McNaughton Tool Post

Re: McNaughton Tool Post

Dave Paine

The EBay auction description stated the post was turned down to 7/8in (0.875in).

This looks just like my McNaughton tool post. The older design.

The space between the sets of pins are different for the different knives.

The two pins on what you refer to as the riser are for the medium knives which are not as deep as the full size knives.

The two pins on the lower part have wider space to accommodate the thicker and deeper full size knives.

Re: McNaughton Tool Post

Barry Irby

I think Dave nailed it. I believe I have the same post. Its one of the earlier posts. I suspect the Post itself is interchangeable, but you better check with McNaughton if you need a different size. Works with whichever knives will fit snugly between the posts.

Re: McNaughton Tool Post

mikeee12345

I measured the diameter of the post and it is right at .80" so it has a little play in it,

I will see if I have a 7/8" banjo laying around and see how it fits, I might get a 1 x 7/8 sleeve

or a 1x 3/4" sleeve and drill it out for a snug fit.

If anyone has any knives that they are not using let me know I would be interested in what you have.

I will either forge a couple of knives or purchase a couple of new ones, thought I would check with everyone here first.

Re: McNaughton Tool Post

Brad Vietje

Yup -- that's the original version, same as mine from about 2001. The tool post can be swapped out for one that fits your banjo -- usually 1". That might be better than trying to use the smaller post -- there can be a lot of stress, depending on what you core, and how big.

The first-generation knives did not come to a point as the newer ones do, but widened to a cutting tip with an angled (but straight) cutting edge. When the newer knife design came out, a lot of people re-ground their knives to get close to the newer (and better) shape.

I only have the largest set of 3 (2 curved, one straight), and wish I had the medium set (small knives came out later). My dad ordered mine from Woodcraft with the medium knife set, but they screwed up and sent the large ones, instead. Passed on to me when he died in 2004. If you find someone with a pile of the old style medium-sized knives, I'd love to get a set.

Safe spinning,

Brad Vietje

Newbury, VT

Re: McNaughton Tool Post

mikeee12345

If I pick up some tool steel to make knives with, what would be best dimension to source

for making the knives? thickness & width?

Re: McNaughton Tool Post

Dave Paine

I have only tried bending 3/8in dia O1 drill rod so far. I used a friends hydraulic press to put a 45 deg bend to make some hollowing tools. This was much more of a challenge than I expected. We bent this cold.

O1 has a much higher yield strength than mild steel. Other tool steels may have greater yield strength than mild steel.

The McNaughton knives are a type of mild steel with a thin HSS cutter brazed into the ends. I can understand why this is done. Bending the steel takes a LOT of force. You need to exceed the yield strength of the metal at all points where you want it to bend, or you will get a series of flat and bent points. You will need at least a mandrel for the inside diameter, a bit smaller diameter than desired to allow for spring back. A piece of thick wall pipe of relevant diameter may be the easiest way to make a mandrel. You will also need some curved piece/mandrel for the outside diameter which makes contact at least on the outer edges ideally the entire OD.

I checked my knives. All are about 1/4in thick. The medium knives are 1in deep. The full size are 1 1/4in deep.

I use the medium knives more often. The full size knives are for larger blanks. Not sure of the diameter but may be 14in + dia.

If you want to make your own knives I would use mild steel and braze a piece of a 1/16in HSS parting tool in the end, or drill and tap for a triangular carbide insert.

The knives are meant to be bent to be part of a circle. I will check the diameters. I do not know off-hand.

Re: McNaughton Tool Post

mikeee12345

I was considering using a length of HSS and annealing the entire piece in a forge and then heat treating and hardening the cutting end of the tool. I was thinking this would allow some flex in the body of the tool and provide a hardened cutting end that could be resharpened and hold an edge. This would eliminate having to braze a piece of hardened steel to the tool which takes time, materials, tools to complete the task. I have a heat treating oven at work that I can use to anneal the pieces of HSS.

Re: McNaughton Tool Post *LINK*

Dave Paine

I have not tried to anneal HSS. I have read that it requires good temperature control and ideally an atmosphere to prevent decarburization which would impact re-hardening the end.

I would try to anneal a short section and then determine how easily the annealed tool steel can be bent. If it is like my O1 drill rod, it will take a lot of force. It is not easy to get a smooth curve.

