Push me…

…and then just hurt me…

(sexist video/word joke wich i won’t link)

I have recently developed the habit of collecting buttons and switches (with the purpose of being used one time or another, not the purely diogenes syndrome/trash bin)).  I mostly prefer pcb and smd ones, because they are the most likely to be used in my projects. Still, this caught my eye:

At a secondhand kitchen appliance store, was this awesome, sci-fi looking, waterproof switch:

117 - Spaceship buttton

This was going to be a quickie post about that single switch, however, while thinking about it, I changed my mind and decided that since we don’t pay much attention to that part of our projects (how many of you have a specific box of switches/push buttons, with more than one of each type, for real projects?

So, here they are some of the standard, most likely to be used buttons out there:


117a - Toggle me

1 to 9:

Those where salvaged from various electronics (always dismantle trashed electronics!). They are unlikely to be used unless I’m going extremely small, or I have space constraints. Plus, I don’t know how much have they been used up, so they’re a bet.

1,2 & 7:

Can be bought over ebay, just look for smd or smt button (or push button if you feel like it)

3 to 6:

I have never seen them over ebay, they might have a different name, or not be avaliable altogether. They’re a kind of specialized switch, normally used for partial position detection (they fully retract). Arrow shows applied force vector to activate them.

8 & 9:

Same story (salvaged, already used) except that they have a plunger activation. Interesting as micro endstops.

10 to 13.

SMD versions of normal pushbuttons. They have different colours and heights. Low profile ones (12) have metallic stems and ultra low profile (13), use capton tape to hold everything.

Depending on how you search, 10 & 11 can have silicone or plastic button, only affects the switch feeling.
There is a special kind of pushbutton in that category wich will have it’s own post.



117b1 - Toggle me117b2 - Toggle me

There are many colors, stem shapes (18 & 21) and heights (22!) Nothing to add about these ones, you already know them.



117c - Toggle me

Mostly used in mouse and portable electronics (portable, NOT handheld).


It’s a special case, quickly disappearing from the landscape, but widely used as mouse button a few years ago, relatively expensive through ebay.


Those are widely used as computer switches, resets and speed toggles. (can anyone remember the turbo buttons on old Pentiums?). You can have them in various flavors: SPDT, DPDT, latching and non-latching.
Very cheap through ebay, there are 8x8mm and 6x6mm ones. Unfortunately, as avaliable as those are, button caps for them are nowhere to be found, or they are very low quality. 24* came from an old computer with it’s switch.

25 a & b:

Those are the mountain kings. They completely caught the mouse switch world and the miniature endstop area. All non latching SPST.

They have a few million clicks life, but I have managed to burn through five since my first computer. (yup, I remember how many of those I have changed XD!)



117d - Toggle me

I still have those around because…why not? The big square one might be used someday, but the rest, are just fancy mementos of how it used to be. Btw, the small one on top, has a horrid, squishy and unpleasant tactile feedback, do not use it under any circumstances other than “factory repair”.

And that’s pretty much it. I hope you enjoyed the button porn.

X-Y Stories.

So, I’m working on the laser engraver, and I have a half completed a big post about what you need, what to do and what can’t be done with a standard K40 laser engraver. (mostly a rant, and then the upgrades). Christoper tough, kindly asked about wire routing and air assist, so here’s a snippet about what I did (and found) about that.

Firstly, air assist:

I machined my own nozzle, threading it for the lens holder, so I didn’t have to fiddle with odd clamping systems (screws mainly). Be very careful with it, the thread in the chinese part is AWFUL. I had to machine a flat in the spline because the teeth haven’t been machined right: 116a - X-Y Stories

That example is not to scale on teeth tip removal, but it accurately represents the shape of the chinese part.

I didn’t want to make a new lens holder (mainly because I suspected that I would find the same ill machined thread in the third mirror support…and it still worked fine, so there was no real need of overmachining pieces)

As for Christopher real question, the cable carriers, I used the smallest knockoff from ebay I  could find. At 7x7mm internal space, it was incredibly cheap (8 usd per meter, with 2 end pieces) so I bought two meters, fueled by greed. XD!.

