Hardware is HARD

If your friend can enable monotonic infill, it would avoid those diagonal stripes where it navigates around the LED holes ...

I will shortly be getting my own printer. I would appreciate any tips like these you can give me!

If they were ribbon cable connectors then I can understand that - you really want the proper tool for pushing those together when they're that wide.

I've got a bag full of old PC IDE cables, so it's easy just to attack one of those instead because they're also 40 pin.

Pin 6 might just be connected by a tiny little track on the Pi Zero's PCB because it's only supposed to be a signal ground. I go to the trouble of grounding all the ground pins on the GPIO. But just for driving relays I guess you can cut some corners, just not too many apparantly.

IF possible, stick to super-popular "legacy" transistors. 2n2222 are very versatile, 3809s are ok if you don't need to handle much power.

There are some 'logic level' MOSFET-family out there that are very good for higher power levels. Again, stick to the classics if possible.

'Connections' ALWAYS seem to be an unnecessary bitch.

Heh, heh ... yep, 'earths' are NOT all created equal. Look into RS-4xx data connections for fun ... some 'earths' can cause HUGE DEADLY current flow :-)u

Clue, two "ground" connections even 500-1000 feet apart are NOT gonna be at the same potential. Oft wondered if you can get actual usable power from that ...... can 0.25 volts dif, at a potential 100-1000 amps, be converted to higher voltage/ lower amps these days ?

The 7th pin, on the top edge, is a fairly reliable ground. Be cautious otherwise unless it's something stupid like powering a fan.

I'm slowly putting together a home-security system with all the goodies - including opto-isolated inputs. It is gonna run on a Pi4 or now maybe on a Pi5, sporting a usable web interface. Switches, detectors, video ... all in one.

Don't think I'd trust a bunch of DuPont wires long term ... at least hot snot them in place.

Good project.

I have all the wiring here for a home security system but I never installed one because I retired at that point and the house was never empty

Used 100% to connect model plane servos. They are pretty good. That units going to be screwed onto a wall and never moved again.

I might add a zip tie or two.

I wouldn't trust it in a car though - there I would follow your advice

I've found it not too difficult to do ribbon insulation displacement cables if you have a vice, but the caveats I can think of are:

Use a VERY sharp pair of scissors to cut the cable. If it isn't cut cleanly, there may be little bits of copper core hanging out, just waiting to short to a neighbour. (Been there.)

Connectors need to be crunched on at very close to 90 degrees to the cable. It's surprising how little margin for error there is, or else there may be shorts between adjacent cores.

The vice's jaws need to cover the whole connector and to close parallel. If the jaw surfaces are serrated, some dense cardboard may help, but you will need them held in place simply to avoid having to keep so many bits all in the right place as you tighten the vice.

David

Curiosity: would it help to use one of the spray-on contact cements or one of the cyanoacrylates (e.g. Zap) to hold things in place while they're in the vice?

I have a few :) You may know some of this.

This one is really important - when you open a reel of filament you will find that the end is clipped in place or fed through holes in the sides. Once you release it DO NOT LET GO of it, not even for an instant, until it is securely fixed in the printer's feed mechanism. If the filament ever springs back onto the roll it WILL tangle (Sod's law applies) and then it will jam during a print ruining the print - usually after hours of printing.

All printing filaments are hygroscopic and need to be protected from humidity. Vacuum bags are essential and a drying box is useful.

When choosing a printer to buy make sure that you understand how the bed levelling process works and that you are satisfied that it is effective and reliable - bed levelling is the single most important thing to get right before printing.

FWIW I currently have a FlashForge Creator Pro and am reasonably happy with it (it certainly isn't perfect and there are many equally good and better options - oh and worse too) - next time I feel like spending money on a printer it will be one of these (no connection I just like the design and reviews):

Look on Tom's Hardware.

