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Modifying screwdrivers and turnscrews



Several years ago I won a set of modern turnscrews … really they were screwdrivers given a classic turnscrew-like look, and called “cabinet screwdrivers”. Well … they looked nice and were easy to grasp.

These ones were marked “Sheffield England” and probably dated back to the 60s or 70s.

More recently I have seen Chinese replicas of these on sale. I cannot comment on the quality of the steel, but if you have similar, then you may wish to make the modification I have made to mine.

The main problem with these (and most modern) screwdrivers are that the blades are not parallel. Instead they taper …

As a result, they wedge into the screw slot, and eventually they will cam out (slip out) the slot when pressure is exerted. This also damages the edges of the slot.

The solution is quite simple, and only takes a few minutes to remedy - Hollow grind the blade until the end is parallel. Use a bench grinder. I did this without any special set up, simply freehanding the blade on the tool rest. Do not alter the thickness of the end of the blade. Only remove the taper. Finally, clean/square up the end on a disk sander.

Here is the result …



And a family portrait ..



While I was at it I also completed a hollow grind on a driver I made from an old turnscrew. This one is dedicated to Stanley plane cap iron and lever cap adjustment.



How do they work now?

Better.



Regards from Perth

Derek

November 2009