Bow lathes

discussion of the niceties of turning on a bow, bungee or pole lathe.

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Bow lathes

Postby Brian Chislett » Sat Sep 25, 2010 7:36 pm

Where can I find details of the 'bow' drive arrabgement. I understand there is a drawing somewhere.
Thanks
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Re: Bow lathes

Postby fish » Sun Sep 26, 2010 9:23 am

heres a pic i am using to build mine:

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Re: Bow lathes

Postby robin wood » Sun Sep 26, 2010 9:26 am

Struggling to find pics for you but it might help to know that folk that use those bow lathe drives tend to call them "bodgers muddle" If you use the search top right and type "muddle" you get 3 pages with various threads that give bits of info.
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Re: Bow lathes

Postby Mark Allery » Sun Sep 26, 2010 3:10 pm

Hello Brian,

I am not entirely sure which type of lathe you are referring to and there is plenty of room for confusion here. I hope that I won't be adding it. So I am goinhg to assume that you are referring to the foot powered (treadle operated) lathe where the return is powered by a bow and bobbin arrangement. The bow and bobbin lathe is often just called a bow lathe on polelathe circles but so is the hand operated bow lathe which operates rather like the fire by friction hand operated bow and is still in use in some parts of the world. The bow and bobbin lathe has been in use in the UK since the late 17th century when it was most probably introduc€ed from Europe. I built one once for demonstration inside one of the buildings at the Weald and Downland museum and I still have it but prefer to use a pole. The bodgers muddle is (I think) a more modern and complicated arrangement of double opposed bows on a sliding shuttle to over come perceived difficulties with the single bow and bobbin. But I know of APT members using all of these lathes and single bow and bobbin are used by some of our fastest professional turners so I'm not sure that the bodgers muddle is actually necessary - however it is up to you to decide what suits you in the end. coincidentally I have a picture taken at the APF show very recently of Dave Jackson using a single bow and bobbin very effectively. Not a good photo as it was just by chance that I got the bow and the bobbin in the frame. I don''t know if or where there is a diagram of this type of lathe but I hope this helps.

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As he came in 3rd place (I think) in the final competition is seems his drive is not lacking in power or effectiveness. I notice that his bow is much more pronounced than those I more generally see and the one that I built which is in the rather poor picture here. I seem to remember that the preferred length of bow is around 4 foot or more and the bobbin should be around 2 inches in diameter - but some experimentation may be necessary. I should also mention that mine suffered from being intended for operation in a room where the ceiling height is just under 6 foot!

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and suffers from a bobbin which is too small in diameter and a bow that is not bent enough to adds very little to the length of stroke achieved - but it works.

Here is a double opposed bow - bodgers muddle - used by Jim steele,

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and finally here is Wayne Bachelors excellent hand operated bow lathe, just to clarify the terminology that I have used.

DSCF8349.JPG
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I hope that I have helped rather than just caused confusion on this subject,

cheers

Mark
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Re: Bow lathes

Postby Robin Fawcett » Sun Sep 26, 2010 7:08 pm

There's quite a bit of info about bow springs in Chapter 4 - Lathes, of Roy Underhill's book The Woodwright's Workbook.
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Re: Bow lathes

Postby Brian Chislett » Mon Sep 27, 2010 1:56 am

Thanks everybody, I think the single bow looks simple and authentic ,instead of bungy cord for inside demonstrations.
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Re: Bow lathes

Postby HughSpencer » Mon Sep 27, 2010 4:52 pm

The diameter for the bobbin will alter the gearing. If it is large it will provide a lot of rope for a small amount of twist/bend on the bow thus it can be considered to be in a low gear - rather like the low gear on a bicycle derallier is the big one. if you use a smaller bobbin you will get more twists/bend on the bow and it will be harder to turn.
I went through all of this when I invented the Bodger's Muddle. The reasons for adopting the double opposed bow are laid out in my article http://www.bodgers.org.uk/plans-menu/59-muddle
Jim Steele has used this on and off over a number of years, I believe he even took it to Japan when he went over there to demonstrate.
However, whatever you try, give some feedback as to its success or otherwise.
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Re: Bow lathes

Postby Donald Todd » Mon Sep 27, 2010 5:49 pm

The simple bow like Dave's suffers the the same phenomenon as a bungee: the lathe cord (+bobbin) migrates to the mid-point. I don't believe that the bow arrangement was supposed to be portable. Compare Dave's uprights with mine. These are so light that I am often asked if I am employing the spring in the uprights! My philosophy is to Keep It Simple, even if it means using something "modern". Rubber bands are 19th century.
I do, however, prefer to use the traditional pole where possible. I have plans to make a collapsible one: like a giant fishing rod! I almost got a second hand sea rod at an auction but someone out-bid me.
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Re: Bow lathes

Postby Mark Allery » Mon Sep 27, 2010 7:23 pm

Donald Todd wrote:The simple bow like Dave's suffers the the same phenomenon as a bungee: the lathe cord (+bobbin) migrates to the mid-point. I don't believe that the bow arrangement was supposed to be portable.


Good point, I think the shuttle designed by Hugh is a great idea and overcomes this problem very neatly.

