Mobyturns
13th October 2014, 05:21 AM
I've been to the NZ Woodturning Symposium and while there came across this interesting item in "Creative Wood NZ" about a failure of a chuck back in March (June 2014 Wood Chat column on p13).
The author writes "I was turning a 80mm block of wood using the long jaws, which was originally designed to internally hold a bowl in expansion mode. I was turning the block down to size, all was well. I stopped to check progress then restarted. I brought up the tool to restart the cut then bang the tool flew out of my hands and skating down the workshop to the back wall. I thought the block had come out ........ Back to the lathe I realised the block was still in the chuck. That was a puzzle but it got worse , one of the jaws was missing and no trace of it, one screw was sitting the ways all alone & forlorn. ...... Checking the internal screws on the jaws I found all were loose. Now all the screws have been replaced......
I do realise I was very lucky to escape a serious injury."
(The missing jaw was latter found attached to the magnetic tool rack at the rear of the lathe.)
The type of chuck is not mentioned and it doesnt really matter however it would most likely be a Nova as Vicmarcs and others are scarce in NZ.
The article poses a couple of safety issues,
Was the jaw selection appropriate for the task?
How long had it been since the chuck was serviced or the jaw slide / jaw cap screw were checked for firmness?
It doesnt take very long to service a chuck; or to blow out the dust from the hex sockets in the cap screws and give them a quick nip up; or to change jaws if the jaws set is not suitable for the task. It also costs about $4 to replace the jaw slide cap screws.
Very simple regular maintenance may have prevented this dangerous occurance, so I hope it prompts a few of us to at least check the screws & jaws, or even better service a few chucks while having an ale.
The author writes "I was turning a 80mm block of wood using the long jaws, which was originally designed to internally hold a bowl in expansion mode. I was turning the block down to size, all was well. I stopped to check progress then restarted. I brought up the tool to restart the cut then bang the tool flew out of my hands and skating down the workshop to the back wall. I thought the block had come out ........ Back to the lathe I realised the block was still in the chuck. That was a puzzle but it got worse , one of the jaws was missing and no trace of it, one screw was sitting the ways all alone & forlorn. ...... Checking the internal screws on the jaws I found all were loose. Now all the screws have been replaced......
I do realise I was very lucky to escape a serious injury."
(The missing jaw was latter found attached to the magnetic tool rack at the rear of the lathe.)
The type of chuck is not mentioned and it doesnt really matter however it would most likely be a Nova as Vicmarcs and others are scarce in NZ.
The article poses a couple of safety issues,
Was the jaw selection appropriate for the task?
How long had it been since the chuck was serviced or the jaw slide / jaw cap screw were checked for firmness?
It doesnt take very long to service a chuck; or to blow out the dust from the hex sockets in the cap screws and give them a quick nip up; or to change jaws if the jaws set is not suitable for the task. It also costs about $4 to replace the jaw slide cap screws.
Very simple regular maintenance may have prevented this dangerous occurance, so I hope it prompts a few of us to at least check the screws & jaws, or even better service a few chucks while having an ale.