McNaaughton Coring System

[Jeff Walters]

Hi. All,
Just wondering if anyone is using a coring system with a Nova DVR XP lathe and what their experience is. My Nov is wired for 115 Volts so it is 1.5 HP. I’m thinking of getting one however I saw a video of someone using it on a Robust American Beauty which is 3 HP and he was bogging it down.
Would I be wasting my money on a coring system?
Jeff

[Dick Strauss]

You can core on almost any lathe. I once did a coring demo on a 12" 3/4-1 hp lathe using the Oneway coring system. With lower hp lathes you have to pulse the coring cutter into the wood instead of maintaining steady pressure. Yes it is slower, but it can be done.

I can stall a 3 hp lathe with bowl gouge if I take a heavy enough cut (it is especially easy as the diameter increase) or I can choose to take a lighter cut and not stall the lathe. We have the choice how we trea our tools. In the bowl gouge case we take a smaller cut and remove less wood per revolution. In the coring case we take less wood off per reveolution by pulsing since we can't take a smaller cut.

The McN is mid-priced but has a steeper learning curve, especially if the knives arrive improperly bent. I'm not a fan of the system or company because it suffers from quality control lapses from time to time and the owner of the company resorts to personal attacks rather than attempting to help address a customer issue. When a company owner shows that they aren't willing to help, I choose not to buy their products!

If you decide to buy a coring system from them, RoboHippy AKA Reed Gray is a good resource for how to bend the mishapen knives into the correct shapes! He posts here often and if you search for this entries here you can gain a wealth of knowledge about coring!

[Jeffrey J Smith]

I bought the macnaughton system back when I was using a 1.5 hp Jet 1642 and it works fine. Did I stall it occasionally? Yep, but, as mentioned above, you can stall almost every lathe made regardless of the horsepower. Lighter cuts, pulsing the blade work to eliminates stalls.
There’s been endless discussion of the learning curve for the macnaughton system; but it’s just a tool. Every tool has a learning curve and I’m not aware of one that makes it simple. You’ve got to play by the rules the tool dictates. From my experience, the macnaughton seems to be totally dependent on the entry angle of the blade. Once you discover how to find that angle and use the correct blade you’re home free (nearly). I’m not by any measure an expert - only attempted a nested set a couple of times, but I use it nearly every time I rough blanks to save the ‘guts’ from becoming shavings - mostly going for three roughouts from an average size blank.
Reed Gray, Dale Bonertz and Mike Mahoney all have excellent information on using the system. The AAW Journal also has an article by Dale that explains his system. Go through the information, make sure your blades are sharp and spend a day with a pile of blanks practicing. It’s largely muscle memory and consistency, not rocket science.

[Dale Bonertz]

Jeff said it very well. If you're going to just core smaller bowls the woodcut system will do you fine. Larger to medium bowls either the Oneway or MacNaughton. MacNaughton has more flexibility and is faster to set up and use once you become familiar with it. Oneway is a good system but more money and limited on shapes. Any and all should work on your DVR.

[Mike Goetzke]

I'm not a frequent turner but took good notes watching the experts videos (Reed, Mike, & Dale). Little scary at first but like Jeff said setup is the most important part. Lower HP lathe may actually be better.

I have a warning of an issue I had. I was coring with the smallest arm - it was brand new. Something happened and all of the sudden the cutter arm looked like a pretzel! Didn't feel like the tool was struggling at all. I looked to see what might have caused this and noticed the tool rest was all the way down. Thinking it over I probably never tightened it enough for the coring forces. So after that I always make sure the tool rest is nice and tight for all turnings. While I type I was thinking maybe I should use a post collar to help with this?

I did contact Reed after this because I remembered reading he had re-bent the arms before. He was kind enough to walk me through it and the arm looks good as new (almost).

Mike

[Reed Gray]

Perhaps it is time for me to do another coring video with the McNaughton... As I say, 'Every one who has ever tried to use it swears at it. Every one who knows how to use it swears by it.'

There are 2 issues I have with the tool. One is that the blades do not have a perfect arc of a circle bend in them, the last about 1 1/2 inches of the blade go more straight rather than following the curve of the rest of the blade. Two is the aiming of the blade is not simple and takes a while to figure out.

