McNaughton Newbie

Discussion in 'Newbie' started by Marshall Sadler, Oct 26, 2017.

  1. Marshall Sadler

    Marshall Sadler

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    I just got my new McNaughton in the mail today. It is the standard size. I also received and watched Mike Mahoney's video on the tool. I have used it twice and have some questions.

    1) It seems that my blades don't slide very well in the posts. Do the blades need to be "broken in" so that they will slide better? Could some light 320 grit sanding help?

    2) My first core was on some Cedar that was AnchorSealed in February. I then tried some dripping wet Walnut. When coring the Cedar, the McNaughton was extremely loud. I am sure that the tool was not rubbing anywhere. The Walnut was better, but still louder than in Mahoney's video.

    3) It feels like I have to open the kerf a lot for the tool to work well. I have had a good time aiming so the open kerf is not from readjusting. Is a big kerf normal/needed for a beginner? I have watched robohippy's and Dale Bonertz's video on the McNaughton. They don't have to open the kerf as much. Does a smaller kerf come with skill or am I doing something wrong?

    Thanks in advance,
    Marshall Sadler
     
  2. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I'm not very proficient yet, but it takes some practice and using a light touch and low speed. There is another new thread on the McNaughton center saver where I described what I did to tune up the blades. I also wax them.

    As beginners, we're definitely not Mike Mahoney nor Dale Bonertz. So, wide kerf and not many cores and not good shapes on the cores are just a part of learning. Practice moving the blades while coring air bowls to see where you are encountering problems. You might encounter binding if the blade isn't square to the guide pins. Also, the blades can catch or drag if it is against either side of the trap because the corners of the gate can dig into the upper edges of the blade.
     
  3. robo hippy

    robo hippy

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    It is difficult to keep the blade on track. On smaller cores, it is fairly simple. The problem is in the curve of the blades, and Kel McNaughton does not agree with me on this. The last inch or so of each blade goes straight rather than following the curve/arc of the blade. This is easy to see if you just look at it with a critical eye, or you can lay it on one of the plastic circle templates. So, as you go deeper into the cuts, the blade always drifts to the outside of the cut rather than following the curve of the blade. This causes binding, and is the main reason you have to open up the kerf. I do have one blade that I fine tuned on the bend, and went a tiny bit too far. It now drifts to the inside of a cut rather than to the outside. On a small core, it doesn't make much difference. On a deeper core where you are cutting in 6 inches or so, it makes a big difference. Start with smaller ones first, like 5 by 10 or 12 inch diameter and plan on getting 1 core. Then work your way up...

    One thing about walnut, for reasons I don't know, it always seems to dull all of my tools, including bandsaw blades, more than most other woods. Not sure what kind of noises you are getting, but keeping the cutter sharp is huge in how it cuts. A couple of upward strokes with a 220 grit hone makes for a better burr, and all coring systems are scrapers.

    robo hippy
     
  4. Bill Boehme

    Bill Boehme Administrator Staff Member

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    So far I only have two experiences with coring ... one was great and the other was unbelievably bad. Fortunately, the first coring was on a very wet piece of box elder and it lulled me into thinking that coring is a piece of cake with an undeserved bad reputation. The next time was with a piece of dry maple. The noise and vibration were unbelievable. It vibrated the banjo loose, it vibrated the tailstock loose, and even vibrated the handle loose from the coring blade. I haven't had a chance to try it again because I haven't been able to get any green wood for practice, not to mention having to recover from rotator cuff surgery and then back surgery. It may still be a few more months before I can give it another try, but I'll figure it out.

    Sometimes black walnut has a lot of mineral deposits that are tiny very hard abrasive crystals that can dull tools almost instantly. Maybe it has to do with the type of soil that the tree grew in.
     
  5. john lucas

    john lucas

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    Bill You described my experience to a T. I cored 9 Box Elder bowls. I bought the system because a lady brought me 3 box elder pieces and wanted large bowls for each of her 3 kids. I thought man what a waste if I just make the 3 bowls. She was paying me enough I purchased the coring system. I had watched Mike Mahoney and another guy core and thought I knew exactly how to do it. I cored all of the those bowls successfully and was patting myself on the back. So I started coring some walnut bowls. It fought me so bad I actually broke one of the cutter bars. I built my own bar and did what Reed talks about. I made it follow the curve all the way to the tip. I also had Mike Hunter retip the tool with one of his diamond cutters. Now it works great. I don't do hardly any coring any more but hope to get back to it to play some more. Maybe when that special piece comes along.
     
  6. Marshall Sadler

    Marshall Sadler

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    Thank you for all of your replies. The blade being out of square may be the problem. Looking at the Standard posts, I can see where the paint has worn on the right side of the "floor." This seems to indicate your diagnosis Bill. How does one fix this out-of-square? Is it just holding the tool differently or will I have to do some filing?
     
