McNaughton revisited, a beginners perspective

[Josh Bowman]

There’s been a fair amout of coring talk lately, so I thought I’d share some thoughts on the McNaughton system as a beginner. The pros make it look easy, but the perspective from someone new sometimes gives some insight into developing the “feel” for a skill. About 16 months ago, I bought the standard and large set from a fellow creeker. Right off I made some cores but it was kind of ify rather I’d get all the cores from a blank. The McNaughton is very easy to cut the bottom out of bowls if you don’t keep up with it. I thought I’d simply add a laser and would become profeincent with it. However the laser would get vibrated out of position or I’d get the blade in a jam. Reed Gray’s and Mike Mahoneys DVD’s are great, but I was still missing something. So when Kathy Marshell got hers and posted some very nice cores, It inspired me to try to learn how to use it with predictable results. After discussing (whining might be a better word) with Kathy, I got a simple raw prespective from a beginner how to use it. She stated her lathe is under powered so she had to stop a lot to and go slow. Also she told me to learn to visualize where the tip of the blade is. That really didn’t sound like a good reason to climb a mountain to get that as wisdom. But I believe those two things really made an improvement. Here’s how I applied them. First I got rid of the laser. Then I would extend the blade in the tightest fitting gate until the tip was at center of the blank, which means you will start the cut above center. 223828 I made sure the chosen blade was sharp by hitting it a couple of times with a dimond hone. Then begins the hard part. I spend a considerable amount of time positioning the gate where I want the cut to begin. The blade should at least match the curve of the blank or even be a little tighter. Looking down on the blank/gate with the blade sitting on top of the blank and positioned were you would like the cut to end in the bottom, line up the gate so the posts are visually on either side of the blade.223829 Then pull the blade back while keeping it in line with the gate posts this will give you an idea to the starting point. 223830 Now spray something on the blade and posts like WD-40 and start the lathe. Faster is not better, 500-600 RPM is enough. You have to develop some control. This thing more than once took my 2 HP PM 3520b to a belt sqealing stop or ripped the blank off of my Talon chuck. As you start the cut, I find with most wood the result is nice curls and the blade will almost pull it self into the cut, hold back, don’t let it start hogging. After you’ve cut in about an inch stop and look at the curve of the bowl and the blade and ensure they are about the same or in the case of a shollow bowl the curve of the bowl crosses the curve of the blade (iaw the blade is cutting shallow). This takes a good bit of visualizing, and is not that easy to do, so do it often as you progress through the bowl. Up until now life is good, but when you turn the curve at the bottom, things seem to change. Just as with a bowl gouge, the McNaughton blades don’t like that turn at the bottom. Some wood I did would screech loudly and cause lots of chatter. Some would behaved nicely . But this is when the blade can start a path futher in by cutting sideways and putting the blade in a bind and cutting bottom out of the bowl. I’ve learned to feel the inside core and not push much on the blade. I will often pull the blade out to clear chips and dust and visualize the tip on the inside core. This seems to really help keep you on track. As an imaginary line runs down the handle to the center of the bowl, the core is almost cut. Look for changes in sound will indicate you’re almost done. The core if cut through will come out fairly quickly, so try to stop and break it out when you have 1 inch or less holding the core. Some of the DAMP folks made an observation that a good turner will get the hang of it faster. I feel that are correct. I was not ready for this thing 16 months ago and feel I’m just barly ready now. Most of these cores are from this weekends work. My little trailer is full of chips from the effort. All in all I like the results the cores are shaped nicely and if you do it right the cutting is almost effortless. Just don’t become complacent, stop the lathe and visualize, study your progress and you can save wood and your temper.
This is result of cutting too deep and shows how the blade binds and cuts sideways. 223831
These are from not keeping up with the blades progress and making lampshades:223832223833
These are mostly from the weekends coring, some are from weeks past, I still feel I need at least this much more in practice!223826223827

[Reed Gray]

Josh,
You do have the old style blades, and tool rest. It is my favorite tool rest, and least favorite blades. The spear point blades are a big step up in ease of cutting, mostly because the cutter centers on the blade rather than being off to one side. It will get smoother.

robo hippy

[Josh Bowman]

Reed, thank you. You have been a great help with this process.

