Intro: Mini Brass LED Torches (flashlights)
This is my first go at this so hopefully it passes inspection...?
I designed and made the first of these torches in late 2006 (shocked myself with that date!) and they have been posted for some time on various engineering forums and on youtube since Dec 2009. This means that all I'm about to do is put up all the build notes that accompany the 4 videos and then add some of the hundreds of still photo's I have in my library.
I know this is weak when it comes to instructable effort since it's already out in the world, but I'm hoping that the original 20+ hours in the video editing alone goes to exonerate me in some way?
I'm thinking that some may find these a fun little project.
The basic version of the torch is mostly made using a metal turning lathe, Some of the more complex versions involve a milling machine as well.
I do try to answer all serious questions and will supply any extra pictures or information if required.
Thanks, hope you like it? :-)
Step 1: The Main Body.
Text to accompany Video 1.
1/ Cut length of 13mm (1/2") hex or 14mm (9 1/6") round brass bar to be finished to 25mm(~1") length. Round bar at 13mm (1/2") will show thread cut on outside and can be hard to get rid of. That's if it doesn't tear through the side?! 14mm bar allows a quick lateral turning with the cap blank screwed tight so it mates perfectly.(before the cap is cut and shaped!) Hex shows thread slightly but a light draw filing or lapping sorts this.
2/ Face off both ends.
3/ Centre drill.
4/ Using 5mm drill, drill through bar.(assuming you have purchased 5mm blue, red, white or green LED?... else a 3mm or 8mm led could be used, depending on power requirements?)
5/ Using 10.5mm drill (prepared for brass if possible.) make a 16mm deep hole for the innards of the torch. Tap the body with a M12x1.5 thread (I always bottom the tap out.)
Cut a recess for the O ring (see video/Crap-O-cad) Just removing the thread should give sufficient space for the main O ring to sit. ( Run the tap back through to chase/clean up thread. remove thread burrs.)
6/ Remove the main body and place to one side. take another length of bar at least long enough to get a parting tool into once it has been cross drilled. .see video1. Turn down to 12mm dia and at least 9mm length.
7/ Cut M12x1.5 thread onto remaining turned section.
8/ Using parting tool cut recess into turned section at base. (approx 1-1.5mm deep depending on the 'O' ring you have selected for the seal)
(you could do parts 7 and 8 in reverse. It wouldn't alter the outcome)
9/ Test fit main body. If a hex bar is used and you want it to line up perfectly then a bit of fine skimming work on the main body length will probably be needed (unless you're lucky)
(The pattern is usually a little off when fully tight, a bit of draw filing or flatting of each of the sides once the torch is completed will true up the pattern enough to fool most eyes. See video4)
If your not too fussed Like in the video, then leave it!
The torch when off will be where you set it. lined up if you want it that way, and when it's on it'll be where ever it is. Up to you what you want it to finish like.
Step 2: The Innards.
10/ Cut a length of thin plastic (packaging like you get paint brushes/batteries etc in is good for this, thin but stiff when cut into a strip. Thickness of plastic must be assessed as slight thickness variations could prevent the batteries from being easily inserted and removed!
I pull the plastic hard over a thin round bar, causing it to curve and hold that shape. Trim the plastic to length and depth.
The depth of plastic shown is in the C-o-C.
It is the height of the two cells stacked. It has to prevent the outer body of the battery/cells from touching the inner of the torch body. Insert the plastic when ready, check for overlap or not enough coverage.
Trim it in small slices till you get it just touching once fitted.
11/ Check LED polarity, easy way, touch the leads onto the poles of one of the cells (if you're using the 3V ones specified)
Else you could use a meter or view the pictures I will add to this at the end.
12/ Cut a disc of plastic rod 1.5-2mm thick 10.3mm dia and drill a 1mm hole 2mm off centre for the LED negative leg. The negative leg is then passed through the hole and cut to allow 3-4mm to protrude. This is then folded across the centre of the disc. (see video/pic's)
13/ Bend the positive leg out horizontally to the opposite side of the disc.make a small V shaped nick in the disc with a scalpel. Bend the leg up around the edge of the disc and into the V (keeping it tight to the disc)
Cut the leg to length, level with the top of the disc (any higher and it might short circuit the cells. See video/pic's)
14/ Insert the completed LED assembly into the main body of the torch and push the led home. This may need a bit of a shove? Use something blunt and narrow enough to go inside the main body. Try not to damage the LED or it's legs!
15/ Insert the insulator strip.
16/ Insert 2x cr927 lithium cell battery's negative end first and keeping the torch pointing downwards screw the threaded section into the body till the LED illuminates.. (these are the cells I use. you can use different and change the thread size or even make a cell size adapter from a form of plastic?)
17/ Screw the unfinished cap into position. The LED will illuminate before the cap is all the way home. Check with a vernier or similar, the gap left between the cap and body sections.
(This is all done because there are always variables, from slightly less or greater depths when drilling to LED legs and exact insulator disc depths. This is a very adjustable design)
The adjustment is done in video 3.....
Step 3: The Tail Cap.
18/ Re-chuck the tail cap blank and remove all but 0.2mm of the length measured.
