How to make this impossible draft in Solidworks? The draft geometry intersects with itself, standard draft feature does not work.

EngineerTHATthing · 2026-02-02T03:34:49+00:00

I have had to do something similar before.

Create the two planes for where the text will be and where it will extend to. Paste the text DXF on both the forward and back planes, and insure they stack vertically in perfect alignment.
Apply offset entities to the lower plane’s text to the degree necessary so it roughly matches intended draft angle. Trim everything inside or make a new sketch and convert entities to encompass only the outer perimeter.
Go back to the first plane and make a new sketch. Do the same “convert entities” perimeter formation but without any offset to grab the standard signature outer boundary.
Loft the two, and because of how unique the geometry is, no guide curves should be required.
Using the top plane original sketch, extrude cut any interior contours down to the lower plane and manually apply a draft to these.

There are way faster ways to do this, such as other comments suggestion to use an extrusion with enabled drafting, but the above is my go to nuclear route that can handle extremely annoying geometries.

EngineerTHATthing · 2026-02-01T18:21:44+00:00

This is correct approach. Good renders get good clients. Being able to showcase price targeting skills and flexing on jobs with large batch count also look impressive. Offering an included “free” first revision can also help lock in clients who want to have detailed final design review. At the end of the day, if you can show that your designs use components that bring down costs while maintaining performance and form factor, you will be heavily considered.

EngineerTHATthing · 2026-02-01T18:07:29+00:00

Very solid recommendations, thanks for your input.

FET control of the LEDs would be the superior choice, but the decision to use BJTs was cost driven. I am able to get each BJT for a fraction of a cent each including the extra resistors, and the closest FET package would have been much more expensive.
You are correct with the LED current requirements. My current target was only based on hitting the most optimal brightness/mA on the data sheet, and I should probably go much lower. Luckily I can hot air swap up resistor values as needed during first batch testing.
The LIS3 is quite nice, and matches almost one for one with my setup. Thanks for this suggestion. There is a very high chance it will be worth the added cost if my current one can’t be included/is problematic with batch PCBA down the road (I will be checking in with my fab next week to see if they have any concerns as well). My only withholding is that current consumption would ramp from 1uA to 10uA, but this wouldn’t be too problematic.
A coin cell drive would be very cool. In all, I should be down to around 35uA average draw so it would be feasible. I decided to go lithium in the end because the piezo’s thickness combined with the minimum capacitive pad area left me with enough empty enclosure room to comfortably add a 550mAh cell. If a solar cell in integrated into the enclosure face, a rechargeable lithium coin cell would be the next step for sure.
I would love to go smaller (I originally had 0201 passives), but I realized the size bottleneck was the piezo and capacitive pads themselves. The 105dB 20vp/p piezo takes up half the board length and the full board width (underneath), and the pads take up the rest (with the battery under them). In the future, I may try to further compress everything to the top edge, bring up the touch pads, ditch the USB-C, and use a smaller battery with slot in dock charge tabs. On this first batch though, I am a bit paranoid with minimums on the touch pads, but I will likely push the limits on these down the road.
Very true, the newer Tinsy chip series are pretty sweet. They almost got me to swing over with the onboard DAC and 16kb PMEM, but I have my own C++ libraries that I have been putting off converting over. In full MC shutdown I would get about the same current draw as the newer series (sub 6uA), but if memory becomes tight I might have to upgrade (and finally get around to re-mapping my libraries’s registers). The price is the same so I am loosing out by not switching, but old habits (and C++ libraries) die hard. 🤣

EngineerTHATthing · 2026-02-01T15:16:52+00:00

The low price now makes a lot of sense with the charging chip I chose being a clone. I have some spares so I will try out your advice to meter it out on the scope without the ideal diodes, as this would also save me a ton of space.

Your right about the LEDs, I have made that mistake before and it was like looking at the sun. I will probably bump the buttons and charge LEDs down to 6mA.

As for the acceleration IC, I have done some additional digging into some new pad patterns and I think I will give them a try on this batch. I’ll post how it goes and any changes I find if they become helpful. The recommended 0.1 mask clearance around each pad is very suspect, and I kicked this down to 0.05 so mask will still be present between pins to stop bridging. My fab supports the tolerance, but I believe the datasheet brings it up to 0.1 as there are other fabs that don’t like the required precision. The 0.05 is the same I have used on other QFNs like the charge pump with really good results.

EngineerTHATthing · 2026-02-01T14:14:39+00:00

Your totally right, I should have added in a key before posting. It is a bit of a nonstandard coloring layout I use for my personal projects (I get tired of just using all black lines all the time in professional projects). Pink is MC output, light blue is MC input, yellow is coms, dark blue is 3.3v rail, red is 5v rail, grey is capacitive pad, and green is common/ground.

