Adventures In Coring With The McNaughton Center Saver

Stuart Ablett

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Tokyo Japan
OK, I bought this tool back in August of 2008, I got it used for a good price and I had some limited success with it, but I don't get a lot of large green wood to turn.

I recently got some more chunks of green wood that were of a good size, so I dug out the coring rig again.

Time to reacquaint myself with the unit, first problem is that the steps on the pin turret have gone missing, so I made some new ones....

I have to run to do a delivery, sorry about that.....
 
OK, I'm back.

Here is the picture I took back in 2008 of the kit that I got....

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It turns out I lost or misplaced the risers for the pin turret, so I made some new ones....

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The larger piece is 6mm thick, the smaller one is 4.5mm thick

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Not perfect, but I think this will work

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A mini blade, it is just below the tops of the pins

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A standard blade, it is also just below the tops of the pins

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Neither riser block interferes with the other.

I contacted Kelton Industries about this and within an hour I got an email back asking for more info about which unit I have, Kel said they don't make it anymore but might have some parts laying around.

Being as I have a piece on the lathe right now waiting to be cored I decided to just make this up and then see what Kel comes up with.

Looking at various pics on the web it looks like the knives are supposed to be just below the tops of the pins, so I think this might work.

I'm really impressed with the quick reply and helpful attitude of Kelton industries. :thumb:

OK one problem fixed.
 
Keep in mind that where the edge of the blade sits in relation to the pins is not nearly as important as where the cutting tip is in relation to the centerline of the blank.
 
OK I'm trying to do catch up here, busy as can be, local festival this weekend, among many other things, so situation normal :D

The next problem I was having is that the knives did NOT slide easily through the gates in the pin turret, they would stick, then they would move in a jerk and dig in deep stalling my lathe.

Here is how they looked.

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That does not look very slippery, so I took my angle grinder with a #120 flap sander wheel and had a go, I liked it so much that I did #240, #320, #400 and #1000.....

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Made them nice and shinny as well as reduced the thickness just a bit, they now slide very well in the gates.

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I also polished the pins on the pin turret as well.

OK I now have knives that slide easily and the riser blocks to set the knives at the right level.

I own Mike Mahoney's DVD on this tool and I watched it again, great, the guy is so talented with this tool, he makes it look SO easy.

I also watched Dale Bonertz video, again, lots of great info, but I was still not having a good time with this....

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Try as I might I was still making funnels :(

I sat down, very frustrated, I even started to price out the Oneway coring rig, or the Woodcut units.... I was really frustrated.

The more I thought about it, the more I could not get my head around how it was supposed to work....

I apologize up front if I sound a bit upset, I was, I could not get this tool to work, I have seen lots of videos showing how well it works, and well it was not working for me............
 
Then it was suggested that I watch a video by Reed Gray, aka Robo Hippy on corring....


At about the 7:49 mark he goes through some modifications he has done to the pin turret, he clamps it down so that it cannot rotate.


Well now we are talking I'll give that a try.


To be continued....
 
The other thing suggested in that video is to resharpen the knives to a flat grind, instead of a pointed grind.

At first I thought this did not make sense, the pointy knife MUST cut better, right?

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Well hang on a moment, as is addressed in the video, the pointy knife actually takes more power, as the length of the sharp bit of the knife that is engaging the wood is longer than just a straight across grind.

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Here is the cutter length on a straight across ground knife.

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That is the total length of the pointed knife.

With the pointed knife I was constantly stalling my DVR lathe, I guess if you have a larger lathe, this would not be a problem, bit it was a problem for me.

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There is a comparison for you, the straight ground knife has only 62% of the cutting area that the pointy knife.

OK, now we are getting somewhere!
 
OK, below you can see that I'm getting some success....

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Starting to looks like it should.

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I think that is a bowl with a core that I can get another bowl out of!!

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Yep, that will work!

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Far from perfect but even the small bowl will work, I had to turn the faceplate screw holes out of the inside but I think it will work.

Here you can see that while my aim and such still needs work, with the flat grind knife, and the non-rotating pin turret, things are working like I think they should be working, in other words well!! :D

Cont...
 
In the video below I adjusted my aim a bit.....


Still feeding the knife in erratically, and my banjo is not in the correct position, but it is a work in progress. I ended up having to change knives as the mini knife was too short, but a bit.
 

I changed to the standard blade, which is longer, and I did not regrind the tip yet, but I think it worked out OK.

The cutting tip of the tool was just a bit below the center, seems that my mini knives and my standard knives do NOT line up as they should, most likely the risers I made are not quite the right size, but I can compensate for this now that I know.
 
After sleeping on it and some more work, a new day has dawned on the coring front.


Much better!

Still lots more practice needed, but I think I've got this now!
 
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And I just had to give that last little chunk a spin too.....


For me the important points were, lock down that pin turret, and the flat grind on the knives, makes the whole thing a lot of fun!

Cheers!
 
Your idea of polishing the knives is a good one. :thumb: I rub mine liberally with paraffin wax. (I keep a block of paraffin at my lathe all the time...I use it to slick up my tool rests quite often.)
 
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