History of coring systems for small-shop turners

[Kalia Kliban]

I recently posted a set of photos of coring a set of big sycamore bowls on my Facebook page and someone asked a great question, which was "how old is this technology?" I had no idea. I suspect the big bowl mills have used some kind of coring gear for a long time, but commercially-available gear appropriate to small shops like mine? No idea. Anybody know how long non-industrial coring systems have been around?

 

[hockenbery]

No real idea. Interesting question
I first heard about coring in a class taught by Liam O’Neil in 1994.
Liam was coring cones from bowls of valuable wood using a straight tool.


I’ve seen some videos of old industrial coring machines with several knives that cut 3-4 bowls from a blank at the same time.

 

[Neil S]

Two of the earliest commercially available coring systems for small workshops that I know about come from New Zealand: The Kel McNaughton Center Saver and the Woodcut Bowl Saver systems.

My recollection is that the McNaughton came out first and the Woodcut next in 1995, but I might be wrong about that order.

I'm not familiar with the history of the Oneway Easy-Core system.

Straight bar 'cone' corers like the Stewart were available in the 1980s.

Before that turners made their own. See George Lailey and Robin Wood.

 

[Hugh]

Way back when, Dennis Stewart came up with a "center saver" straight bar for his arm brace. That is the first one I remember. Tapered round bar with a small piece of carbide on the tip.
There is a bowl mill on the East Coast....not sure where.....that was old when I heard about it.
There is a fellow in Sweden or Holland or near there that recently made his own bowl corer like the old bowl mill has. But, his uses a carbide cutter, something like Mike Hunter's KorPro cutter.
There are videos around of the old bowl mill and also one on the fellow who made his own. They just cut a round in half and mount that on the machine.

 

[Mike Johnson]

My guess would be about 5000 or 6000 years ago, when I visited one of the museums in Cairo they had a huge collection of stone turned bowls
several of them were cut from the same billet of stone that showed the same aggregate pattern in the set of bowls. The earlier Egyptian stone
works were far superior to the later works.

 

[robo hippy]

I will agree with Mike above.... I have seen Robin Wood, famous spring pole lathe turner, using his own forged tools for coring. Maybe at least as long as there have been metal cutting tools. Watched an old Chinese gentleman using a sit down spring pole type lathe, which was a pedal on either side and rope in between. He turned 5 or so end grain bowls from one log section, and he hollow cut the bowls in stages. I think the McNaughton was the first curved blade modern coring tool.

robo hippy

 

[Neil S]

I have seen Robin Wood, famous spring pole lathe turner, using his own forged tools for coring. Maybe at least as long as there have been metal cutting tools.

Robin and I have exchanged stuff, like tools and bowls, and he is very informed about all matters to do with the pole lathe and early turning methods.

His book on The Wooden Bowl is wonderful read on the history of the wooden bowl and is the authoritative work on the topic, IMO.

I would recommend every bowl turner have a copy of it on their book shelf.

 

[Neil S]

Way back when, Dennis Stewart came up with a "center saver" straight bar for his arm brace. That is the first one I remember. Tapered round bar with a small piece of carbide on the tip

Richard Raffan has just released a video in which he is (among other things) coring with the Stewart straight arm corer.

The other thing which I found interesting in that video is he using a crow bar (perhaps called a wrecking or pry bar on your side of the pond) to prise off the cored bowl! I've set the following link to the point in the video where he does that. In the remainder of the video he is roughing roughing down the outside of the bowls with a spindle gouge (he says they are cheaper than bowl gouges and do the job just as well on the outside) and then the insides with a bowl gouge. As you can see he is back in production mode with those...

View: https://youtu.be/6TTuRNtl7BQ?t=1025

In the past I've whacked away at the cored bowls with my hands to snap then off. I might adopt Richards crow bar technique in future to save my ageing hands...

 

[john lucas]

Rude Osolnik was using a straight coring bar when I first saw him at a TAW symposium somewhere around 97. Not sure the year. My friend Joe Looper was using one somewhere around that date and Joe learned it from the Moulthrops.

