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Undercutting the Volute


Shunyata
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My undercuts are relatively flat as shown in the picture.  And with this shape, chamfering has to be very light or it doesn't look good.

I would like to aim for a much deeper undercut like you see on Markies or French instruments.  But I don't really have a feel for how to do this.  Does anyone have a general suggestions for technique other than get in and try?

I plan to carve a bar of soap to get a feel for the geometry.  But dealing with the grain and fine details carries its own challenges. 

Screenshot_20220526-095411.png

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19 minutes ago, Wood Butcher said:

 Use a more curved gouge. Cut deeper.

I shape the channel by cutting radially, starting from the outside edge and cutting toward the eye.  It sounds like you are cutting around the circumference, following the shape of the circle.  Is that right?

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The bevel should be cut before you work on the outside grooving. That's how you keep the center ridge from sticking up. In fact cutting the bevel as early as possible helps to see what is going on anyway.

I use a long thin knife sideways or diagonally for all of the convex part and a gouge only for the lower half of the back.

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I cut the flat spiral first using a saw, then undercut (as described above) and save the outer fluting for last.  But I use gouges for all of the outside fluting.

I am interested in hearing how others handle undercutting.  We have several votes for radial cuts.  Any other techniques?

 

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53 minutes ago, Michael Darnton said:

The bevel should be cut before you work on the outside grooving. That's how you keep the center ridge from sticking up. In fact cutting the bevel as early as possible helps to see what is going on anyway.

I use a long thin knife sideways or diagonally for all of the convex part and a gouge only for the lower half of the back.

Michael,

 I think he is talking about the sides of the volute not the fluting.
 

As far as cutting the chamfer early in the process it depends what model/maker you are emulating. There are some makers who cut the chamfer last indicated by a central ridge which IS higher than the edge chamfers. I suspect you have seen this even more often than I have.

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I understand now.

I am not sure how to phrase it, without it sounding bad, but the scroll you have shown, which you wish to replicate, does not look nice or quality to me. I would find something else to replicate.

Regarding the working, I think you already approach it in the right way. You could try a more scooping cut, rather than dead straight.

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Shunyata,

I agree with Mr. Butcher that the example you showed is not a good choice to copy. Hard to see from pictures but I think I prefer yours. Perhaps if you slanted the walls of your pegbox in  a little more at the throat you would find that you can make the under cutting deeper but still fairly flat along the radial direction. Obviously the curve of the under cut increases as the turns get smaller but I like the area just above the pegbox and around to the forehead of the scroll 'to be slanted but not really hollowed. Hard to describe but if you look at some classical period scrolls I think it would help.

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On 5/26/2022 at 4:03 PM, Shunyata said:

My undercuts are relatively flat as shown in the picture.  And with this shape, chamfering has to be very light or it doesn't look good.

I would like to aim for a much deeper undercut like you see on Markies or French instruments.  But I don't really have a feel for how to do this.  Does anyone have a general suggestions for technique other than get in and try?

I plan to carve a bar of soap to get a feel for the geometry.  But dealing with the grain and fine details carries its own challenges.

I don't see why with flatter undercuts the chamfer must be thin, I don't see any relationship.

However, to dig the volute and the turns more, you will simply have to use more curved gouges, because as the depth increases, the flatter ones are no longer able to turn well making clean cuts. Another suggestion is not to use the scrapers but only the gouges, because scrapers have the tendency to flatten the surfaces to the outside.

If you want to make your undercuts deeper you will have to pay attention to the transition between the pegbox and the volute, increasing the depth very gradually so as not to end up with the end of the pegbox too narrow or not to leave an abrupt change between the flat pegbox wall and the beginning of the volute hollowing (unless you are making a Del Gesù copy:lol:)

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2 hours ago, Davide Sora said:

If you want to make your undercuts deeper you will have to pay attention to the transition between the pegbox and the volute, increasing the depth very gradually so as not to end up with the end of the pegbox too narrow or not to leave an abrupt change between the flat pegbox wall and the beginning of the volute hollowing (unless you are making a Del Gesù copy:lol:)

Amusingly, I am working on a Del Gesu copy right now.

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2 hours ago, Davide Sora said:

However, to dig the volute and the turns more, you will simply have to use more curved gouges, because as the depth increases, the flatter ones are no longer able to turn well making clean cuts.

