Instruction/Data Sheet
Page 3
Place the eccentric boss into the main body and rotate it so that ‘0 is visible in the sight window. The wood will
run concentrically at this position and retighten the eccentric boss screws.
Carefully screw the wood onto the screw-chuck making sure it is tight against the body of the chuck and inline
with the lathe.
Turn the lathe on a safe speed appropriate to the capabilities of the lathe and using a roughing gouge, turn the
outside of the wood down to the round.
Switch the lathe off to check that the entire square has been removed and you have a round piece of wood.
Now mark 1 1/8” (28mm) from the end for final parting as mentioned earlier to give clearance for the screw
chuck.
Next put the toolrest in the ‘safe toolrest position’ and hollow out the cup shape of the goblet with a hollowing
tool to a depth of approx 1” (25mm).
Switch off lathe, check, switch on lathe, sand and finish.
Return the toolrest to the ‘safe toolrest position’ along the length of the wood and turn the outside of the cup,
following the internal profile using a 3/8” (10mm) fingernail spindle gouge.
Switch the lathe off, check for a clean cut, switch lathe back on, sand and finish.
Now using a 3/8” cove cutter or similar tool turn the first cove at at the base of the bowl. Mark the cutter/tool to
ensure all the coves will be the same depth.
Switch off the lathe, check for a clean cut, switch lathe back on, sand and finish.
Now undo the two eccentric boss screws in the side of the main body and rotate the boss so that ‘10’ is visible
in the viewing window.
Place the tool rest in the “safe toolrest position”
As the wood is now off centre we will reduce the speed of the lathe for safety. It can be increased with
confidence and experience.
Switch the lathe on and watch the wood spin to understand what the wood is doing now it is rotating off centre.
* Care must be taken when turning off centre work. Approach the wood very carefully and allow for the fact that
you will only touch the wood in one place on every rotation.*
Place the cove cutter level with the left hand side of the first cove and create the second cove adjacent to the
first to the depth mark on the tool.
Switch off the lathe, check the cove, then sand and finish by hand as before.
Now undo the screws and move the eccentric boss to position ‘20’ and re-tighten.
Move the tool rest to a new “safe toolrest position” and slow the lathe down, as the wood is now more off centre.
As with the previous cove, place the tool on the left hand side of cove No.2 and create cove No.3 to the same
depth as before.
Switch off the lathe, check the cove, then sand and finish by hand.
Now undo the screws and move the boss back to position ‘10’ and re-tighten.
Move the tool rest to a new “safe toolrest position” and switch on the lathe.
As before, place the tool on the left hand side of cove No.3 and create cove No.4 to the same depth as before.
Switch off the lathe, check the cove, then sand and finish by hand.
Now undo the screws and move the boss back to position ‘0’ and re-tightened move toolrest to “safe toolrest
position”
Place the tool on the left hand side of cove No.4 and create cove No.5 to the same depth as before and again
switch off the lathe, check the cove, then sand and finish by hand.
Now turn the lathe speed back up as the work piece is now running on centre. Turn the base from the outside
diameter to flow into the last cove using the spindle gouge.
Robert Sorby
Instruction/Data Sheet
ECCENTRIC CHUCK PROJECTS
