Help! Stuck drill bit.

[satchm0h]

So, I was drilling this blank to try my hand at a Kate Harrow hobby knife. It's a long blank, so I went pretty much all the way in. I stopped the lathe, unlocked my tail stock and started removing the bit. That is when it just stuck in place. I think I let the bit get too hot and it seized up. When I turned on the lathe, it would not spin and just errored. I tried vice grips on the bit and channel locks on the blank, but the vice grips just spin on the round bit shank. I put the drill chuck in the headstock, and turned down the end a bit and can see the drill bit about a quarter inch from the end.

I know I can just turn the acrylic off the bit, but was hoping to salvage the blank. Any thoughts? Maybe a torch to heat up the bit?

Thanks in advance,
~ted

 

[jeff]

Do you have a heat gun? That would be my approach. Or dip in boiling water.

 

[satchm0h]

Do you have a heat gun? That would be my approach. Or dip in boiling water.

I do have a heat gun. Would you suggest heating the whole thing? trying to blow down the hole? heating the shank of the bit?

Boiling water may be a good call.

 

[jeff]

Heat the blank. You want it to expand. If you heat the bit it will expand too.

 

[jttheclockman]

I would try the other way and put it in the freezer. Maybe need to do a combination. You can also shoot some lubricant in the end. Rock it back and forth.

 

[jeff]

Plastics have a considerably higher coefficient of thermal expansion than metals. Putting it in the freezer is going to shrink the hole and tighten the grip on the bit. What happens to a hole when a material is heated can be a hard thing to get one's brain around. One way to think about it is that the walls of the material shrink when chilled, making the hole larger. But that's not what happens.

 

[jttheclockman]

Plastics have a considerably higher coefficient of thermal expansion than metals. Putting it in the freezer is going to shrink the hole and tighten the grip on the bit. What happens to a hole when a material is heated can be a hard thing to get one's brain around. One way to think about it is that the walls of the material shrink when chilled, making the hole larger. But that's not what happens.

This is why I said he may want to try alternating. Can not hurt to try. What it might do is just get the plastic to move some to loosen grip. I always use Denatured Alcohol to cool my drill bits. It works well for me for over 15 years.

 

[Jarod888]

If you had some dry ice, I would pack it around the drill bit ONLY. Make a shield, something realively heat resistant and place it between the bit and the blank. Warm the blank with the heat gun. The dry ice should shrink the bit and the heat should expand the hole.

The issue is you may have melted the acrylic into the drill bit flutes, essentially creating a bond between the two. If that is the case, likely there is no salvaging the blank.

When drilling acrylics, always use the peck method, in and out frequently. Use water or mineral oil as a lubricant. If you use oil, you are going to need to clean the inside of the blank with dawn dish soap to get out the oils residue so that your glue will bond.

 

[Woodchipper]

Take your time drilling. Had to destroy a blank once for drilling too fast; slow drilling speed on drill press but feeding too fast.

 

[dogcatcher]

I use automatic transmission fluid when drilling resins and acrylics. ATF from the dollar stores is cheap. Also a great wetting agent when wet sanding the acrylics and resins.

 

[wouldentu2?]

Put one end in the freezer and the other in boiling water.

 

[farmer]

Heat gun on the blank.
At a certain point trying to get the bit unstuck you might bend the drill bit.
I rather break the blank first.

I always use compressed air blowing the cutting out of the hole as its being drilled with a blow gun .
I also use a Gun drill on coring some my pool cues or pipes .

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But using compressed air is your friend .

 

[SteveG]

Some materials are very heat sensitive, and will begin melting or deforming around the drill bit, reacting to the heat of drilling. Once that happens, there is no chance to remove the bit from the blank. It is almost as if the bit were cast inside the plastic. The only way forward is to break the blank away in pieces, and save the drill bit. Knowing the heat sensitivity of the individual blank is helpful prior to any drilling operation.

 

[ed4copies]

Jeff's approach is workable.

I have had the same experience--trapping the bit in the blank. This procedure works:
Put the whole assembly in the oven, heat to about 200 degrees. Leave it there for 10-15 minutes
When you think it is somewhat melted, but before it deforms, grab the chuck in your hand, with an oven mitt
and grab the blank in a vice grip pliers--rotate backwards (counter-clockwise) and the bit will come out.

I have tried freezing before finding this method--it did not work at all.