Coring adventures - or My Experience with the McNaughton Centre Saver

[Nigel Tracy]

Hi all!

After reading long debates online about the Kel McNaughton centre saver vs. the Oneway vs. the other systems I finally took the plunge and purchased the less expensive, purportedly more versatile, McNaughton centre saver. Since all the information I found here at the creek was very helpful (thanks creekers—especially Reed Gray!), I thought I should post my results to add to it.

My observations are as follows for first use, coring a 13” blank from a 17.5” blank of some kind of very slightly spalted, slightly figured maple.

After reading about the infamous McNaughton learning curve, I was sure to first borrow both the DVDs I could find on the subject. Mr Mahoney and Mr Grumbine both made it look pretty easy I thought.

Tool setup was instant, and the knives came very sharp out of the box. The first inch or so of cutting seemed to be the most difficult and I experienced vibration until the tool had grooved its way in to the blank.

It does take some brainpower to visualize the path of the cut in order to aim it correctly. I read online about a few methods for helping to aim, but like Mahoney and Grumbine, I just “eyeballed it” and it worked out ok.

After getting started, I was excited to experience the knife feeding very smoothly through the cut. I had to adjust the toolpost a couple of times when the knife started rubbing one of the cores. I also had to stop the lathe to clear out shavings, although I think the slightly spalting, figured maple produced particularly “sticky” shavings. Also, after a quick sharpening before the second coring, the cutting action went even better, suggesting that my tool was dulled somehow during the first coring and, having zero experience with the tool, I wasn’t aware that it was a little dull.

It took me about 15 minutes for my first core—a far cry from Mr Grumbine’s two minute display that can be found on youtube; but like any first time, I know there’s room for improvement.

All in all I would say that it was what I expected, a specialty tool, requiring some skill to operate. Like turning in general, an understanding of edges, angles, wood behaviour, safety, etc., was required, but my limited experience (turning for less than one year) seemed to be enough.

Some more thoughts & tips from my limited experience:


Be 100% sure to hold the handle up to solidly “wedge” the knife between the toolrest and the gate thingy and go super slow when first presenting the tool to the wood. I suspect that not doing so is the most common reason for catches. I lightly tap-tapped the end of the tool handle to ease into the wood
Also when initiating the cut, keeping the toolrest back an inch or two helped greatly, since that way the full height of the knife was supported by the little posts instead of the reduced height of the knife down by the tip
My lathe automatically shut off a couple of times when shavings jammed. I’m sure that made the process a whole lot safer.


I recorded the whole event and it’s up on youtube in case you wish to watch. (My long-distance girlfriend wanted to see the maiden voyage—and yes, her interest in my woodworking makes her a keeper in my books! :) I’m sure my technique isn’t perfect and feel free to comment or offer advice—that’s the reason I joined the Creek!

http://www.youtube.com/profile?user=dxerboy#g/u

I was super happy to have success with it (as you can see in the video--haha), and wanted to encourage anyone up for the “McNaughton adventure” to go for it!

Nigel

P.S. Fine print: this post is not intended to spark any “heated” debates about coring systems. It is just an account of my experience! :)

[Bernie Weishapl]

Coring looks pretty good to me for a first Nigel. Sounds like you had a good experience with it. Thanks for sharing the video.

[David E Keller]

Thanks for the update... I was only able to find parts 2 and 3 on youtube. I'd love to see the first segment, too.

[Nigel Tracy]

Yes sorry about the missing part 1. Youtube "rejected" it because it was 11 minutes and there's a 10 minute limit.

Now trying to figure out the best .avi software for editing video.... guess this is turning into "digital video editing adventures" too...

I'll indicate on this thread when it's up :)

[Michael Jasani]

Great work Nigel. I have a McNaughton system sitting on the shelves but I haven't been able to muster the courage to use it yet!

I guess using a green blank might be a little easier on the arms and btw everytime you cored a piece did you have to put a tenon on it and then chuck it to core it again or can one core the smallest one first and then go to the bigger one?

[Nigel Tracy]

Thanks for looking guys and part 1 of the video is currently uploading to youtube. Sure does take a while...


... btw everytime you cored a piece did you have to put a tenon on it and then chuck it to core it again or can one core the smallest one first and then go to the bigger one?

