Start Model Engineering

Polish up your turning skills with this novel brass torch

Create your own shape and choose the colour for your LED and make one or two for your friends

There are two famous people in Wales and they both play billiards. The first is a chap called Terry something-or-other and he is renowned for his ability to send even the most ardent insomniac into a deep and blissful sleep on a Sunday afternoon.

The other chap is called Ralph. He’s also known as ‘Divided Head’ - I am not too sure why but I suspect it may have something to do with an incident involving an up and over garage door.

Recently Ralph caused outrage amongst certain old school model engineers when he revealed his lathe mounted mop polisher.

Any road up Ralph has unselfishly agreed to disclose his method of making little brass torches. I am ignoring the fact that my local petrol station is currently offering an impressive looking multi bulb LED torch for a mere £2.50. Ralph’s torches are truly little gems and make lovely gifts for family and friends. Not only that but they are fun to make and provide an opportunity to hone your turning skills and demonstrate your creative talents.

So, without further ado lets get the boys on the baize.

Ralph has produced this excellent series of 4 videos with step by step build notes to guide you through the construction but before you sit back and enjoy here is a cut away sketch showing the various components.

A cut away sketch showing the components and assembly

Video 1

1/ Cut length of 1/2″ hex or 9/16″ round brass bar to be finished to 25mm length. Round bar at 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 ! 9/16″ 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 M12×1.5 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 M12×1.5 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 order … 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.
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.

Video 2

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.
Depth of plastic shown is in drawing. 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 small slices until you get it just touching when 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) alternatively you could use a meter or search for data on the web to identify the Cathode and Anode.

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)

13/ Bend the positive leg flat horizontally to the opposite side of the disc. Bend the leg up around the edge of the disc (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)

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…. 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..

17/ 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)

Continue reading A mini project for your mini-lathe

Stainless steel version of the LED torch. The hexagon barrel and jump ring in the tail make it easier to twist the torch on and off.

A good deal of interest was created following the report on Ralph’s brass torch project and as I was looking for a relatively easy project to get me back into the workshop after the long drawn out winter I decided to give it a go.

After a trial run making the first torch I then set about making a batch of six - three in brass and three in stainless steel. Even free cutting stainless steel is more difficult to machine than brass so I shall be sticking to brass in future.

I can add very little to Ralph’s (AKA ‘Divided Head’) excellent build notes except to say this is a fun project - oh and if you do run into difficulties do read through to the end of  Ralph’s notes where there are helpful solutions to most problems that you may encounter. You’ll find plenty of inexpensive LEDs and CR927 button cell batteries on ebay.

I would like to have shown more photographs but each torch seemed to disappear amongst family and friends as soon as it was completed.

I’ve been pondering for a while on the possibility of making ‘Divided-Heads’ mini torches in Acrylic but was not too sure if I could cut threads in the acrylic material. In addition, on the originals, the brass body is relied upon as a conductor and forms part of the electrical circuitry.

In practice I avoided both potential problems by retaining brass for the internal workings and simply added an acrylic coat to the torch.

A visit to a local woodworker supplier revealed a range of Acrylic offcuts which are mainly intended for pen making enthusiasts who turn the barrels for their pens on woodworking type lathes.

Any concern about machining my torch barrels on a metal working lathe were unfounded in fact the Acrylic turned beautifully although care was needed when drilling as it is very easy to melt the plastic.

I am now preparing dimensioned sketches prior to making a batch of Acrylic torches for family and friends.

A display of finished acrylic torches plus a couple of ealier brass versions.

My original feature courtesy of ‘Divided Head’ (aka Ralph), on mini brass torches has attracted nearly as much interest as the building of steam engines and it’s easy to see why.

They are a fun way to gain experience on the lathe, turning, facing and cutting threads using taps and dies. Then over to the polisher for the application of the obligatory dose of bling They also lend themselves to personal interpretation so you can release your creative talents and really go for it. The little mini-torches are also popular with the laydees and make welcome little gifts for family and friends.

This post is all about a new slant on the mini torch. Whilst retaining the tried and tested basic design this opens up a new field of design by producing an outer shell in acrylic. Acrylic blanks used for amateur pen making are readily available and they come in a wide range of colours and patterns. Acrylic is easy to machine on the lathe - fast speeds and slow feed is the order of the day when turning and facing. For drilling, slow speeds and slow feed will help to avoid meltdown through excessive heat.

Encouraged by my first prototype I decided to go for a short production run of six torches in the hope that the economies in setting up time would show time saving per unit. Whilst working to set dimensions I wanted to change the outer appearance of the torches by using a variety of acrylic finishes.