In need of Viola making advice

[jordanmcdowell15]

I'm about half way through with the sound box of my first viola. Im interested in getting some advice before I close it up, while there's still time to tweak things. I've searched and read many MN Viola making threads and that's where I got my basic idea of how I want to build the instrument. I'm not sticking strictly to any one specific set of plans or model. Now that I'm in the actual process there are areas in which I would like more specific guidance.

I bought my tone wood from internationalviolin.com which is what I'm used to working with. I stole some ideas from the tertis model and wrote down everything I could find by luis manfio on the measurements of his builds along with keeping notes from other experienced makers.

Here's my first question. Should I remove anymore thickness from the back? If so, where? Here is a graduation map. Hopefully you can read the numbers.

The back still feels stiff to me but my only reference comes from my violin builds. The only tap tone I listened for was the one where you balance the plate on your thumb, tap the top bout while listening to the plate vibrate. I probably don't know what I'm listening for. The sustain is not bad and the tone is clear in my inexperienced opinion. The entire channel(just inside the purfling) is 3.5 mm and it has a 2 mm plate/rib overhang. There will be less than usual recurve or scoop at the plate edges(tertis idea).

Surely you do not have enough information yet, so Im happy to provide anything else that may help someone give advice. Thanks in advance.

Overall length 417

Upper bout width 190

Middle bout width 134

Lower bout width 258(tertis idea)

Back arching height 18mm

Thickest area is placed at 223 mm from the bottom... Reverse stop position

Back weight 185 gm before scraping the pencil numbers(seems heavy)

Rib height is a steady taper from 40 mm at the end pin to 35 mm at the neck.

Garland weight 78 gm

 

[Davide Sora]

As you can imagine, it is practically impossible to give such indications simply based on numbers and measures, without feeling the real thing. But since you ask, and based only on single numbers (so at your own risk to take what I'm telling you for good) for me the weight of the back is too high, and the thickness in the center as well. The back of my last viola (more or less Guarneri model, 415 mm lenght) when finished with the edges already rounded was 134g, wood density 0.58, max thickness 5,0 mm at 236 mm from lower edge, height of the arching 18.4 mm, minimum transverse radius 95mm, wood from 1988. I could also tell you the tap tones, but it does not seem to me that you have very clear ideas on how to identify them and therefore it is better not, also because the model differences make them not comparable anyway. In any case, in my way of interpreting them, they indicate a stiff back rather than the other way around.

[jordanmcdowell15]

Thank you Davide! I agree about the weight. I was following Manfio's advice about thickness but now that I've graduated mine, it seems that I must be using higher density wood. Im glad you specified about where you would remove wood because my guess would have been uneducated at best. I'm at 4mm+ around the c bout edges. Should these areas be trimmed to say 3.4 or so as well? Thanks

[Davide Sora]

2 minutes ago, jordanmcdowell15 said:

 I'm at 4mm+ around the c bout edges. Should these areas be trimmed to say 3.4 or so as well? Thanks

I think it can be done, but giving such indications is even more risky and less reliable based only on numbers

[Jim Bress]

Hey Jordan, You know that when we were taping plates we were mostly just trying to look good while resting.  I'm looking forward to seeing/hearing your viola when it's finished.

-Jim

[jordanmcdowell15]

Lol Jim. Good to hear from you. I thought that's what you guys were doing.

I do record that particular tap tone and a couple others for my violins with my studio software, but I'm not at all sure how they should compare to this viola. I don't want to rely on that too much of that anyhow. I think I may be better off going off of feel for stiffness for now until I find a tap tone that works consistently. 

I'll be sure to record a viola version of ashokan farewell. Maybe we can get a rise out of ole Joe Thrift.

[jordanmcdowell15]

Alright... I made a boo boo. For some reason I cut my f holes in 10 mm south of what I had planned. I was going for a 223mm stop length. Ended up at 233. Oh well... I see that Guarneri experimented with f hole placement and there's quite a bit of variation, so I'm not too bent out of shape about it. This placement did have an impact on the alignment or uprightness of the f holes. I kept wondering why I was having such trouble placing them more upright without moving the bottom eyes too far from the edge.  Now, they're leaning quite a bit. I do think this may be detrimental to the vibration of the top plate but I'm willing to complete and replace the top if needed later. I really wanted them to be almost parallel. Darn it. Maybe next time. Does anyone have any input on this situation? Possible outcomes tonally? Should I consider trashing it and start over? 

 

Figuring the angles at the heel and the neck length have always been basically handed to me via templates from books or posters. This time, since I'm not copying anything in particular, especially with the new stop length problem, I had to figure it myself. I think the best way to go about this is to draw it on paper. So here's what I've come up with. I would like to know if any of these figures look wrong enough to make the instrument unplayable or at least aggravating.

This is a 417mm viola with a now 233mm stop length. I've come up with 2 options for neck/ string length. Obviously I can move the nut placement anywhere in between but here are what I consider the 2 extremes. I don't know which is the more important parameter to stick to. Please advise. 