 

[Graham Dolby]

Way back when, Dennis Stewart came up with a "center saver" straight bar for his arm brace. That is the first one I remember. Tapered round bar with a small piece of carbide on the tip.
There is a bowl mill on the East Coast....not sure where.....that was old when I heard about it.
There is a fellow in Sweden or Holland or near there that recently made his own bowl corer like the old bowl mill has. But, his uses a carbide cutter, something like Mike Hunter's KorPro cutter.
There are videos around of the old bowl mill and also one on the fellow who made his own. They just cut a round in half and mount that on the machine.

There was an article in one of the wood magazines, over 30 years ago, about a father & son shop in Ontario that used an ancient, curved blade corer for their salad bowl business.
I think they are still in operation.

 

[Doug Freeman]

The other thing which I found interesting in that video is he using a crow bar (perhaps called a wrecking or pry bar on your side of the pond) to prise off the cored bowl!

I use a pry bar if rocking by hand doesnt do it. However, if you core end grain bowls, prying doesnt work - it will pull the center of the cored bowl out. You want to cut to center with end grain.

 

[robo hippy]

Yup with that Doug. Did that once or twice. It can happen with crotch wood and with burl as well. Those pieces need to be cut all the way off. This is one of the 'fine' points of learning to use the McNaughton. By the time you get to the very end of a deeper cut, the cutter is below center. Learning to 'feel' when this is happening is key. You have to raise the tool post a bit, or for me, a 'professional', if I have the long handles on, I will drop the handle a bit till I can 'feel' it cutting on dead center. You start to get a lot of vibration when below center, and I think it makes it more prone to catching.

robo hippy

 

[Dan Hewitt]

Hi Kalia,

I learnt from Mike Mahoney the history of the Mc Naughton Bowl coring product (Mike please correct me if I have misinterpreted anything). Evidently the idea for this product was conceived around a table in the 1980's at one of the early AAW symposiums in a conversation between Kelton, Ray Kee, Richard Raffan and Mike Mahoney. Influence on the design was the Parting Tool used by Bodgers as they turned green wood with their Pole lathes many hundreds of years ago.

My understanding is that the Stewart product was launched about this same time, I don't have the information to confirm this.

The Woodcut Bowlsaver original was launched to market in 1995 after an almost 5 year development process involving many prototypes to ensure the product was right. Ken Port and Errol Udy who led the design of this product wanted to deliver a bowl coring product that is simple to use, versatile and effective and safe (disclosure I am the current owner of Woodcut Tools).

My understanding is that the Oneway Easy Core product was launched to market in the early 2000's.


Best regards

Dan Hewitt

 

[Nathan Roper]

Do the different coring tools out there produce different profiles or all they all about the same? The reason I ask is because a friend has one (not sure which one) and I got a bowl from him but I don't really like the way it slopes near the lip. To me it feels like it comes out too broad and makes a sharp angle that doesn't fee awesome when you hold the bowl in one hand. I guess I like it when I can wrap my thumb over the edge and its a smoother feel on the hand if that makes sense. I'm wondering if what my friend uses is one profile but a different brand would produce a different shape.

 

[Doug Freeman]

Do the different coring tools out there produce different profiles or all they all about the same?

There are 2 basic types, fixed path (Oneway, Woodcut) and what I’ll call flex path (McNaughton, Michelsen).

Fixed - have a fixed pivot for the blade, user sets the pivot point. The radius for each blade is fixed, so the profile cut is fixed, but the user selects the thickness of the core. A thicker core allows more profile change. The pivot point selection determines how much of a 1/4 circle is cut. Just imagine a 90 deg 1/4 circle, but you may only want the last 45 deg, a broad, shallow bowl.

Flex path - the pivot itself can move allowing a bit more shaping of the profile. That flex path has limits, as the blade has to have clearance, and these are more difficult to learn, as the blade can be “caught” in the kerf. Based on comments in this forum, these require a bit more lathe hp due to the catching of the blade in the kerf.

I have the woodcut bowlsaver 2 blade. I have no problem using it with a Nova Galaxi at 120v, which specs at 1.75 hp (the dvr motor does have more low speed torq vs vfd lathes). Ive been very pleased with the results, and wish I had gotten the 3 blade version. I did not understand how the pivot point could be moved around, as well as core thickness, to alter the final bowl shape. A 17” bowl blade can be used to produce a 12” bowl with a shallow profile (say the last 45 deg of rotation) and with enough thickness, the rim can be shaped however with a gouge.