[Peter Elliott]

I noticed that too and read (maybe from Kel) to grind those to a point. It's about 45 degree point with a 15 degree rake (give or take)

223839

[Jim Burr]

Great write-up Josh! I really want to get into coring this year, and although the shapes are limited, I'm getting more fond of the Oneway system. From the looks of things, you've got the hang of it!

[Steve Vaughan]

Josh, thanks for all that info. It's very helpful to me. I've got the set but have used it only a couple times and your information is gonna be helpful to me to get that set out and give it another try. I ran across this guy's site some time back. He's got some pics showing how easy it is for some folks. Some of ya'll probably have already seen it: http://www.wonderfulwood.com/articles/bowlcoring.html

[Kathy Marshall]

You've been busy Josh! Sure looks like you've got the hang of it, lot of nice cored sets you have there!

[Reed Gray]

Peter,
In your attachment, the picture if the new point is correct, the illustration is not. If you look closely at Josh's third picture, you can see that the inside curve of the blade goes straight, and the cutter is dog eared off to one side, and not centered on the blade. This makes it impossible to correct your cut to the inside. Personally, I grind the spear point down to a square tip. Mostly it gives less cutting surface in the wood at one time, from slightly over 1/2 inch to about 3/8 inch. Mostly less cutting pressure. The idea with the spear point is that it makes it easier to cut a core all the way off as opposed to cutting down till you have only about a 1 inch tenon and breaking it out. If you core end grain, burl, or crotch wood, if you try to break the tenon off, you can rip right through the bottom even if it is 3/4 inch or so thick. Been there, done that, more than once. The main problem with cutting the core all the way off is that with cutting pressure, and flexing of the blade and tool rest, your cutting tip is considerably below center by the time you get there. Just try to remove the remaining stub and you will see what I mean. You can raise the tool rest to compensate, or (warning, professional trick, do not attempt!) I drop the handle slightly to raise the tip. When you have done a bunch, you can feel when the tip is too low. The spear point is better suited for fish tailing as Mike called it in his first coring video. I don't do that, but plunge straight in, and if I have to correct the aim, I come back up and take some extra off the inside or outside.

robo hippy

[Dan Hintz]

Josh, thanks for all that info. It's very helpful to me. I've got the set but have used it only a couple times and your information is gonna be helpful to me to get that set out and give it another try. I ran across this guy's site some time back. He's got some pics showing how easy it is for some folks. Some of ya'll probably have already seen it: http://www.wonderfulwood.com/articles/bowlcoring.html

Steve,

That's Grumbine's site... I've asked him to help me with some coring this weekend when I travel up there to pick up my Robust. I'll let you guys know if there are any revelatory moments for me...

[Russell Eaton]

I have had 1 try at the McNaughton and managed NOT to make a lamp shade. I am going to wait till Reed's video shows before I do any more. I have several real nice ambrosia maple blanks with some nice spalting in them, and just don't want to mess them up. I enjoyed this take from another person. I went very slow on my first try, and even readjusted the cut, it came out pretty well.

[Richard Jones]

While not a substitute for Reed's great video, this newsletter has some good info: http://www.rmwt.org/newsletters/2012-newsletters/rmwt2012-02.pdf

I have a 3-day weekend coming up, and I am going to try a marathon rough-out session, complete with coring.

[Josh Bowman]

Richard,
I believe a 'marathon' is the correct way to go about this. Reed will tell you that it takes lots of practice. I agree and still am not ready for an expensive piece of wood.....but I think I'm close. What I didn't and couldn't show was the number of failed attempts. One of the two I did show was my last core yesterday, so I still have some to learn. However, I knew that core would give problems since it was so small and shallow.
Not trying to monopolize the thread, I left out something that I think is helpful. I started coring in the order that Reed does. I put a reverse tenon in the top center and take the large bowl first. If you watch what you're doing, you will at least get the largest bowl out, and at worst it will be too thick and leave you with a shallow core.

While not a substitute for Reed's great video, this newsletter has some good info: http://www.rmwt.org/newsletters/2012-newsletters/rmwt2012-02.pdf

I have a 3-day weekend coming up, and I am going to try a marathon rough-out session, complete with coring.