For my first time I decided to try the largest first--I think Mahoney mentioned in his video to sometimes focus on the "money" bowl, and not try to precisely calculate what depth to core to in order to leave enough for the larger bowls. But yep for sure one can just go from smallest to biggest too

[Mark Levitski]

Thanks, Nigel. I have had the McNaughton system for a couple years and like it a lot. Thanks for the tip on backing the tool rest off a bit. I'll try that. I've been moving it as close as possible. A good trick I've found to minimize the catches is to not only keep the tool up against the gate, but also twist it to take any play out of it rotation-wise. This seemed to eliminate for me any catches, especially when first presenting the tool to begin the coring. I have never had to sharpen yet after many, many cores. That straight tool sure makes a nice, long-reach parting tool as well.

[Steve Schlumpf]

Nigel - glad to see that your first time using the coring system worked well for you My experience was not as good but I do figure the problem was with me and how I attempted coring. Maybe I'll try again someday - but I am in no rush!

Looking forward to seeing your cored set of bowls once they are finished!

[Nigel Tracy]

Thanks again Steve et al for looking :)



Looking forward to seeing your cored set of bowls once they are finished!

I'm looking forward to them too, since it's by far the largest bowl I've done so far. Now the hard part--the waiting (and finger crossing) while they dry!

[Rick Hutcheson]

That worked good for you. Glad to see your first core was a success.
I sharpen with a diamond stone about 5 or 6 strokes on each side of the blade every time I use the tool. I just hold the blade in one hand and the stone in the other and give it a few strokes, from the bottom side of the blade up so it makes the burr on the top of the cutting edge. Watching the bevel edge you can ususally see a little sap or wood stuck to it. I hone until I see I have hit the full cutting edge raising a burr on the top I think then go to the other side.
I can tell by the cutting action that it does help. I have tried to do multiple cut on one sharpening and can tell it is dull, compares to the light touch up before I started.
Some things I noticed it looked like you were pulling the handle toward you and flexing the blade trying to get it to curve in. I have found that if you push the end of the handle with your right hand straight at the tool post the blade glides right in on the correct path a lot easier. Also to remove the chips I leave the lathe running and just withdraw the tool and guide it right back in. Seem to work easier than the way you were trying to swing the blade up to pull the chips out with the lathe stopped.
But this is just the way I have found works for me. Everyone developes a method that works for them. Whatever works for you is the right way I guess.
I have a web page set up with some pictures and comments on it. Also there is a short video there showing some of the tips. http://www.scrollsaws.com/WoodLathe/Mcnaughton.htm

[Nigel Tracy]

Hi Rick, thanks very much for the pointers.

As for clearing the shavings, they were packing in so tightly that pulling the tool out with the lathe on was making me nervous. You can see in the video that they were so packed that I had to use the tool to pry them out a couple times! On my next try while coring the core, so to speak, things seemed to way, way "looser" and I was able to pull the knife out to clear any clogs as you suggest. Maybe just shaving issues the first time around (I hope!).

And you're right about the force on the handle. I think I started to figure it out by the end of that first core--don't try to "guide" the curve, just push it in and it will do the work. Agreed :)

Your sharpening tip is timely. I was just about to ask about that. I don't have a diamond hone. Would my 1000 grit slipstone do the trick? or do I need diamond? and what grit?

Thanks again :)


That worked good for you. Glad to see your first core was a success.
I sharpen with a diamond stone about 5 or 6 strokes on each side of the blade every time I use the tool. I just hold the blade in one hand and the stone in the other and give it a few strokes, from the bottom side of the blade up so it makes the burr on the top of the cutting edge. Watching the bevel edge you can ususally see a little sap or wood stuck to it. I hone until I see I have hit the full cutting edge raising a burr on the top I think then go to the other side.
I can tell by the cutting action that it does help. I have tried to do multiple cut on one sharpening and can tell it is dull, compares to the light touch up before I started.
Some things I noticed it looked like you were pulling the handle toward you and flexing the blade trying to get it to curve in. I have found that if you push the end of the handle with your right hand straight at the tool post the blade glides right in on the correct path a lot easier. Also to remove the chips I leave the lathe running and just withdraw the tool and guide it right back in. Seem to work easier than the way you were trying to swing the blade up to pull the chips out with the lathe stopped.
But this is just the way I have found works for me. Everyone developes a method that works for them. Whatever works for you is the right way I guess.
I have a web page set up with some pictures and comments on it. Also there is a short video there showing some of the tips. http://www.scrollsaws.com/WoodLathe/Mcnaughton.htm

[Reed Gray]

For sharpening, the coarser the stone, the better. Most of the time I just brush it on the grinder wheel (150 grit).