Option 1:

neck length 142.5mm nut to edge of plate(150 to end of neck block)

string length 380mm

Option 2:

Neck length 150mm nut to edge of plate(158 to end of neck block)

String length 387mm.

All other parameters are the same

8mm overstand

8mm inset into end block

32mm finger board projection at bridge

37mm bridge height(on paper anyways)

Neck thickness including fingerboard 22@ lower end and 20 near the nut

Fingerboard radius 38mm

Fingerboard length 305mm

Tailpiece I have is 129mm so after length will be somewhere around 64mm.

String clearance in middle of fingerboard 4mm.. that's 3.5 and 5mm at A and C respectively. I can't quite wrap my mind around the relationship between the fb radius and bridge arch so I hope I'm not throwing myself off there. 

Am I missing anything?  

One last question... What do your knives or other tools look like that are responsible for the end grain areas below and above the wings? Either my knives are not sharp enough or I'm using the wrong tool all together. Those areas on mine are quite ragged. 

[Rue]

10 hours ago, jordanmcdowell15 said:

Alright... I made a boo boo. For some reason I cut my f holes in 10 mm south of what I had planned. I was going for a 223mm stop length. Ended up at 233.

... 

...and in 300 years...an expert will write a long, detailed article describing how the luthier spent years studying, experimenting and doing complex math...before deciding to move the f-holes 10 mm...

 

[Christopher Jacoby]

jordan I would do neck length and fingerboard length proportional to your effhole placement as it exists. The ratios between them exist for a reason, and especially if something goes a little wonky, can help a viola work and feel like an intentional machine.

SO you're working with Neck Length: 2/3 Mensur, and Fboard length 5/6 String Length

[David Burgess]

On 10/29/2022 at 11:43 PM, jordanmcdowell15 said:

Alright... I made a boo boo. For some reason I cut my f holes in 10 mm south of what I had planned.

This might not be a big deal. I have experimented with tweaking dimensions and proportions all over the place, and typically, even the high-level experts didn't notice. Your outcomes may vary.

[JacksonMaberry]

On 10/29/2022 at 8:43 PM, jordanmcdowell15 said:

What do your knives or other tools look like that are responsible for the end grain areas below and above the wings? Either my knives are not sharp enough or I'm using the wrong tool all together. Those areas on mine are quite ragged.

I find it easier to cut the endgrain areas while the plate is still 6mm or so thick for some reason. My f hole knife is my only non-curved edge, but curved would be fine too. Long and thin, double beveled. Try to position the edge such that it is in contact with several growth rings if possible, and use a slicing cut.

[jordanmcdowell15]

Thank you Christopher. That is exactly what I was looking for. 

Good to know David. Very comforting. 

And Jackson... Im sure I need more time and experience in those areas and probably a sharper knife. I use pretty much what you use based on it's description. For the technique, I'm picturing the knife at more of an angle as it comes through the plate, in order to catch multiple growth rings. This is something I haven't tried yet so, thanks. Always learning!

[Davide Sora]

On 10/30/2022 at 4:43 AM, jordanmcdowell15 said:

One last question... What do your knives or other tools look like that are responsible for the end grain areas below and above the wings? Either my knives are not sharp enough or I'm using the wrong tool all together. Those areas on mine are quite ragged.

You can see my knife and how I use it in this video. It is dedicated exclusively to this work because the tip is very delicate and would be easily damaged if it were also used for other jobs.

 

[Marty Kasprzyk]

On 10/29/2022 at 11:43 PM, jordanmcdowell15 said:

Alright... I made a boo boo. For some reason I cut my f holes in 10 mm south of what I had planned.

>

>

Does anyone have any input on this situation? Possible outcomes tonally? 

 

if you are bowing close to the bridge a 10mm lower position of the bridge might cause your bow hand's thumb knuckle to more often hit the right hand lower bout's sharply pointed knucklebuster.

 

 

[jordanmcdowell15]

Davide, as always, the video is amazing. Thanks for posting them. I can only dream of being as steady and graceful as you. Maybe one day I suppose.

 

I hadn't thought of that yet, Marty. That would be a pain for sure. If it gives problems I will remake the belly. I intend on stringing it up before varnish as I anticipate wanting to make graduation adjustments.

[slf]

 

[JacksonMaberry]

You can always ignore the inner notches when placing the bridge. You see it rather often on weird old violas, some of which sound pretty damn good

[slf]

On 11/3/2022 at 8:40 AM, JacksonMaberry said:

You can always ignore the inner notches when placing the bridge. You see it rather often on weird old violas, some of which sound pretty damn good

 

[jordanmcdowell15]

That sounds like the most sensible thing to do. The instrument was designed with a particular stop, string and neck length in mind. And I don't think ff hole misplacement should dictate such consequential changes. Thanks for the advice. 

[JacksonMaberry]

Sure! Rules are made to be bent.