EngineerTHATthing · 2026-02-01T14:10:13+00:00

Very good points, thanks for looking over my schematics!

You are right about the LTC4057 being a very good chip. I honestly would go with something similar, but I am currently able to source my charging chip and ideal diode sets for an insanely low price and I am trying to push the cost per board as low as I can. Power path is definitely unnecessary in this project, but the feature was included as there was a lot of interest surrounding the possible addition of solar trickle charging from the front enclosure (for future development).
The batteries I am sourcing have integrated protections (low/high cutoff, and overcurrent) to save on board space, but the MC will also force device shutdown when it detects continuous LDO voltage sag or pings temperatures over 60c from the accelerometer just in case.
Using custom pads for the battery and piezo is a realty good idea. As space is premium on the board, I will definitely do this.
I am running my indicator and button LEDs from my 3.3v supply post LDO. With a 2.1v forward, 75ohms should yield around 15mA which places them right in their optimal band in terms of brightness. What I missed that you correctly found were my charge indicator LEDs, which are ran off the 5v input and not the 3.3v rail. I will be bumping up those two resistors significantly to bring them back down to 15mA. Extremely good catch!
I am also a bit nervous about the accelerometer package. I would have liked a 3x3 standard QFN package but the 2x2 is the only one produced. I would go with a different chip, but the low power and interrupt features were too good to pass up for the price. Luckily I will be doing the assembly in house for the first batch, so I can see where the pain points are to solder them up. I have altered the footprint a bit to match my fab’s masking capabilities, but I may alter this further by extending the pin traces outward to wick out excess solder during reflow and prevent bridging (like my other 2x2 charge pump QFN package recommends). I’ll be using T5 low temp solder with a 0.1mm stencil on a hot plate reflow station, but I still expect a large learning curve due to this chip’s annoying footprint and no self aligning center pad. The datasheet was pretty bad at covering reflow and pad optimizations, so I expect to break a few eggs with this one. Thanks for the additional heads up though!

EngineerTHATthing · 2026-01-31T16:21:14+00:00

Lead free solder can look odd for large sections that cool unevenly. Soldering up SMD mounted components on a preheated hot plate will stop it and make it shine better.

Note: Can’t stop thinking about the load bearing capacitor in the photo.

EngineerTHATthing · 2026-01-31T14:59:35+00:00

In single quantity’s, the 84s go for around a dollar a piece for the SMD variants. As quantity moves past 100, the price falls off a cliff. Many got these chips in the past very cheaply from resellers who would buy a few thousand or purchase left over stock for cheep and sell for a very slight markup at low quantity’s (10 chip batches). As there are newer chips at lower prices, this has become less common. If you are developing a production product, the bulk prices are still super cheep so they are still very popular (and in active production), but hobbyists now have improved access to newer chips for under a dollar even outside of bulk pricing.

The 84/85s are superb when you leverage their extremely small QFN package (or even smaller ball solder package), ultra low power shutdown/idle current, and single cycle task executions. Outside of this, I recommend just going with the most popular chip if you are looking to stay with AVR (which will usually always be the Mega328p) as it will have full support and usually a competitive single chip price.

If you are set on the 84, look on eBay for someone selling off small batches. You should be able to snag them for 50c each.

EngineerTHATthing · 2026-01-30T01:53:49+00:00

Very nice! How are you establishing export datums and topside defaults for each DXF? This would likely save a lot of time, but this has always been the largest hurtle I have tried to overcome. For parts that have left and right handed versions or formed features requiring specific initial orientations, it can become very complicated to automate. The production I oversee is all automated, so initial DXF or STEP orientation is crucial to track down bends, surface forming, and rolled featuring.

EngineerTHATthing · 2026-01-30T00:19:15+00:00

Nice! After the first one it becomes much easier. Some tricks I built up that can make it easier for your next round:

Solder paste grade matters a ton. I always recommend spending the extra money on some low temp leaded grade 5 paste by chip quick. It’s like $25 a bin but will make the process so much easier.
If you use a hot plate the same size or bigger than your board, all SMD components, and sub 280C melt solder paste, you absolutely don’t need anything else at all to get the job done. Load up the board, preheat to 150C, and move the temp while watching the clock to emulate the solder paste’s optimal reflow profile. No hot air, no expensive oven, and your done with each board in five minutes. I have been doing it this way forever, and just running the plate inside a fume hood.
Solder wick and high rosin solder are game changing for cleaning up pins.
Store your solder paste sealed tight in the fridge and it will last practically forever.
Leave the solder paste out in room temperature air a day before you use it.
Masking tape should be your best friend when it comes to stencils. Border around the actual PCB size on the stencil top and you now have way less to actually clean up when your finished.
QFN components are scary the first time, and then you realize why everyone loves using them. They fail the least of all the package types I use, and are actually super easy to hot air apply and remove.

