Faust M. Ruggiero
07-16-2012, 9:37 AM
When a project ending catch happens I try try to learn why. I attempted to mimic one of David Ellsworth's Spirit Forms this weekend. The form was only 5" in diameter and 4 1/2" deep but I was working through a 1/2" entrance hole. I've made these before but in all honesty, it takes me less time to hollow a much larger form through a more forgiving entrance. There is just no way to see inside and all work is by feel. I suppose that's what makes them fun and certainly part of makes David's work so special.
I use a combination of home made tools and a branded "bent tool". The catch had nothing to do with the tool shape or brand. However, a 1/2" hole makes any tool shaft larger then 3/8" kind of useless. My home made tools use a 1/8" square steel cutting tool. The bent tool I was using had a 3/16" cutter. Naturally, a 3/8" bar requires a light touch and any catch can prove devastating so I hold all nut my straight tools in an arm brace. Well, I got a catch that was bad enough to bend the crap out of the tool and whack the upper side of the entrance hole hard enough to split the form. So, I licked my wounds, mental only, and cut the remains in half learn what happened. My error was easy to see.
.236982236984
The first mistake was not having the tool where I thought it was. I marked the cutting pattern I should have followed on the left side of the half cut. The black line inside the form shows where my tool actually was. With such a small shaft in ring porous wood, (ash) it is best to shave the wood away using only a portion of the cutting edge. My cut forced the entire width of the cutter into the wood. Once the catch started it was self feeding. The shaft bent allowing the the cutting edge to finally release but not before causing it to hit the top of the opening hard enough to break it. The hollow form was mounted on a faceplate or I am sure it would have gone into orbit. I was always a believer in face plates for hollow forms but this was proof how securely they hold the work.
236983
If you look closely at the picture above you can see the cut that caused the crash. In one rotation the tool dug over 1/4" into the wood.
236985
This is the damage to the tool. The straight shaft tool is for reference. I will straighten it out and give it another try.
Meanwhile, I spent yesterday hollowing a 8" x 8" form through a 1 1/2" opening. I felt like I could walk inside and look around and believe me, the difference between a 3/8" tool and a 3/4" tool is more than can be measured on a ruler. I hope my mistake helps someone else.
faust
I use a combination of home made tools and a branded "bent tool". The catch had nothing to do with the tool shape or brand. However, a 1/2" hole makes any tool shaft larger then 3/8" kind of useless. My home made tools use a 1/8" square steel cutting tool. The bent tool I was using had a 3/16" cutter. Naturally, a 3/8" bar requires a light touch and any catch can prove devastating so I hold all nut my straight tools in an arm brace. Well, I got a catch that was bad enough to bend the crap out of the tool and whack the upper side of the entrance hole hard enough to split the form. So, I licked my wounds, mental only, and cut the remains in half learn what happened. My error was easy to see.
.236982236984
The first mistake was not having the tool where I thought it was. I marked the cutting pattern I should have followed on the left side of the half cut. The black line inside the form shows where my tool actually was. With such a small shaft in ring porous wood, (ash) it is best to shave the wood away using only a portion of the cutting edge. My cut forced the entire width of the cutter into the wood. Once the catch started it was self feeding. The shaft bent allowing the the cutting edge to finally release but not before causing it to hit the top of the opening hard enough to break it. The hollow form was mounted on a faceplate or I am sure it would have gone into orbit. I was always a believer in face plates for hollow forms but this was proof how securely they hold the work.
236983
If you look closely at the picture above you can see the cut that caused the crash. In one rotation the tool dug over 1/4" into the wood.
236985
This is the damage to the tool. The straight shaft tool is for reference. I will straighten it out and give it another try.
Meanwhile, I spent yesterday hollowing a 8" x 8" form through a 1 1/2" opening. I felt like I could walk inside and look around and believe me, the difference between a 3/8" tool and a 3/4" tool is more than can be measured on a ruler. I hope my mistake helps someone else.
faust