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Center Saver

C

cwearing

Joined
May 20, 2004
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New Glarus, WI
Considering anything 6 inches and up square what is the minimum thickness desirable to consider the Kel McNaughton or similar bowl saver? Thank you in advance.😕
 
cwearing said:
Considering anything 6 inches and up square what is the minimum thickness desirable to consider the Kel McNaughton or similar bowl saver? Thank you in advance.😕
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The mcNaughton is quite flexible with regard to shape due to the multiple blades so it depends on skill and desired end product.
I have seen Mike Mahoney core 14 nested bowls from a burl. His small bowl is about 2" round and a 1/2" high.
With a 6" diameter burl 3" high he might get a bowl for every 1/2" of thickness.
6w 3h, 5.5w 2.5 h, 5w 2h 4.5w 1.5h, 4w 1h, 3.5w .5h.

The last core people take is not always useful and some people core because it is faster for them and the core takes up less space than the shavings.
I rarely core a bowl less than 12" diameter and would rarely turn a 12" bowl less than 5" high.
So my answer would be 5" minimum thickness. Unless I had a special project.

I think this is a question that has no "right answer" except the mcNaughton is going to take a 1/4 to 3/8" Kerf
So you could cut a 3/4" disc in half and get two 1/4" discs So maybe that is the physical limit.
Draw a picture of the cross section sketch the kerfs and see where you want to go.

Al
 
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With my skill level with that thing, I would consider 3" thick as the minimum. You need material for the original tenon, and for a tenon on each cored piece. It would have to be some special piece for me to core a 6" blank. Those tiny bowls just don't sell for me. People just don't seem to see a purpose, and it takes a special customer to see a bowl as a piece of art. Something to just look at and enjoy. Me? I love looking at a little bowl.
 
For every day utility bowls, I never core below about 10 to 12 inch diameter and less than 3 to 4 inches thick. The kerf on the mini set of blades is under 1/4 inch. The medium blades is 3/8, and the large set is slightly more than that. considering that you have to open up the kerf most of the time as you core, you can lose more wood than that. I have a video up on You Tube about using the McNaughton, and so does Dale Bonertz. I don't think Mike Mahoney's is up, but for a while, Craft Supplies was giving one away with the purchase of the system. You can take very tiny cores if the wood is very valuable, but most of the time, from a production stand point, it isn't worth the effort.

robo hippy
 
I only have experience with a large piece of wet box elder that I rough turned to about 20" diameter and about 8" thick before taking it over to a friends shop to core out what we could with his McNaughton rig. Since the wood was very wet we cut the cores extra thick and wound up with three cores. This was a learning experience for both of us so we came to the conclusion that we probably went about the process backwards ... we did the largest core first which meant wasting some wood to make a new tenon for the next core. The coring process itself was quite intuitive and went quickly. However, it is far from foolproof so you need to carefully plan what you will be doing.

As far as its usefulness is concerned, I would say that it is most useful for 16" diameter and larger pieces of wood. It can also be useful for smaller pieces of "special" wood that is too good or expensive to waste.
 
Richard Coers said:
With my skill level with that thing, I would consider 3" thick as the minimum. You need material for the original tenon, and for a tenon on each cored piece. It would have to be some special piece for me to core a 6" blank. Those tiny bowls just don't sell for me. People just don't seem to see a purpose, and it takes a special customer to see a bowl as a piece of art. Something to just look at and enjoy. Me? I love looking at a little bowl.
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How little is little????? My "baby bowls" may be 3-4". One can put overnight jewelry in it, temporary home for coins, a little pot pourri, nuts,cocaine,etc 😉 . I have sold a few. Gretch
 
I core just about everything I rough out with the Macnaughton. If I've got timber that can be roughed into 20 - 24" blanks, I shoot for 8 - 9" depth and core out 4 blanks - sometimes 5. I'm not going for nested sets, but I think good wood is a shame to waste. I do save the smallest cores. If the wood is relatively plain, I use these for 'tuning up' my cuts before going to the larger blanks. Eventually, it all turns to shavings, but sometimes a pretty little form emerges and gets saved.
 
Bill Boehme said:
This was a learning experience for both of us so we came to the conclusion that we probably went about the process backwards ... we did the largest core first which meant wasting some wood to make a new tenon for the next core. The coring process itself was quite intuitive and went quickly. However, it is far from foolproof so you need to carefully plan what you will be doing. .
Click to expand...

Two excellent points.
1. save the largest bowl !!!!!
2. There's is a learning curve.

Like anything else with turning, people that core a lot never have problems they just follow the tool in with wiggle to open the kerf slightly.

I don't core often enough to get that good.
I do a mix of small first large first.
I first core the second largest bowl down to a 4-5" connecting tenon. The core the next largest down to a 3" connection tenon, core out the small bowl, the finish the cores from small to large.

This works pretty well for me. When I lay the blade on top of the blank, I can see where it has to enter the face and a what angle.
 
Taking the largest core first is what I do, and especially if you green turn to final thickness, this is the best method. Our next club meeting is a coring demonstration, which I am not doing this time. Preparing for it though, I did 2 cored sets of 4 bowls each. The last little bowls are maybe 4 inch diameter, and slightly over 1 inch deep. I might have gotten a 5th bowl out of one set, but there was a crack off the pith that was not on the biggest bowl, almost non existent on the second bowl, but about an inch deep on the 3 and 4 bowls. I turn those cracks all the way off when I find them. McNaughton does have a laser pointer for their coring system, and I did use it for a while. Mostly it lest me know if I am off track from where I want to go. If you are coring for twice turned bowls, you can take the smallest one first, on out to the largest, but make sure to save the largest 'money' bowl...

robo hippy
 
robo hippy said:
Taking the largest core first is what I do, and especially if you green turn to final thickness, this is the best method. Our next club meeting is a coring demonstration, which I am not doing this time. Preparing for it though, I did 2 cored sets of 4 bowls each. The last little bowls are maybe 4 inch diameter, and slightly over 1 inch deep. I might have gotten a 5th bowl out of one set, but there was a crack off the pith that was not on the biggest bowl, almost non existent on the second bowl, but about an inch deep on the 3 and 4 bowls. I turn those cracks all the way off when I find them. McNaughton does have a laser pointer for their coring system, and I did use it for a while. Mostly it lest me know if I am off track from where I want to go. If you are coring for twice turned bowls, you can take the smallest one first, on out to the largest, but make sure to save the largest 'money' bowl...

robo hippy
Click to expand...

After thinking about what you say, it makes more sense to go from large to small because you can more easily control the thickness of the largest bowl which is important in green wood. This is important whether turned to final thickness while green or having the "right" thickness to allow for warping while drying. If we had more experience, we could have done a better job of planning. We ended up with two nice blanks and one that was rather small and shallow. While I could have turned a small bowl from the small one, I wound up using it as a jam chuck and other similar things. So, it didn't really go to waste.
 
Charles,

Please let us know if the replies have helped. The thread has probably taken a few detours, but hopefully it has somewhat answered your question. A six inch square block is somewhat small for coring. The answer somewhat depends on the size and type of bowls that you like. If it were me, I think that I could get one core out of a blank that is 12 inches square3 and 2½ to 3 inches thick. If 16 inches square and 4 inches thick I think that I could get three cores. It depends a lot on the dryness of the wood and the skill and experience of the person doing the coring.

I bought several very nice large (and expensive) pieces of wood at SWAT this year so I feel that a coring rig is in my future.
 
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