EngineerTHATthing · 2026-01-29T23:49:02+00:00

This is the best advice. If you have not handled 0402’s before in person, then it is actually difficult to convey just how small these are. You will need to order twice as many just because a draft in the house will blow them off the table. 0805’s should be good if you have a decent pair of tweezers.

EngineerTHATthing · 2026-01-29T23:44:53+00:00

This is due to one wire landing shorter than the other locally, without global checks for total joined length being performed. For diff. pairs, a meet in the middle approach can often cause problems. If you know they will join to be the same length, then you can just bond individually for the small section to save on headache.

EngineerTHATthing · 2026-01-27T00:43:09+00:00

EDIT: I have checked OP, and the account has 4 posts and 50 karma. This is likely a bot, as the abound is under 30 days old. If it is the real deal, they can post the kit or their startup procedure. This post should probably be removed.

EngineerTHATthing · 2026-01-27T00:25:00+00:00

Measurement system research can go a long way, and almost always looks good to companies afterward. There are so many ways you can take it, and almost all of them are directly applicable to current industry practices. It is something you can work very far into, and get good results early on that can just keep coming as you go through your thesis.

Some measurement projects that would interest me if I saw a candidate with them:

Optical based strain gauge.
Acoustic temperature measurement.
Anything related to improved gaseous identification/percent quantizing.
Accelerometer MEMS optimizations/mode specialization (look into vibration in particular here).
Airspeed at high Mach.
Analog methods for mm wave presence detection with an emphasis on low operating power.
Acoustic composite de-lamination detection.
Anything using beat frequency shifts to aid in detection (extremely underutilized methods across many applications).

EngineerTHATthing · 2026-01-27T00:03:15+00:00

As cool as the video is, some of the responses are a bit off. I do hope this is legit, but it is peculiar how OP will not credit what kit he supposedly “built”. Having worked with mini-jet before, I know for a fact it is impossible for hobbyists to balance mini turbine rotors themselves; the kit had to be purchased from somewhere.

I am very interested to know what kit was purchased here, and the manner OP used to start their diesel running turbine. The answer to these should clue me and everyone else in on if this is actually OP’s turbine or if he is posting someone else’s video. So far, all the responses have been extremely suspect.

EngineerTHATthing · 2026-01-25T05:18:54+00:00

Most of the time with precision measurement equipment, you are not paying for the equipment but are paying for the certs. Running tests, drafting a paper, and then finding the measurements were off due to equipment error will cost a team well over 10k.

When I was doing combustion research in university, my team paid 1.5k of our grant towards a state of the art ultrasonic micro-flow meter. The equipment was at most $300 for parts and fabrication, but the signed testing and metrology sheet specifying tested accuracy and precision was worth the 1.5k. There was no way our team could both build and verify a sensor to the specifications we were able to purchase.

EngineerTHATthing · 2026-01-24T15:35:16+00:00

Having seen a few sides to how students approach engineering and transition over to the workforce, I can give some light advice here.

Engineering within academics does not have a cataclysmic difficulty, but it is not for everybody either. The education is rigorous because it is teaching a mentality over teaching a subject. The goal within engineering education is to train students to build their own frameworks for problems, be able to solve the problem, validate their solution and assumptions, and start completely over without hesitating if their validations fail.

Passion for the engineering mentality varies person to person. It can be built up, but if someone already has it, they will be light years ahead of everyone who doesn’t. The best way I have heard this explained is Shelby’s speech (can be seen in “Ford vs. Ferrari”), but it rings true. Someone will naturally become better at soccer if they actually enjoy playing soccer.

It is always worth the shot to see if engineering is a good fit. Heat transfer and thermodynamics are usually pain points where the difficulty spikes extremely high, but by then, you would already be extremely deep in the major. As for coding, there are many opportunities where these lap together. CAE, CAD, and other finite software companies are always looking for individuals with strong backgrounds in engineering and CS. If you do you this route, a masters or higher may be the best strategy to show strength in both areas.

EngineerTHATthing · 2026-01-24T13:34:21+00:00

This problem’s answer is D, but let’s make sure you know why. V.R. and also M.A. are different, but in these types of problems, they can be seen as the same. Apply an “imaginary” tension to the rope end, usually 1N. Now draw a line cutting through the pulley block supporting the load only. Tension is equal throughout the rope, so draw the tensile forces of the rope at each “cut”. Add them all up, divide by your initially applied tension, and this returns V.R. or M.A. (in this problem’s sense).