The biggest difference between the OW and BS is blade support. The OW has a blade support that is moved into the kerf (manually) as the cut is made deeper. The BS hangs the blade out over a support. For the ~13” max core size my 2 blade can do, there’s no issue, but cant speak to how the larger blade would act. Theoretically the supported blade is better, but isnt needed for the size I can do.

 

[Kevin Jenness]

All the curved coring tools necessarily cut a circular arc. The differences are in the radius of curvature and the ease of orienting the curve in the blank by locating the pivot point.

 

[Dave Bunge]

All the curved coring tools necessarily cut a circular arc. The differences are in the radius of curvature and the ease of orienting the curve in the blank by locating the pivot point.

I agree with this and would add that the difference is not just in the ease of locating the pivot point, but in the flexibility/versatility of where you can put the pivot point.

With the Oneway, the pivot point is a solid post, which will hit the bowl blank if you get too close. The implication is that the deepest core you can make is equal to the radius (e.g. the 11" coring knife is limited to 5.5" deep core max).

With the McNaughton, there is no post; the pivot point is out in space. So you can make deeper cores, where the pivot point (center of the cutting arc) is below the surface of the wood. This lets you make taller more conical or vase like core shapes. But the cut surfaces are still circular arcs.

I own both but mostly use the Oneway since I find it to be more reliable on large cores.

 

[Bill Blasic]

I have owned all 3 systems at the same time. The McNaughton is the hardest to learn and safely use. The Woodcut is fairly simple to learn, does a good job but is the least versatile by being hooked up to the tail stock. The Oneway is the most expensive but fairly easy to learn but it is a lot more versatile than people give it credit for being. With the addition of the Hunter Tool Systems Korpro cartridge its a game changer. Oneway should have had Chris Ramsey do a video on its use as he can do stuff with the Oneway that has not been thought of, that was my main reason of taking lessons from Chris a few years ago. I sold the McNaughton and the Woodcut.

 

[Lou Jacobs]

But the cut surfaces are still circular arcs.

I am still learning the fine points of my McNaughton but I think one of the advantages is that the cut does not have to be perfectly circular. Since the cutting edge is wider than the stock it is mounted on, the knife can be shifted as the cut progresses to make a slightly flatter or steeper curve as you go.

 

[robo hippy]

Well, all of the coring systems use blades that are a section of an arc/circular curve. The thing with the McNaughton is that the 'flatter' curves are arcs of about 9+ inches (can't find my big plastic circle arc lay out thing.....). The Oneway and Woodcut are 1/4 sections of circles. That flatter curve makes it easier to core deeper forms, and wider flatter forms. Well, easier once you figure it out. I do need to bend my own McNaughton blades some day....

robo hippy

 

[Kalia Kliban]

Robin and I have exchanged stuff, like tools and bowls, and he is very informed about all matters to do with the pole lathe and early turning methods.

His book on The Wooden Bowl is wonderful read on the history of the wooden bowl and is the authoritative work on the topic, IMO.

I would recommend every bowl turner have a copy of it on their book shelf.

I've read The Wooden Bowl cover to cover multiple times. It is indeed most excellent!

 

[Neil S]

I've read The Wooden Bowl cover to cover multiple times. It is indeed most excellent!

...

 

[Kalia Kliban]

Richard Raffan has just released a video in which he is (among other things) coring with the Stewart straight arm corer.

The other thing which I found interesting in that video is he using a crow bar (perhaps called a wrecking or pry bar on your side of the pond) to prise off the cored bowl! I've set the following link to the point in the video where he does that. In the remainder of the video he is roughing roughing down the outside of the bowls with a spindle gouge (he says they are cheaper than bowl gouges and do the job just as well on the outside) and then the insides with a bowl gouge. As you can see he is back in production mode with those...

View: https://youtu.be/6TTuRNtl7BQ?t=1025

In the past I've whacked away at the cored bowls with my hands to snap then off. I might adopt Richards crow bar technique in future to save my ageing hands...

Thanks for posting the video. I always learn something new whenever I watch him at work.