The Turning Dilema - RPMs vs Risk (semi-long)

But my white

They're right. It's not so much the number of bites as it is Newton. Remember MV(squared)?

I try to keep at pucker factor six, maximum.

Same-o

You want to keep a light touch with a sharp tool. Speed? Same-o

Best rpms are the ones you feel comfortable with. Favor lower, because the odd chunk that may unexpectedly depart will leave with less available energy to bust your chops.

How about some "rules?"

First rule is to avoid anything thrown by the lathe. Don't stand in harm's way at startup, listen and watch for signs that anything's working loose. Keep your on/off switch near the tail of the lathe where you won't have to reach through the zone, either.

Second rule is never give away leverage. Keep the toolrest close. It gives you greater mechanical advantage, serves as an iron barrier between you and the work.

Third rule is to be methodical - always A-B-C.

Anchor the tool to the rest. Turning is about rotating things against a fixed tool to make them round, after all.

Bevel to the wood. Lay it right down , then English your way into the cut, letting the bevel guide on the space it's made for itself after it begins.

Cut for the curl. Your shavings should be curls, preferably continuous twisted curls, and they should fall, not fly.

Before you reach to turn off the lathe, disengage the tool from the cut, lift the bevel, then remove it from the rest. Willing to bet 75% of catches and curses happen because of inattention, not during the cutting, but the (inadequate) clearing.

And wear a full face shield rated for impact protection...with a hard hat if you like. Things don't always jump the way you think they will. A faceful of wood that's traveling away from the lathe is a bad, painful, and often expensive thing. A faceshield can be had for $10 and up. Cheaper to buy it before the first time, rather than before the second time.

Cranking up the speed is a crutch, and mostly a modern-era crutch. Doubly so if you're not doing production turning where 5 minutes more time will impact your income in a bad way. Some expert has claimed (IIRC) that you need never turn above 1000 RPM (or was it 300?). I'd certainly rather have a lathe that went from 100 to 1000 than 500 to

You must control the tool - despite the motor, turning is still essentially a hand-tool activity, and requires user control of the tool (unless you're using a spindle-copying jig, and thats not really turning, IMHO.) Practice on firewood for a while - cheap, guilt-free if it gets damaged beyond reclaiming, and gives you experience.

I like it slow.

I'm turning bowls and plates, and I start at 450, and final cut at 950 rpm. That's it. I do get a smoother cut at the higher speed, so I shift to it after the piece is round and all the corners are gone.

I've done less spindle turning, but it has been very satisfactory at the low end of the range.

I figure the less speed, the less momentum, the smaller the bruise when it hits me.

I do speed things up to 1500 rpm when I polish the wax. I had a 12" laminated plate (old butcher block counter) delaminate on me at that speed. The knot on my arm is still there after two weeks.

It's not the bite you are taking that causes the problem, it's the bit that the chisel takes when it develops a mind of its own.

I don't like to do white knuckle turning. If I'm putting finger prints into the tool handle, I stop and do a dry run to see where the tool edge is. If I get tense, I catch.

It's a wonderful sport.

Walt C

Charlie b wrote: ...snip.... at least the center/ spindle turning ...snip.. Initiating a "cut" properly and completing it properly is requiring far more concentration, coordination and, frankly, stress than it probably should. And RPMs seems to be one of the major causes of my low to moderate anxiety."

Hi Charlie, First, relax. Second, forget RPMs as a number rather hear and feel speed of the turning wood according to the wood, you and the tool. I think RPMs should only be for car mechanics.

No, you have your hand or touch and the cutting edge of the tool; this remains the same if your RPMs are 10 or 3,000.

1. Recomended roughing to round with a 1/2" or 3/4" roughing gouge RPMS, given the following: - starting with up to 1 1/2" square stock - 10 to 14 inches between centers and stock "approximately" centered

A 3/4" roughing gouge is a little big for a 1 1/2" square stock that is 10 -

Take some maple, cherry, walnut or, your favorite, mahogany and practice. Don't practice on pine or punky wood because you'll get frustrated. Try roughing that 1 1/2" blank with a bowl gouge, any size, see how that feels. Do not worry about flying projectiles because most spindles will crack and both sections will fall before they fly.........bowls fly!

Charlie, I've been supporting myself with architectural reproduction work (aka spindle turning) for over 10 years. I've gotten catches and broken a lot of very thin spindles. I don't try to beat the clock so I guess I couldn't be labeled as a production turner.

Some times you have to lower the speed for a nice clean cut, some times you have to raise the speed for a nice clean cut and some times you just aren't going to get a nice clean cut (throw that piece of wood away and get a better one). I rough with a roughing gouge, a skew, a bowl gouge and/or a detail gouge.

Again, relax and forget the risk vs rpms because the only risk is (as George said) "inattentiveness". There really are no hard fast rules except BE CAREFUL; use whatever tool feels and works good for you, use whatever speed you like or get the best results. Try them all then decide for yourself what works for you.

Now go have fun.

Ruth

snip

Going to make some plumb bobs, eh?

"Ecnerwal" wrote: (clip) Cheaper to buy it before the first time, rather than before the second time.(clip) ^^^^^^^^^^^^^^^^

Good way of putting it. I like economy of words, so I won't say more.

When I started seriously thinking about getting into woodworking I found rec.woodworking. Got a lot of good advice, direction and help from a lot of knowledgable, talented people. Now, when I can I try to follow their example and lend a helping hand when I can.

