Blew Up!

[MCSO5164]

I was in the shop last night preparing some blanks for turning. The wife wanted me to make her Granfather a pen and her Uncle a pen. Both are coming into town for a birthday. Anyways, I was using some Olive, one blank being dark in color and kind of unique looking. I start drilling it out and when I'm almost done I hear a cracking noise. I take the blank out of the vise and it is cracked about half way up the body. I am using HSS brad points and do not drill very fast on a very old drill press. Has anyone had this happen and should I slow down even more? Is Olive or any other wood known for this? Thanks for any advice. Terry

 

[rdewolfe]

just slow down more and when you feel resistance let your bit come all the way back out of the blank to get saw dust off your bit ( it should just come off the bit on it's own)

 

[BullDurham]

All heavy dense wood with alot of oil or sap will built up heat when cut or drilled. you need to cool the blank down or it will crack on you. you can use water on some woods to cool them down when drilling the more dense one are best for this like ebony and olive.

 

[leehljp]

Blow outs on pen blanks are very common. It is not any specific wood as just about all wood will do that. It is the thinness of the blanks that require a different technique from drilling holes in boards and plywood.

For me, I take small bites about 1/8 to 1/4 of an inch at a time and pull the bit out. For the last 1/2 inch I take about 1/16 inch bites. On some woods, hard ones in particular, I often cut a blank a 1/2 in longer than needed and drill down to within 1/8 of an inch before finishing. Then remove the blank and cut the end off with a saw. Many others do this to prevent blowouts on brittle wood like snake wood and other hard woods.

 

[txbatons]

I've had olivewood split on me more than other woods...well except for red cedar. I now do it just like Hank describes and take my time and that seems to have helped a lot.

 

[bitshird]

The problems do occur often on oily woods, not just the hard stuff, Olive being one of the oiler, what happens is the drill shavings stick to the drill bit from the oil, and in effect the friction causes them to expand, cracking the wood, after drilling oily woods be sure and clean your drill bit with DNA or even WD 40, just wipe it off, especially behind the drill margins the drying oil makes a great glue to hold the drill shavings fro your next project, just peck drill, with short increments even though the wood feels soft,

 

[cowchaser]

Might try putting less pressure on the vise when holding the blank for drilling also. I have had a few blow up because they were being squeezed to hard. Only remember 1 or 2 times I can account for it with wood, but have had a few acrylics also.

 

[Rifleman1776]

Slow rpm, about 500-600 is good, slow advancing and frequent withdrawls to remove chips and allow some cooling. Don't blame the olive wood, it is just a fact of wood working/turning life.