">
">
">
">
Why build a 12foot 8inch wooden pen? Well, because an American claimed to have the world's biggest pen which had an overall length of six foot. Really though, our six member group,"The Proserpine Woodturners" needed a project for our upcoming annual workshop "The Proserpine Turnout 2005". We had previously made an 8foot 6inch diameter bowl as a centerpiece for this annual workshop. We figured that the pen would provide a challenge as it was to be a working, writing model based on the 7mm slimline kit pen. |
">
">
">
">
Firstly we had to build a lathe with a long enough bed and centre height to turn the two six foot blanks on. The lathe needed to have enough power and be capable of turning the heavy blanks reasonably slowly, especially during the boring operation. The headstock was made using the front differential unit from a Nissan Navara four wheel drive. This assembly, with the axles removed, provided a nice compact, self-contained unit. The face plate was attached to the pinion shaft. The clutch assembly, which was made up using a disc brake assembly salvaged from a motorcycle, was mounted to one axle side. The othe axle side was driven through a four speed Matchless motorcycle gearbox by an 11hp Yamaha stationery engine thereby giving us a range of turning speeds. Although a little noisy, this setup gave us the power and necessary speeds needed, but most importantly a very smooth clutch take-up. A tailstock was fabricate from a trailer stub axle assembly, as was a sturdy fully adjustable steady unit. |
">
">
">
">
">
">
">
">
We had a practice run using a hoop pine trunk, but the final pen was made using a Red Cedar log, which proved to be a good choice as it had nice colour and being a tree that had died due to the prolonged drought, was very stable with very little shrinkage. We set up each six foot blank between centres and turned them round with a running surface at either end for the steady's wheels . The steady was then placed in position and we removed the tailstock shaft. A set of nylon bushes were then inserted into the tailstock housing to run our 1¾" boring bar through. The cutting head consisted of a 4inch sawtooth bit, behind which we mounted two adjustable cutters, giving us a total hole diameter of approximately 10inches. A two foot long handle was needed to keep it under control while it was being fed into the timber. This proved to be the most physical part of the project and we all took turns during this operation. After boring in three foot we then reversed the blank and did the same from that end, breaking through into the previous hole to form our hollow blank. We turned a spigot which would accept the metal fittings, that is nib, centre band and cap, on the end of each blank. |
">
">
">
">
">
">
">
">
When finished the blanks were thoroughly soaked in Penetrol, both inside and out, as they were to be left for some months to settle down. During this time we put several coats of Penetrol on each section and were amazed at the result. When remounted the sections the had less than " runout!! and not a single crack was to be found even though we were experiencing summer heat. |
We would have liked to have had the nib, centre band and cap made up of brass, but due to the high price we had to settle for aluminum, which was only of the cost for these components. After consultation with the foundry, we set about turning the mould patterns. As they were to be quite large we decided to build up the shapes using rings of MDF glued together. By drawing up a plan we were able to calculate the correct angle at which to part off each ring. A jig fixed to the tool post allowed the parting off tool to cut this angle accurately. This process allowed us to get the shape very close to what was required, thus minimizing the amount of turning to be done on both the inside and outside of each pattern. The nib pattern caused the most problems as we had to construct a special jig allowing us to glue up the tapered rings accurately. When finished each pattern was given a thick coat of paint to allow them to be easily slipped out of the mould sand. |
">
">
">
">
">
">
">
">
The pen fittings were cast at the Delta Iron Works in Ayr, a foundry that has been in operation for 100 years. After collection, the aluminum castings were mounted in a metal turning lathe and the inside surfaces were machined to fit the spigots on the blanks. The outside of each piece was then turned to the required profile and polished. An aluminum clip was fabricated and fixed to the top cap, while a timber marking roller ball point and it's reservoir were fitted into the point of the nib assembly. This meant that we should we find someone big enough, he will be able to write with it. Before assembly, the two wooden blanks were run between centres and the outsides turned to shape. The Red Cedar was sanded down to 320 grit and once again we used two coats of Penetrol to finish. |
">
">
">
">
All the parts were then assembled and pulled up tight with a through bolt that ran from nib to cap, making the pen a very strong assembly. |
">
">
">
">
The result was a very spectacular wooden pen that attracted quite a lot of media attention, but best of all gave out small group a lot of fun and good experiences. The 12foot 8inch "Big Pen" now resides in the Proserpine Museum with our 8foot 6inch "Big Bowl". |
">
">
">
">