For digging the volute more,  it sounds like your cutting direction is starting to become more tangential... following the curve of the spiral.  (My cuts in  the very top picture are radial, cutting from the edge toward the eye.)  Do I understand you correctly?

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5 hours ago, Shunyata said:

For digging the volute more,  it sounds like your cutting direction is starting to become more tangential... following the curve of the spiral.  (My cuts in  the very top picture are radial, cutting from the edge toward the eye.)  Do I understand you correctly?

Not exactly tangential, I don't know how to call them, maybe curved cuts. Showing is easier than describing, here you can see well:

https://youtu.be/HbeyAdJJV3k?t=380

https://youtu.be/SEv4DchDO_s?t=55

For the finish I go more radial, but I would call it more Amati style than Del Gesù style:)

https://youtu.be/SEv4DchDO_s?t=366

To dig deeper, even when cutting radially, your gouge must always be more curved than the surface you are cutting in.

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5 hours ago, Shunyata said:

Amusingly, I am working on a Del Gesu copy right now.

Then you might as well ignore my comment on the transition, leaving a clean and edgy cut where the flat of the pegbox wall ends and the gouge cut begins, very typical of del Gesù, although not necessarily good to be imitated:lol:

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On 5/28/2022 at 1:36 AM, Davide Sora said:

Not exactly tangential, I don't know how to call them, maybe curved cuts. Showing is easier than describing, here you can see well:

https://youtu.be/HbeyAdJJV3k?t=380

https://youtu.be/SEv4DchDO_s?t=55

For the finish I go more radial, but I would call it more Amati style than Del Gesù style:)

https://youtu.be/SEv4DchDO_s?t=366

To dig deeper, even when cutting radially, your gouge must always be more curved than the surface you are cutting in.

If this wasn't you I would question this method. Don't most 'good' makers cut radially, i.e. from outside, and smooth chissel marks in the end (or leave them as Guarneri did). 

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1 hour ago, uguntde said:

If this wasn't you I would question this method. Don't most 'good' makers cut radially, i.e. from outside, and smooth chissel marks in the end (or leave them as Guarneri did). 

Perhaps most makers, but certainly not all, not even in ancient times. However, a radial component of the cuts is always present, but the way in which cuts are made depends on the final result you want to achieve, the carving work is a purely aesthetic factor, copying at all costs is not always the best thing. However, considering the ancient luthiers, I am of the opinion that some of the Amati cut more similar to how I do, the Guarneri were the most ostentatiously "radial".

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In what direction the cuts are made is really not the issue.

How the gouge is ground and sharpened is the most important factor. A proper carving gouge with a curved cutting edge is needed. David Sora's videos couldn't be more clear as to what is necessary.

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I have very sharp, well-shaped tools.  My original question was about what techniques people use. 

Davide (whose work is a never-ending source of inspiration and education... I would love to see and play one of his violins!!!)  has provided a well-rounded answer based upon his approach. 

Other responders seem to say that technique matters little, you just need a feel for what you are aiming for.  My work on a soap block should instill this understanding.

But I will definitely follow Davide's technique.  Again please accept my gratitude, Davide, for all of the teaching you have shared with me.

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4 hours ago, Shunyata said:

I have very sharp, well-shaped tools.  My original question was about what techniques people use. 

Davide (whose work is a never-ending source of inspiration and education... I would love to see and play one of his violins!!!)  has provided a well-rounded answer based upon his approach. 

Other responders seem to say that technique matters little, you just need a feel for what you are aiming for.  My work on a soap block should instill this understanding.

But I will definitely follow Davide's technique.  Again please accept my gratitude, Davide, for all of the teaching you have shared with me.

Working with the soap block is a good exercise to understand the shapes, but with the limit of being too homogeneous and too forgiving under the gouges. Often the cutting technique is strongly influenced by the wood fiber, which sometimes forces us to change the cutting direction with respect to our original intent. Identifying and learning how to properly cut areas where the direction of the grain changes is key to achieving a clean finish while maintaining control over the shapes we have in mind.

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2 hours ago, Davide Sora said:

Often the cutting technique is strongly influenced by the wood fiber, which sometimes forces us to change the cutting direction with respect to our original intent...

So true!  With wood you will know every cut whether you are with the grain, at an angle to it, or cutting across it.  With soap, you could use little more than the force of writing with a pen.  With wood, your muscles will be used quite differently, and sometimes the figured maple will give you a new challenge again.

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