McNaughton Center Saver Questions

[Brian Effinger]

Hi Everybody – I’ve been away from the creek for the last few months because of work, and even worse, I’ve barely done any woodturning! Things are starting to slow down to a more normal pace, and it is good to be back. Anyway, on to my questions.

Two weekends ago, I got to see Andy Cole demonstrate at my club, and the first thing he did was core a natural edge set of bowls with the McNaughton. Wow!!! I was impressed. I had arranged the demo, so I also got some wood for him – from a large 15” half log to some smaller 8 to 12 inch natural edge blanks so he would have some choices. I had assumed he would take the largest blank to core, but he ended up with a 10” blank and was able to get 5 bowls out of it. Did I mention I was impressed? Of course he made it look easy, but I know it isn’t, at least for beginners. Now, being a mild tool junkie, after seeing that, I want a coring rig too.

The only hang up may be my lathe. I have a Delta 46-460 12” with 1 hp. At the hand’s on, the next day, I asked Andy about it, and he felt I wouldn’t have a problem coring on it, but I wanted to get a few more opinions and ask a few more questions. So what do you guys & gals think? Will my lathe be up to the task?

Also, I’m thinking of skipping the micro system and getting the small system from Woodworker’s Emporium. I’ve looked at McNaughton’s website, and it looks like this would give me the standard 5 pin tool gate. Will the standard gate take all of the blades offered – from the micro to the jumbo? If I upgrade my lathe in the future, I want to be set up for coring without having to buy a new gate, just larger blades. And speaking of the gate, I would buy it with the normal 1” post (so I can upgrade) and buy a 5/8” post so I could use it with my current Delta. Is this size post available, and will small diameter give me trouble?

So, for those of you with the McNaughton set-up, what do you think of my plans? Am I on the right track (possibly) or just plain crazy (most likely )? I’d appreciate any feedback and advice. Also, if there are any questions that I didn't ask, but should have, let me know.

Thanks.

Brian

[Kyle Iwamoto]

Andy is amazing. He can rough a bowl AND talk about it at the same time.
The Delta should be able to core, but much slower than Andy can. I've cored with the micro set on the mini Jet, so it can be done, although it takes a long time since the Jet is so underpowered. I would agree to skip the micro set. I think that's made just for the 10" minis, and they are very thin blades. I since have upgraded to a bigger lathe, and the standard McN set, but still stuck at 3 bowls from a blank. Some day I'll get 4 and then I'll be able to get 5 bowls like Andy. Just need some practice.

[Rick Hutcheson]

I have cored many bowls on the Delta 46-460 and the McNaughton stardard knives and the mini knives. If you start stallling the lathe just slow the feed rate a little. I have done runs of 10-15 bowl cores one after the other without any problems.

[Reed Gray]

1 hp is a bit minimal for coring. With the micro blades, which have a smaller tip, not a problem, but with the small set of blades, you will have problems with stalling the lathe. You would have to take light cuts. You do not need to have all of the blades either. The small curve, and medium curve will take about 90% of all the cores you will attempt. Might save you a bit. With your 12 inch lathe, you might have to shorten the tool rest post, and if you upgrade, then you would need to get another longer post. For your 5/8 inch post, they do make a tool rest for that, and it is not interchangable with the large tool rest.

robo hippy

[Josh Bowman]

Brian, I have a theory, I'm thinking big lathes are some of the problem with the McNaughton system. The reason is, if your lathe is under powered you tend to hold back and keep the path clear for the blades, therefore not binding and bending. With my PM 3520, I can take way too big of bite and have made many lamp shades and burnings and squealing stops! After seeing Kathy Marshall have good luck with hers on her PM90 (I think), I talked some with her and concluded I was being too aggressive. Since then, I keep a lite feed and keep the path clear and envision where the blade is going and have had logarithmic success. I envy getting 5 bowls from a 10" blank, but have gotten 4. As far as the size, I have the standard and large set. I have yet use the large blades. Really you will only use a couple of the standard blades most of the time anyway. Good luck and beside, if it doesn't work, what better excuse to buy a bigger lathe to go with your coring system. Either way you win.

[Rich Aldrich]

Brian, by all means use this as an excuse to upgrade. Seriously, I have a McNaughton coring system with the 1 1/2 hp Jet 1642. I have only used the coring system 2 times and can stall it. I think with practice, stalling will be minimzed. I think the 1 HP will handle it, especially if you take your time. After spending time with an expert, you probably know some of the tricks that will make it work.

[Mike Cruz]

Now, I haven't done a whole lot of coring, mainly becuase I kept getting catches that would lauch the blank...breaking the tenon on occasion. But this is what I found out after Dale Bright came over and gave me a little lesson. I was pretty much doing everything right. HOWEVER, as Josh pointed out, a big lathe has too much power. My PM90 (with risers to give it an 18" swing) has a 2 hp motor. If I turn the speed up on the hand dial to 1400 rpm or so, THEN dial down the speed with my potentiometer to 800 rpm, I no longer have full torque. Then if I am too aggressive or get a catch, I simply stop the lathe. MUCH better results.

