Category Archives: Others


Four bar mechanism made of paper

Today I am introducing “Four bar mechanism made of paper”

The four-bar mechanism is very useful in the design of mechanical components. The best way to understand four-bar mechanisms is to build it by yourself.  Here, I am introducing how to make a four-bar mechanism with only a paper, screws and nuts. It is very easy to follow.

If you want to know the theories of four-bar mechanisms, see the wiki. Here

1. What you need to prepare

One sheet of paper, four screws and nuts, and a nail (or any sharp one)

2. Procedure

  1.   Prepare a sheet of paperSlide2
  2.  Tear the paper like thisSlide3
  3.   Fold two timesSlide4
  4.  Write numbers like the pictureSlide5
  5.  Make holesSlide6
  6.  Now you should have four bars with eight holesSlide7
  7.  Connect bars. Here the sequence is very important. If you do not follow this sequence the linkage will not rotate because interference with other linkages.Slide8
  8.  Connect allSlide9
  9.  Hold (4) and rotate (1)

This is the result.

This is a Grashof mechanism.

So far, I have introduced how to build a four-bar mechanism made of paper. I hope that this post helps your projects. If you have any question, please leave a reply.

Loading Speed Comparison of Free Web Hosting Companies. vs vs

This posting is to compare the loading speeds of the following three free web hosting companies. vs vs

The above sites are the most popular free web hosting sites, and the hosting conditions are all decent. But the biggest problem for me was slow speed of website loading.

Thus, I made same blogs on different hosting companies, and compared loading speeds. I wish this post can give you valuable information.

The speed test was conducted in

The below is the result of loading speed. : 1.188sec : 8.389sec : 15.431 sec

You can see the screenshots.


Loading speed test result of, because I finally selected this site as my hosting company, the domain is my current domain.

Loading speed test result of


Loading speed result of freehostingeu

Conclusion: I strongly recommend


Before going, I also tried, but it’s speed is also very very slow. I don’t recommend it.

I wish this post can save your time. Have a nice day.



I am Youngmok Yun, and writing about robotics theories and my research.

My main site is, and Korean ver. is