Andrew Zonenberg

@azonenberg

Infosec, HW/SW RE, high speed digital, test equipment, network hardware, microscopy, FPGA/ASIC, , KD2HKV, . Tweets are my own.

The lab
Vrijeme pridruživanja: rujan 2013.

Medijski sadržaj

  1. 4. velj

    I broke three endmills before I figured out how to do this. Working with 100 μm tooling requires an incredibly light touch. 10-20 μm per pass is a heavy cut, 5 μm is probably better. R22 is an EIA 0402 footprint, pads are 500 μm square.

  2. 2. velj
    Odgovor korisnicima

    Why not both? (done on 's FIB, but sadly not by me)

  3. 26. sij

    No desoldering braid? No problem! Ok, machining solder off an 0402 pad is kinda stupid. But it was a good test run for some tooling changes. Also, at least for small areas, 5 μm per pass seems pretty doable on this mill.

  4. 26. sij

    Made a little jig for PCB work on my mill (on the same mill, of course). Machined from 1.5" x 1/4" 7075 aluminum bar stock. It clamps to the T-slots on the mill table and holds a 1.6mm PCB by the edges, held above table level to provide clearance for bottom-side components.

  5. 20. sij

    The only remaining step was to code up a nice touchscreen HMI to crunch the data. It collects water level measurements at 1 Hz, does some averaging to reduce noise, then calculates tank volume and flow rate in L/hr.

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  6. 20. sij

    Note the water on the floor in the bottom right corner of the previous pic. That's not spillage from the bucket I was testing the sensor on, that's an active leak into my lab. I also grabbed a Gentex horn/strobe and some water-sensing cables to place along walls in trouble spots

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  7. 20. sij

    The parts I ordered after the Christmas flooding incident had come in, so I set to work building a proper monitoring system. I started with a DIN rail mount kit for a Raspberry Pi, a couple of I/O boards, and a 4-20 mA submersible liquid level sensor. Here's the dev setup.

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  8. 20. sij

    After the initial rush settled down I dug a bit deeper and found the cause: a shoddily installed ABS gutter downspot that was slipped over the end of a PVC pipe with no attempt at a seal. The ABS was cracked and the PVC was almost certainly clogged, so it all needs to be redone.

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  9. 20. sij

    I grabbed a shovel and began digging a trench from the sidewalk toward several particularly wet spots of the front yard, in hopes that pulling water away from the house would help. When I got near the end of the driveway, the trench started rapidly filling with water.

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  10. 20. sij

    I had previously RFQed for proper drainage upgrades, but the contractor was unable to do the work until the summer because significant excavations in saturated soil would collapse before any pipe could be laid. So it looked like I was on my own for the short term.

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  11. 20. sij

    The water table in the entire property has always been high, and I planned to do drainage improvements outside in the near future, but it had not been a clear and present danger beforehand. This is my driveway last week. It's not even raining.

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  12. 20. sij

    Backstory: When I got home from Christmas holiday travels, I found the whole first floor of my house had flooded. It was dry, but obvious water marks told the story of terrible events in recent days.

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  13. 20. sij

    I maaaay have just gone full SCADA on my sump pump.

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  14. 15. sij

    Nothing like a hot drink on a cold night...

  15. 11. sij
    Odgovor korisnicima i sljedećem broju korisnika:

    Just need to deal with some stormwater drainage problems, and figure out what the contaminant in my polishing process causing these nasty scratches is. (This is a single strand of 12AWG solid copper wire heavily tinned with SAC305 by hand, showing bulk solder and IMC)

  16. 10. sij
    Odgovor korisnicima

    Proposed system block diagram. Just logical connections, not all buses etc shown.

  17. 9. sij

    Via connected to the wrong layer? Not to worry! Practicing more: deleted the ground plane connection for this via and reconnected to a different net. For scale the passive is an 0402, traces are 0.1 mm / 4 mil. References: * *

  18. 9. sij
    Odgovor korisniku/ci

    Horrible perspective, but... Given the diameter and wall thickness of C, plus some property (Young's modulus perhaps?) of the material it's made from, calculate the force required to snap C.

  19. 8. sij

    Here's some practice work on a random scrap 4-layer board. Rough cut with a 1.5mm carbide endmill, the small pocket was done with an 0.25mm. EIA 0402 resistor for scale. Toward the end of the machining operation I was taking off 5-10 μm per cut. This thing is small but no joke.

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  20. 8. sij

    Picked up a new toy for my lab: Sherline 5410 3-axis milling machine. Rigged up an extra stereo microscope to get a better view for precision work like PCB circuit edits

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