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So, finally decided that I’m going to build a roller mast bending jig. 
I’ve got my wheels via the next people at Amazon, but now have to decide how far apart to set them?
The middle wheelbwill go up and down vertically to adjust the bend and Im thinking that the further apart the softer the curve but presumably too far and there are other problems?
Any thoughts or tips?

Darin

0F3D1C76-1E6D-40FF-95A0-6EB67ED3E0DF.jpeg

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I put the outer wheels 12 inches on center. One local friend made one with the wheels about 8 inches on center and it took a lot of effort to push the mast forward and back - the pressure would cause the wheels to lock and deformed the mast out of round. The effort is much reduced with the wider spacing. Pics of mine below.

The wheels on mine were cut from a piece of 3/4inch oak plank (left over from a furniture project). I cut out three disks using a hole cutter. Then I chucked each disk in my drill press and spun it while holding a Dremel with a sanding drum against the disk to create a groove that serves to locate the tube. One improvement was that I added a pivoting straight edge lever across the top to act as a gauge and marked it for the correct setting for various masts (Bantock 6061, French 7075, and Easton 7075(thicker wall than French))

Works great. Easy to use and adjust - I mark the tube for center line at several points to orient the mast as I push it - it will try to twist - and mark the lower bend point, so I know here to stop. I push the mast forward once - and pull it back until it springs out of the jig - sight down the tube to see if it needs more - and adjust the nut and repeat. Just turn the top nut to increase the pressure a bit.

With the wheels that you purchased, They should spin easily - but on the right (feed) wheel you may need to file down the flange on the outside so that you do not put extra pressure on the mast as you ease it into the jig.

John

Tube bender 003.JPG

Tube bender 002.JPG

Tube bender 001.JPG

John Ball

IOM CAN 307 (V8)

In my private capacity

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Darin

The green device is a 3D model of the bender that Dave Alston had made, The other is the one I made, after trials I moved the wheels closer together (Advantage of the construction as wheel position is easily adjustable). By having them closer found it easier to control amount of bend and position on the mast of the bend.

 

DSC02699.JPG

mast bender.JPG

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I have used both of these, Dave lent me his (some time ago of course) and also Eric's one. Dave's was a Rolls Royce piece of engineering and easy to use. I had to prevent the centre wheel of Eric's from swinging; which was causing un repeatable bends. Both have to be extremely carefully used to avoid rotation whilst bending. Also care to avoid working the soft alloy and making it more bendy.

Despite what some may say; this does take a lot of practise and a supply of old masts to do it with. The need for mast pre bend and the requirement for special tools only adds to the complexity of sailing the One Metre class. The pre bent rig must me stored straight to relieve the sail luff, so a box becomes essential. There is no escaping this though and we all have them.

To sum up, I still prefer the "round the waist" method.  Graham Bantock describes another method on his One Metre rigging plan (RP16D), that also works.

Richard

 

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