Mainspring Energy Mechanical Engineer Interview Questions
& Process

First there was a 30 min screening with the recruiter. Then I had a 1 hour one on one with the hiring manager. After that, there was a 5 hour panel interview. They really rush their interviews and then ghost you. It's been 3 weeks since my final interview, and I even prepared a presentation and interviewed for 5 straight hours. They could at least send a rejection email. I'd avoid this company.

The recruiter reached out after I applied online for the Mechanical Design Engineer, Sr. to Staff position. We had a 30-minute call covering salary expectations and reasons for seeking a new role. Following that, I interviewed with a manager. After this, there was silence from the recruiter for two weeks. After I followed up twice, a different recruiter contacted me and scheduled another video interview. Two days after that, I was informed it was the final round of video interviews. Six more interviews were then scheduled with various individuals including team members, managers, and a vice president. I was also tasked with a 20-minute presentation on a challenging engineering problem. Within two days of the final interview, a manager called to inform me that they would not be offering me the position. Most interviews were technical, typically involving a 30-minute segment on resume review and behavioral questions, followed by a 20-minute segment with brain teaser questions related to GD&T, heat transfer, mechanics of materials, and basic physics, aimed at assessing my problem-solving and brainstorming approach. All interviewers were professional, making it a positive overall experience. I inquired about the company's runway and financing, and they provided a good overview of what to expect in the next couple of years. It genuinely seems like a great place to work with an interesting product.

I had a recruiter call, then a manager round, followed by an onsite panel interview. During the onsite, I presented a project I worked on, and then faced back-to-back interviews with 5-6 people from the panel. It took a full day. After that, they did a reference check where the manager spoke with two of my references for about 15 minutes each, asking about my work ethic, technical skills, and personality. They then made me wait three weeks for a decision. The recruiter then called me for another interview with a different hiring manager who gave me an exam with 8 medium-difficulty questions to solve. A week later, they informed me my skills weren't sufficient and reposted the job. It seems like they weren't sure what they were looking for. A tip for them: don't ask for references and then contact them before making an offer, as candidates usually interview with multiple companies and their references can't handle random calls.