So, the blades: I am guessing that they are bent to form in one of the bending lever/roller type things. This does work, but it is impossible to get enough leverage on the very tip to get it to bend perfectly. In manufacturing, if they want a perfect arc, they bend a couple of inches longer than they need, and then cut off the end. Since the tip goes more straight, the blades always follow that straight top, which is why this system always drifts to the outside of the cut. On small cores, this isn't much of a problem. On big cores, it is a major problem, with the trajectory being off 1/2 of more of an inch. This is why you see just about every one who uses this tool open up the kerf at the top of the cut so the blade can go more towards the center, which is the intended path. I think the easiest way to fix this would be to heat the tip with a torch, and then hammer it on a form, probably 2 forms, one for the inside and one for the outside of the blade. No clue as to what this would do to the metal that is laminated onto the tip for cutting. I have put a couple of my blades in a vice, well, just the tip, and applied a hammer. This helps some, and I even have one blade that tracks to the inside. If you try to take the cut in one pass on a bigger bowl, some times you can do it as long as there is enough torque on your lathe. You can and will see smoke coming out of the cut, you can hear the noise of the blade as it binds in the cut, and when you pull the blade out, if you touch it, some times it is hot enough to raise blisters. You will also see burn marks in/on the wood. You can learn to work around this.

The aiming part takes some practice. Simple version is that if the blade you are using matches the curve on the outside of the bowl, if you try to keep an even wall thickness as you go down with the core, you will go through the bottom of the bowl and put notches in your chuck jaws. You need to aim more towards the center of the bowl. Both Dale and I hold the blades up over the top of the bowl to help with the aim. This is a link that I recently found which takes that process one step farther, and first time I saw it, I was 'well, why didn't I think of that?' A good idea:

https://www.youtube.com/watch?v=NOAfJZEKCFc

There is one other problem with the McNaughton that seems to evade a lot of users. This coring system, and the others, both the Oneway and Woodcut are scrapers. We all know, or should know that with scrapers, on the inside of a bowl, you need to be at or slightly above the center of the bowl line because if you get a catch, the tool drops out of the cut, where if you are below center and get a catch, it digs in deeper. So, to set the height of your tool rest for coring, I think they say to use the long blade, lift up on the handle, and center the cutting tip on the center of the bowl or a spur drive point. Well, not bad, but not accurate. I do have a stop collar that goes around the post of my coring tool rest. I had several instances of the tool rest vibrating loose and falling down before I figured this one out. For setting the height, I don't do it by the book. A point that has been missed is that lifting the handle does not equal the pressure on the cutting tip as you near the center of the bowl. If you add the long lever and the flex in the system, with a long blade, this can put you as much as 1/2 inch below the center of the bowl line, and the inevitable catches will dig in deeper. If you have ever tried to take out the nub left when the core is free, you can see what I mean. I start 1/4 inch above center, (I added a 1/4 inch piece of plywood to the top of the collar), at least, on bigger bowls. When I get near the end of the cut, I can now 'feel' if the cutter is below center of the bowl. I then can raise the tool rest slightly higher. This does, almost, eliminate most of the problems. You still need to practice. I think being below center creates most of the vibration and catching issues there are with this tool. It doesn't correct the drift.

robo hippy

[Mike Nathal]

I start 1/4 inch above center, .............
robo hippy


Curious, at about the 6 minute mark he states he cuts below center. I have only cored once, I was not getting a smooth cut until I raised my tool height. But his cutting is exceptionally smooth (vibration -free). .

[Reed Gray]

I remember making a comment to him about that, but don't think I got a response. How much chatter you get depends a lot on the wood. Cherry or Madrone, won't chatter as much as black locust. If you are having to force the tool at all, your blade is most likely bound up in the kerf, or you need to clear the chips. Learning to go light handed with this tool is the same as learning to 'float' the bevel on your gouges. I think it is easier with gouges...

robo hippy

[Maria Alvarado]

The experts have already chimed in, I will only add that I have the Nova 1624, which is the belt driven version of yours and using the 'pulsing' method I have had few issues coring cherry or maple. It is a real learning curve! You will want to pay attention to blade size. With a 16" swing you probably can get away with the Standard set and/or smaller to give you up to 14" cores. I also find the tailstock gets in the way if you are trying to support your work on smaller and certain shapes of cores. Reed has lots of good advice:) That said, it's great getting more bowls from a blank. Have fun!