  7. robo hippy

    robo hippy

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    Bill, the problem with the dry wood is similar to the problem doing regular cutting and the differences between dry and wet wood. Mostly you just have to go slow feed/cutting rate, and keep a good sharp burr in it. My horror story was when I was coring some black locust, I had one of the first 3520A models which had a cast iron pressure plate under the headstock. I cracked it. I was turning slow speed and the headstock just tipped forward and came to rest on the lathe. I checked at the local Woodcraft Store, and PM had switched to a steel pressure plate. PM wanted to charge me for the replacement part. I politely informed them that they went to steel because the cast was failing and they were to send it out right away at no cost. They didn't like that, but complied anyway.

    My banjo does come loose from time to time. Most of the chatter comes from dull tools, and from the tip being too low. I start out with it a good 1/4 inch above center. If you set the height by using just handle pressure and your longest blade, that doesn't take into account what happens when the blade/cutter actually is cutting. There is a lot of flex in the blades and tool rest and if you start out at center height, by the time you reach the bottom of a 6 inch deep core, you are at least 1/2 inch below center. All coring blades are scrapers, and with scrapers on the inside of the bowl, you always cut above center or you can/will get nasty catches. I keep the McNaughton rest on a sleeve/collar that keeps that from vibrating loose.

    robo hippy

     
  8. Marshall Sadler

    Marshall Sadler

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    I sanded all of my McNaughton bars with 220 grit paper on all four sides, slighting rounding over the corners. I then put the 220 grit paper on my bed ways to square up the bars. I also squared off the cutter on one of my bars. It seems that it is harder to start the cut compared to the point. Once you get going with the square off one it is easier. All these modifications worked wonders for the coring experience. I successfully cored two 7 inch Walnut bowls tonight. Bill, you mentioned using wax on your bars, what wax do you use? I am guessing either paraffin wax or Johnson's paste.
     
  9. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I used Johnson's Paste Wax, but paraffin wax ought to be fine.

    I used a file to insure that top and bottom stayed flat. After using a fine pitch file, I used carborundum sandpaper up to 1500 grit and finished with metal polish. Here is a picture showing how the file was used.

    image.jpeg

    Here is a picture showing the blade square to the guide pins.

    image.jpeg

    And, another picture showing the blade binding between the guide pins when the blade isn't kept square.

    image.jpeg
     
  10. robo hippy

    robo hippy

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    The last set of blades I got were from when the Mark 8 first came out. Can't remember exactly any more, but that was when Kel started making the large set of blades from the same thickness of metal as the standard size. For the first number of years, and the first versions of the spear point tip, I believe the blades were cast stainless, so silver and shiny. Not positive, but I had some rather coarse carbide brazed onto some, which I later broke off, and under the shiny exterior, was a coarse particle metal, so that is why the guess of cast stainless. The outside edges top and bottom, had a 1/4 round profile (allows for a little better clearance in the kerf), and there were no milling marks. Those milling marks shown in the above photos need to be removed from the bottom if they are on there. There were many variations of stuff to put on the blades to help them slide through the gates as you cored, and to help with the inevitable binding that happens as you go in. WD 40, Pam no stick spray stuff which is canola oil, I used my walnut oil/wax pad from my finish, and then just generally didn't put anything on.

    As far as the blade binding in between the pins, I noticed early on that with the turret/pin base, which Kel designed to float, would automatically pivot and some what bind the blade as soon as the cutter engaged the wood. That is why I lock mine in place, flat spot or hole in the tool post and crank the set screw down tight.

    I keep thinking that maybe I need to make my own variation of this tool......

    robo hippy
     
  11. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Thanks for all your comments, Reed. I have had the same thought about locking the turret down. I couldn't see anything good about letting it float free.

    About the blade in the pictures, that's what it looks like after being filed and sanded and polished. :D You should have seen what it looked like before I cleaned it up. It looked like it must have been cut with a plasma cutter. The cut also isn't square to the flat side which is a characteristic of plasma cutting which results in a tapered kerf. So, that is the reason that one side of the blade in the pictures still has some ridges while the other side is smooth. The blade rides on the smooth side, but I'm not impressed with the lack of quality control. I like the idea of rounding the top and bottom and might round the corners a bit more than what I currently have.

    The large blades in the Mark 8 are the same thickness as the standard blades and I agree with you that they ought to be thicker.

    I reshaped the curve at the end a bit by grinding rather than bending, but it still doesn't quite have the same curvature as the rest of the blade.

    image.jpeg


    One other problem area is the back of the trap where the top corner of the blade can dig in. See picture below. If I had an extra pair of hands I could have held the blade while taking the picture so you'll just have to use your imagination. I plan to do some more filing and grinding to alleviate that problem.

    image.jpeg


    If you get around to designing an improved coring system I'll be your first customer. :)
     
  12. robo hippy

    robo hippy

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    I did send Kel some tantung and silver solder ribbon a year or more ago. They do make tantung in Australia. Haven't heard back from him. I am not sure what cutting method they are using for cutting out the blanks, or what metal they are using. I have some standard cold rolled steel around and it appears to be much more sturdy than what Kel is using now. My robo rests are laser cut from stainless, and the cuts are a lot smoother than that. No idea, but one worth investigating...

    robo hippy
     

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