Modifying Flex Shaft Hand piece Mandrel

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A simple way to turn a rubber wheel mandrel into a drill bit extender or an adapter for different drill and bur shaft sizes such as dental drill bits to be used in your flex shaft motor handpiece.

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Every now and then you have to drill a long hole through something with your hanging motor.
This is a real drag if the piece cannot be clamped into a drill press or a vice.

Like a long delicate bone carving that has to have a 2 mm hole through.
One of those, that if it was broken it would be irreparable and also had a lot of sentimental value attached to it.

So here we will show you how you can modify a standard rubber wheel mandrel.

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Select a 1.5 mm screw that screws in to hold the rubber wheel.

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Ream it out using larger ball burs.

Do this on the bench using your hanging motor.

First 1.6 mm then 1.8 mm then 2.1 mm for a 2 mm drill.

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Once it is reamed out file flat on the ends and punch it.

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Drill a 1.5 mm hole through both sides.

That is the correct size hole for a 2 mm tap.

Drill the hole right through so there is space for the tip of the tap to go deeper in.

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Then tap it.

Only one side needs to be tapped.

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You can use a brass or stainless steel screw.

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Then trim the screw off and cut a slot in it with your piercing saw.

Then use a cup bur to make it domed and smooth.

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Cut the mandrel shorter so the cone starts right up against the chuck.

Make a flat section on the drill bit so that the lock screw holds the drill there.

You can use a cut off disk for this.

That way the lock screw does not have to be tightened very tight

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Drill bit fitted and locked.

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You can make a mandrel to fit your diamond burs too.

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The mandrel cone is right up against the chuck so there is minimum wobble.

 

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