[Jeff Walters]

Thank you to everyone who responded to my message. It has been really helpful. As soon as I get the money saved up I believe I’ll be getting a McNaughton queen system. And if I have problems I’ll be back online here. 😁

[Mike Hunter]

To chew up HP it is the combination of SFPM, feed rate, and depth of cut. SFPM or RPM chews up the HP, so it is best to run the lathe at the lower RPM. Next is feed rate, so it is best to keep the feed rate low to minimize the HP requirements. The cutter does not know if it is taking 1/8" DOC or 1/32" DOC, so it is minimal on the HP consumed, but you may overcome the strength of the blade and make a pretzel.

[Dale Bonertz]

As Reed mentioned you want to be above center when you line up the tip, about 1/4". This is for two reasons, 1st as you extend the blade through the turret in its full extension you will notice that it runs down hill a little. You can test this by just extending the tip through the turret and measure it to the bed of the lathe then extend it all the way through the turret and measure again and you will see that it is a bit lower (make sure you hold handle up tight so the blade is against the t-arm. The second reason is force, as you core and the more you extend the blade from the turret there is more force pushing it down. When you set the height of the blade make sure it is fully extended from the turret when you set it 1/4" above center. When you do that and then the force on the blade when coring and being pushed down you will be cutting at center when you reach the bottom.

Reed also mentioned that the blade may get very hot. You can spray WD 40 in the kerf at about the 1:00 to 3:00 position while coring (mostly when using the larger blades is this neccesary). It will slick the walls so shavings eject easier and cool the blade thus shrinking the swelled blade from heat to glide in the kerf much smoother. No the WD40 will not stain the wood, at least I have never noticed staining, and if it did it would be on the surface only which would get turned away anyway. I do need to mention I do this while the bowl is turning and the tool is in the kerf but not cutting. Once done spraying I re-engage the tool cutting edge. Watch the chips come flying out and the tool glides well again. I hope that makes sense for you all.

[George Heatherly]

I have a DVR and a McNaughton. Just as others have said, it is certainly possible to use the combination. My personal experience is that if I stall the lathe, it is not a gentle process. I find it very jarring! I would almost be afraid to use it with a really powerful lathe for fear that it might take the tool away from me.

I do like the system. It just seems much nicer to get 3 bowls from a large blank instead of only one bowl and a huge pile of shavings.

[David Bolson]

Hi. All,
Just wondering if anyone is using a coring system with a Nova DVR XP lathe and what their experience is.
Jeff

I have a Nova 2024 (same electronics/motor as DVR XP) and I use the Oneway coring system. Never came close to stalling. I don't think you're supposed to push so hard with a coring system that it even could stall. Good luck!

[Reed Gray]

Dale, as near as I can tell, the heat on the blade comes from it rubbing on the wood, not from the cutting. The rubbing is because the blade does not track true, and as you go deeper and the blade drifts to the outside of the bowl, the inside/core is rubbing on the inside of the blade. I have tried WD 40 and Pam, which is canola oil, and just don't use them any more. A slightly higher rpm and a single kerf, rather than a more open kerf help the chips come flying out. Before I ground my points down square, I had more problems with clogging. I did retip a few blades with tantung, and kept them square as well.

robo hippy

[Dale Bonertz]

Reed I hear you, I know that's what heating the blade. I agree with the single kerf for sure however as you spray the WD40 into the kerf as it spins it slicks the side walls in the kerf and also helps cool the blade. Works well for me. It is all personal preference for example I don't care for the square end on my cutters. I tend to have a slightly longer sharpening on the outside edge from the tip than the inside. Since the outside edge needs to cut more wood it tends to push the tip inward where less pressure on the interior cutting edge is cutting. I also shorten the tip angle closer to square but not quite that far. Again that is what helps me in the drift rather than trying to bend the tip. Everyone needs to play around a little bit to find what works best for them to gain the confidence of the tool.

