Coring with the mini Mchaughton on a Delta 46-715

[Bob Opsitos]

I decided to pick up the mini mcnaughton for xmas from Lee Valley. I figured with their return policy if it proved unworkable on my lathe (14" swing 3/4HP) I could always send it back. At least that was the thought, turns out I need to cut the post length to bring the cutter to centerline before I could even try it.

So far I've cored two blanks:
One in some dry wormy maple starting out at a 9" blank and another blank of what I thought was maple but is more open grained (ash maybe?) that was a little over 10". That one wasn't dry yet.

I got one inside bowl out of both using the tighest curved knife. It wasn't a bad process at all. I think I would have been less concerned had I not read all the horror stories; every time it would make some noise and such I was expecting it to jump off the lathe and maul me :D. I would have gotten more bowls out had I been less paranoid and cored out the larger bowl initially thinner, rather than leaving it thicker on the wormy maple bowl. But hey it was my first time using it.

I was higher up in speed, maybe, 700-800RPM, which Bill Grumbine's video segement on the Mcnaughton, recommends. Didn't get a ton of streaming shavings, but a combination of dust and smaller discontinous shavings.

I'll get around getting pics once I finish the bottoms of the wormy maple bowls.

Thanks
bob

[Bob Hallowell]

Bob,
did you run into any problems with your lathe not having enough power? I was under the assuption that you need a 2hp or greater and I only have 1 1/2hp so I have stayed away.

Bpb

[Reed Gray]

With the smaller motors, it is possible. Use the higher speeds, and let the tool feed itself. You may be able to get away with using the medium set of blades also, using the same method. One modification I made is to grind the spear point off square. This makes your cutter about 3/8 inch wide, as opposet to the spear point which with both sides measures about 1/2 inch wide. If you can take a 1/2 (or 3/8) inch wide shaving with a scraper off a bowl without your lathe bogging down, then you can core. Higher speeds, and light cuts. With my PM, I push the blade in, this makes the coring faster, and the PM has the torque. I do have the laser pointer, and really like it, no more guessing if I am too deep, or too shallow.
robo hippy.

[Bob Opsitos]

Bob,
did you run into any problems with your lathe not having enough power? I was under the assuption that you need a 2hp or greater and I only have 1 1/2hp so I have stayed away.

Bpb

Nope. At least not for the blank size and type of wood I used. I didn't stall it once, and I'm not sure I really even came that close. You just go slow. I was using the "factory" spear point grind.

Reed, I gave some thought to cobbling up the laser, but wondered about it's value since I was thinking I really need to know where the cutter will go during setup vs in use.

Thanks
bob

Bob

[Reed Gray]

The main reason for the laser, and I am sure that you can make your own, or buy, is that this system doesn't always go where you aim, and your aim can be off. With the Oneway and the Woodcut systems, they are on a fixed pivoting point, and will only go to one spot. I made enough lamp shades to warrent the necessity of the laser. I developed the habit of aiming shallow rather than going for the prefect core every time. This did cost me some bowls, and as a production turner, this costs me money. I would always get the big bowl, and a medium bowl, and a small bowl (6 inch thick blank). The smaller ones sell less often, and the extra medium bowl that I would lose would sell more often. I hate going through the bottom almost as much as I hate ending up with a bowl that I cored having a 2 inch thick bottom. Aiming is a learned skill, and I got better, but the pointer almost makes it almost perfect. If you are off course, then you can see, and correct for it.

As far as horse power, 1 hp will do fine, 1 1/2 and above are no problem. All of the coring systems have 3/8 inch wide cutters, except for the McNaughton mini set which is 1/4 inch wide, and if you can remove a 3/8 inch wide shaving with a scraper (all cutters cut with a scraping action), then you can core. This might even make a good prictice exercise, use a 3/8 or 1/2 inch scraper, and see what it takes to remove that size kerf: speed, and pressure, and what it takes to bog down your lathe. With the McNaughton, when it drifts (it always seems to drift to the outside of the intended kerf) you can get some binding of the blade in the kerf, so this can add some extra drag, but you can come back to the top of the cut and widen the cut to release the pressure. Use the low speed range if you have one, and don't really push it, take lighter cuts. I doubt that the mini lathes have the power to core, but thus far, none of the systems are designed for the mini lathes. With the McNaughton, as with any tool, you can take light or heavy cuts, depending on how hard you are pushing your tool.
robo hippy