[Reed Gray]

I am tending to think that the catching problem has more to do with being too low to start with. To set the cutter height, you extend the cutter full length, and then pull up on the handle. This is close. If you consider the down ward pressure when coring, especially if you are extended out a way, this extra pressure will have the tip considerably below center, and you never want to cut with a scraper, inside a bowl, below center height. All of the coring systems cut as scrapers. After you have cored a lot, you can feel when you are below center. You raise the tool rest, or (professional driver on closed course DO NOT ATTEMPT) I will some times push the handle down a tiny bit to get the core totally cut off, rather than breaking the core out. I only do this if I have the full handle length on. If you want to see how much the blade deflects, try to remove the stub left when the core breaks out. While this is not in any recommended teaching method I have seen, I am usually 1/4 inch above center when I start. If you are too high, the vertical blade will not fit into the rounded kerf. If you are too low, same thing plus you are cutting below center.

Another thing I have discovered over the years is that the blades are not bent to a perfect arc of a circle, and they can be fine tuned. I have argued/discussed this point with Kel, and he does not agree. I have also talked to Mike Mahoney about it, and last time, I might have explained it a bit better because he commented 'you might be on to some thing'. The older versions of the blades had very inconsistent bends. The newer ones, especially the Mark 8 are pretty good. However, the very tip tends to go straight rather than follow the arc of the curve that the blade is bent to. This is a very slight deviation, but 1/32 of an inch at the end of a 6 inch blade can throw you off a lot. If it was a perfect arc, then the blade would not wander as you go in, and you should be able to plunge all the way in without having to open up the kerf. You should not have to move the blade other than to clear the chips. The blades always wander to the outside of the cut. I lay the plastic circle template over the top of the blades to check them out. Since my tool rest has the vertical posts locked into place, I can put the blades in them, and tweak the tip in just a hair. If you over tweak the blades, they will actually pull towards the inside of the kerf. Most of us have just gotten used to opening up the kerf for compensating for this.

The circle template

http://www.woodturnerscatalog.com/p/...ircle+template

robo hippy

[Al Rogers]

Reed raised the question about the tip of the cutter being below center-line, at the end of the cut. On first McNaughton coring system I tried, I would adjust the cutter tip to be at center for the start of the cut, the cutter close to the gates. If I extended the cutting bar to full length, the cutter was almost a 1/4 inch low, without any down pressure on it. Has anyone else noticed anything like this with their McNaughton systems?

Another thought (dangerous for me). If the tip veers toward the outside during the cut, could this be countered by grinding the tip with a larger facet on the outside edge ( move the center point toward the inside)?

Your thoughts

Al

[Josh Bowman]

the cutter was almost a 1/4 inch low, without any down pressure on it. Has anyone else noticed anything like this with their McNaughton systems?

This was my first mistake I made with mine. I treated it like any other tool and centered it for the start of the cut with the tools tip drawn back into the gate, that along with other mistakes created all kinds of unpredictable results. I now determine how far the tool will be extended to complete the cut and pull the banjo back and push the tool all the way to that point through the gate (that has the tool extended almost to the handle). Then raise the gate/holder to be on center line. Then reset everything for the cut, that puts you a little high on the start of the cut, but it's controllable. As the tool advances into blank, the center became more important, especially as you're cutting around the bottom.

[Reed Gray]

There is flex designed into the gates, tool rest and blades. If it was too rigid, things could break. I believe it angles down a bit also. Then when you add the pressure of the cutting action, it goes down some more. If you have a very well used blade, it will have a twist to it, just lay it on your table saw and watch it rock. Just the torque pressure of many cuts over a lot of time, even with out many spectacular catches. You can clamp it in a vice and twist it back. I had thought about cutting in a bit, then raising the tool rest, but didn't want to do that. Starting 1/4 or slightly more will compensate for the down pressure and flex, and it does not interfere with the use of the tool. Again, it is a scraper, and on the inside of a bowl, you do not want to cut below center height with them.

With the original blades, they had the cuter edge all off to the outside of the blade. I did every conceivable profile I could think of (bevel to the outside, inside, square and spear point), and it made no difference in how it will track. The blade will follow the direction the tip points, no matter what the curve of the blade is. If that tip is off even a tiny bit, the blade will wander. This is why I have 'fine tuned' my blades. I also ground the spear point off. It makes no difference in how the blade tracks, and it makes for a smaller cutting surface, and I get way fewer plug ups by shavings in the kerf.

Still the fastest and most efficient coring system to use. It does have more of a learning curve than the other systems.

robo hippy