Bowl Turning times

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Bowl Turning times

Postby Twalsh341 » Wed May 21, 2008 11:50 pm

Hi, I'm new. My name is Trevor, and I'm in Philadelphia, PA. A long ways from most of you guys...horay internet.

After building my first pole lathe, and turning my first pole-bowl, let's call it, I was wondering how long it takes some of you guys to go from a log round to a bowl before drying/finishing? For arguments sake lets use an 8 inch diameter bowl for the finished product.
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Postby robin wood » Thu May 22, 2008 7:11 am

Well my first bowl was about 8" and it took me two evenings, but I had less information to go on than is available now. Also speeded up rather now.
http://www.robin-wood.co.uk bowls, books and courses
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Re: Bowl Turning times

Postby gavin » Thu May 22, 2008 2:25 pm

Twalsh341 wrote:Hi, I'm new. My name is Trevor, and I'm in Philadelphia, PA. A long ways from most of you guys...horay internet.

After building my first pole lathe, and turning my first pole-bowl, let's call it, I was wondering how long it takes some of you guys to go from a log round to a bowl before drying/finishing? For arguments sake lets use an 8 inch diameter bowl for the finished product.

- well, we could have a bowl-turning race at next Bodgers ball!
- like the Log to Leg race
- I rather think Robin Wood would win it!

To answer your question, I reckon 2 hours should do it by the time you have a cup of tea and feed the cat, and also think of several different ways you could have set up the lathe better.

When you start, the hardest trick is knowing how to undercut the middle core of the bowl. Now that just takes time to learn, and also to be confident you use the right part of the best available hook.

I measured one ( of six inches diameter?) about a year ago: 57 minutes 32 seconds from roughly bandsawn blank, and - for the really technically inclined - I burned 517 kilocalories, measured by my Polar wrist-watch exercise heart-rate monitor. I do recall another bowl of 333 kilocalories, but I forgot what time that took. Working out at 500 kilocalories per hour is very hard work and is not sustainable.

I recall Ben Orford entered a bowl in the Half-hour challenge in the Bodgers Competition in 2006 (?). I think he started with a prepared blank ( as I did above) so presumably he cut my time above in half.

Robin Wood compares skilled workers' wage rates in the year 1412/13 to the price at which bowls were bought on p 92 of his book " The Wooden Bowl" ( buy a copy from him quick!!) and he calculates the rate to be 16 per day, which I reckon would be one every half-hour for an 8 hour day , or 45 minutes if they did a 12 hour day. They would have cross-cut the logs then axed out the blanks, so they must have been pretty skilled!
Last edited by gavin on Fri May 23, 2008 8:41 am, edited 1 time in total.
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Postby Nicola Wood » Thu May 22, 2008 3:15 pm

We did a fun video of Robin racing a powered lathe a short while back:
South Yorkshire Wood Fair, Sheffield, 6 October 2007 and Robin axes out two similar bowl blanks from a sycamore tree felled nearby about half an hour earlier. From a nearby marquee they carry out a friend's electric lathe and set it up under the trees next to Robin's foot-powered lathe. Mike sets up his portable generator, Robin has a cup-a-soup and a sandwich. An expectant crowd gathers ... man vs machine ... who will be quickest turning a bowl?
The answer's here http://www.youtube.com/watch?v=tDgIGzw4VtA 8)
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Postby Twalsh341 » Thu May 22, 2008 5:45 pm

Very good info, thanks. Gavin, that was the hardest part, undercutting the core, it took a lot of experimentation to get the tool I was using not to bind in the walls or mandrel. I know there are gooseneck style hook tools, but what profile/hook size do you find works best? I forge my own tools, so they shouldn't be hard to come up with.
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tool to undercut?

Postby gavin » Thu May 22, 2008 10:44 pm

Draw a question mark: " ? "
Using that as inspiration, make up some shanks and try it out.

I know these words are not very helpful, and what will help you more is my posting pictures of the mandrel undercutting tools I like to use.

But you'll have to wait a few weeks for that, as I am doing a new production run just now. When I have 4 or 6 that work really well, I'll post pictures of them.

I do have some tracings of Lailey's tools. If I take pictures of them, can anyone put them into drawings using some program such as Adobe Illustrator like Nicola Wood did with her lovely spoon technique drawings?
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Postby Twalsh341 » Thu May 22, 2008 11:05 pm

I could do the drawings, I'm in college for industrial design...All those types of programs are bread and butter for us. You can send them to my email address, twalsh341@yahoo.com
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Lailey bowl hook photos

Postby gavin » Fri May 23, 2008 8:55 am

Image
some Lailey hooks at MERL
You'll get an idea of profiles. If you chose to sketch these with Photoshop, that could help any folk that want to make their own.
The curves are in fact 3 dimensional, not 2 dimensional.
There is a centimetre scale bottom right.
The pink material on the tips is dental putty - I was casting the tips so I could reproduce Lailey's design in dental resin and then offer those facsimile tips to a blacksmith to reproduce.

