HF monster speed question

Bill Lantry

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Hey, folks,

I saw the post about the monster tools and jig. My question: how fast (or slow) are these hollow forms turning as you're making them? Should I not even be thinking about this given my present minimum lathe speed of around 650 rpm?

Thanks,

Bill
 
Bill, the speed I've been using depends on the size and the wood, and what I feel comfortable with. I think it's Bill Grumbine who says if either the lathe or you are shaking, turn down the speed. A good rule of thumb (once a piece is round) is this one, by Dale Nish:

http://www.woodturnerscatalog.com/pdf/safe_lathe_speeds.pdf

I've learned that in a lot of cases, speeding things up smooths the cut, but it usually also increases the chance that a minor mistake will become a major event. Until you feel real comfortable about your tool presentation, I'd stay in the lower rage for safety's sake. All it takes is a small mistake at high speed to become a big problem. Low speeds are more forgiving.

One counterpoint to this is the more voids in the wood, the more high speeds help keep the cut smoother. There are limits, though. Think of a car on a washboarded dirt road. If you go too slow, the bumps beat you and the car to death. Speed up a bit, and you're floating on the tops of the bumps. Up the speed a bit more, and you're sliding sideways on your way to being upside down in the ditch. ;)

Most of my HFs are done between 800 and 1200 RPM, but as I gain experience, I suspect those speeds will increase.
 
I run my speed just as Vaughn says. Around 800 to 900 to hog the wood out. When I get near the end I kick it up to around 1100 to 1200 for the smoothing cut which are light cuts.
 
Another thought comes to mind, and you probably already realize this Bill, but the surface speed of the wood is really the determining factor, more than actual the RPMs of the spindle. For any given RPMs, the bigger the diameter, the more feet per second travel past the cutting edge. So while 1200 RPM might feel real comfortable on a 3" piece, that same 1200 RPM might feel suicidal on an 18" platter. (Dale Nish's formula takes that into account.)

Also, in re-reading your original question, I think the more straightforward answer would have been to say hollow forms are generally turned at about the same speed as bowls of a comparable diameter. At least that's how I do them. ;) So your 650 RPM lathe would work as long as you're starting out with fairly round stock.
 
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