[Baxter Smith]

Interesting read Josh. I have come close to picking up a Mcnaughton a couple of times when they have been offered here but can't justify the extra cost in my mind!(yet):)

[Mike Cruz]

Josh, and Reed...some help please...

So, after my wonderful first try at coring, I thought I'd head to the shop and try my hand at it some more. First up was a 13" x 4" cherry blank. I hollowed out the center (forgot to do that Sunday), then started on my core (this was going to be just two bowls). All went well, except for the fact that the inner bowl was more like a plate. And it was so thin (1/2" or so) that after drying, I'm not sure there was enough to make a tenon and return it. So, I ended up with a bowl. No biggie, still got a bowl out of it, and I still have another blank.

Second blank up, 14" x 6" Cherry. Again, I true up the tenon, and it runs remarkably true when chucked up. This one is destined to be 3 bowls. I marked the three rings. I hollowed out the middle (hey! I remembered again), then started my cut. Everythings going great, curlies, not jambing, then POW! the blank flies off the lathe. I pick it up and the little inside bowl (that was more than 1/2 way cored already) is split in half (half still on the blank, and 1/2 laying on the ground). So, I clean that all up, and start the next bowl core. Still can get two bowls out of it, right? I got catch after catch. Everything is going great, then POW! I started to doubt my tenon, but I don't think it is that. I mean yeah, it came out of the chuck like 4 times, but two of those times it cracked the tenon! So, after the first cracked tenon, I recut a tenon. After the second cracked tenon, I decided to call it, and yet again, ended up with only a bowl.

Whether or not the chuck was holding the tenon stong enough was not the issue. Why I kept getting catches is. Just before the last attempt, I though...okay, I'm going to make sure my kerf is good and wide. It was, but the catch comes out of nowhere. I know I was at center, checked it with no blank on there and I was dead center on the spindle, then with the blank on, and still dead center. Everything seemed to be moving smoothly. I wasn't binding the cutter. It would just dig in deep really fast.

My collegues have suggested that it might be a burr on the cutter that is causing the catches. If that is so, what is the best way to get rid of the burr. Josh, you mention that you use a honing stone to make sure it is sharp. Can you go into detail into how you hone it? Which surfaces you hone and in which direction? Pics are always welcome.

Oh, and Josh, GREAT review. That was very helpful. I think I have the setup, feel, and visualization of the cutter head down okay. It is just these stupid catches that are getting me. Thanks.

[Josh Bowman]

Mike, again I'm new at the coring game, but I have had the lots of catches, Reed even kept one on his DVD! Here's what little I know. At first, I used my Talon with #2 jaws, I feel they are not big enough for a large 10" or greater bowl. So I now use the #3 jaws and even make the tenon large enough so the jaws are about 1/4" to 1/2" from closing. I tighten them and stop often and retighten them. But that's only part of the problem. I find with certain wood, like the Hickory, when you start turning the curve at the bottom, things get grabby. Some Oak has acted that way as well. The other wood I cored this weekend which is a mystery wood right now (I was told it was Oak, but it has a closed grain) it cored very nice all the way. When I start getting the vibration and dust coming out, I pull the blade out often. Some times the grab is from too much dust building up as your turning toward the bottom, I really feel that. As I mentioned I've locked the spindle during my weekend coring! That really makes bad words be said! As with any scraper you need to ensure you're on center line when you're fully extended. I often even kind of pull back on the handle so it takes small cuts. Other than that, as far as my experience that's all I can do. And often just grit my teeth! Remember though the blade should never bind, it should move in and out freely while the lathe is turning.
As far as the honing, I grind with my D-Way wheel to replicate the angle from McNaughton, then I have some cheap diamond hones, the Green, Blue and Red ones you get from Woodcraft cheap when they are on sell. At least at the beginning and more if the wood is acting up, I stop and hone, keeping the little diamond strip on the heel and tip, I have been going from coarse to extra fine, but the last I did I only did the coarse and it seemed to cut better. But all I do is keep it flat as possible on the heel and tip and rub back and forth. I then check the sharpness by touching the tip to my thumb nail and if it catches, it's sharp.
As violent as this all sounds, most of the time I'm able to just lean against the lathe and put slight pressure on the butt of the handle, it's just again some woods are not core friendly.