Turn down the threaded section to allow a 8mm dia and 1-2mm deep stub to be formed.
19/ At his point either, remove the work from the lathe or attempt the screw the body with batteries on sideways.... and fit it as per 16 and 17, remove just enough for the light to turn on as the cap and body edges meet.
Remove with VERY fine cuts (even a file or emery tape) the amount needed to get the light to turn on just as the cap and body edges meet.
20/ Dependant on your O ring size make the recess Using a parting tool or 1-1.5mm thick tool (specially made for another job?). Cut a recess into the face of the cap. (See video.)
Wide enough to take your O ring and deep enough to allow it to stand a hairs width over the centre stub.
21/ Once satisfied that the O ring is to the correct height. Glue it into position.
(I use superglue)
22/ Cross drill a hole through the bar, approx 8mm from the mating face of the tail cap (thread end) this is for the split ring. (I use 2.5mm see video/drawing)
23/ Part off the cap, (or hack saw) allowing for the correct length to be achieved when making the eye on the cap (I allow 4mm over the top of the cross drilled hole).
24/ Screw the tail cap on to the main body and using the body as an arbour to hold the cap in the lathe. Turn it down to a shape of your liking. (See video, freehand shaping is your own and original every time!)
(use a small bar in the split ring hole to undo it after this process, it will have tightened with the cutting forces)
Step 4: The Finishing Touches.
25/ Turn the torch around and turn your desired concave dish design (being careful not to hit the led!... you could remove all the inners if you wish) You could have the LED protruding? Just be careful not to remove so much material that the LED sticks out and could become scuffed easily, a little scratching effects the light output greatly!
I styled some of the simple ones with stepped cuts and rings. But I am sure your own design desires will lead you to a finish of your choice.
26/ At this point I draw file or flat the hex body. (see video)
I gave a nice turned finish on the round ones and polished some of them to remove imperfections. (Polishing is not a requirement, I just like it :-)
27/ Add a split ring, brass coated ones can be purchased very cheaply from a key cutters/hardware store. Takes some doing not to scratch the cap when fitting the split rings though!
(I use a round pointed bar to open the ring to 3 or 4mm and then to hold the ring open as I pass the ring through the cap. Then transfer it to the end as it comes around so that it doesn't scratch as it snaps shut.)
Once the ring is on it's pretty easy to turn on and off. Might require a smear of petroleum jelly on the O ring?
If the grip between the body and main O ring on the cap is weak when turned off ( Off - should be no more than one flat, or on the round torches less than a ¼ turn anti clockwise) and it needs to be tighter to prevent the parts from separating.
Then you can cheat with a very narrow strip of black insulation tape under the main O ring.
It must be exact length. An overlap will alter the depth considerably.
They MUST be slightly stiff to turn, as this stops you losing the body of the torch off the cap as it rattles around on your keys or in your pocket.
If you take too much off the tail cap and it doesn't reach the cells.(when screwed in to make the ON contact.)
You can re-make the LED disc/insulator a bit thicker.... This will raise the LED leg (be careful not to damage the legs removing and re-bending them) and raise the batteries... Be sure to check that the insulator sleeve depth, it should be fine. But check it all the same.
(you can make the discs in small increments till you get one that's right if need be)
Well, that's it... Wonder who if anyone will take up my little project?
More than happy to receive pictures of any that you make :-)
Step 5: The Parts List...
Brass bar - 13mm or ½" hexagonal for the torch shown in the video or 14mm or 9 1/6" round. Minimum length required 50mm (25mm body and then the cap from the off cut....I try to use as longer bar as possible to make the cap on though for safety and ease of machining)
LED - 5mm very high brightness type .... 32000mcd for white....(clear focused casing)
There are many, many types of LED, colours and intensities.
From past experience always go for clear narrow focus, 15 0r 30 degrees work well for most applications and as for the mcd rating The higher the brighter is the way it's supposed to go But it's a mine field if you go looking for the best for the buck!
You shouldn't pay more than a couple of quid for 50 or so posted from China/Hong Kong via e- blag.. I certainly wouldn't get 'em from the high street retailers here in the UK.... Rip off!
Batteries/cells CR927 lithium. I use 2. This gets a lot of "that's 6volts" and "what about your resistor" Oh and don't forget.... "the LEDs won't last" .... Well, I've still got the prototype on my house keys and it's on it's 3rd set of batteries... 6 years and still working. Seems like non of the above is an issue!
Rubber O ring - to fit collar of cap 10mm internal 1.2mm dia material (you can alter dimensions of cut to suit your O ring.
Rubber O ring - to fit contact point of cap 3-4mm internal 1.2mm dia material
(Again O rings can be found to fit your cuts and cuts made to fit your O rings )
Nylon or equivalent impact resistant plastic bar @10.3mm min' dia'.
Thin stiff plastic strip to be cut to size (depth of 2 cells and enough length to seal outer wall of torch from cells.)
½"Brass coloured split ring
Step 6: A Few Stills...
Just a few....
Step 7: And If You're Feeling a Little Fancy...
Step 8: Crap-o-Cads....
A few Crap-o-Cads to aid the builder :-)
I had to replace the written text as apparently it was shockingly hard to read!