Archtop Guitar Plate Issue

[mbhwhitney]

Hi guys - 

I'm working on some archtop plates in Fusion. I've learned a lot so far from a fellow builder and Fusion user, Vince Morel (excellent videos on YouTube) who also references a user, @TrippyLighting who has a great screencast here on the forums on how to model an archtop plate similar to something on a Les Paul-style of guitar.

In short, I've imported a blueprint, drawn in the cross-section curves, perimeter and longitudinal arch and then patched the outer surface, inner surface and then stitched both surfaces including the sidewalls. As a side note, I built the model as one half and then mirrored things along the centreline.

Here's where I'm stuck:

When hand carving plates, one will leave a consistent 'flat' around the perimeter and into the neck and tail block portions as shown in the attachments (photo):

Interior of archtop plate: Flat mates with liners and neck / tail blocks.

Also shown is a CAD model from somewhere else that illustrates the 'flat' region in the perimeter and neck block area very well (looks like it was done in Rhino 3D) - this is essentially what I'd like to achieve on the inside surface.

CAD model clearly shows this 'flat' I'm referencing.

The last image is my Fusion model (purple). Perhaps you can mentally extrapolate my process using a patch that follows several cross section curves. However, you can also see that  it doesn't create the flat region.

Sub-par 'flat' area from my model.

Outside of plate looks decent - needs some minor tweaking.

I'd love to learn how to automate this carving process and how to create these models to expedite workflow and then fine-tune the recurves / finish sanding etc. on the other end by hand. My Fusion knowledge falls in the 'enough to be dangerous' category but I'm having a good time learning and moving over from Rhino 3D. If anyone has a solution here and is willing to do a screencast, I'd be extremely grateful.

[TrippyLighting]

Can you share your model?

[mbhwhitney]

Hi Peter - happy to. 

The model I'm working on is symmetrical as you can see. An example of how this neck-block region may look on a non-cutaway guitar looks something like this:

You can see how the perimeter that will mate with the sides' liners and neck/tail block are crisp and flat.

'Step two' for me is to incorporate the cutaway and modify these 'flats' to follow suit on the interior carve of the plates - again, something like these:

Thank you for taking a look.
Cheers!
Mike

[TrippyLighting]

Sorry for the late reply.

If you want a flat perimeter, then you should not use a loft rail that has curvature in that area.

You should probably model that flat area first and then loft from there.

[mbhwhitney]

Hi Peter - Thanks for taking a look and for offering up some advice. I had some tunnel vision around my approach and figured I needed to somehow manipulate what I'd modelled to get that flat 'rim'. I'm going to attempt to model that flat rim (app 7/8" portion) and a larger area over the blocks, separately, and then try to loft the interior into that....

I'll update things here should it help anyone else down the road (or if I get stuck 🙂 ).

Thanks again.