It's fun - AND very useful. I've been making progress, but I'll have more time when fully retired. Recently picked up a multi-relay board meant for a Beaglebone Black - but adaptable. Perfect for alarm sounders and even turning on room lights. Sometimes you need AMPERAGE.

Retiring, I need to know what's going bump in the night AND be able to see/know what's going on when I'm not home. Do NOT trust commercial providers one bit. So ...

Look into the popular commercial alarm systems. I think the Honeywell/Ademco ones are the most popular. They're incredibly versatile, but they employ HORRIBLE programming approaches oriented around terminals with like 25x2 or 25x4 LED displays. It's clunkier than a FORTH pgm, and I speak from experience. A proper, if simple, web interface is THE way to go. Been there, done those, so ....

Let my tombstone read "I did it MY way" :-)

Ok, what's it cost these days to be deep-frozen, $300k ??? Kinda like the lottery, if you DON'T play you CAN'T win ..........

Yea, but SOMETIMES you have to go away, even if to a stupid dental appt. It'd be nice to have a system where you COULD be informed of odd goings-on. Easy these days to send a text over the web.

Alas, actual "human-form detection" worth a crap is still kinda the realm of boards much more powerful than any Pi. Yea, yea, some packages, even cams, CLAIM to offer something like that, but read the fine print. 95+ percent of your 'positives' are gonna be FALSE. A bush in the wind WILL kinda emulate a human-form pattern a dozen times a day. Seen it.

The only thing worse than a false negative are lots of false positives. Hey, WAY back in the day, I remember when the public schools decided to have the cops bring sniffer dogs to find lockers that smelled like reefer. So, the potheads made a point to put a little reefer dust and/or roaches in the lockers of the Honor Roll students. The program was terminated immediately :-)

Solder IS the best.

But, remember "wire wrap" ? Still have the tools for doing that. The more-extensive wrapping CAN be as reliable as soldered connections.

No, actually it often isn't...

The problem with solder on *stranded* wire is that it wicks up the wire and reduces it's flexibility by binding the strands together: That creates a stress concentration where it stops and a likely cause of fracture failure under vibration. That is why crimps are the choice for cheaper connections in high stress environments (e.g. automotive) or if you must solder you absolutely need to mechanically support the wire upstream of the solder joint.

I was trained, as an apprentice, on military spec hardware construction: Wire wrap was one system that was used extensively in early digital hardware backplane prototyping.

Once the design was stabilised they tended to replace all that with a 2 layer PCB.

Yes. especially in high vibration environments where components are not mechanically connected except by their leads or pins.

A good wire wrap connection (done with a power tool - we always used Gardner-Denver) is gas tight and extremely reliable as well as being faster and easier to modify than soldering.

I was told, back in the day, that it's more reliable. Many mainframes had wire-wrapped backplanes. I recall seeing engineers come in during maintenance time to replace wires due to upgrades or bug fixes; their being wire-wrapped made it rather easier.

If you can find a copy, Tracey Kidder's book "The Soul of a New Machine" is a nice read. He is a professional writer who was embedded in the team who designed and built the prototype Data General 'Eagle's. This was one of the first 32 bit minicomputer systems. Both prototypes were constructed as wire-wrapped frames.

Dunno. I was thinking more of double sided tape.

David

I use octoprint (octoprint.org) on a Pi 2 I had lying about.

To design items I use tinkercad.com. If you already know about CAD use whatever you're familiar with. I was 77 when I started and this was adequate.

Pass the designed object (.stl file) to prusa slicer:

Adhesion of the object to the print bed is THE major problem, too lttle adhesion and the print WILL at some stage float off the bed, too much adhesion and it will be impossible to remove from the surface. I use a magnetic layer, you remove it from the bed and bend it to remove the print.

The instructions will say use a sheet of paper to set the nozzle height. Use a 0.30mm feeler gauge.

If you intend to print gears or pulleys come back to me.

If you're prone to frustration take a tranquiliser before you start.

Good luck

Another Dave