McNaugton Center Saver

[Tom Keen]

Ive been interested in this tool for awhile and finally bit the bullet and ordered one. It arrived a couple days ago.

What a BEAST!. Ive managed to core a couple of roughed out bowls but I think Im on a steep learning curve. Two pieces of wood = 3 bowls.. guess thats better than 2 bowls :) I figured out how to adjust the height of the tool rest..pinched a finger tip and in general made myself really nervous...anyway:

My question:

Ive been reading about proper use (the enclosed directions stink), watched the video etc etc. One article I read suggested that with smaller lathes, I have a 1.5 Jet 1642..it might be helpfull to narrow the cutting tip 1/16"..ie smaller kerf..easier on the machine and the user.

Sharpening: Ive been honing with a diamond card..just enough to raise a wire.. anything else I should be doing?

and... I never thought 1.5 hp would be too small...at least not for awhile..

Thanks in advance for any help.

Tom

[Mike Vickery]

The curve really is not to bad. I will admit if I dont use it for a while I get rusty though. I dont turn much really small stuff so usually I will only take one core out of a bowl unless the original blank was pretty big, so your are not doing to bad.

I also just raise the burr with a diamond card. I do resharpen it on the grinder every once in a while when it needs it but you do not need to do that very often.
I did not narrow the kerf but I have a 2HP lathe so can't comment.

[Martin Braun]

A couple things I found (though you may already be doing or have found something smarter)...

) extend the tool all the way through the gate to the place where I think I will end up, and then adjust the tool rest so the tip of the tool is at the center of the spindle axis. (of course bring the tool back to the starting position to begin the core)

) make sure the tool is clean, sometimes a little extra WD40, or whatever else I have laying around helps it move more smoothly through the gate.
some folks have even run a water line or use a sports water bottle to flush the kerf while they core, though I have never tried it

) I try to advance the tool through the gate without too much force or flexing of the blade

) always keep the tool in contact with the cross bar on the gate.

) on particularly large pieces I will core off the outside bowls first. this way if I do get a catch it will have less of a tendency to throw the blank because the cutting edge is closer to the chuck (less leverage for the lathe).

) sometimes I run into wood that has a lot of internal stress, and the kerf will start to close up, usually in 2 spots opposite each other at the side grain. in that case, one has to go back & widen the kerf

I'm no pro, but that's what I've learned. Let us know what else you find works. I'll be coring this weekend, so if I think of anything else, I'll let you know ;).

[Christopher K. Hartley]

Congrats Tom! with all that wood you have you should have thousands of cored bowls in no time at all!!:eek: :)

[Jason Clark2]

The biggest help to overcome the steep learning curve was the Mike Mahoney video. IMO it should be required viewing for anyone who purchases the McNaughton system.

Personall I always work from the largest to the smallest, leaving the faceplate in place the entire time. The largest bowl is the money bowl and should be the primary focus. Coring 4 bowls out of the middle of a piece is great but it's not worth it if you ruin the largest piece in the process.

I leave the faceplate in place for a reason, with the bowl reversed and secured in a chuck I use a live center in the tailstock and insert it directly into the treads on the faceplate. That way the blank is supported from both ends.

Once the core is removed I true up the inside of the blank before removing it and the chuck from the lathe, threading the core, with the faceplate still attached, back onto the lathe to true up the outside and form a tenon.

Later, rinse, repeat.

http://www.fourcornerswoodturning.com/acaciaset.jpg
Jason

[Paul Andrews]

I assume you are using the standard set of blades. I have a 2 hp machine and have no issues using the standard blades. With the largest blade of the jumbo set, I can stall my lathe near the end of a core and have to back out and widened the kerf.

If you have not tried to core a natural edge piece yet, this may cause some issues. As soon as you start the coring you need to hold the blade back, and only allow it to enter the piece very slowly until the blade is in constant contact with wood. It only took one blank orbiting the shop to understand this concept!

Enjoy your center saver, it will save lots of bowls that otherwise would be mulch.

[Jim Becker]

Tom....I don't SEE any center-saver... ;)

(Congrats!)

[Kevin McPeek]

A few things I have found, I am by no means an expert so take what you will from it.
I find that frequently backing out to clear chips helps a lot. That is what seems to stall the DVR except when I just jam it in to quick.
I also widen the kerf a little by moving the tool left to right while pulling it out to clear chips.
Keeping the speed a little higher than I originally did seems to smooth out the cuts also. I core at about 400-500 RPM depending on the size of the core.
I haven't lost a bowl from the chuck since I went to power grip jaws either. I lost a few and tore off a tennon or two with the standard jaws.

