New Coring tools - Woodworking Talk

john lucas · 10-13-2009, 10:00 AM

I built a simple jig to let me bend the steel cold instead of having to heat it. To try it out I made these coring tools this weekend. The bottom one has a HSS cutter silver soldered to the arm. The middle one has a new Hunter carbide cutter screwed to the tip. The top one has a piece of high Carbon steel welded to it. Here is a detail of the Carbide cutter tip. Mike Hunter will re-tip your existing McNaughton tools with this cutter.

BilliOwen · 10-13-2009, 08:17 PM

These look great. This seems to put me on the right track to the question in my thread. Thanks

john lucas · 10-14-2009, 01:36 PM

Bill these are totally different that tools than hollowing tools. Coring tools are used to get more than one bowl out of a bowl blank. Hollowing tools are used to hollow a vessel through a small hole.

jdixon · 10-14-2009, 10:02 PM

John, could you tell me what the advantage of bending it cold rather that heating it is? I'm assuming heating reduces the strength?

John

john lucas · 10-14-2009, 10:36 PM

The advantage is not having to use the heat. The bent pieces are the same with or without heat as far as strength. If you are using tool steel you can affect the spring like qualities by heat treating it properly so there is a difference in heat bending vs cold bending. However for most of what we do there isn't any advantage.
There is one difference and that is the type of heat source. When I was bending 1/2" rod with a Mapp gas torch you could only heat a small area. metal bends where it's hottest and resists bending where it isn't as hot. Consequently I got sort of a segmented curve. I can get a clean curve by heating the metal in my forge which heats up the whole piece to an even temperature.
By cold bending the metal is already at an even temperature. It just takes more physical effort. Bending 3/4" steel bar is pretty difficult unless you heat it.
Based on the above I wanted to cold bend to save fuel, I can bend it inside, and I don't accidentally burn myself.

jdixon · 10-14-2009, 10:48 PM

Thank you John for your detailed response! I made my first tool this weekend. Just a 1/4" piece of round cold rolled steel that I ground into the shape of a round scraper. I was thinking of making another and trying to get a bend near the top, sort of a swan neck or bent angle. Mainly to reach into ornaments for hollowing. Wasn't sure what the best way to do it was. heat or cold bend. sounds like since it will be one bend and not a long continuous bend I think heating will work fine. I'll try to get a pic up of the one scraper I made. I know it it will make Mitch happy as he has been on me to try my hand at making my own tools.

Thanks again for your knowledge.

Have you got a chance to use your coring tools yet? They look great!

John

john lucas · 10-15-2009, 10:17 AM

I've bent all my small hollowing tools with heat. I propane torch is plenty of heat for up to 5/16" thick steel. Since I use water hardening drill rod I simply heat it, bend it, re-heat the tip to red hot and quench it. Take the rod to the oven and heat it for 1/2 hour at 425 degrees and let it cool. Then just grind to shape.