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.
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- This shows the hexagon bar reduced to 15.5mm diameter to form the main barrel. You will notice that I am using a broad tipped indexable cutting tool which is ideal for the rapid removal of metal with reduced dangers of damaging a tool tip in the normal position. The next stage was to drill a 5mm hole through the full length followed by an 8.5mm hole to a depth of 18mm. This was then tapped M10.
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- Next it was the turn of the torch caps to be turned in the lathe to the same external diameter as the main body, i.e. 15.5mm. I use machine feed more and more these days which does give a better finish. The section to be threaded is turned down to 10mm with a chamfer to start the die.
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- A groove was cut with a parting knife blade to provide clearance for the thread against the shoulder of the cap. This groove also takes the ‘O’ ring which reduces the likelihood of body and cap becoming separated whilst in the pocket or purse.
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- The thread was cut with a 10mm die and after the first cut the die was reversed and run over the thread again. This is to counter the taper effect of the die – tricky to explain but trust me – do it, you will get a nice clean thread without any binding. Don’t forget to use a high pressure cutting lubricant to ease the task and protect your tools.
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- Six completed torch barrels which later will receive further machining in the lathe to fit the acrylic overcoats. Note that a 1mm deep recess has been turned at the top of the thread to accomodate the ‘O’ ring. Note also that the internal battery chamber has been drilled an extra 2mm over the original torch to provide more thread contact.
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- Next job was to use a small boring tool to machine the reflector at the business end of the torch. Once set up it was a quick job to machine all six torch bodies. After the final cut run the tool in and out several times for a smooth finish on the reflector surface.
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- It’s a good idea at this stage to drill the 2.5mm hole for the brass jump ring. The vice backstop aids easy positioning of the workpiece in the vice. I drilled to a depth of just 13mm to avoid drilling through into the supporting level.
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- The ‘pen makers’ acrylic blank is roughed to shape slightly oversize and centre bored to 12mm. I later invested in a special 12mm acrylic drill bit which gives a much cleaner cut. Drill slowly and remove swarf frequently to avoid overheating and melting of the acrylic.
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- The diameter of the main body is turned down to provide an interference fit with the internal diameter of of the acrylic sleeve. The sleeve is pressed on to the body and a touch of CA adhesive secures it in place.
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- The acrylic sleeves for the end cap are bored to 8mm and the brass centre turned down to fit accordingly. You will see from the finished torches that narrow collars (1.5mm) separates the acrylic sleeves on body and cap.
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- The main body is turned down to match the internal diameter of the acrylic sleeve which is slid into position and retained with CA adhesive.
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- I found this stage of proceedings was immensley satisfying and with a little practice a good professional finish can be obtained.
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- Having inserted the LED and batteries as per Ralphs original the cap (held in an ER32 collet on mini lathe) the thread is machined to the precise point as detailed in the original build notes.
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- All that remains is to clean up the machining on the end cap reducing the ring post down to around 5mm and fitting a small brass jump ring.
Hi Wong
This drawing is to the size that you are wanting. If you are making in brass (without acrylic casing) simply follow the outer dimensions – I hope that makes sense ! Hopefully this should connect you with the image. http://i256.photobucket.com/albums/hh200/cormorant2/CCF21052010_00000.jpg
Let me know if you have any problems and remember I woulod be very pleased to receive pics of your finished torches. Good luck !
John
Hi Wong
Good to hear from you. I will get back to you soon with dimensions etc. Your 17mm brass rod will be fine but I just need to check the various dimensions. Be in touch soon.
John
Love it!
Well and truly out blinged :)
Top job John.
I’m going to have to copy your build notes now ;)
Ralph.