A simple way to turn a rubber wheel mandrel into an adapter for different drill and burr sizes.
Every now and then I have to drill a long hole through something with my hanging motor.
This is a real drag if the piece cannot be clamped into a drill press or a vice.
Just such a piece came across by bench the other day.
A long very delicate bone carving that had to have a 2 mm hole through.
One of those, that if it was broken, it would be irreparable and also had a bucket load of sentimental value attached to it.
So I modified a standard rubber wheel mandrel that I buy at my jewellery tool supplier.
It's got a 1.5-ish mm screw that screws in to hold the rubber wheel.
So I ream it out using progressively larger ball frazers.
I do this on the bench using my hanging motor.
First 1.6 mm then 1.8 mm then 2.1 mm for a 2 mm drill.
Once it is reamed out, I file a flat on the ends and punch it.
I drill a 1.5 mm hole through both sides.
That is the correct size hole for a 2 mm tap.
I drill the hole right through so there is space for the tip of the tap to go deeper in.
Then I tap it.
Only one side needs be tapped.
I used a brass screw because I had them.
I thought they might be a bit soft but they work fine.
Stainless steel would be better but they are a mission to make, so brass it is.
The shortened screw.
Then I trim the brass screw off and cut a slot in it with my piercing saw.
Then I use a cup burr to make it domed and smooth.
I cut the mandrel shorter so the cone starts right up against the chuck.
I also made a flat section on the drill bit so that the lock screw holds the drill there.
I use a cut off disk for this.
That way the lock screw does not have to be tightened very, very tight
Locked and loaded.
I caught a dentist in the wild and tamed him, so now he gives me his old diamond burrs.
His blunt burrs are my sharp ones.
So I made a mandrel for those burrs as well.
The cone right up against the chuck so there is minimum wobble.
Any comments can be written on a 500EU note and posted to me.