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Urban Luthier

3D print your own Violin Bending Iron

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I'm a little fed up of the available bending irons on the market and decided to start work on my own. Commercial products like the IBEX or Chinese irons seem to be the wrong profile. (At least for me)

 

I was inspired by the video on Hans Johannsson's site showing how he simply bends the rib to a near perfect fit in one go. I figured his success (apart from sill), has to do with the profile of the bending iron.

 

I'm fortunate to have access to a lot of 3d tech at work so I sketched out a profile and did a couple of 3D prints on the Dremmel 3D printer as a prototypes. 

 

I'm not sure I've got the right profile yet, and would love some feedback. Basically this one has an upper-bout radius of 10mm and a lower-bout radius of 15 mm. The over all length is 80 mm and it is 70 mm high. I drew the profile curve from the two circles so the resulting profile is a tiny bit tighter than the radii noted above.

 

The bottom image shows a 11 mm by 60 mm cutout for the heating element and two taped screw holes

 

Here are a couple of images. I'll post the STL file a bit later for those who want to try to print their own.

 

Once I get it right I will share the data so anyone can CNC their own locally.

 

Chris

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Thanks John. I think you are right -- the treble end may be a bit tight. It may be a bit long also at 80 mm. I find there is always a bit of spring after i bend, what I want to to get the profile right so when I bend snugly the around the form, the rib springs to a near fit for a strad profile.

 

I was inspired by these examples. The first form Hans Johannsson and the second from Bertrand Bellin's site

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the sharp end looks too sharp to me.

I find the shape of the Chinese one I have pretty spot on to be honest.

But I agree that the Ibex one is not much use for violin.

 

I agree with all of this.  I got an Ibex iron several years ago, and struggled with the fat profile.  Now I have a newer Chinese one, which I feel is just fine.  It's just a bit small for doing a rib all in one shot; I have to shift the rib over slightly after bending one end... but that's a ton better than having the profile too long or too fat.  If I wanted to do a 3/4 instrument, I'd need this one.

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I made mine exactly the profile from the mould, but the ribs always have a bit of spring back and require being over-bent slightly.

 

After using it for a short while, I made the radii a little tighter and shortened the overall length between the radii by about a 1/4". Now they bend just about perfect in one operation.

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The c-bout bender does Strad on one side and Del Gesu on the other,,,,

cut out with a saber saw and bolted on.

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This old baby glows red in the dark,,,

even has a serial #,,,,was worth a small fortune I'm sure.

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While the c's are cookin I bend the small curve of the bouts on this,,

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then slip it into this,,

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Cummings diesel piston sitting on a hot plate.

It bends flawlessly perfect.

By the time I make the rounds It is time to put in another c-bout to bend and so forth and so on and on,,

I plug it all into this converted hot plate that I have thanklessly forced into the menial task of controlling the current.

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I do a couple a dozen at a time so this is convenient,, and I have a tendency to be lazy.

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I've got an iron like the one in Bellin's photo.

I've never been able to make a c bout fit just by doing one continuous bend. I find the pointy end too pointy for this.

I usually end up doing both upper and lower parts on the wider end of the iron, but bringing the rib around further and holding a bit longer to give a tighter radius on the upper end. Sometimes I'll tweak the curve a bit on the pointy end.

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Thanks for the feedback. Attached is a modified version with a little softer curve for the upper bout. Still 80 mm wide and 70 mm high.

 

Thoughts?

 

This shape really appeals to me as Bill pointed out you need to over-bend them a little. However I think the idea of having one side with a little more curve as Evan suggests is right for the same reason that the end are different. It just gives you more possibilites 

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With the heating element and the screw taps in the same location it should be possible to use the same base and swap in and out irons with different profiles: 3/4 violin, viola, cello etc. Kind of like swapping out a frog on a Lie Nielsen plane!

 

with a bit of tweaking in CAD and 3D printing physical prototypes, it should be possible to get the right profile for the right need

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You might be OK with that. It's not required to do a full wrap around the bending iron; only enough to get the curve on the ends sufficient to join the corners of the upper and lower bouts.

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I'm getting close to finding the shape I like. Once I'm done I will make the 3d data freely available.

 

I'm also looking at a prototype casting for an old Norris thumb plane. This one will take a little longer...

 

 

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So not exactly a Noris plane but I did model an old ESE thumb plane I have in my kit. Those who have used these know they are fantastic quality, but sadly no longer made. The idea is to model something and eventually get a cast made. This is more of a side project to test some of our 3D printing tech.

 

 

Chris

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This is a dumb question, but what is the different between a 3D printer and a CNC machine?

 

It seems like the same idea to me. How am I not seeing a difference? Is it because the "printer" feeds a material in a different way? Or do you use the printer to model that part in plastic but it is actually created on a CNC machine in metal? 

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Accretion means it could "print" some materials like ceramic slips etc? 

 

As an example of the potential materials available see the list on the left hand side at the ExOne site.

 

This is the 3DSystems video gallery:

http://www.3dsystems.com/video/gallery

 

And this provides glimpses of what these technologies can do:

http://www.3dsystems.com/quickparts/prototyping-pre-production

 

And the Stratasys catalogue of materials:

http://www.stratasys.com/materials

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