Drill out the brass tube??

[MPVic]

I was given a beautiful Banksia pod blank, drilled & glued in the brass tube with epoxy. As I turned the blank, the brass tube started showing through the resin - it will only become more obvious the closer I get to finished shape.
I thought of drilling out the brass tube (7mm), back painting the blank (which I should have done in the first place) & replace the tube. Has anyone ever tried this? Any advice would be appreciated. Thanks in advance for your help.

 

[JohnU]

I've never drilled a brass tube out so idk how easy that will work. I know the epoxy will loosen up with heat (from my early days of getting blanks too hot while sanding.)
Just thinking…. Wondering if you couldn't use a wood burning iron to insert in the tube and warm it up, loosening the bond to push it out.

 

[Mr Vic]

Another option is to hold the blank with it loose on the mandrel. Let the mandrel spin inside the tube and let friction heat the tube loosening it up.

 

[magpens]

It would be nice to know the diameter of the blank in its present state, and the size of the glued-in brass tube.

Since your blank has already been drilled to accept the brass tube, had the brass tube glued in, and then turned (at least partially down to size), I do not expect that drilling out the brass tube has a high probability of being successful, partly because the Banksia pod is a somewhat fragile material, but also because much of the structural strength has already gone due to material removal in the first drilling and subsequent turning

I would think that the wall thickness of the Banksia material is no more than about 0.150" presently.

Assuming that your proposed drilling would be done on the lathe . . . . .

Your drill bit for removing the existing brass tube will not have perfect alignment with the axis of the blank and that fact will result in some forces that will tend to move the bit off axis. . And even a little bit of off-axis could work to damage the fragile hollow cylinder of Banksia.

You probably get the drift of what I am thinking . . . .

 

[Charlie_W]

Heat is the way to go. You can use a large nail or a bolt. Heat with a torch and insert into tube. You may need to re-heat as you get the tube moving. Note that there can be some bad fumes from heating the glue so do this outside.

 

[carlmorrell]

I tried drilling out a tube once. It did not go well. I have successfully removed knife handles that were epoxied by heating in water. The epoxy softens from the heat. But the tube is still going to need encouragement to come out, perhaps with a transfer punch.

 

[Jans husband]

I had to drill out a brass tube a couple of times, eg when I didn't get the tube fully into the blank before the CA glue I was using gripped.
I always drill on the lathe.
I put the largest drill or disassembly rod which fitted inside the brass tube into the tube and then installed the blank into the headstock and the drill (rod) into the tailstock. This centres the hole as near as you possibly can and overcomes the axis problem Mal has mentioned.
Then remove the drill bit and drill through with the correct size drill in the usual way, removing the stuck brass tube.

I have never used a Banksia pod, but would have thought if it is strong enough to be machined, my process would be worth the risk- especially if others don't come up with a better possible solution.

Whatever, best of luck,

Mike

 

[MPVic]

Thank you to everyone for your suggestions! Using heat seems to be the recommended method - thanks again.

 

[MPVic]

It would be nice to know the diameter of the blank in its present state, and the size of the glued-in brass tube.

Since your blank has already been drilled to accept the brass tube, had the brass tube glued in, and then turned (at least partially down to size), I do not expect that drilling out the brass tube has a high probability of being successful, partly because the Banksia pod is a somewhat fragile material, but also because much of the structural strength has already gone due to material removal in the first drilling and subsequent turning

I would think that the wall thickness of the Banksia material is no more than about 0.150" presently.

Assuming that your proposed drilling would be done on the lathe . . . . .

Your drill bit for removing the existing brass tube will not have perfect alignment with the axis of the blank and that fact will result in some forces that will tend to move the bit off axis. . And even a little bit of off-axis could work to damage the fragile hollow cylinder of Banksia.

You probably get the drift of what I am thinking . . . .

Thanks for the caution, Mal - appreciated.

 

[howsitwork]

I would second the heat to remove it as once you get over about 300C the epxoys will soften considerably and could probably push the tube out. Drill it, as Mal said unless there's a lot of material left around the tube ( and from your description it doesn't sound like it) is fraught with challenge !

 

[Jans husband]

OK- having read the input from others, try the heat method first!!
My suggestion is more likely to work as an alternative with a wood or acrylic blank. It has certainly worked for me.
Pleas let us know how you get on Mark

Mike