Ryedale Woodturners


Simon Hope

SIMON HOPE

Thursday 2 June 2016

Snainton Woodturning Supplies

Simon Hope made the long trip from Essex to give a demonstration involving thread chasing. He chose to make an acorn tape measure holder, inspired by our very own Albert Kitching's bells.

Threaded acorn

Simon Hope

The demonstration was about making a two piece acorn box, joined together with a screw thread, which holds a tape measure. Simon told us how he got his inspiration from "an old Yorkshire bloke who showed me a screw-threaded bell tape measure holder when I was demonstrating at the Harrogate Show a few years ago".

Bell shaped tape measure holder

The old bloke was club member Albert Kitching, who was sat on the front row watching the demonstration tonight.

Simon kept the bell that Albert gave him, and liked the idea enough to develop his own version of the tape measure holder, using an acorn shape.

For the demonstration he used a piece of sycamore for the acorn, and bubinga for the cup. He started with the acorn nut, turning it and hollowing it to a cylinder.

Chasing mechanism holding chuck

Simon's thread chasing jig is, like all his tools, a precision made piece of engineering
(with a £200+ price tag to match!). It sits in the toolrest, and accepts the chuck which still holds the piece to be threaded. the cutter fits in the headstock on an M2 taper, which is held more securely than just by friction by a taper lock bar pushed through the headstock and screwed in place.

Superglue for hardening

Sycamore is not the hardest of timbers, so is not ideal for taking a fine thread. Simon hardened it up using some thin superglue spread liberally where the thread was to be cut.

The thread cutter works best at very high speeds. A chamfer was made first to feed the cutter in, then after a couple of push cuts, the cutter fed itself along until the thread was done.

The spigot was sized to 1mm bigger than the female thread, which for a 16 tpi thread Simon had found to work well.

Thread cutting jig

The cutter has a click mechanism which allows the correct settings.

Once the threads were cut and checked for good fit, a little oil was applied for lubrication, and Simon then turned to making a small top "handle" out of blackwood, which was attached to a dowel that went through the centre of the acorn, and formed the mechanism for retracting the tape measure.

Acorn tape measure

A slot was cut in the acorn to feed the tape measure through, using a small circular saw in a Dremel. The tape was wound around the dowel, everything was put together and we had an acorn tape measure to look at.

After the break Simon showed how to cut threads by hand, without the aid of his jig, using the standard male and female serrated tools generally available for this job.

Hints and tips
  • A compression chuck is useful for finishing a small shape - a ring cut to size held in the jaws.
  • Always wear goggles or face mask to protect against flying shards when cutting blackwood
  • 0000 wire wool is the best way to finish blackwood - it is naturally very oily so doesn't need wax or oil adding.
  • Keep the speed the same when cutting male and female threads.