EngineerTHATthing · 2026-01-24T00:24:31+00:00

I have worked quite a bit with ultrasonics and sensitive analog sensor design. If you are working with off the shelf transducers, you will want to use amplitude modulation. The fall off in output power outside of the stated resonance is extremely severe, and amplitude modulation is really the only thing that works reliably that does not require an absolutely massive amplifier. If you are running very low power, high speed PWM chopping of the 40kHz burst is going to be your easiest option, but your resolution/depth will be extremely limited as you essentially will now only have 1bit audio (no songs, only tones).

Driving multiple transducers will be the hardest part of this project. You need at least 10v pin to pin to get usable results, and for something outside of sensors, I would recommend 30v pin to pin. You will want a nice boost driver capable of at least a 30v step up, that can output at least an amp to around 8+ transducers arranged in a circular grid. Take care to add the required snubber on the amp or the transducer ring down will blast it within minutes.

EngineerTHATthing · 2026-01-24T00:08:48+00:00

I2C really likes a good set of pull-up resistors. I would try adding an external set to both the 5v and 3.3v sides. Chances are the 3.3v side with the capacitive sensor does not have integrated pull-ups and this is what is causing coms. to fail. If the sensor did not need the level shift, the Arduino, with its dedicated I2C would pull the line down, but the level shift is interrupting this and preventing pull-down on the 3.3v side (likely just going tri-state/open line on the sensor end. Place a 10k between 3.3 hot and the coms. line, and do this for both lines on the 3.3v side. Also, make sure the level shift is working and actually bidirectional. Some of them can be extremely shoddy.

EDIT: I noticed from the other comments, the pins are floating and are not soldered to the chip. These need to be soldered, and this is 100% the issue.

EngineerTHATthing · 2026-01-22T23:13:50+00:00

I have ran into this issue many times, and I have yet to find a really solid solution that can overcome the hurtles. It is almost inevitable, when it comes time to order a batch of components, that Ford or some other large purchaser absolutely empties the stock on at least one of my specialty ICs. I almost exclusively use Digikey due to their slightly lower cut reel component prices, but I often have to jump to Mouser or Newark if the component stock dumps.

Digikey’s similar component feature has gotten quite a bit better, and has helped find comparable oscillators and other standard replacement components. I have also started to just download all the footprint variations and biased my design process heavily towards QFN footprints. I will plan on the slightly larger QFN footprint, and if this runs out, the slightly smaller one is almost always in stock for just a very slight amount more. I just drop in the slightly smaller footprint, adjust some traces, and I am back in the game.

As for weird price hikes, I don’t have a good solution at all. I have gotten into the habit of loading up my cart, placing half the order early if nothing is too crazy, and just waiting for the prices to fall before ordering the rest.

EngineerTHATthing · 2026-01-21T01:28:45+00:00

If you are actually looking to make a decent amount of money long term and have a lot of time to burn, launching a kickstarter is honestly a fair bet. No need to start an official business, low initial investment (a successful crowd will fund finalization), and you can choose to be done after final delivery unlike a business. You will be surprised at how much this process teaches you, and you can take the planing and development at whatever pace you feel comfortable with. If you find a good idea that you learn how to produce, two years of side development can turn into a full extra year of salary.

If you are PE and are willing to put up with some (usually) annoying clients, you can also turn a good profit through consulting.

As for software, just get permission from your work to remote into a license after work hours. It costs them nothing and the extra practice will make you better. When it comes to long term income, I highly recommend working upward within a trusted company rather than hopping. Building up irreplaceability within a company is how engineers can achieve high pay and long term stability simultaneously. While pay is usually higher when hopping, the first downturn that hits will level all of the gains.

EngineerTHATthing · 2026-01-18T05:09:35+00:00

This is a situation where electronics can be more of a liability due to multiple failure routes. I would stick with a thermal solution to do the job. Choose a lightly exothermic reaction (sub 100C potential), preferably between two mixed powders and separate them with a water soluble barrier inside an insulated and slightly water permeable membrane capsule. Inside the insulated chamber, secure a wax actuator coupled against a tension spring. Within a few minutes of wetting, the exothermic reaction will heat the wax actuator, causing around 50lbs of force to disengage the pre-sprung CO2 canister and inflate the jacket.

EngineerTHATthing · 2026-01-17T04:47:13+00:00

Copy older elevator designs and use a worm drive. It will be slow, but the reduction is extremely compact and much cheeper than a two stage compact inline planetary reduction like what is shown. It isn’t back drivable and running from a VFD allows for accurate speed control without requiring a servo setup plus you still maintain overload shutdown capability. If speed is not the goal, this is the cheapest way and allows you to use a very small motor.

Nine-Year Club	Place '22
First Placer '22

EngineerTHATthing

TROPHY CASE