I have since discovered it is in fact more effective to get blacksmithing skills & equipment yourself, than to get a smith to do the work.
BUT: if you have a smith who also turns bowls, those are the tools you want to buy.
The only such "turning smiths" worldwide I know of are Ben Orford, Andy Hilton, and myself. And I am not selling at the moment, whilst I re-build my forge and play with my new power-hammer. :D

And if this image is too wide for your screen, can any one tell me how I make it smaller??
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Re: Bowl Turning times

Postby Fuzzy » Sat Feb 18, 2012 5:47 pm

This post might be dead now, but Gavin- do you have any images of the tip shapes? It would be interesting to see what Lailey did on those. Do you know if he made his own hooks?
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Re: Bowl Turning times

Postby gavin » Sun Feb 19, 2012 12:43 pm

Fuzzy wrote:This post might be dead now, but Gavin- do you have any images of the tip shapes? It would be interesting to see what Lailey did on those. Do you know if he made his own hooks?

Yes, he did make his own hooks.
I took these 3 images in 2006 at MERL of their object 59/32 i.e collected in 1959 and it was the 32nd object collected that year. You'll see the small eye. The hooks were made of various bits of steel fire-welded together. Some showed the tooth pattern of a farrier's rasp - so I guess he recycled old files like we do.
Image
Image
The pink stuff is dental putty I used to take castings of the tips.
Image - sorry about out of focus, but that's what I have.
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Re: Bowl Turning times

Postby Fuzzy » Mon Feb 20, 2012 7:14 am

Thanks! Of course, now I've got another question: The main stock is rather large, looks to be about 1/2" square. Does this help prevent chatter, or provide stock to re-forge the end when it wears out (1/2" would be enough to draw it out in one heat if you're practiced at it), or both? As it's welded up from a couple of bits of steel, I might think that he would just draw out a new bit when one wore out, and once it got too short welded two together to get the most life from them.
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Re: Bowl Turning times

Postby gavin » Mon Feb 20, 2012 4:55 pm

Fuzzy wrote:Thanks! Of course, now I've got another question: The main stock is rather large, looks to be about 1/2" square. Does this help prevent chatter, or provide stock to re-forge the end when it wears out (1/2" would be enough to draw it out in one heat if you're practiced at it), or both? As it's welded up from a couple of bits of steel, I might think that he would just draw out a new bit when one wore out, and once it got too short welded two together to get the most life from them.

You need the stock to be 12 mm minimum diameter, else it will chatter, especially as the tool rest to tip distance increases. 19 mm diameter is too much - unless you have power hammer. Try using old coil car springs as raw material - known as OCS. Get Land Rover or similar springs if you can, they are mebbe 14 mm.

I strongly recommend you just do it. For now, post no more questions, but get on with it. Then post pix of your experiences along with more questions and that will inform others after you. It would be lovely if you can find someone to help you, but do not wait for that.
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Re: Bowl Turning times

Postby Fuzzy » Tue Feb 21, 2012 2:23 am

As a blacksmith, I was merely commenting on what I perceived to be a bit of forethought and frugality in the design of that particular tool. My forge is currently under snow, and once it thaws out I will be using "sucker rod", a 16mm high carbon steel cast-off from the oil drilling industry similar in characteristics to 5160 (leaf spring steel). I'll post pics, of course.
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Re: Bowl Turning times

Postby gavin » Tue Feb 21, 2012 8:13 am

Fuzzy wrote:As a blacksmith, I was merely commenting on what I perceived to be a bit of forethought and frugality in the design of that particular tool. My forge is currently under snow, and once it thaws out I will be using "sucker rod", a 16mm high carbon steel cast-off from the oil drilling industry similar in characteristics to 5160 (leaf spring steel). I'll post pics, of course.

That will be helpful. Good you have resources - but sad you must wait for them to emerge from snow.
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Re: Bowl Turning times

Postby nnykamp » Tue Feb 21, 2012 3:22 pm

Hey Fuzzy, I'll be very interested to hear how the sucker rod works out. We've got it in great abundance here in Iowa, lots of cattle farmers use it to build fencing. I know machinists will make tooling from it, but I was concerned that it wouldn't be able to handle the shock of wood turning.
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