Official Luthiers Forum!

Hi

I am about to build the Fox bender from the LMI plans.

On the form the steel dowels lip the outside edge of the form, I have seen other forms where the dowels a set back from the edge a few mm and I have also seen wood dowels screwed to the side which sit flush to the edge of the form.

Opinions on the best form design would be appreciated.

Regards

John

I am assuming you are speaking of the cross supports on the bending form. Well here is the thing the tubing or dowels you speak of are to support the wood evenly across the width of the sides to aid in preventing cupping. If left unsupported the wood would want to cup in the middle. So In my mind the must be flush to the outside of the forms. Most of my bending forms have aluminum tubing spaning the form and set flust to the outside. However my newer forms are solid plywood requiring no spaners. I do have a notch cut out in the center of the waist for waist support bar to fit into as the waist is bent. Many dont use this bar but I feel it is very important to suport the waist as it is being bent to prevent faciting.

I have one solid form and the rest are made with 1/2" dowels set flush with the outline and held in place with thin CA glue. These work real well and are a lot cheaper to build. I cut one side if the bending form and sand it smooth then screw it to the other side and use a pattern router bit to copy the good side. While still screwed together I drill out the dowel holes with a forsner bit. I unscrew the sides, tap the dowels in, square up everything and then use thin CA to glue in the dowels. I can make up one of these forms in less than 1 hour, I use the cutouts from making the outside body mold so other than the dowels the material is free.

Fred

_________________
Fred Tellier
http://www.fetellierguitars.com
Facebook page http://www.facebook.com/pages/FE-Tellier-Guitars/163451547003866

I did think of experimenting with bendable ply wood but didn't think I would get the tight radius in the centre, I will be using the cross bar in the bender, I may user hardwood for this instead if aluminum purely as it is available. I suppose steel was a legacy from the lamp heating system, if I use a blanket do you think I can get away with wood dowel? Its much easier to source and as it can screw inside the form I can get a closer fit to the edge.

J

Bendable ply?? I said nothing about bendable ply. I used 8 sheets of 3/4" ply cut into the shape and laminated togather. There is nothing bent in my forms. Avalability of aluminum tubing is high. Home Depot and most hardware stores carries 1/2" OD aluminum tubing at about $2.50 per foot. N need to worry about deflection. The spand is only 6" long. At that length it is very strong plus it is a piece of tubing it is very ridged anyway.

Ok, thanks

I have seen forms with solid faces but have no knowledge about how or what is used to make them.

Ply soundsd like a good idea, do you say you raidius the corners off to follow the contour of the form ?

John

OK I guess I am lost somewhere along the path. I cut and match sand 8 pieces of 3/4" plywood into half a body shape + 1" at the bottom. I laminate these 8 piecs of half body shaped plywood togather. I band saw a notch slightly deeper and wider than the was support bar on the waist valley and that is my shaped mold. this is what the wood conforms too i am not sure what you are asking about radiusing the corners off to mach the shape of the form. These 8 pieces once shaped then laminated togather is the form ( I.E. the part that goes inside4 the bending machine that you bend your wood arond)

I think I get it 8 * 3/4 = 6" its more or less a solid form - correct ?

is it heavy ?

John

Yep but that is a good thing in my opinion

I do the same thing as Michael, with the 8 layers of (in my case) MDF. I leave the middle 2 pieces about 3" wider (at what would be the centerline of the guitar) which makes a nice keel so I can clamp it in my bench vise. It is heavy, but stable!

Steve

I do the same thing as Michael, with the 8 layers of (in my case) MDF. I leave the middle 2 pieces about 3" wider (at what would be the centerline of the guitar) which makes a nice keel so I can clamp it in my bench vise. It is heavy, but stable!

Steve

This looks like a good option, more time and more cost but worth the effort I think.

When trimming to the master is the bearing on the top of the router bit and the master template in the middle, its difficult to see from the pictures.

J

Solid Mould build

Can anyone explain the significance of making a 2" line from the bottom of the sheet

"Layout for the full body template begins by offsetting the bottom line up 2" from the factory edge of the ply."

As it seems to get trimmed off later on in the process.

J

If pictures speak a thousand words - video must be a million

http://www.youtube.com/watch?v=TQ3ufWxQ ... r_embedded