Josh, and Reed...some help please...

Everythings going great, curlies, not jambing, then POW! the blank flies off the lathe.

Whether or not the chuck was holding the tenon stong enough was not the issue. Why I kept getting catches is.

My collegues have suggested that it might be a burr on the cutter that is causing the catches. If that is so, what is the best way to get rid of the burr. Josh, you mention that you use a honing stone to make sure it is sharp. Can you go into detail into how you hone it? Which surfaces you hone and in which direction? Pics are always welcome.

Oh, and Josh, GREAT review. That was very helpful. I think I have the setup, feel, and visualization of the cutter head down okay. It is just these stupid catches that are getting me. Thanks.

[Richard Jones]

Josh,

I've done these "marathons" before, and really need to get some stuff roughed out as soon as possible. I have a bunch of cherry and walnut blanks that need attention or I'll have to turn them all into boxes instead of bowls!

Pics maybe later this weekend if I'm not all done in.............................

[Mike Cruz]

Josh, I was coring wet Cherry. I wasn't getting any dust, and catches happened 1/2" in to 2/3 of the way in. Oh, and my tenon was 5"+ and I was using a Stronghold Chuck.

So, when you hone, do you hone the bevel and/or the top (flat) part?

Reed, any advice you can give would be appreciated, too.

[Rich Aldrich]

Nice post Josh. I have one but have had similar issues. I was going to wait until I get a laser, but this is a good way to start without one.

[Reed Gray]

Well, it could be a lot of things. I never hollow out any of the center. Just in case I aim a bit shallow, it leaves me some extra meat for my core.

Breaking tenons or recesses can be a couple of things. Undersized is probably the main one. I prefer a dove tailed recess. An adjustable wedged joint is very strong if the mating surfaces fit very closely in diameter and angle. My big Vicmark is 2 5/8 inch diameter and is fine for bowls up to about 16 inches. For tenons, you want about 1/4 the diameter of the bowl minimum, and again angles and diameter should match closely, though when turning green wood, you have to oversize to account for shrinkage, or have smaller jaws you can remount with later. Depth wise, I never go beyond 3/16 inch. The extra is not needed. If the wood is soft or punky at all, I generally won't bother. Very hard woods like Osage, or locust can tend to crack off much more easily than softer woods. I would guess it is because the wood tends to be more brittle, and breaks rather than bends with the stresses. Also, you can over tighten to the point where there is so much stress on the wood that any extra stress can cause failure. Snug it up in each key hole a time or two. I do orient the jaws at 45 degrees to the grain, rather than 2 jaws on end grain, and 2 jaws on side grain. It makes a small difference.

As for catches, some times they just happen, and I am not sure why. If you have a rigid hold on the tool, that seems to make it catch more. If you are pushing it into the cut, that tends to make it catch more. It will self feed, and almost no pressure is needed. Let the tool cut at its own pace. I have experimented with speed a lot. Slower speeds seem to dig in more. I figure that is mostly because the tool is feeding faster than it can cut. I core around 500 to 800 rpm, maybe some times higher, though I don't have any rpm read out on my lathe, and never have, so can't really tell you there.

I do like to be slightly above center. There is flex designed into the system, and as with all scrapers, they are safer when cutting slightly high. By slightly high, maybe 1/8 inch or so.

Another thing, and this tool a lot of getting used to, is keeping the blade up against the top of the T part of the tool rest, or the top of the square tube on the Mark 8. We are used to holding the handle down on almost all other gouges and scrapers, which becomes second nature to us. With the McNaughton, you raise the handle till contact has been made with the top of the tool rest. This is not 'normal' to us. If you hold the handle down, it doesn't take much force on the cutting end to dig in, and you can not support it very well with just the handle. Note Bill's extra long handle on his short video using the tool. If you are holding the handle down, this is the same as holding a scraper handle down and point the cutter up into the spinning wood, and that will make it dig in deeper, rather than falling out. The Mark 8 has a through bolt that goes under the blade after it is positioned to keep the handle up against the top of the tool rest. This is great for beginners to 'remind' them to keep it up. Of course, you have to use it. I learned without it, and don't find it necessary.

