Better Sheet Metal Parts With Chemistry | Hackaday

2022-12-03 21:06:44 By : Ms. Helen Xu

[Applied Science] wanted to make some metal parts with a lot of holes. A service provider charged high tooling costs, so he decided to create his own parts using photochemical machining. The process is a lot like creating PC boards, but, of course, there are some differences. You can see the video of the results, below.

Some of the parts could be made in different ways like water jet cutting or even stamping. However, some things — like custom screens — are only really feasible to do with a chemical process like this. Metal Cut

Better Sheet Metal Parts With Chemistry | Hackaday

Like PC board etching, you deposit resist on the metal and then use a reactant to eat away the parts you don’t want. Cleaning the metal is essential before putting on the resist. Using water, it is easy to tell if the metal is clean.

There were a few interesting wrinkles to the process. For one thing, the parts are etched in a mesh bag so that as the parts come off the base plate, they stay put in the bag. Some of the equipment is borrowed. For example, a sous vide cooker holds water at a fixed temperature. A cheap laminator adds dry resist film to the metal with a simple modification.

We imagine that any of the normal ways you do PC boards like direct toner transfer would work to set up the resist. However, in this case, [Applied Science] uses tools means for screen printing masks to produce photomasks. The etching tank used was especially impressive and looked like it had the potential to make a huge mess.

The results were tainted a bit because of a problem with the etcher, but they still looked pretty good. If you are already set up to to do PC boards, this probably isn’t a big stretch.

We’ve seen a lot of different ways to approach chemical machining although, more commonly, with electicity.

Neat project and even though it is a completely different process it reminds me of this method however one thing i did notice with it and it has descent resolution but sometimes descent is not near good enough for anything that can not have cracks on the edges. really a sinker edm is needed at that point and heck older ones in this area as long as you do not need a huge footprint are going for under 1k any more. Yeah expensive but if you need stuff to be accurate that is the tool to have.

Looks like a handy technique for things like custom tone wheels and encoders, and possibly for thin petal valves.. not sure that’s the word I want, can see the thing in my head.

As used in pulse jets. Yeah noise! 100% efficient motor! (converting fuel to noise).

Not typically done with resist though. Etching primer, acid and a battery charger are great for cutting thin spring steel.

In the early 80s, I worked for a company that built geophones. Chemically cutting the metal springs was the only way at the time to produce the precision needed. Suppose they could be laser cut now days…

not if heat would denature/detemper the spring steel, while electro/chemical processes are typically room temp to sub-boiling

As usual, another excellent video from Applied Science. Some remarks:

@00:00, the rulers such as shown in the beginning are often etched too. Etching does not have to be full depth. @04:26 I don’t know what those flip pins cost, but I usually use the thin male headers with round gold plated pins for this. @08:05 I guess that drying in a vacuum chamber would also work very well. Rinsing the (contaminated?) water off with (clean) isopropanol also speeds up the drying.

It also reminds me of andysMachines. (also featured on Hackaday). He etches graduation marks of the building of “Gear Hobbing Atttachment (Milling machine) Part 2” It starts a@07:20 with a vinyl stencil. As etchant he uses vinegar + salt and a 12Vdc source.

I haven’t watched the video yet so I’m not sure if they are mentioned, but can I suggest that anyone interested in this process takes a look at gobos? A gobo is a metal disc with a pattern cut or etched through it, which is used in a theatrical light fixture to project a shape/pattern/image onto stage.

Full colour glass gobos do exist, but by far the most common type are still basically bits of metal with very intricate holes in them. They need to be metal so they can cope with the very high temperatures that they are exposed to.

For some examples have a look at the Goboplus website. They can also make custom gobos, if you want an intricate pattern in a bit of metal but don’t want to have to etch your own.

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Better Sheet Metal Parts With Chemistry | Hackaday

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