 116b - X-Y Stories
Be careful!, I have reversed my head position to be backwards! (in case it looked odd to you)

7x7mm have enough space to easily carry a standard aquarium air hose plus six 1,3mm (AWG 16) cables. (only 3 in this photo). Drill, thread and screw at will. (you can barely see a screw just underneath the hose. It’s threaded directly to the plate, no nut

I also guided the X stage cables (on the Y direction) but made a slight modification. Sinte the endpiece has free movement to almost 180ª, I was worried that the movement of the stage up and down might break the cables, so I glued the first element in a forced 90 degree angle, so to force the carried cables to a maximum deflection angle of 45º.

116c - X-Y StoriesSorry for the overexposure.

I used the original screw hole for the end limit to attach the carrier, so I didn’t had to risk damaging anything.

If you want to know more about those strange end limits, look at the previous K40 post.


Guitar Hero, the Emergency Nichrome song.

So, today I had to improvise a tool to make 45 cuts at a time (for the sake of efficency) in 30 foam bars, so they could be divided and glued to cardboard to make board carriers for 3600 boards.

Easy, just drill some neat looking holes, put some rivets in there to hook the cutting wire, and there you go.

115a - Guitar hero
Reminds me of a guitar mast…sort of…

The thing is that I didn’t had nichrome wire at hand, at least NOT a spool of it. Some thinking head dared to suggest using copper…yeah, engineer pls, leave the improvisation to the practicality experts…

Of course, copper wire might have worked as a last resort, ultra emergency, that-or-I-will-cut-my-veins solution, however, working at an electronics engineering, with a somewhat decent warehouse, you DO have nichrome wire around.

Where?, did you say?

Wirewound ceramic resistors!

115f - Guitar hero

Just crush a big one (10+ wats) with a big vice, and you’ll get about a meter of whire. Magic! I used three(3) 47R. power resistors.
Also, don’t forget to use a low ohmic value, otherwise you’ll get too thin wire, and it will break easily.

115b - Guitar hero

Nylon spacers where used to have almost exactly 10mm heigt while hammering them down, so I didn’t have to take measurements while inserting them.

Also, should you use a similar lenght as mine, be warned, this used 240VDC at 1,2Amps. (288Wats!!) Interestingly, the width of the cut is somewhat controlable through wire temperature, so you can make life easier on the lateral connectors on the board sides, when sliding it and out of it.

115c - Guitar hero
Of course, I don’t have the remainder of the wire carrier hanging in there when working!, I just took the photo before cutting it out.

And the cutter? It worked like a charm! Even with a lot of slack of all that wire lenght, the cuts where decent enough as to not need to put some springs in there to mantain tension.

115d - Guitar hero

And the leds are protected all the way to the customer.

So neat!.

115e - Guitar hero


Capacitor Resurrection, the 8th Farad.


113b - tweezers

Totally looks like this:

113a - tweezers

So, there was this problem with some capacitors (about 8.000 of them) that got damaged  (on a 50% chance) on depanelizing and we had to rush an emergency removal procedure across half the country. So important was this that I almost didn’t got to make a spare clothes bag! (and still, having to wear the same T-shirt for four days was not my best idea for making new friends out there, luckily, we haven’t got to summer yet.)

At first, we had to improvise for removal, since the boards where already mounted in their final aluminium frames, a blob of solder and side motion where out of the question, both for space restriction and possibility of flux tarnish.

So, I dremelized some soldering iron tips to look like this:

113e - tweezers

You might already know what the problem is. For those who don’t, copper has this habit of dissolving in tin, at about 6.8% at 400 oC. If you couple that with the fact that each capacitor added a small amount of tin. You end dissolving each tip in about two to three hours. Not good.

So, while we where eating the tips like there was no tomorrow, our purchasing manager managed to convince an OKI commercial agent, to lend us a tweezer soldering iron so we could finish the job.


113d - tweezers

These are so awesome!

At the end of the fourth day, we had this all over that green table you see:

113f - tweezers

It’s only a fraction of all the removed (either dessoldered or broken) capacitors.

I also had to devise another tool for a second process, but I’ll leave that for another post.