Sharpening is using a coarse diamond hone on the face of the bevel. DO NOT HONE THE TOP OF THE CUTTER!!!!! There is a very thin veneer of hard metal on it which is the cutting edge, and you can hone that off and your tool will not cut. The burr on the cutter is minimal, and it does the cutting. This burr is not the sturdy type like I use on my scrapers. A few swipes up the bevel are fine, and a coarser stone makes a more sturdy and long lasting burr. I just take mine to the grinder and kiss the bevel lightly.

Start with the standard set of blades, and 10 to 12 inch diameter bowls. Much easier to learn on than 14 inch bowls.

To select the proper blade, I form the outside of the bowl first, then pick the blade that is closest to that shape. For 90% of my bowls, this is the medium curved blade. I would like to see one blade between the medium curve, and the tight curve. It would fit my bowl shapes better. The bowls, at least for me tend to get flatter as I go in.

10,000 more times!!!!!!!!!!!!

robo hippy

[Mike Cruz]

Thanks, Reed. From what you are saying, I'm doing pretty much everything right. However, I might be gripping the handle too tightly. The only other thing I don't do/haven't done, is hone the tip. Maybe that's the key. My tenons are plenty big. And I want to be clear that I understand that you get catches now and again, but when that catch either dislodges the blank, or ruins one of the cores by splitting it in half, that's another story. I'll give her another go next time I get a chance...

Thanks for all your input.

[Reed Gray]

If you are half to 2/3 the way in, the catch could be amplified by chip build up, and/or the blade binding in the cut because of drifting. I have split the rim of more than one bowl by having a sudden shaving jam. Usually, if the blade is binding, there is smoke, and/or steam coming out as well. I can't say that I have ever split a piece in half. My only guess there would be that the piece already had a hair line crack in it, and that was the main reason for failure. If you are having to fight the core at all, there is some thing wrong.

robo hippy

[Mike Cruz]

Aboslutely agree with you that if I have to fight it, there is something wrong...I'm just trying to find out what. ;) The cracked in half core was when the blank discharged from the chuck and was likely snapped in half by the tool. The log was sealed within 24 hours of cutting. Cut into slabs and sealed immediately.

I have a feeling that there are two culprits: One, a clog of chips, even though I wasn't aware of any (and upon inspection of the blank, there was an obvious dig into the wood), and Two, when I set up the tool and turret (tool rest), I set it up in the middle of the blank, but not with the blade extended. So, next attempt, I will set it up with the blade extended, clear chips often, and really take my time. I'll keep ya'll posted with my progress.

Oh, and thanks, Reed, for your help and advice. They are greatly appreciated.

[Peter Elliott]

Peter,
In your attachment, the picture if the new point is correct, the illustration is not. If you look closely at Josh's third picture, you can see that the inside curve of the blade goes straight, and the cutter is dog eared off to one side, and not centered on the blade. This makes it impossible to correct your cut to the inside. Personally, I grind the spear point down to a square tip. Mostly it gives less cutting surface in the wood at one time, from slightly over 1/2 inch to about 3/8 inch. Mostly less cutting pressure. The idea with the spear point is that it makes it easier to cut a core all the way off as opposed to cutting down till you have only about a 1 inch tenon and breaking it out. If you core end grain, burl, or crotch wood, if you try to break the tenon off, you can rip right through the bottom even if it is 3/4 inch or so thick. Been there, done that, more than once. The main problem with cutting the core all the way off is that with cutting pressure, and flexing of the blade and tool rest, your cutting tip is considerably below center by the time you get there. Just try to remove the remaining stub and you will see what I mean. You can raise the tool rest to compensate, or (warning, professional trick, do not attempt!) I drop the handle slightly to raise the tip. When you have done a bunch, you can feel when the tip is too low. The spear point is better suited for fish tailing as Mike called it in his first coring video. I don't do that, but plunge straight in, and if I have to correct the aim, I come back up and take some extra off the inside or outside.

robo hippy

Reed, I got that info I think off Kel site. So if I am reading correctly, you like square edge? Do you narrow that kerf at all?

Also, there are 2 versions of tools if I am correct. The older ones are solid carbide tips welded on to the blade. The latest style has the veneer of carbide welded on top, which is why you leave that alone.