A lot of work to make a knife. Lee Valley sell the McNaughton knives. Your tool post will use the standard (what I called medium) and large knives.


http://www.leevalley.com/US/Wood/page.aspx?p=49128&cat=1,330,49233,49232&ap=1

Re: McNaughton Tool Post

robo hippy

Making your own blades is a complicated process. I have been trying.... 1/4 inch cold rolled steel will work. The problem is in the bending. The industrial approach for getting a perfect arc of a circle is to bend the piece a couple of inches longer than you need, then cutting off the tip. Getting enough leverage at the tip to bend it is very difficult. If I was going that method, I would bend it as close as I could, then use a hammer or brake/press to get the tip closer. From my attempts, I think it would be easier to bend the tip more than you need, then put it over a form and pound it to perfect. Ideal for me would be to find a laser cutter that does tubing, and program it to cut the entire profile, then pound the tang flat. Much more simple. Next, you need a cutting material. I use Tantung (google Big Ugly tool) which needs to be silver soldered to the blade. I think it works better than what Kel uses. I sent him some to play around with, but haven't heard back from him. If you try the bend your own method, you need a heavy duty bender. Think rebar bender/cutter where you have hardened steel, and a long handle. It really takes a lot to bend this 1/4 inch bar stock. I have 2 bolts, 5/8 inch diameter, set with about a 3/8 inch gap, and sitting in some hickory. I can fine tune the blades, but not do the whole bend by hand, and I am on the Brute Squad. I have no idea about heating to bend, or tempering, or annealing, or exceeding bending limits. All of the arcs for the blades are supposed to be perfect arcs of a circle. If the bends aren't perfect, all the way to the tip, they drift as they cut rather than staying on track.

The old style blades had the cutter dog eared off to the outside of the blade. The newer blades have a spear point that is centered on the blade. This was a huge improvement.

robo hippy

Caution, get the heat treat wrong and SNAP!

Dick Coers

With the amount of overhang on these coring knives, a brittle knife is going to snap off in the blank. And it just doesn't snap into two pieces. You'll get shrapnel!

Re: McNaughton Tool Post

mikeee12345

Thanks Robo,

You turn a lot of wood how would you compare your time with coring a bowl blank with traditional

turning tools compared to using a McNaughton system? You have to set up the tool and measure

your bowl blank and mark your entry points etc. With a sharp tool you can remove a core quickly

but loose the core of the blank in wood shavings on the floor. For a production wood turner not

concerned with saving the core is there much of a difference in the time it takes to remove the core

between both methods?

On highly figured and segmented billets is the main reason I want to use the McNaughton.

Re: McNaughton Tool Post

robo hippy

I figure the time savings is mostly on turning the cored pieces since you have the shaping done, and all you really have to do is refine the shape a bit, then finish cuts. It takes a bit of practice to become proficient with this tool. I don't core below about 10 inch diameter, and 4 inches deep. I end up with too many tiny bowl blanks if I do... If I just turned out the inside, it would take maybe as much time as turning a 3 bowl cored set, maybe a little less.

robo hippy

Re: McNaughton Tool Post

mikeee12345

That certainly would speed up the process on the cored blanks.

Any recommendations on size of chuck or type for holding the bowl blank when using the McNaughton?

I would assume the McNaughton system puts a fair amount of torque on the billet.

Not too much fun moving out of the way when the billet leaves the chuck. :-(

My reflexes are getting a little slower as the years go by. :-)

Re: McNaughton Tool Post

robo hippy

Check out my videos, one on mounting things on the lathe, one on the McNaughton, and a host of others, You Tube, type in robo hippy

robo hippy

Re: McNaughton Tool Post

mikeee12345

Robo,

I have watched a number of your video's.

Plenty of excellent information in each video.

Your new video's always pop up on my recommended video's.

Thank You for sharing the knowledge you have amassed from the endless hours on the lathe.

Those video's take a lot of time to produce, record, edit, sound track, upload etc.

Re: Caution, get the heat treat wrong and SNAP!

mikeee12345

Many years ago I worked in a tool and die shop where we built punch press dies from scratch.

We used a lot of tool steel and heat treated a lot of parts.

We always used a Rockwell Hardness tester to check the hardness of the pieces.

Re: Caution, get the heat treat wrong and SNAP!

John C Lucas

Its pretty easy to anneal tool steel to a hardness that isnt brittle. You can buy temple sticks or other ways to know exactly what temperature you have heated to. Ive been tryiny to do some research on making springs and finding out what kind of steel and how to temper it. Don,t know if a spring is what you want for coring bars. Would it be better if a bar broke, bent ,or sprang back to shape. Obviously it would be best to not get the catch in the first place.