Donald Todd wrote: Compare Dave's uprights with mine. These are so light that I am often asked if I am employing the spring in the uprights! My philosophy is to Keep It Simple, even if it means using something "modern". Rubber bands are 19th century.



I only mentioned the approximate date for the introduction of the bow and bobbin as I had to do some research for the museum when I demonstrated it in a 17th century cottage. Personally I am all for using the appropriate technology whatever that turns out to be - and it will differ for different people no doubt.

Dave's uprights are completely overspecified - probably more to do with what was lying around and he has also cleverly built his shelter into it as it supports a fair sized canvas with some windage on it as well as a display table = so you should look at it the other way around, the lathe is built into his display stand. I have seen Ben Orford demonstrate with a lathe which relied on the whip/spring on the uprights. His bungee bowl lathe appears to use a combination of serious bungy and spring in the uprights.


Donald Todd wrote: I do, however, prefer to use the traditional pole where possible. I have plans to make a collapsible one: like a giant fishing rod! I almost got a second hand sea rod at an auction but someone out-bid me.


Interesting, I had similar thoughts and wondered whether one of those lightweight poles that people use as flag poles as festivals would be as good. Like you I don't have a spare beachcaster! Be very interested to hear how it goes.

cheers

Mark
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Re: Bow lathes

Postby Donald Todd » Tue Sep 28, 2010 9:23 am

You still have the problem of space for the pole. As I demonstrate facing the audience I have to put bright flags on the stake and pole to stop folk tripping over it! This does not look very traditional! The main problem with the bungee, is the increasing force required as you depress the treadle, which is most apparent for children. We've discussed this before here.
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Re: Bow lathes

Postby Kevin Downing » Wed Aug 27, 2014 8:34 am

I made my first bodgers muddle and I find it stiff and I get only about 2 feet travel. Are my bows too stiff? I followed the dimensions on the plans but my bows vary between 35mm x 30mm in places to 30mm x 30mm instead of one and a quarter inch square. Do I need to be exact with their cross sectional dimensions? My bows are 5 feet long, not 4'6". They are cleft from an ash log about 7 inch diameter and you might make out the inner bark on the outer edge. The bobbin is almost exact as per the bodgers muddle plans but about an inch longer. I used 3.5mm starter cord instead of 3mm. Do these also make a difference?
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Re: Bow lathes

Postby simon » Mon Sep 01, 2014 2:09 pm

I use a bodgers muddle and get more than two feet of travel. My bows are of ash and thicker in the middle, where they are fixed and thinner at the ends where the string is attatched. I was not too careful about dimentions, so long as they bent. I don't think cord size matters much. Try taking a bit of wood off the bows. The more they bend the more twists on the bobbin the more string you can pull. I will get 21/2 to 3 turns on a 1/12 inch diameter billet.
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Re: Bow lathes

Postby jrccaim » Wed Sep 10, 2014 4:59 am

Erm, I am somewhat confused. There are two types of bow lathes. In Type 1 we have a pair of centers. A cord is wrapped around the work held between the centers. A bow -- just like the one used to launch an arrow -- is attached to the cord, wrapped around the work. With one arm, the turner rotates the work, back and forth. With the other arm, he or she works the wood with the usual suspects (turning tools). In Type 2 bow lathes, a bow (again, like the thing used to shoot arrows) sits on a pedestal above the lathe. It preforms exactly the same function as the dear old pole -- it returns the lathe to zero, so a Type 2 bow lathe is exactly equivalent to a pole or bungee or even door spring lathe. The bow stores up energy on the downstroke and returns the lathe to zero. I have tried them both. I find Type 1 really beyond my abilities. I feel I need to be like Zaphod Beeblebrox, see Douglas Adam's A Hitchiker's Guide to the Galaxy. Zaphod had three arms. A distinct advantage :) I have but two arms. However, lots of people manage quite well with just two arms. I find I am lost without the third arm :)

A Type 2 bow lathe has no advantages or disadvantages (from a turning viewpoint) than bungee, pole, or doorspring. But with a bow, bungee, or doorspring you don't need a big space to accomodate the pole. So these lathes are more compact.
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Re: Bow lathes

Postby Kevin Downing » Thu Sep 11, 2014 11:42 pm

From your description, Type 1 is the one Wayne Bachelor is using, photo 8349. I have never tried this. Its a long time since I read the Douglas Adams books. My father never read the books but gave his life looking for a third arm for certain jobs too such as replacing springs in Outboard engines. Just when you think you have it replaced, it decides to go sproooingggg and makes a leap for the ocean.
Type 2 is the one Dave Jackson is using, photo 9600. However, the Bodgers Muddle is what Jim Steele is using, photo 9611. Plans are elsewhere on this website. This is what I aim to make. And in time for the Forestry Exhibition next week. However, as I have not got enough travel, I reckon my double bow is too stiff even at 25 to 30mm square. So I will revert to a pole but can only carry one the same length as my car, 4.4m, on the ferry. Otherwise the ferry co. will make me pay the next size up. A 4.4m pole is not what I am used too, its a bit short. So I have a 5m pole and the last 600mm is cut off. I will join the two sections using a smooth half inch bar slotted into each side to the depth of my drill bit.
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