I know my blades do not have the carbide veneer and appear to be solid carbide ends.

[Pat Scott]

How big is your tenon? On a 14" bowl I like to have minimum of a 5" tenon, and make sure it's deep enough also (almost as deep as your jaws).

What speed are you turning? 500 rpm is what I use. Is the cutter at center?

If there is a burr you can take a hone or flat slipstone to the top of the cutter and knock it off.

Make sure to withdraw the cutter often to clear shavings. It's amazing how fast they can build up and bind the cut.

The only time I've had a bowl come off is when I pushed it and used too small of tenon. I didn't think it would work but thought I'd give it a try. Never had one split like yours, if there is no knot, maybe just an internal stress in the wood ("tree shake"). If you've cored other bowls successfully maybe it's the wood instead of you or your technique. Maybe that piece is telling you to stop trying to core it and just turn away the inside?

[Mike Cruz]

Pat, the tenon was over 5". And about 1/2" deep.

I was turning at 600 rpm. Cutter was at center, but at center with the turret up close to the blank...I didn't check it with the tool extended. I will do that next time.

Um, everything I've heard says don't do ANYTHING to the top of the cutter...but yes, I will begin to hone the burr.

When I say that a core split, I was taking the inner cores out first, so the one that split was about 8" in diameter. It happened when I was about 2 1/2" into my core and got a catch...dislodging the blank from the chuck with the tool still in the kerf. So, "something" had to give, and it wasn't going to be the steel that was locked in place. That is why the inner core snapped in half.

I do appreciate your input, help, and advice. Thanks.

[Pat Scott]

Wow, good one then. 2-1/2" deep isn't that deep that I doubt shavings building up are the culprit. Don't let the tool handle drop down (which raises the tiip). Yeah I've read the same things, that you're not suppose to touch the top of the cutting tip, but how else do you remove a burr? I assume your tool was sharp, for me the sharper the better. When the tip gets dull, not only do I have to push harder, but if the tip does catch it seems like a sharp cutter will cut through the catch whereas a dull cutter stalls and catches. Hope that made sense.

I hate coring honey locust, it seems to catch and stall my lathe no matter what I do. Never cored Cherry before but it's a softer wood than locust, more like Walnut. I've cored a bunch of Walnut and it's OK as long as I clear the shavings.

Maybe double check that the cutter tip is on center? Do you have another piece from the same tree/log to see how it behaves?

[Mike Cruz]

I HAD two pieces from that log...the first cored just fine. :rolleyes:

Yes, Cherry and Walnut are very similar. So you would expect them to act the same.

I've been very vidulant to keep the handle up. When I got the catches, there wasn't a SLAM form the tool, then the blank...it was immediately the blank. And I was getting the catches right off the grinder... Maybe the wheel I was using is too coarse...

[Reed Gray]

I never saw any solid carbide tips, all that I have seen are the veneered type, and I have no idea what the metal is, and never saw tips that were welded onto the blades. The veneer is maybe 1/64 of an inch thick, or thin. The Woodcut blades do have Stellite (another very hard metal that can be sharpened on standard grinder wheels) brazed onto the blades. The Oneway system has removable tips, and I have no idea which type of steel they are. Mike Hunter can retip your blades for you as well. He did an experimental one or two for me. One had a long carbide tip that screws in. I didn't like that one. The other he did for me had a 3/8 inch square piece that screwed on, and made a triangle tip (one corner of the square points forward, so you can use till dull, then rotate).

I have never honed the old burr off before putting a new one on. Never noticed a need for that. DO NOT HONE THE TOP OF THE BLADES! Only the face of the bevel.

By grinding down to a square tip, you reduce the cutting surface, and over repeated sharpenings, you do lose some width of the blade till you have ground to the end of the veneer. I will be looking into brazing some tantung or stellite onto the tips of some of my blades. One thing for sure, the cutter needs to be tapered to travel through the cut. The square tip has considerably less tendency to clog with shavings than the spear point. Once you open up the kerf wider than the blade, the shavings seem to clog even more. Not really sure why.

robo hippy

[Peter Elliott]

This is one of mine, no paint on the entire blade. It's the large blade system. My painted ones have the carbide veneer like you mention.,

224013