I decided to gift a 3d printed 10th Doctor sonic screwdriver to a friend of mine who likes the series a lot, and i wanted to make it a little special, so i edited Wpilgrim's (credits to him for the original design) version. I wanted it to light up when extended, and i also wanted it to turn on the light by itself, with no ugly buttons to push. I'm quite satisfied with the result. If you buy a bright led you can use this as a torch too!
Here's what I did:
I added a microswitch in the inner sliding part and carved along a line inside the body (the outer part), where the switch button sticks out, so that it is normally unclicked. The upper part of the notch gets thinner and thinner, to push down the switch button when the slider is fully extended, turning on the blue led inserted in the lens.
I chose a small (100 mAh) lipo cell which fits perfectly to get the most out of the small free space inside the body. If you want to use coin batteries you'll have to edit the circuit and / or stl files by yourself.
The circuit is very simple: Battery cathode -> swtich Normally Open pin, switch common pin -> 30 ohm resistor -> led cathode, led anode -> battery anode
I chose a 30 ohm resistor because, due some voltage/current tests with
this led, it makes it shiny enough without drawing too much current (the actual I/V value changes as the lipo cell voltage drops from 4.2 to about 3.5 volts (and so the voltage on the current limiting resistor drops too), so you can see 30 ohms as a compromise, not too much current when the battery is charged, not too low when it is nearly discharged
The bottom part is attached to the body thorugh a joint, so that you can open the screwdriver from there and recharge / replace the battery when it runs out
I also edited the slider, to better match the original tv show's screwdriver, and the lens, which now is thinner and has a hole for the led. I've tried without the hole but the led light was barely visible.
- Filament (black and white)
- 3mm blue led (the brighter the better!)
- Single cell 100mAh Lipo battery (I've chosen this one because it fits perfectly inside the body, you can use smaller ones too, you can find them on ebay)
- 30 ohm resistor
- Standard 12.8mm x 5.8mm microswitch
- Spare wire
- Soldering equipment
- Enamel paint (I used Humbrol modellism enamel)
Step 1: Printing
Here are the parts on thingiverse:
Print the body and the "inner outer" with white filament and the bottom2 with the black one. The other pieces will need painting so it does not matter which colour you choose. If you have some transparent filament and want a more realistic screwdriver use that to print the "inner outer".
As far as printing parameters are concerned I suggest a resolution between 0.1 and 0.2 mm and about 35% infill (some walls are quite thin). Print every piece vertically, not laid on the side.
Step 2: Painting
I've used Humbrol enamel paint (I don't suggest using acrylic), silver (# 11, for the "top", "inner inner", btm1 and some parts of the body) and midnight blue (# 14, used only to paint the lens). Use some tape to prevent painting unwanted areas.
Reapply once or twice to make banding less visible.
Step 3: Soldering and Assembling
Solder a long piece of wire to the led anode and a 30 ohm resistor
(actually I've used 2x15ohm) to the other leg. solder some wire to the other side of the resistor. Push the wire through the "inner inner" hole until the led head is inside.
Insert the "inner inner" in the "top", and then in the "inner outer".
Pass the wire soldered to the resistor through the switch housing hole, cut it so that only about 1.5 cm stick out of the hole, and solder it to the switch common pin. Solder a piece of wire to the Normally open pin, then run the cable inside the housing and through the bottom hole. Now you should have 2 cables going outside the slider.
Remove the metallic lever of the switch, there's no space inside for it. Push the switch inside his housing, making sure the button faces towards the top (where the led is housed). When you push it in the extra 1.5 cm of wire should push the led outside the hole too, to its final position.
Now solder the battery anode to the wire coming from the led anode, and the one coming from the switch to the battery cathode. BE QUICK! It's not a good idea to heat up a lithium battery (just search Lipo fire on youtube)
Push the battery and then the sliding part inside the body, through the top hole. Be sure the switch is facing towards the carved side of the body.
Glue together the two bottom parts, push them in the bottom part of the body and rotate it. Don't glue the bottom to the body, when the battery runs out you can open the screwdrivier from here and charge it. Glue the top to the inner outer, insert and glue the button, glue the lens to the top making sure the led fits the little hole fine.
Step 4: Profit!
When the lithium cell runs out you'll need a lipo charger to recharge it, you can find some cheap ones on ebay.