I cut down a Bradford, or similar, ornamental pear the other day. Got some approx 16" blanks. Tried coring with the McNaughton with no luck. In this dense wet wood the tool self feeds and jams. I'm wondering if I'll have better results if the wood is a bit drier. Anyone have a similar experience?
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Coring Bradford Pear
- Thread starter Tom McDonnell
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You might need to raise the gate a bit. The tool could be flexing enough that the cutter is too far below center. When the cutter is near the bottom it is likely to self feed. If so, you need to hold it back from self feeding. Also, make sure the kerf is wide enough that the cutter isn’t being pinched.
Since you said the tool jams, the kerf needs to be wider and don’t let the shavings clog the kerf.
Since you said the tool jams, the kerf needs to be wider and don’t let the shavings clog the kerf.
Thanks, I have the tool slightly above center but it may be flexing more than I thought. I'll try raising it a bit. I do widen the kerf when I core. I've used the McNaughton quite a bit and have sorted through the usual difficulties: broken tenons, lampshades, etc, but I've never had this much difficulty. I tried to hold it back from self feeding without success.
I have cored literally hundreds of Bradford Pear blanks with the Oneway system without any problems. Using Korpro cutters it cuts like soap and finishes like Marble.
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A few tricks that I try when I can feel the tool binding
Check the height
Wider kerf, wiggle the tool as you feed it, spray the tool with Wd40, pull the tool out and feed it in to clear the kerf.
Check the height
Wider kerf, wiggle the tool as you feed it, spray the tool with Wd40, pull the tool out and feed it in to clear the kerf.
Thanks, new coring system is not on my list but I appreciate the feedback. Read good things about the Oneway system.
I've seen the wd-40 trick mentioned in a few coring threads, always wondered if that could cause finishing problems down the line?
Well, green pear cuts like butter. I do have a video up on You Tube about coring with the McNaughton. If the shavings are plugging the kerf up, a couple of things could be happening. Most common is that the blade does not have a perfect curve arc. My guess is that Kel profiles them first, then bends them, so the tip tends to go straight rather than following that perfect arc. This means that the blade ALWAYS drifts to the outside. I have not blistered my fingers yet, but that blade gets hot, and you get burn marks on the wood. The more I open up the kerf, the more the shavings seem to plug up the kerf. I go as far as I can till I can feel the blade binding, and then pull back to the top and take a little more off of the outside of the kerf. This opens up the kerf in the correct, to me, manner. Mike Mahoney "fish tails" as he cores, which means he wiggles the handle back and forth a bit to keep a wider kerf. If I practiced that method, I would be better at it....
As for height of the cutter, I keep mine at maybe 1/2 inch above center to start the cut, and I have an end grail collar to go around the tool post. There is a lot of flexibility built into the system. If you start at level with the center, by the time you get near the end of the cut, you are well below center. Ever try to remove the stub left, with the cutter, when you get to the end of the core? First thing the cutter does is drop 1/2 inch or so on bigger bowls.
Smooth sides help the chips eject. This is why I don't fish tail, and why I come back to the top and open up the kerf on the outside of the cut, not the inside of the cut. Some times, you can reposition your banjo to help the cut go in a little easier. This does remove some of the "pressure" of a bound blade. I will use glide coat on the gates for the blade and some times on the actual blade. The slick stick from Woodturner's Wonders can work as well. You will end up turning all of the stuff off as you finish turn.
The deeper you core, the bigger the drift problem is. Mike Mahoney commented when I saw him at the Oregon Woodturning Symposium 2 years ago, that he cores 95% of the time with the medium curve blade. Me too!
robo hippy
As for height of the cutter, I keep mine at maybe 1/2 inch above center to start the cut, and I have an end grail collar to go around the tool post. There is a lot of flexibility built into the system. If you start at level with the center, by the time you get near the end of the cut, you are well below center. Ever try to remove the stub left, with the cutter, when you get to the end of the core? First thing the cutter does is drop 1/2 inch or so on bigger bowls.
Smooth sides help the chips eject. This is why I don't fish tail, and why I come back to the top and open up the kerf on the outside of the cut, not the inside of the cut. Some times, you can reposition your banjo to help the cut go in a little easier. This does remove some of the "pressure" of a bound blade. I will use glide coat on the gates for the blade and some times on the actual blade. The slick stick from Woodturner's Wonders can work as well. You will end up turning all of the stuff off as you finish turn.
The deeper you core, the bigger the drift problem is. Mike Mahoney commented when I saw him at the Oregon Woodturning Symposium 2 years ago, that he cores 95% of the time with the medium curve blade. Me too!
robo hippy
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I’ve not noticed it. Spritz the WD40 on the blade. There isn’t a lot to transfer to the wood.
When I return the dried bowl I remove the surface layer that came in contact with the bar.
Even the areas close to being in round when remounted will get a 1/32 to 1/8” removed.
Thanks Robo, when I bought the tool some years ago, I watched your video as well as Mahoney's and Dale Bonertz's. I've cored a bunch of different woods but have never had it grab so severely. Interesting that you have the tool that high above center. I'm going to give that a try when I get back to it. Have gone through the other steps you mentioned in the past. Usually run a wider kerf along the outside and that may be because the tool doesn't have arc that it came with anymore. When I win the lotto I'll build Ronald Kannes machine and keep doing craft fairs till the money runs out.
I have cored lots of Bradford pear.
Might not be Bradford Pear but some sort of ornamental Pear, which I think was derived from it. The wood comes off the gouge like butter as described but the coring tool rips chunks out. I tried going above center which helped only slightly and also tried a blunter sharpening angle. I'll try coring again when the blanks are semi dry.
Putting ~ 5-10 deg negative rake on the cutter tips solves most of the self feeding issues.
The only time I have noticed the tool to self feed, it is when you are at the bottom of the core, and going into the end grain rather than through it. I have had some "catch" problems, but mostly that is due to being below center. As with any scraper, on the inside of the bowl, you want the cutter to be at or slightly above center line. Worst catch ever when coring some black locust, it snapped the cast iron pressure plate on the bottom of my 3520A.
robo hippy
robo hippy