After making several shrink pots, I thought it would be educational to try and make an end-grain cup or tumbler using the spindle lathe and bowl lathe. I had a tip-up and tip-down gouge tool for bowl turning but also another gouge sometimes referred to as "the politician" that was designed for cutting into awkward spaces such as the inside of a cup. I am grateful to Yoav Elkayam for his detailed video about cup turning and taking the time to pass on his wisdom and experiences. I also gather that Jarrod Dahl from USA was instrumental in disseminating aspect of the craft of making different cups with a pole lathe on a visit to the UK.
I started the project with a log from a young local ash sapling from recent storm damage. This was shaped to a cylinder using an axe followed by a large draw-knife. A mandrel was mounted onto the cylinder for shaping the outside, bottom and top surface using a pole lathe. This was straight forward and gave nice patterned surfaces as shown below:
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| Outside surface of the ash tumbler about 9 cm diameter and 11 cm tall. |
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| Bottom of mug after shaping with tip-up and -down tools to produce a concave surface. |
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| Turning the inside of the mug using the "politician" |
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| Double edged "politician" a bent gouge made by Ben Orford. This is a bent gouge with dual sharpened edges and also cutting blades after the hook. |
The inside excavation was difficult and I found it more challenging than bowl turning because it is nearly impossible to get clean cuts and nice shavings because the gouge is cutting across the end-grain. Hence generally it is a noisy business and challenging to get the gouge in the right position when deeper in the tumbler. The choice of gouge at each stage depends on the individual and best to go with what ever works for you. However, I used the tip-up tool for the start of the excavation and the tip-down to shape the core as I penetrated into the cup. The wall was left quite wide to start with, about 8 mm, to help protect the side from the gouges. I found it difficult to use the tip-up tool when deeper in the cup and so used the "politician! to get deeper and later to thin the wall to about 5 mm. I kept the base fairly thick at about 10 mm to stabilise the empty tumbler but also this is my first attempt and I was nervous about breaking the base when removing the core. The final reduction of the core near the base was mainly done with the "politician" but made a terrible noise producing mainly sawdust with the occasional shaving. It was at this stage I managed to slightly crack the core where the mandrel was inserted because I had turned the wall thickness too thin. I repaired this by gluing in the mandrel into the core and leaving it to set overnight. This worked fine and saved the day. However, it is a good lesson in that the core needs to be as small a diameter as possible to allow space for the gouge, but remain strong. In general woods are much stronger along the grain than across, so that the core can be narrower with end-grain turning than with bowl turning. So in the later, the core is generally greater than 1 inch and can be snapped at this size but with end-grain, the diameter needs to be less than 1/2 inch. Hence great care is needed in removing the core with end-grain turning.
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| Inside of tumbler after chiselling the bottom of the core ready to twist it from the bottom. |
Once the base of the core was about 1.5 cm diameter, the tumbler was removed from the pole lathe and the core was chiselled as shown in the above photograph. It then easily twisted away from the base.
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| Core after twisting off the base. |
The inside bottom of the cup was gouged level using a hook-knife and gouge. The outside of the base was carved with a straight chisel and mallet. It is difficult chiselling/gouging across the end-grain so the less you can leave of this, the better.
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| View of the outside of the tumbler after chiselling the bottom leaving a concave surface. |
I finished of the inside of the cup with a shallow hook knife (the same one I use for finishing the inside of shrink pots). I was not able to get a smooth surface with the bowl carving gouges so this proved a easy solution.
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| Finished cup after one treatment with walnut oil, |
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| Inside of the cup showing the grain pattern. |
The cup was treated three times with walnut oil and left to dry over a week. I then tried testing it by filling with cold water and leaving it at room temperature. After about 10 minutes there was some weeping on the bottom, a few drops of water appeared. I then tried with a cup of hot tea and this also showed some weeping on the base. There was no sign of weeping on the sides of the cup. I guess this is to be expected as the end-grain is effectively small vertical capillaries. I then tried soaking the base (to a depth of about 1 cm) both inside and out (standing it in a bowl) for 24 hours using pure tung oil (food safe). After soaking, I drained off the tung oil and left the cup to dry at room temperature for a further 24 hours after which I removed excess oil with a rag and then left the cup to dry at room temperature for a week. On testing again, I found a few drops forming on the base but not sufficient to cause problems in use. I intent to polish the outside with beeswax and leave it at that to see how it performs in the longer term.
