that GD there were 4 people but only 3 were talking….as I mention talking to Babu is like talking to a Wall which shows u a finger _I_ on scolding.

The easiest way to work out and remember all the dimensions is to draw them in a piece of paper which I did, we change the dimensions many times to get a smooth motion.

After Cutting and drilling the Links they were slightly deformed so we hammered each link so that they become straight.

After making each link and drilling all the holes in it the next step is to make the frame which holds all the legs and motor. Frame is simply an AL strip we just have to cut it and dig some holes where it is required.
Before drilling the leg holes in Frame we should have the exact distance between the center point of 3 Gears

i.e The distance between the center of 1^st and 3^rd Gear will decide the distance between two adjacent legs on same frame.

According to the position of Gears in mesh we had to make 3 holes in two Frames and 2 holes in other two Frames of 5mm diameter which cost us Rs.5 each.

IMPORTANT : All the holes in the Frame and links MUST BE ALINGED , even a slight variation of holes in two frame can restrict the motion( that’s what happened with us initially).

Six Gears were required for the motor to transmit motion to the smallest link(crank), so we purchased 6 plastic gears which cost us Rs40/- each( only one or two shops had plastic gears at that time in our city) , the holes already present in the gears where very useful BUT BUT BUT the main problem arises when we try to mesh the motor with other gears, due to large amounts of teeth and small thickness of gear they start to slide over each other, the torque was also high.

So we had to purchase another set of Gears with thickness>6mm.

Now the Most Important of all the “TRANSMISSION SHAFT” , it is ‘THE MOST’ important thing which transmits all the Torque from MOTOR-to-GEAR-to-TRANSMISSION SHAFT-to-CRANK.

Initially we thought that a 80mm long BOLT can act as shaft to transmit the torque, so we continued by taking that theory and we found that the NUTS which we used to control the gears and to hold the Frame are tightening whenever the bolt rotates ,Also we tried to fix the BOLT and crank which must be done so (i) we apply M-SEAL to join them( another stupid idea ,I know) after trying 20-30 times we lost our patience and decided to try something new.

(ii) Another idea which came out of GD is that to weld the BOLT and CRANK, but the question was that crank is made of aluminum can it bear the heat of welding, Can this be done. So once again we all went to that sardarji’s workshop regarding this and he replied “ tum fir aa gaye , jab dekho kuch na kuch karte rehte ho” . LOL the good news was that I was standing outside as always and the WELD can be done, he did a marvelous job and welded all the bolts and cranks.

As you can see in all the joints the nut have been restricted from motion, any motion between links causes the nut and bolt to tighten up, so to avoid this M-SEAL is applied on it.

LUCKILY & UNFORTUNATELY this welding theory didn’t last long, the motion was very much restricted. Gears couldn’t take that much high torque so once again we had to change our thoughts about this theory and had to come up with something new.
The new thought was to change the transmission shaft and I order to do that we went to market to purchase a steel rod of 5mm diameter and 1meter long which cost us Rs.60. Then we cut this shaft and took it to sardarji’s workshop once again and told him what to do.

This new shafts includes the CRANK’ dimensions with holes and the TRANSMISSION SHAFT’S dimensions with holes to fix the Gears. It costs us Rs 400 (just a night before submission) in just 7 hours(whole night from 10p.m) we re-opened it and fixed the new shaft and I am extremely sorry that I don’t have the running video of the final MECHANICAL SPIDER.

Few hurdles came up as the time was approaching……. All of sudden D.C motor stops working and We didn’t had any other as inventory, so we had to interchange all the Gears of 30RPM( use motor of 15 RPM) motor with a 1000 RPM motor.

new shaft

Let me tell you all something about my college (SRIT). This college ruined my life, they have destroyed my life in every possible way they could. No one ever bother whether I study or not, whether I attend my summer vocational training, they never gave any advice for projects. Fake campus interviews, Fake marks………….So many of my friend told me not to do such hard work, leave it as it is and submit, no one in the college is going to check or test, it doesn’t matter whether it works or not BUT to me it matters. The only thing which I regret is that I had to submit it before making any further improvements.

Lastly i just wanna apologizes to my friends for being Little rude.

The videos leaves a huge smile on my face every time when i watch them :) :) :)