As to the shavings plugging up in the kerf, if you don't already know, I grind the tips of my blades square, removing the spear point. I recently retired one blade that was worn out (had it retipped by Mike Hunter, but like square tip better), and took up a new one just to see what the spear point was like. I found out that I was getting clogged up a lot more than with the square point. I heard Mike Jenson (McNaughton rep for the US, or at least I think that is his name) say that the spear point helps the shaving fold in half so it is smaller and clears out easier. Well, maybe it is Murphy's law, but they seem to open up wider for me and clog up. Square tip works better for me. The idea of the spear point was from Mike Mahoney. The purpose was to make it easier to cut the blank all the way off, rather than going most of the way and then breaking off the last inch or so. This works fine on straight grained pieces, but on crotch or burl wood, if you break the core out, it can rip right through the bottom. DAMHIKT

Another fine tuning tip I am working on is the tips of the blades. There is a PDF some where by some one, and they showed the blades on one of those plastic circle templates. Well, confirming a long held suspicion, the tips do not seem to follow the curve of the blade. The blades are stamped, rather than cut from round stock, and the tip can't be in the stamp, so it doesn't follow the curve and goes straight. This I think is the main reason they tend to drift to the outside while cutting, and it is almost impossible to remove some wood from the inside of the cut. I bent the tip in slightly on one blade by using the support fingers that I have screwed down tight to the tool rest as I don't like them to move. Well, I tweaked it just a hair too far the first time, and it drifted to the inside. I bent it back a hair, and I can go all the way in without it drifting, having to move the tool rest, or open up the kerf. Now to check all the other blades and try to fine tune them. This is still in the experimental stage.

robo hippy

[David Peebles]

Thanks for the link to the video, I loved it!! I use the Oneway system myself, but I did love the joy you showed with your finished coring. I have been there myself. It is a really good feeling.

Thanks for the videos,

Dave

[Rick Hutcheson]

Hi Rick, thanks very much for the pointers.


Your sharpening tip is timely. I was just about to ask about that. I don't have a diamond hone. Would my 1000 grit slipstone do the trick? or do I need diamond? and what grit?

Thanks again :)

I use a 600 grit diamond hone. Mainly because that is what I had already. I don't use the grinder because that seems to take off a lot more material than you need to. Your slipstone should work, will just take a few more strokes. Like I say I look at the edge for sap or dirt, the hone until it looks nice and shinny on the cutting edge part. Not a lot of honing but seems to be enough to get it to cut better and keeps it sharp.

[Bob Bergstrom]

Dale Nish just quoted Richard Raffin in his "Ask Dale" column why he didn't hone his tools. Raffin answered that he felt a hone edge will dull quicker than a freshly ground edge. I wonder if the same applies here. If I just touch my coring tip to the grinder it does cut better. Of course, the tip disappears quicker too.

[Rick Hutcheson]

My guess would be no in this case. The edge is more of a scraper edge burr than a skew type sharp edge.

[Allen Neighbors]

Nigel, Well done! I watched all three parts. Little more practice, and you'll be teaching the rest of us.
Thanks for taking the time to video all of it. :)

[Reed Gray]

Making lamp shades is frustrating. It seems that you either aim 1 inch too shallow, or 1 inch too deep. McNaughton does have a laser pointer for the system (I had mine welded to the tool handle, as I didn't like the way it was supposed to set up), and Randy Privet of Monster tools makes another. While this doesn't improve your aim, it does let you know where you are, and if you need to correct your aim. I used it for a while to guide me, now it is more for reference, as practice does as much, but if trying to get the maximum cores out of a small blank, it is really handy.

For aiming, I do two things. First, I hold the blade up against the side of the blank, to compare the curve of the blade to the curve of the bowl. If the blade has a flatter curve than the bowl, then I aim more towards the center. If the blade has a tighter curve than the bowl, I aim more down the side of the bowl. I also hold the blade up over the top of the bowl blank in the exact position that I want it to go. This helps set up the tool rest and support fingers, and give a visual reference as to what I want to accomplish. I have seen some graph paper things to help with this, but that is too much work, and going back and forth for me.

