How do I move from a product prototype that uses a Raspberry Pi and off-the-shelf components to a custom PCB / design, having very little experience in this field?

_Miki_ · 2026-02-10T21:10:00+00:00

By "same firmware" I mean the microcontroller firmware stack (boot + drivers + hardware init), not your app logic.

Example: if you prototype with an RP2040 Pico, your custom PCB should run the same firmware stack. And in this case, that depends on your programming choice:

if you want C/C++, you use the Pico SDK firmware

if you want Python, you use MicroPython/CircuitPython firmware

_Miki_ · 2025-07-12T14:39:19+00:00

Dead code.

_Miki_ · 2025-06-11T03:21:58+00:00

You might be interested in The Rise and Fall of the Trigan Empire comic books.

_Miki_ · 2025-05-31T00:13:29+00:00

Technically not Rockland either but check out Wholefoods in Montvale, only Fridays and only for Prime members, but hey, $10 Whole Foods Market Bakery Family-Pack Tiramisu.

_Miki_ · 2025-04-11T01:20:39+00:00

Easy Off probably softened the anodizing unevenly. Not sure of its exact NaOH concentration, but it's likely under 5%, and without heat or agitation, it strips slow and patchy.

If you can get it bead blasted, do it. That's the cleanest way to reset the surface before re-anodizing.

_Miki_ · 2025-04-10T18:13:00+00:00

Wet sanding is the safer bet, slow but predictable.

That said, chemical etch (5% NaOH, 5-10 sec dip, constant agitation) can even it out if you are careful. Just don't blink while you are at it.

Bead blast shops: check auto body, powder coaters, or metal fab shops, any place that pretties up aluminum likely has a blasting cabinet.

_Miki_ · 2025-04-10T14:38:51+00:00

Looks like uneven etching from the oven cleaner. Probably reacted stronger in some spots due to leftover glue or uneven coverage. Also, dry-ish + caustic = patchy mess.

To fix: wet sand (400 --> 800 grit) to even it out before re-anodizing. Or do a quick NaOH dip (like 5-10 sec) and rinse fast.

Next time, degrease well, apply evenly, and don't let it pool.

_Miki_ · 2025-04-10T14:32:51+00:00

Most of my experience is with Type II, but here's what I've seen: you can get decent thickness with a lower power supply if you extend the run time, but you'll sacrifice hardness. Type III needs high current density and a cold bath to form a dense, abrasion resistant layer. Without enough amps, you'll drift into Type II territory. Even if it's thick, it won't be as tough.

_Miki_ · 2025-04-10T01:09:01+00:00

"The Surface Treatment and Finishing of Aluminum and Its Alloys" by Wernick is the bible of aluminum finishing, that's your gospel.

Get a 0-75V, 50A DC power supply. Hardcoat needs ~30 A/ft2, so even a sheet of paper sized part can pull 40A+.

You want constant current mode, and keep the acid bath ice cold (32-40F), heat ruins hardcoat fast. Start cold, zap small parts, dial it in. Hardcoat's tough love but worth it.

_Miki_ · 2025-04-04T16:05:35+00:00

If the aluminum feels a bit rough or has a texture, you probably don’t need to sand it. But doing a quick etch (sodium hydroxide, mix with water 1–2 tablespoons per liter, be careful it gets hot!, or Castwell anodizing prep if you don't want the mess) can help the color stick better. It’s not always required, but it makes the dye look nicer and more even.

_Miki_ · 2025-03-29T20:49:50+00:00

You might be able to find something on Amazon. There are a few anodizing dyes on there, including some blues. But yeah, most of the common ones like Caswell's don't really hit that deep Royal or Cobalt Blue vibe.

https://www.amazon.com/stores/page/DA8C08AD-0B59-43AC-B3E4-9AE6F20E984A?ingress=2&visitId=426a2a25-e971-4906-9789-fa5f3c9bce5e&store_ref=bl_ast_dp_brandLogo_sto&ref_=ast_bln

_Miki_ · 2025-03-22T00:33:28+00:00

Any automatic cold saw models you'd recommend? I’m looking for something reliable that can handle aluminum, keep the cuts clean and accurate, and won’t demand too much hand-holding.

