Here are the top 10 websites for Mechanical Engineers:

Before sharing the list of top 10 Websites we would like to mention about a good source of information for Manufacturing Technologies.

Hubs.com
Hubs is a global manufacturing service provider and also they have created useful practical manufacturing knowledge content for Designers and Engineers. Their wide variety of knowledge base content could be accessed here.
Hubs also create exceptional manufacturing technology useful videos and playlist like Mastering Manufacturing, CNC Machining Materials, 3D Printing materials and much more.

and their youtube channel could be accessed : here

1) ASME.ORG

ASME is an acronym of AMERICAN SOCIETY OF MECHANICAL ENGINEERS is a non-profit organization which provides a platform for mechanical engineers. It promotes skill development through various programmes like E-fest targeted mainly for students. It also provides various opportunities for skill development for young professionals known as Early career engineers through various volunteering programme. It provides research and networking opportunities via seminars, journals, and conferences. it provides the whole set of knowledge in 10 professional development programmes. The membership base of ASME is 127000 professional engineers.
ASME has also developed an online platform known as ASME community. ASME community is developed for engineers to connect and network with each other similar to a social platform. Engineers can prepare groups and share ideas and learnings. There are some official groups available in ASME website for preparation of PE examination as well. visit ASME community for more details. You can create free profile even if you are not an ASME member.

2) Physicsforum.com 

If you want to ask any question about mechanical engineering or require any help for homework then physics forum is a large space. A large no. of professionals, students, and Engineers contribute to this forum and their answers are very relevant. You can also share the knowledge by contributing to the answers. Either you want to ask a question or you want to answer a question both the ways this website is useful for great learning.

3) McMaster

McMaster is a popular website for finding mechanical components. Whether you want to have 2d drawing or 3d model its a very popular website for having mechanical components.

4) MIT OpenCourseWare.

Its a resource to open courseware. it is open and available to anyone who wishes to learn anything related to their field.It is a permanent MIT activity

5) EDX

EDX was founded by Harvard University and  MIT in 2012. It’s an online platform providing MOOC courses. It provides high-quality courses from the world’s best universities. The world’s top university, Nonprofits and NGO’s are their partners.
For more information on online courses visit : ONLINE COURSE SECTION

6) Popular Mechanics

They provide good articles related to mechanical engineering.

7) MatWeb

It a website of the database. it has more than 78000 data sheets. It is a great source of knowledge. The other service that the website provides is provides opportunities to post advertise on their website, webhosting and website design.

8) Icrank

This is a website well known for Apps, links and vendors. The first link Apps contains lots of apps useful for calculations for mechanical engineers. Like Design of spring, Convert units, Standard tap drill sizes, designing oring gland, and many more.

Links are given to very useful knowledge material sites for design process, discussions and forums, Jobs, materials and Reference books and much more.

This website also lists some of the useful list of vendors for various manufacturing support and processes.

9) Engineers Edge
This is a very good example of a very huge website for mechanical engineers for having engineering basics. The website has many calculators for performing various calculations. There are lots of videos too the video like how to built a gear pump, Rotary piston pump, Gear measuring with CMM and dynamics of machine.

10) Engineers Handbook
This website is a great resource for students and researchers. The website has explained various terminologies with diagram and that is what makes it more useful. It has information of various mechanical processes, materials used in various mechanical processes, unit conversion formulaes with explanation with an option to find specific information on website.