As to getting the proper height of the blade, you move the tool rest back so that the blade is fully extended. If you do it with the blade up close, by the time you get to the center, you can be considerably below center. There is a fair amount of flex in the system, both in the blades and the tool rest. Just try to remove the stub in the bottom of the bowl blank and watch the blade chatter. I did make a collar/hollow tube of end grain turned wood to go around the tool rest post to set the tool at center height. This saves a lot of fiddling around, and if you start chattering, it won't slip down at all. It seems to be the same for each set of blades, with the possible exception of the micro blades.

robo hippy

[Ryan Baker]

Another fine tuning tip I am working on is the tips of the blades. There is a PDF some where by some one, and they showed the blades on one of those plastic circle templates. Well, confirming a long held suspicion, the tips do not seem to follow the curve of the blade. The blades are stamped, rather than cut from round stock, and the tip can't be in the stamp, so it doesn't follow the curve and goes straight. This I think is the main reason they tend to drift to the outside while cutting, and it is almost impossible to remove some wood from the inside of the cut. I bent the tip in slightly on one blade by using the support fingers that I have screwed down tight to the tool rest as I don't like them to move. Well, I tweaked it just a hair too far the first time, and it drifted to the inside. I bent it back a hair, and I can go all the way in without it drifting, having to move the tool rest, or open up the kerf. Now to check all the other blades and try to fine tune them. This is still in the experimental stage.

robo hippy

That's really interesting. I have suspected for a while that this was the case, but I haven't gotten around to actually checking my blades yet. Might have to do a little tweaking to mine too.

[Nigel Tracy]

Thanks everyone for looking and commenting. I'm very happy to be able to share something of interest to the community that has provided me with so much help! :)



As to the shavings plugging up in the kerf, if you don't already know, I grind the tips of my blades square, removing the spear point.

Thanks for chiming in Reed. It was your posts here on the Creek that convinced me to try this system out, and I'm glad I did. Thanks again! Now a question: do you grind your tips exactly square at 90 degrees? I ask because in the Mahoney video there's a shot of an "older" straight-across tip, but it's not at 90 degrees.


I use a 600 grit diamond hone. Mainly because that is what I had already. I don't use the grinder because that seems to take off a lot more material than you need to. Your slipstone should work, will just take a few more strokes. Like I say I look at the edge for sap or dirt, the hone until it looks nice and shinny on the cutting edge part. Not a lot of honing but seems to be enough to get it to cut better and keeps it sharp.

Thanks for the tip Rick :) And I had actually found your webpage on your experiences with the Mcnaughton. I looked for everything I could find--and there's not much on the web. Thanks for that!

[Reed Gray]

The old original tips were dog eared to one side. I had heard that a number of people were trying out different tip configurations. I tried every variation that I could think of, beveled to one side, the other side, spear, and square. They all cut pretty much the same, profile didn't make any difference on how the blades tracked when coring. With the old tips, with the cutting tip flush with the blade on the inside of the knife, and wide on the outside of the knife, I think it drifted more than the newer spear points. They are centered on the blade, just a bit wider on both sides of the knife, and cut better. You can actually correct your track by taking some off the inside of the cut. I do grind the tips straight across, square to the blade. Mostly, it is less surface area cutting the wood at one time. With the spear tip, you can get shavings slightly over 1/2 inch wide. With a square point, your shavings are about 3/8 inch wide. Not a lot of difference, but it works better for me. As I said before, the spear point does work a bit better if you are going to cut the blank all the way off rather than getting close, and they breaking the core out. Most of the time, I cut till they fall off, with a stub remaining that is about 1/2 inch wide. Perhaps the most important thing if you are going to cut it all the way out is to be at center height at the core. There is a lot of downward pressure whey you are out as far as the tool will reach, and you will be considerably below center unless you push the handle down. NOTE: this is against any recommendations from the company and most people who use the tool. Kind of a "professional driver on closed course, do not attempt" thing, but it can be done if you are very careful, or raise the tool rest about 1/2 inch or so. If you want to see how much flex there is in the blades and tool rest, try to cut the last little bit of stub in the bottom of the cored bowl with the coring blade. One scene that I probably should have included in my DVD.

robo hippy

[Mauricio Ulloa]

Awesome Nigel. Thanks for posting your experience here.