Turning thin - a question

[Mike Minto]

i've recently started to turn pieces thinner than i have in the past (fear of ruining a piece - now that i've got several i think are nice on display, i'm getting bold :p). anyways, i think i've been turning too fast to safely turn thin pieces - having a lathe with variable speed now allows me to turn slower than ever before, and i'm finding that although it takes a little longer, turning this is not as difficult as it was before. is this how you guys get your work thin? maybe, 150 or so on the rpm? thanks for any advice.

[Scott Hackler]

I have turned several things pretty thin and I dont slow the lathe down at all. The key for my thin stuff it to thin the rim to the desired thickness and work my way in. I have made a couple decorative cowboy hats after watching the master at work and there is good logic behind turning thin a little bit at a time and NEVER go back to that spot, as the wood will flex too much. do a search for Johannes Michelsen on youtube and prepare to learn. Using a bright light as a guide is a great tool.

[Ken Fitzgerald]

Mike,

Scott's recommendation is borne out by Lyle Jamieson in his turning video Hollow Forms the Easy Way. He has your start at the outer edge working your way in. Don't come back because once you go beyond "Point A" there is less support if you try to come back to Point A and it's probably flexing anyway.

[Steve Schlumpf]

Mike - I keep the lathe the same speed and thin the turning down in stages. I used to start at the rim and hollow out with continuous sweeps towards the center but when it gets thin, it really starts to flex. Taking it thinner in stages allows for support for each area you are thinning. Takes getting used to - but it does work.

[Cyril Griesbach]

Turning thin is fun and you've been given great advice so far. That being said, it's more of a "look what I did" thing and all turners go through that stage. It's a great skill set and experience set to have when needed but is only appreciated by other turners.

[Ken Garlock]

Good morning good people.:)

Being a rank amateur in the world of turning, I would like to ask just what IS "the same speed?" My recent experience with making pens is to rough at 1500 and put the skew to work at 3000 to 3500. I suspect that doing thin bowl work would require speeds in the low 2000 or less.

As one bold fresh TV person says: What Say You?;)

[Ken Fitzgerald]

Ken,

I typically turn spindle work several times faster than faceplate work.

Bowls....I would turn much slower than pens......It really depends on the piece of wood and the way it is cutting.

[Scott Hackler]

I turn almost all of my bowls (except for the monster ones) at 1080 rpms. I will slow the lathe down to the 300 range for those out of balanced blanks, but as soon as the blank is round, it gets turned and sanded (usually) at 1080. Sometimes I will slow down the lathe while sanding (for heat reasons) but with the power sander going, I dont really see a problem with heat and I dont lower the speed. (sure works faster!)

When I turn pens its around 2000 rpm.

[Ken Garlock]

Thanks for the response Ken and Scott.:cool:

It seems reasonable that you want and need a slower speed as the diameter of the bowl increases. After all, you don't want the bowl to fling itself apart. I was looking for some ball park numbers, and it appears that around 1000 is a good number, perhaps higher for smaller items.

[Steve Schlumpf]

Ken - once the blank is balanced I turn the speed up to 850 to 950 rpm. I am used to that speed for bowls and hollow forms - so I just keep the same speed for turning thin.

I will agree that turning thin is more for turners than anything else and while it may also be a phase we go through while developing our skills, I also believe it is something that must be learned if you ever plan on doing any piercing work.

[Wally Dickerman]

Mike, you mentioned 150 rpm. Surely that's a typo. When I have beginner students I start then out at 1200 on a 7 inch bowl. Because they've never turned before they feel comfortable with that. As they advance I recommend 1600 to 1800. The higher speeds give better results. Smoother and easier cutting. Thick or thin, doesn't matter.

As others have mentioned, when cutting thin, work your way down the inside of the bowl in short increments. Don't come back to the thin area to touch up. You'll have vibration problems resulting in bowl-busting catches.

Unless I'm turning functional pieces, most of my turnings are thin walled.

You should understand that surface speed of the wood is what counts, not rpm's. A pen blank at 3000 rpm probably doesn't have as much surface speed as a 6 inch bowl at 1200 rpm.

Wally

[Allen Neighbors]

I agree with Wally... I turn most of my 9 to 12 inch bowls at around 1800 or so rpm. When I want to turn really thin... 1/8" or so.... I thin about an inch of the rim at a time, gradually deepening the bowl as I go. I do use a bowl steady to keep the flex out of the rim as much as possible.
It's true, though, that the faster speed can be dangerous for questionable wood, so don't let it fly apart on you. I have taped the outside of a piece of included wood, after it's shaped, so I can turn the inside without it coming apart on me.
But it's much easier for me to take lighter cuts at higher speeds, and get better finish cuts.

[Bernie Weishapl]

Most every bowl I turn is 300 to 500 rpm while getting it balanced. After that it is around 950 to 1250 rpm.