cnc CNC Templates and Moulds

[Mike B]

Making the Violin Mould and Blocks Messiah - DRAFT - Not Tested - V0001.crvI'm working to create a basic set of CNC-router-ready files. The current 2D files are in VCarve Pro and 3D files will be created in Fusion 360 or similar. They will be shared here as an aid to others. 

The attached file is for the Messiah "symmetric" modified Strad PG mould as provided by  http://www.makingtheviolin.com/ and serves as a jump-start for those who are working to produce a CNC-routed form. 

To do:

1. Add holes to "inside corners" (complete 9/27; not yet tested)
2. Add CNC instructions
3. Perform test run

The next items to be posted will include:

1. Template for Messiah Top
2. Silicon thermal blanket Rib Presses and Instructions
3. Roughing model for the Top
4. Roughing model for the Bottom
5. Roughing model for the Neck

These are designed to be produced in a straightforward manner.

These models will later be modified to include an example CAM configuration and "registration" methods for alignment of parts with a 3-axis CNC router.

Please feel free to add comments, improvements, and photos of test-runs!

Reference: Messiah, MTV Symmetric PG Form.

Update (9/27/2020): Provided several modifications to the baseline file. 

Making the Violin Mould and Blocks Messiah - DRAFT - Not Tested - V0001.crv

Making the Violin Mould and Blocks Messiah - DRAFT - Not Tested - V0001_4.crv

Edited September 28, 2020 by Mike B

[Mike B]

Here is a PDF that has been "right sized" from the SVD files provided on makingtheviolin.com

The left is the top and back template (assuming they are the same). The right is the template for the ribs and blocks. Each template is marked with its "actual" dimensions and the "template" dimensions as cut.

This is designed for laser printing at makerstock.com on 18x24 inch acrylic, MDF, or plywood stock.

This file requires an update as I noticed that the text is incorrect for the dimensions and title of the rib/block template. 

Update: I did not copy the rib form to the file - I noticed this as I was prepping to send it out for laser cutting. There are additional steps that need to be done in the attached file.

 

Template 1 TopBack and Ribs.pdf

Edited September 29, 2020 by Mike B

[Michael_Molnar]

When I have time, I’ll compare yours to mine. 
 

[Mike B]

That would be excellent!

I'd be particularly interested in how you handled the kerf for your cutting method (I'm using a laser cutter) and if you chose to "shrink" the template any to allow for the size of the pencil lines. I'm curious to know what standard other people use.

V/r,

Mike

Edited September 28, 2020 by Mike B

[Don Noon]

At one time I had a form with cornerblock cutouts similar to that.  But I found that it was a pain to get the odd angle when cutting up a mess of cornerblocks, so now I use the boring 90-degree angle.

I'm skeptical of the silicone thermal blanket approach.  I don't know any makers that use that method, although I have seen some articles about it.  How would you apply enough pressure to the form to prevent cracking? How do you control the temperature to be uniformly hot enough but not burn?  Do you intend to make a special bending form with excess curvature to compensate for springback?  At one time I considered such a method as well, but the practical issues overrode that neat idea.

[JPherson]

3 hours ago, Don Noon said:

At one time I had a form with cornerblock cutouts similar to that.  But I found that it was a pain to get the odd angle when cutting up a mess of cornerblocks, so now I use the boring 90-degree angle.

I'm skeptical of the silicone thermal blanket approach.  I don't know any makers that use that method, although I have seen some articles about it.  How would you apply enough pressure to the form to prevent cracking? How do you control the temperature to be uniformly hot enough but not burn?  Do you intend to make a special bending form with excess curvature to compensate for springback?  At one time I considered such a method as well, but the practical issues overrode that neat idea.

Don,

I saw a YouTube video of KC strings doing something similar. I believe the heated element or blanket was on the bottom and the counter form was secured to that. Seems to work upto cello at least. 
here is the video. The rib bending starts at about 3:50. Hope this is what you are talking about. 
Video
 

Jesse 

Edited September 29, 2020 by JPherson
Added the video link

[Geigenbauer]

Adding a YouTube video from Two Cherries Instruments where he is using the blanket technique.

 

 

[Mike B]

The Two Cherries instrument, while being a highly parametric design, used some interesting techniques for bending. I've watched his videos, among others. 

One example of a well-used silicon blanket bending method is employed by Greenfield Guitars as shown in the early parts of the video below. Unlike the Two Cherries version, this incorporates vices so that pressure can be applied once the sides are up-to-temperature. 

I've not yet decided on a method to apply pressure for the clamping mechanism. I've also considered a machined aluminum form heated from behind - that is something to try later when I want to practice my metalworking skills...

 

 

 

[Mike B]

19 hours ago, JPherson said:

Don,

I saw a YouTube video of KC strings doing something similar. I believe the heated element or blanket was on the bottom and the counter form was secured to that. Seems to work upto cello at least. 
here is the video. The rib bending starts at about 3:50. Hope this is what you are talking about. 
Video
 

Jesse 

Having never built a cello, I'd love feedback on how easy this "looks" to those who can compare. 

[viorel]

Cello 3d my 3d work is free for use, enjoy the stl file

cello_form_3d.stl

Edited October 24, 2020 by viorel