hollowing end grain on a lathe

Dan_Shade · December 02, 2012, 07:25:48 PM

I keep getting catches when I try this.

Do any of you guys have any tips on how to do this?

Don_Papenburg · December 02, 2012, 10:20:28 PM

Very sharp tools . A firm guerilla grip . Might try a scraper type tool ,but it needs to be very sharp also.

Okrafarmer · December 02, 2012, 10:26:11 PM

Maybe try roughing it out with a gouge, and then going down the rest of the way with heavy grit sand paper, followed by finer sand paper. Will take a while, though, and get hot. :-\

Dan_Shade · December 02, 2012, 10:42:02 PM

i have a technique problem, sharp tools just make a deeper gouge.

Sandpaper is for turners that can't use a skew! (I am using a 1/2" gouge for the hollowing, but I pretty much use a skew exclusively on spindle turnings, the outsides anyways)

Okrafarmer · December 02, 2012, 10:46:24 PM

You aren't trying to use a skew on the inside, are you? That could be your problem. ;) I meant for the hollowing out process. I never had much problem with tear-out when doing cross-grain bowls, but I only did end grave hollowing a couple times. I don't recall having much trouble with it. Once i did soft maple (dry) and the other time I remember, I did crabapple (green). No problems. But obviously, I am not very experienced at it. ;D

Lud · December 02, 2012, 11:53:39 PM

Best tool for endgrain is called a Termite. An excellent investment for any turner. I imagine SD will agree.

Otherwise, a fingernail grind on a bowl gouge will work and if you drill out the center after you've mounted it in a chuck, it'll be a lot easier. ;)

Left Coast Chris · December 03, 2012, 12:56:45 AM

Suggest the Easy Wood Tool rougher or finisher in the large size. They are small carbide scrapers on the end of a 1/2" square steel shank. I also have a large M2 steel scraper that is extra heavy 1/2" thick and 1" wide that works well for hollowing end grain but the Easy Wood Tool is fastest. I love mine.

SwampDonkey · December 03, 2012, 06:22:41 AM

I have a termite with interchangeable heads. They can be sharpened with a cone shaped stone on a Dremel or drill press. Also I use radius scrapers. I have turned more pieces with the rings, than across them because you don't worry about a bowl going oval. Cherry, maple, elm all behaved. Best if you can avoid the pith, but I've never had a piece split from drying. I have had one on occasion split when it dropped from my hands. :D

Okrafarmer · December 03, 2012, 08:18:27 AM

There ought to be some tailstock tools you could get, too. Such things are used all the time for metal lathes. They wouldn't be considered free-hand, but they get the job done.

Tree Feller · December 03, 2012, 09:53:02 AM

It helps to drill a depth hole first. Using a bowl gouge with a side grind, adjust your tool rest so that the tool is at or slightly above center...never below center. Cut from the center to the rim on end-grain...opposite of side-grain hollowing. Keep the tool rest as close to the stock as possible. The further out the gouge extends past the tool rest, the greater the chance of a catch.

SwampDonkey · December 03, 2012, 11:12:53 AM

Yes, good advice Tree Feller.

Jemclimber · December 03, 2012, 12:17:14 PM

A "steady rest" is also very helpful for larger or longer pieces. It support the perimeter.

Dan_Shade · December 03, 2012, 05:21:06 PM

thanks guys.

I'll look into one of those termite things

WDH · December 03, 2012, 10:23:16 PM

The termites are all right, just stay away from the Powderpost Beetles

.

Dan_Shade · December 03, 2012, 10:40:47 PM

i found my richard raffen book. I'll try a few of his techniques when I get back in the shop.

Holmes · December 04, 2012, 09:45:14 PM

Quote from: Tree Feller on December 03, 2012, 09:53:02 AM
It helps to drill a depth hole first. Using a bowl gouge with a side grind, adjust your tool rest so that the tool is at or slightly above center...never below center. Cut from the center to the rim on end-grain...opposite of side-grain hollowing. Keep the tool rest as close to the stock as possible. The further out the gouge extends past the tool rest, the greater the chance of a catch.

What speed do you recommend?

Lud · December 05, 2012, 09:34:39 AM

We lathe guys are assuming you have a drill chuck that plugs into your tailstock, often times a #2 morse, and that you'll be drilling right on the lathe.

I run the lathe 250-500 rpm, and advance the tailstock into the center. As I can only wind it in a couple of inches, I retract it, clearing out the shavings, and then advance the tailstock into the hole and wind again. The drill is not turning so when I pull it out I put my hand on it to see how much heat is being generated. Big and little bits have different progress rates. Slow can be safe but it can be hot too. In the words of Mr. Gunn, "Make it work!"

I've ground off threads of screw tips on drills I use on the lathe cuz you have to be able to pull it out.

A piece of wood dowel , marked in inches, can tell you how deep you've gone and, when laid on top of the stopped blank , can help you visualize how far you need to go. ;)

Tree Feller · December 05, 2012, 10:15:00 AM

Quote from: Holmes on December 04, 2012, 09:45:14 PMWhat speed do you recommend?

The formula for determining rpm is Diameter in inches x RPM should = 6000 to 9000. For example, I would hollow a 10" diameter bowl at 800 rpm so 10 x 800 = 8000 which is within the optimum speed range. That is for a balanced turning. You should start rough, unbalanced blanks at a very slow speed rpm and only speed up once the blank is rounded and in balance.

After a while you will intuitively know the best rpm and will not need the formula but it is a good guide for beginning turners.

Lud · December 05, 2012, 11:42:23 PM

I think he was talking about drilling speed, wasn't he?

For bowl turning,I guess you could use that formula for a max. I like to start slow when I'm roughing in and as the turning smooths out, I can bump the speed up. And I'll go higher than turning speed if I'm scraping.......with a very light touch. ;)