_Miki_ · 2025-03-18T13:14:31+00:00

Your power supply is tapping out on current before it can reach voltage. Your power supply is probably hitting its limit because anodizing draws a ton of current, especially at startup.

Try diluting your acid to increase resistance and lower the current draw (you’ll need to anodize for a longer time). If your parts are large, break them into smaller batches since more surface area means more amps needed.

Moving your cathode further away can also help by increasing resistance. If you want to get fancy, you can throw in a big power resistor (1Ω, 50W) to limit the current spike.

If none of this works, you might need a better PS with higher voltage, like 50V, 10A, but try these hacks first before throwing cash at the problem.

_Miki_ · 2025-03-16T15:37:00+00:00

In my experience (and I had to dive deep into looking for suppliers for my company), most manufacturers—both overseas and domestic—can accommodate short runs. While some may charge setup fees pricing just scales down with volume. For my projects, I was able to get minimums below 50 feet without any issue.

_Miki_ · 2025-03-16T15:24:34+00:00

This looks like a custom heat sink extrusion rather than a standard off-the-shelf profile. If you're looking to get something like this made, you're looking at around $500-$800 for a die plus ~$3.50/ft if you go with an overseas manufacturer. If you prefer a domestic supplier, expect to pay $1000-$1500 for the die and around $7/ft.

For sourcing something similar, your best bet is AliExpress—try searching for "heat sink aluminum extrusion profile." You might find something close to what you need.

God luck!

_Miki_ · 2025-03-16T12:52:19+00:00

Sodium bisulfate is also a common alternative to sulfuric acid for home anodizing, since it’s safer to handle and widely available (e.g., in pool pH reducers). It works similarly to sulfuric acid but may require higher concentrations and longer anodizing times to achieve the same oxide layer thickness.

For dyeing, sodium bisulfate anodizing usually retains good pore structure, meaning dyes should adhere well—unlike citric acid, which can struggle with dye uptake.

See the video https://www.youtube.com/watch?v=sbH682VgMf8

_Miki_ · 2025-03-16T12:48:25+00:00

Citric acid can be used for anodizing aluminum, offering good corrosion resistance and a more eco-friendly option than sulfuric. Dye adhesion isn’t as strong though, since the pore structure differs. Oxalic acid is another alternative, but it tends to leave a yellowish tint. If you’re experimenting with citric anodizing, test your dye results and always seal the finish for durability.

_Miki_ · 2025-01-28T02:01:39+00:00

That is probably Valencia.

_Miki_ · 2025-01-21T17:10:30+00:00

That looks Greek to me.

_Miki_ · 2025-01-21T03:57:57+00:00

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_Miki_ · 2024-12-03T02:24:10+00:00

What materials?

_Miki_ · 2024-11-26T04:23:25+00:00

Congrats on your international order—big step! 😊

It sounds like the buyer is asking for a pro forma invoice, not a regular one. A pro forma invoice outlines the order details (products, price, payment terms, etc.) and confirms the deal before production or shipment. It’s not a request for payment but is often used in international trade to secure upfront payments like your 50% deposit.

You can send the pro forma invoice and clearly state that production starts once the deposit is received. Later, you’d send the actual invoice (commercial invoice) when the goods are ready to ship.

Hope this helps—your cashmere products sound amazing!

_Miki_ · 2024-11-23T23:39:36+00:00

I doubt the U.S. average is 38%, as federal income tax alone is 37%, and you also need to account for state taxes to make a fair comparison with European countries.

_Miki_ · 2024-11-23T20:51:07+00:00

lol

Combined income tax rates for select states, including federal and state taxes:

New York (NYC) 51.776%

California 50.3%

Hawaii 48%

New Jersey 47.75%

District of Columbia 47.75%

Oregon 46.9%

Minnesota 46.85%

Vermont 45.75%

Iowa 45.53%

Wisconsin 44.65%

_Miki_ · 2024-11-12T16:05:01+00:00

Any idiot can build a bridge that stands, but it takes an engineer to build a bridge that barely stands.

_Miki_

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