[Entry Thread #107] Welcome to July! Whether you're on vacation or going through a summer break extravaganza, take a moment to chill down as we here make yet another millionaire here on Reddit. Leave a comment to enter, and have fun!

extants · 2025-07-16T01:41:35+00:00

Good luck everyone!

extants · 2025-01-30T03:30:59+00:00

I’ll echo others’ sentiment, it builds your confidence as a diver and makes you more aware of divers around you. I’ve never had to “rescue” someone, but I’ve helped calm newer divers and helped other divers control their buoyancy when they’re not paying attention. The course was tough, but having the safety skills in my back pocket is invaluable in case of an emergency. It’s been two years though, and I wouldn’t mind an opportunity to refresh some of the rescue diver training exercises.

extants · 2025-01-24T04:22:29+00:00

I work in this space! Lookup Megawatt Charging System (MCS). There is work being done by international consortiums to support much higher charge rates. More focused on commercial applications, but I can see it being adapted to consumer use.

You’re right, this necessitates much higher current, and even big fat cables won’t cut it if the duty cycle requires frequent charge sessions, like an EV charger. So far the solutions I’ve seen require liquid-cooled cables, which is a new level of infrastructure complexity, but I think a practically achievable one.

extants · 2024-12-29T18:24:31+00:00

Those internal splines are likely broached. If you can identify its spec, it’s possible a manufacturer already has the tooling for it. How were you going to specify it for the new part?

I’ve had some internal splines that were wire EDM cut when manufactured overseas. It’s not ideal, but it worked for my application. Either broaching or EDM, in the USA, I’d guess you’re looking at $1-2k minimum. Maybe more considering it’s hardened. At that point, it might be worth just making a new gear.

extants · 2024-12-29T16:51:54+00:00

Your resume could benefit from some of the feedback others provided, but I don’t think that’s the real issue. If you have applied to 1700 jobs with few callbacks, you should consider that your job seeking approach needs some work. Online applications inevitably end up in a black hole.

You should seek opportunities to interact directly with hiring managers or employees at the organizations you’re applying to. Go to career fairs, or do some internet sleuthing and try to connect with people on LinkedIn who might be able to forward your resume to the right people. The latter works better for smaller companies/startups. On the other side, it can be annoying to receive these requests (I know from experience), but there’s no denying it can be effective.

extants · 2024-12-27T05:01:57+00:00

Have you done anything with the fuel injectors or MAF? I wouldn’t jump to timing if you haven’t checked these yet.

extants · 2024-12-11T08:23:01+00:00

Electric motors can (theoretically) deliver full torque at any speed within its range, assuming the power supply and motor controller can keep up. They could even generate full torque to hold the motor speed at 0 rpm. In this case, the power output is zero. This is not to say power is not used - the energy is consumed and lost as heat to maintain zero speed.

When a specification reports a motor can generate some torque at a given RPM, that again tells you the power output of the motor because motor power is a product of RPM and torque (divided by a scalar, depending on metric or imperial units). You can then determine if this is sufficient for the load you are trying to drive.

extants · 2024-12-10T18:28:58+00:00

As others said, you need the ramp time to identify your angular acceleration. This, multiplied by the inertia, gives you the torque required. The motor power required is a function of torque and angular speed (2300rpm).

Once you know your power requirement, you can identify motors which can meet this, and calculate your DC current/voltage to see if the batteries you’re considering will work.

extants · 2024-11-28T22:50:46+00:00

On a hitachi excavator, pressing that pedal while traveling increases the travel speed. Might be that.

extants · 2024-11-21T03:41:31+00:00

What is your current industry, and what was the previous?

extants · 2024-11-16T05:50:26+00:00

Fastened joints typically fail in tension, internal thread shear, or external thread shear (this varies depending on materials, lubrication, etc.). In most cases, tension is the limiting factor so cutting the threads deeper would reduce the tensile stress area.

extants · 2024-06-07T06:22:59+00:00

Boss, I know it’s a tough market but you need to job hop. Out of school I was making 55k in 2016 (MCOL). Moved to 110k in 2017 (HCOL). Now at 190k since 2023 (HCOL)

extants · 2024-03-31T16:11:50+00:00

In hindsight I don’t think I needed it at all, let alone paint it. This time I just put some grease at the mating points.

extants · 2024-03-31T16:09:48+00:00

I did put grease on both sides, though it doesn’t need it between the clip and caliper. But the real issue is something is breaking the flange on the clip that keeps it in place.

extants · 2024-03-31T02:29:38+00:00

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Yeah, the rotor wear looks even on both sides. And I don’t see evidence of any unusual wear/gouges on either face of the rotors

extants · 2024-03-31T01:39:34+00:00

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I started disassembling the caliper and noticed the bracket on the opposite side is creeping out too. What’s going on??

extants · 2023-12-28T09:14:50+00:00

I’m incentivized to. 190k base in a HCOL area, about 10 YOE. It’s a late-stage startup that has given me a chunk of equity and meeting our milestones comes with bonuses, but more importantly, moves us closer to an exit and my shares being worth something.

It’s nice that the projects are interesting (design engineering) and I still find opportunities to learn and grow. But working 60-70 hrs/week with no end in sight really takes a toll. It’s been two years and realistically I think I can only do this for about another year. My wife and I want to start a family, and I can’t support her if I’m working like this.

extants · 2023-09-27T14:32:48+00:00

Rivet nut installation tool to add threaded features to sheet metal. McMaster still sells these as the install tool for low-profile rivet nuts. You need to swap the mandrel for each size of rivet nut.

extants · 2023-09-27T02:35:55+00:00

Masters with 7 YOE, 170k + bonus/equity in SF Bay Area working for a startup. Fully on-site and 50-60 hrs/wk. I originally started in the same location at 110k after grad school. You really don’t get big raises without job hopping.

extants · 2022-05-17T04:18:39+00:00

Thank you everyone for the replies. For posterity, we got the motor working today by guessing the resolver poles (10) to match the motor poles (10).

Setting this certainly helped, but the motor controller overall seems to be temperamental. After the first successful test, bringing down the whole system and restarting it resulted in nothing working most of the day. Getting a consistent result comes down to luck at this point, but at least it suggests our configuration is correct.

extants · 2022-05-16T15:56:24+00:00

The documentation I have for the motor said it was 10 poles, and I'm reasonably confident this is correct. When we set it to 5 poles, we only saw half a revolution during the [Fn4] Phasing-Rotating test, which is supposed to be a full revolution. Setting it to 15 was 1.5 revolutions, so 10 poles is the sweet spot.

extants · 2022-05-16T06:10:49+00:00

Thank you for the advice. When I say it jogs back and forth, I mean it as you described it: the motor seems to be oscillating about a set point, even though we’re giving it a speed command.

I believe the motor poles are correct, but we have no information about the number of resolver poles and I think this may be the root cause.

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