howsitwork
Member
I've always been intrigued by these and having seen a method to make one decided to try it.
I wanted a true ( ish) toroid form which caused me issue when reversing it to turn the other side round as the line grip in the centre allowed it to move slightly as I cut so it would then wobble and need resetting. This became irritating so , after deliberation, a shallower taper mandrel was made and hot glue deployed to hold it stationary, I used the hard setting hot glue commonly deployed in upholstery or carpet fixing , it smells but works a treat.
Spalted beech with a 12 mm test tube 120 mm long. I drilled with mandrel in place to avoid centre splintering as the drill came through.
I've now modified the production method by using paper joint split turning technique . This allows faster turning and easier sanding of the pieces.
These two have mdf laminated on one side . You curve one side externally then drill through the centre from that side . Once the hole is drilled then mark-up to leave a 10 mm parallel section in the centre . I then made a stepped mandrel with a tight fit on the 40 mm hole and long enough to reach the far side of the 10 mm parallel hole . You can then see where your curve must end internally . This makes it far easier to turn to.
You can then tap it off the mandrel , reverse it , checking again the mandrel just reaches then end of the 10 mm parallel section, and turn it. I found it helped to turn the mandrel face abutting the toroid until it reached the line.
You then use a wide chisel and hold it firmly on the bench or in a soft jaw vice . Invoke which ever norse god you choose and tap it firmly and the paper joint splits as per photo , although please note the work face HAS been scraped and sanded to 180 grit before sealing it. Before I thought to take this photo.
They have been drilled though but got no photo of that. I can do if anyones interested?
i will then use a small drum sander through the centre and some abranet to round over the 10 mm parallel area once I tap out the mandrel.
I wanted a true ( ish) toroid form which caused me issue when reversing it to turn the other side round as the line grip in the centre allowed it to move slightly as I cut so it would then wobble and need resetting. This became irritating so , after deliberation, a shallower taper mandrel was made and hot glue deployed to hold it stationary, I used the hard setting hot glue commonly deployed in upholstery or carpet fixing , it smells but works a treat.
Spalted beech with a 12 mm test tube 120 mm long. I drilled with mandrel in place to avoid centre splintering as the drill came through.
I've now modified the production method by using paper joint split turning technique . This allows faster turning and easier sanding of the pieces.
These two have mdf laminated on one side . You curve one side externally then drill through the centre from that side . Once the hole is drilled then mark-up to leave a 10 mm parallel section in the centre . I then made a stepped mandrel with a tight fit on the 40 mm hole and long enough to reach the far side of the 10 mm parallel hole . You can then see where your curve must end internally . This makes it far easier to turn to.You can then tap it off the mandrel , reverse it , checking again the mandrel just reaches then end of the 10 mm parallel section, and turn it. I found it helped to turn the mandrel face abutting the toroid until it reached the line.
You then use a wide chisel and hold it firmly on the bench or in a soft jaw vice . Invoke which ever norse god you choose and tap it firmly and the paper joint splits as per photo , although please note the work face HAS been scraped and sanded to 180 grit before sealing it. Before I thought to take this photo.They have been drilled though but got no photo of that. I can do if anyones interested?
i will then use a small drum sander through the centre and some abranet to round over the 10 mm parallel area once I tap out the mandrel.