This group is a lot calmer AND just as helpful. I think I'm gonna like hanging out here as well. Thanks - much appreciated. Hope I can be an beneficial addition to the group.

charlie b

(I took the midi lathe off my bench and semi-put it away for a while. Had to do that so I wouldn't try turning toothpicks. This turning thing is really addictive - and a lot less expensive than what it costs to build solid wood furniture and the like. Have a To Do List I have to get back to - utility shelves, a big gate with arched top and panels, a table to glue up, a cabinet for younger son's LPs (he's a retro throw back) a door and drawer faces to put on to finish my sharpening station cabinet AND the coopered door mini-cabinet for router bits. Play time's over for now - back to "work")

Hello Rotationista,

I'll echo what Ruth said about relaxing. Catches happen - it's a part of the risk of creating work in which the person is in complete, unrestricted control of the cutting edge. People are fallible when presenting a sharp edge to spinning wood. But if you're tense and stiff the outcome could be injurious or at the least unsettling to your confidence. A moderately light touch is all that's required.

Think about feeding a board across a jointer or into a table saw. Being tense and pushing against the machine's ability to cut is bound to lead to an "event" or an injury. When you push against the cut you'll be off balance if something at the point of the cut changes - leading to a potentially nasty situation.

A similar understanding is in order for woodturning. Allow the legs, shoulders, arms and fingers to control the rate of cut as well as the direction. (As Ellsworth recommends in one of his videos, let the large muscles do the majority of the work and let the small muscles put in the delicate work.) Take light cuts. No, lighter than that. Allow the edge of the tool to do the work. If you do happen to present the edge incorrectly and get a catch your balance won't be affected and the tool isn't in a death grip which will worsen the catch. A moderately light touch allows you to pull back more quickly and there's no body weight in the cut that you've got to reverse direction and pull back.

My personal preference for lathe speed is either 1250 or 1800 rpm - and

After 4 years of turning a lot of wood, I still get catches. But they haven't been disastrous for about 3.5 years now - they're usually just a spiral gouge that screws up a bead on my last finessing pass. Ain't that always the way?

Owen wrote: ....snip.....

Why is that, Owen?!? And that "last finessing pass" could easily be done with the 120 grit tool. : ) Have you ever had a really cool spiral gouge and wish you could intentionally reproduce it?

Ruth

I think he was giving it to us straight up - no juicy stuff here -- course it will pass.

So damn true.... It's just SO easy to catch the edge of a goblet or the side of a bowl when you think the cut is "over" but haven't got the chisel out of reach of the wood...

I hate when that happens.. one of those things that make you feel really dumb when you do it, because you "know better"..

mac

Please remove splinters before emailing

One question that always comes up at demos that I (or anyone else does) is "At what speed are you turning?" On my lathe, the speed knob fell off, and just won't stay on any more, plus the readout is on the back side of the lathe (PM3520). I always say to turn at what ever speed you feel comfortable with. Rough bowl blanks, turn the lathe up until it starts to wobble and vibrate, then back it off until it is smooth. I turn all bowls on the lower speed range, so small ones will finish turn at 1750. When I started, I didn't turn over 500. With spindles, it is the same way. I turn out a number of basting brushes. When starting, I would turn in the 500 range also. Now 3000 seems slow. Adjust speeds to your comfort level. Start slow and work your way up. robo hippy

I think speed is a relative thing.. I've turned small goblets (3/4" - 1 1/2" diameter) at 850 or 1,100... but when I'm roughing a 12 inch bowl, I wish the Min. speed of my lathe was a lot less than 450....

I've considered changing the pulleys, since it (jet 1442) has 8 speeds and I've never used anything over the 4th speed... I can't imagine turning ANYTHING at

mac

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Charlie... while you're doing your flat work, add another item to your list... design a stand for your midi and get it off the bench..

With your design and woodworking talents, you could make a very functional stand that would probably include tool holders, shaving catcher, wheels, etc., etc...

mac

Please remove splinters before emailing

hmm... Owen has got me thinking, which is a GOOD thing.. *g*

I used to be constantly worried about things launched off the lathe... and thinking back on the 15 or 20 times (at least) that this has happened, none has done much more than drop and roll...

OTOH, most of the tools that I use for flat work have me worried about kick back, which IMO is worse than a bowl falling off the lathe..

mac

Please remove splinters before emailing

In my opinion, you are going at the problem from the wrong side.

Of course the higher speeds should be used only when you feel safe (and I mean _safe_) to use them.

Your problem is not the speed (was it Ralph Nader who coined the phrase "Unsafe at any speed"?) but the danger of getting a catch.

The cure is not in choosing a slower speed, which only leads to "slower" catches, but learning to present the different tools to the piece in a safe, non-catching manner.

There _are_ ways and means, you know, as soon as you find yourself a qualified instructor.

In sports, they say that He who coaches himself has a fool for a trainee.

This is doubly true in woodturning, since the tools of the trade are much sharper than most sportinggear.

Bjarte

Have you ever seen Jimmy Clewes demonstrate? He cranks the speed up to max and leaves it there. Quite a few in the front row of the group made nervous chuckles and shrank in their seats a tad but I'm sure Clewes wouldn't do it if he had any doubts.

He commented something on the lines that higher speeds make a smoother and more controlled cutting action - if I remember right.

Wonder how he explains the cut you get with a carving tool at considerably below 5 fpm?