Good luck and enjoy the free bowls.

[Reed Gray]

I have posted about this a number of times. If you want less cuttig pressure, I grind the spear point down until it is square. This gives you a 3/8 wide cutter as compared to a 1/2 inch wide profile with the spear point. The spear point was developed by Mike Mahoney. Its purpose is for cutting all the way down till you cut through the stub rather than cutting down till you have a 1/2 to 3/4 inch stub and breaking the blank out. This is helpful for crotch and burl pieces where the grain isn't running across the bottom. I have pulled through 1/2 inch thick bottoms with these types of grained woods. Make a collar to go around the post of the tool rest that will keep your blades at center height. It is the same for all the blades. Core until the shavings start to pile up, clear the shavings and cut some more. Cut until the blade binds. The blade will drift to the outside of the cut. I don't know why, it just does. Learning to correct for this is the biggest hurdle to get over in learning to use this tool. Come back to the top and remove a bit from the outside of the kerf. Come back to the top, and remove a bit on the inside. Bump the tool rest slightly to the inside. One or all of these can be used to correct for drift. I also always keep a little pressre on the handle pulling it towards me so that the cutter rides the inside of the kerf. Slight pressure only. I lock the gates down to the tool post. This makes it easier to remove a kerf on the inside of the cut. If you are having to force the tool, then something is wrong. Try to find some one local who has one and knows how to use it, and watch them. This really helps. Keep at it. It is a good tool and does work, but it has a learning curve.
robo hippy

[Martin Braun]

"The blade will drift to the outside of the cut."

I think this is due in part to the fact that the blades are not quite consistent in their radius. To me it seems they are getting the user to widen the kerf (to enable better chip ejection) by design if more than half the blade is used. Has anybody else noticed this?

[Reed Gray]

My hunch on the drifting is that the blades are longer than the other systems out there (Oneway and Woodcut). This allows them to flex as you cut. Try to take out the stub at the bottom of a cored bowl and you will see what I mean.

There does seem to be some inconsistencies with blade radius. This can cause binding also. Some day I will make a template for each blade and check, but I have only had one that was out of shape, and I could feel it. This is out of maybe 15 blades total that I have. The blades do bend with extended use, and a few catches. Most of the time it is a twisting bend which means you can put it in a vise and apply some counter twist with a big pipe wrench, or adjustable wrench. This can also cause them, when bent to be cutting a little bit under center. This isn't much of a problem until you get to the center. You can raise the tool rest, straighten the blade, or lower the handle (caution, this is a "professional driver on closed course, do not attempe" situation).

You can remove, or not even use the face plate. Drill a recess, or turn one out after removing the face plate. This way the chuck never has to come off.

I would like to think that I could make a core with one pass. Most of the time when I make a course correction it is inside of the kerf, not so much starting at the top. You do end up widing the whole kerf, but not by much. Well, not so much when you do get more accomplished with the tool.

As far as chip ejection, keeping the inside of the kerf smooth works best. Any bump on the inside can cause the shavings to clog up. This is why I don't use the fishtailing method (back and forth). If the kerf widens on the inside much, this can cause clogs. Some people make the opening of the kerf more of a funnel shape to help with shaving ejection. I have tried this, and haven't noticed any difference.

With the old style blades, I did grind off the ears on them to make a smaller profile. I would end up taking a double cut to get a wide enough kerf to go all the way down.

Most of the time, I can make the entire cut without having to bump the tool rest to the inside to correct for drift.

I have one of the laser pointers that McNaughton makes. I really like this. Over years of using the tool, I developed the habit of aiming slightly shallow. It seemed like I was always ending up 1 inch too deep, or 1 inch too shallow. If I aimed shallow, I might lose one bowl to depth, but none to lampshades. Now, with the laser pointer, I know exactly where I am, and I can aim for the perfect core every time. If I am off course, I can see it, and correct.
robo hippy

[Tom Keen]

This is great infomation.. really appreciate it! Had a little better luck today. I got through a cherry blank with only small catches and never stalled the lathe.

What I did different. I sharpened the blade (very lightly honed on the 120 stone) I widen the kerf and went really slow. Whenever the shavings stopped flowing I stopped and cleared the kerf.

The shaving seem to be stalling at "the bend". I think Ill focus on making sure this curve is smooth and widened.

It was really nice to have the second bowl (so far Im five bowls from three blanks!) It was expecially nice to see a smaller pile of shavings on the floor.

Thanks for all the help... keep it coming.
Tom