A few tips to build the D-Box (or another printer).
Wiring of the effector.
The wiring is direct to the board, without routing outside the chamber.
This means that 1m cables are just the good length to the board, with sufficient margin for no stress on the plugs.
This simple route makes me decide that there was no need to install a local plug. No plug will simplify work and improve the reliability. If anything to change, it is quite easy to redo 4 to 5 zip ties or simply add news to the existing loom.
However, thermistor are not that reliable and with the effector dismounting system, they are submitted to more stress than usual (indeed, I broke one thermistor wire while working on the effector). So it is a good idea to install in place another thermistor, which will be folded along the loom, ready to be installed in case of failure of the first one. You can get 5 thermistors wired with 1m cable for less than 3 euros, shipping included, so why bother ?
For the equipment supplied with too short wires (fans), I simply solder them. You shall have the soldered segment properly protected with thermoretractable sleeve and attached on the effector, to have no mechanical stress on it (see photos).
Using Dupont terminals.
Dupont terminals are low cost and as the power carried in a printer is low, they could be used for anything except heating. The problem is they are quite difficult to crimp with ordinary pliers. So you need a ratchet type crimp tool and learn to use it. It is NOT recommended to solder, as this create a hard point which under stress, WILL broke one day.
Molex connectors are better, but more costly. The same Chinese ratchet crimp tool (SN28B) is sold everywhere at very different prices, so search a bit. I get it on eBay for 12.69 euros, shipping included.
Note that to remove a Dupont pin or plug, you need to lift the small plastic tongue locking it with a micro screwdriver.
Using crimped terminals for anything with power and for the mains.
It is normal practice to never directly connect a flexible wire to a terminal block. You shall crimp either insulated or uninsulated terminals (use thermoretractable sleeve for the uninsulated), and for use with terminal blocks, ferrules/sleeves.
Unfortunately, insulated (automotive type), uninsulated and ferrules need different crimping tool, which are also different from the Dupont crimping tool. Using low cost crimping tool needs a lot of strength and athletic capacities for a bad result. So again, a ratchet crimp tool may help for insulated automotive type. Ferrules are easier to crimp with non amplified crimp tool.
For the mains, I have also used rigid wires, which don’t need terminals. It is NOT normal practice for machinery, but I considered that the usage was ok with the limited vibrations of my printer. You may decide according local regulations for machinery.
My ferrule crimp plier is a high quality Knipex 97 72 180, got for 29 Euros (on Amazon).
I get on Ebay the insulated terminal ratchet crimping tool Silverline PL55 for 14.16 euros, shipping included. Silverline is poor quality brand, but this tool is ok for limited use, better than the basic tool sold with terminals asortments. This tool may need adjustment (see the teethed wheel on the side).
Help for “big fingers”
A printer is full of small size nuts and bolts, located in difficult to access places, so a reminder of what could help:
Magnetic screwdrivers. They may help nut or screw placement
Adhesive tape. not easy to remove but always useful, tape screw or nut on screwdriver/key
Thick grease. Not clean, the mechanics method could be used to maintain washers. Beware with plastic !
A very small drop of cyanoacrylate glue (shall not go on threads) may help maintain a washer. Be sparse.
Screw a nut only one turn on a supporting screw to help positioning.
Magnets to recover fallen parts
Tweezers
A magnifying lens on an arm with diode lighting around the lens.
A headlamp. I use it a lot. Buy quality, this is an important universal tool (I have a Petzl).
Go take a coffee/a break if something goes wrong repeatedly.
Use thermoretractable sleeves
They not only isolate, but mechanically reinforce soldered wires or links to plugs.
Could be heated with a lighter or preferably a heat gun.
Tensioning wires
Clean the holes (2mm diameter)
Use 1mm wires (Dyneema or Spectra)
use a rigid electrical wire (small gauge) to pull the PE wires through the holes
Makes knots to lock your tensioning wires.
You shall makes 2 simple knots, as close as possible, then a third simple knot in the space between the two first ones. with that, your wires will stay within the 2mm holes.
To attach the spring, hooks may be done with 0.8mm piano wires, folded with pliers.
The mains kills
I used the mains (230V) for bed heater and chamber heater, because I see no point using a power supply for simple heating. This is simple and easy but caution applies.
The weakness of this solution is the thermistor, which don’t have double insulation from the heater pad, but simple one.
If feeling unsafe, you may prefer using a separated temperature controller for this reason (this is not what I have done).
The mains kills. It is repeated frequently, but often readers don’t take care, thinking of it as a legal protection of web author. Sorry, but professional electricians dies from electrocution with medium voltage (this occurred in a company I was working for), so even if well experienced, don’t be arrogant and take care of yourself.
Mains heating requires a physical emergency shutdown button killing all power. I prefer have it at my forehead height (mind why ?).