One other note sometimes the rubbing on the blade can happen if the user has turret set too high. As you track the rubbing starts about 1/3 way down the cut. The wood starts rubbing the bottom edge of the blade from about 1" to 4" back from the cutting edge which can get it very hot, smoking hot literally (this also depends on the size of blade being used). If one stops and lowers the turret even a 1/16" to 1/8" helps with the clearance on the interior blank rubbing so hard on the bottom edge of the blade.

All this dialogue is great from folks so people can try different things to find what works best for them.

P.S. Reed it is too bad with live so far apart. It would be fun to get together with you and collaborate on a good video. We could try many different things and most likely solve a lot of issues for folks.

Happy turning

[Pat Scott]

How can you tell if your blade needs to be replaced? As you sharpen the tip it gets shorter and the kerf gets smaller because the cutter is tapered. When is it time to replace a "worn out" blade or how do you know when it's worn out?

[Reed Gray]

I did experiment with tip shapes. The original ones had a tip that was all on one side of the blade, and kind of swept back or angled back to the outside. I tried that, square, and angled to the inside. It didn't seem to make any difference in how the blades tracked in the cut. I was chatting with the Oneway people in KC at the symposium there, and the rep commented that the spear point on their tip kept the blade centered in the cut. I don't agree with that at all. I had them ship me a tip that was hardened, but didn't have the chip breaker point on it, and sharpened it like a standard tip, leaving a good burr. It tracked fine, with no tendency to wander off course. It, to me anyway, cut far better and with less effort than their standard tip, and you don't have to take it off to sharpen.

robo hippy

[Jeff Walters]

Hi All,
Looks like I really started a lot of conversation. I have been away for a bit because of schedules. I also watched a lot of videos on using it with Robo Hippy's being my favorite. I did get the McNaughton and have used it once. It was with a piece of heavily spalted Maple and like everyone said, there is a learning curve. My biggest problem was the screws in the handle coming loose. I have put some Lock Tight on them and we'll see how that works. The person I bought the Nova DVR off of said I should rewire it for 220V so I get a little more horsepower out of it and less chance of burning up the motherboard. Does that make any sense to our DVR owners here?
Jeff

[Reed Gray]

I have turned and cored on a DVR. I am pretty sure it was wired for 110. The thing that surprised me about that lathe is how much torque it had, especially considering how small the motor looks. Not sure what difference it would make.

robo hippy

[Jeff Walters]

Hi All,
I have been using the McNaughton off and on for about 6 months now and feeling a lot better about it. I had lots of issues with the 2 grub screws, the seat the blade, coming loose. I fixed that by using Locktite on them however the issue I am still having is the thumb screw that tightens down on the blade keeps coming loose and I cannot use Locktite on it. Any suggestions on what I can use? Do I have to make separate handles for each blade and use Locktite on all screws?
Thanks,
Jeff

[Reed Gray]

Well, I never knew they had a thumb screw. I have always used the 2 set screws, and can't remember if they loosened up or not, but I do make sure to snug them down pretty good. I keep a T handle hex wrench handy. Since I have a couple of sets of them, I pretty much keep the blades I use most often in one handle, which is 4 of them. Mike Mahoney cuts his handles in half and used each end. I do keep one long handle. If you start off at center height, by the time you get to the end of a deeper core, you are often well below center because of the cutting pressure and the flex that is designed into the system. I do start with the cutter 1/4 inch or so above center height. I can 'feel' when the cutter is too low to finish cutting the blank out. Most of the time, if I have the long handle on, I will lower the handle a bit. Note here, this is master level skill. For most, you should raise the tool rest a little bit. I won't try this with a short handle on the tool.

Scrapers, and all coring systems use a scraper cut, on the inside of a bowl, you want to be at or slightly above center. This is because if you get a catch, the cutter will drop out of the wood. If the cutter is below center, it digs in deeper. This is the most common cause of extra vibration when coring.

robo hippy