Brian Timmons's Bench

[Brian in Texas]

On 11/5/2025 at 3:12 PM, Will Turner said:

Looks great, looking forward to seeing the progress on this one, especially with the local instruction.

That's making all the difference, really. Having someone looking over my shoulder saying "Do this" or "Don't do that" is invaluable.

14 hours ago, Vincent C said:

Looking good, Brian!

Thank you.

[Tets Kimura]

On 11/4/2025 at 11:40 PM, Brian in Texas said:

The willow that will make the back of this viola is fairly plain, although it has little spots of birds-eye figuring here and there. But I chose this wood for how it sounds, not for how it looks.

Next time I'll need to clean up the c-bouts, which I didn't want to rush through last night. It still needs more work finish sanding the edges. It’s sticking out from the line here and there. But this is just fresh off the rasp.

FWIW, a slab-cut willow or poplar back tends to shrink a bit in width during making, and even more during the varnishing process. So it’s safer to leave a little extra overhang, especially around the lower bouts.

When I use willow/poplar, I finalize the outline only after the back has been exposed to UV for several days, with the arching and thicknessing already completed.

Also, be careful with the shape of the lower corners. In particular, the treble lower corner looks overly hooked if you follow the pencil line.

[Brian in Texas]

3 hours ago, Tets Kimura said:

Also, be careful with the shape of the lower corners. In particular, the treble lower corner looks overly hooked if you follow the pencil line.

Good eye. Indeed, I accidentally took off a bit too much wood in that spot. A couple of days ago I glued a patch in place there to bring it closer to the originally intended outline. It has since been trimmed back and the overall outline looks much better now.

Last night I was working away at establishing the long arch of the back. Just a brief clip sharing the satisfaction of working with a sharp tool.

 

[Brian in Texas]

Rough arching on this willow viola back is done. There are a few small undulations, but it’s close enough that I’m thinking it’s time to use the Sacconi compass. Not being super picky about the surface now, since it’s going to be scraped back later as I make adjustments based on the lines drawn by the compass.

[MikeC]

Are you using templates for cross arches? 

 

[Brian in Texas]

3 hours ago, MikeC said:

Are you using templates for cross arches? 

 

Yes, indeed. Are you asking because something appears wrong to your eye? I'll admit I had a hard time taking a picture that seemed to capture how light plays off the surface.

[MikeC]

It could be the straight on angle and lighting that makes it not look quite right.  Take a low angle photo from either end, neck or tail.   I'm just an amateur online, so get guidance from your mentor, he will have a much better view in person. 

A low angle view from the end gives a better visual of the shape of the arch.  

The curtate cycloid shape may be a little bit controversial,  it's been discussed here on MN.  But in general it gives a good shape to an arch.  I have templates copied from the Strad Titian CT scans, but if I didn't have those, I would make curtate cycloid templates.  

In other news, I'm off for a week of vacation so hopefully will get work done on the neck for mine.  

[MikeC]

Do something like this to visualize the arch shape,  hold a straight edge over the plate to cast a shadow.  

 

[Brian in Texas]

57 minutes ago, MikeC said:

Do something like this to visualize the arch shape,  hold a straight edge over the plate to cast a shadow.  

 

Good idea. I'm at the day job now but I can do that later.

[Brian in Texas]

21 hours ago, MikeC said:

Do something like this to visualize the arch shape,  hold a straight edge over the plate to cast a shadow.  

[MikeC]

ah, that looks good,  it was hard to tell from the face on view.  For the end block areas I like to continue the recurve around.  I use the template for the widest part of the lower bout on the long arch at the bottom block end.  And widest template for the upper bout on the neck end.   If you look at a CT scan of a strad the plate is nearly flat over the blocks so on the inside there is not a steep drop off from where the block ends and the arch starts.  If that makes sense.  I'll show a picture if I can find one. 

 

[MikeC]

maybe I'm exagerating a little bit but here's a side view of the Titian down the center.  You can see here that there is not a steep drop off from the gluing surface of the plate to the end blocks.  

[MikeC]

And here's the Plowden.  Guarneri Del Gesu.  Looks nearly identical to the Strad.  

[Brian in Texas]

I'm starting to get the outer arch of the back symmetrical. My inexperience using a Sacconi compass aside, I think it's starting to come together. The innermost ring is bulging in the middle compared to the others. I'm yet to address that. This is is where I left off working on it last night. Obviously I'm not too concerned with the quality of the surface at this point, since it's all going to be scraped smooth once I'm done with this stage. Apologies for the quality of the image. It's a screen cap taken from a video.

[MikeC]

Looking good.  I made one of those pencil marking things,  the pencil point tends to get stuck on the wood so it's a pain to use but it's useful to get the contour lines anyway.  

[Davide Sora]

16 hours ago, Brian in Texas said:

I'm starting to get the outer arch of the back symmetrical. My inexperience using a Sacconi compass aside, I think it's starting to come together. The innermost ring is bulging in the middle compared to the others. I'm yet to address that. This is is where I left off working on it last night. Obviously I'm not too concerned with the quality of the surface at this point, since it's all going to be scraped smooth once I'm done with this stage. Apologies for the quality of the image. It's a screen cap taken from a video.

 

 

12 hours ago, MikeC said:

Looking good.  I made one of those pencil marking things,  the pencil point tends to get stuck on the wood so it's a pain to use but it's useful to get the contour lines anyway.  

In my experience, if the Sacconi compass is too large, it becomes tough to use and inaccurate. Making it (them) smaller and lower increases rigidity and stability, making it easier to obtain clean, accurate isolines. Another factor that greatly improves stability and ease of tracing is having a flat surface resting on the underlying flat plane of the plate, rather than the single raised point under the pencil. This raised point is needed for tracing thicknesses (which, in my opinion, is the true purpose for which the Sacconi compass was designed as it is), but for the isolines of the archings, it's a nightmare to use. I had to make a bigger, taller one for the cello (you can see it in this video: https://www.youtube.com/watch?v=aJzxx-qOqK8 ), but I never use it for violin or viola, there is no comparison to the ease of use and accuracy of the smaller ones.

 

[Brian in Texas]

@MikeC Thank you. I'm using a colored pencil (black) because it's harder than a regular #2 pencil and it seems to work ok without getting stuck in place.

@Davide Sora Thank you for weighing in, especially with plans and measurements! On my teacher's advice, I made a compass to his measurements, and it's large enough for a cello. I think I should take your advice and make a smaller one to see how much easier it is to use. It's also interesting that according to him, having a raised dome under the pencil is what makes the whole system work, but for you, you use the flat wood instead. I give more weight to your school of thought, as you are trained in the Cremonese tradition and my teacher is self taught.

So yes, I will be making a smaller compass with a flat bottom. 

[Davide Sora]

17 minutes ago, Brian in Texas said:

@Davide Sora Thank you for weighing in, especially with plans and measurements! On my teacher's advice, I made a compass to his measurements, and it's large enough for a cello. I think I should take your advice and make a smaller one to see how much easier it is to use. It's also interesting that according to him, having a raised dome under the pencil is what makes the whole system work, but for you, you use the flat wood instead. I give more weight to your school of thought, as you are trained in the Cremonese tradition and my teacher is self taught.

So yes, I will be making a smaller compass with a flat bottom. 

Since we have a flat surface underneath the plate when we draw the isoline, having the compass resting on a larger surface than the single point allows us to slide it without losing the pencil's perpendicularity. Furthermore, we only need to concentrate on sliding and applying only the light pressure needed to trace. With a single point, we would have to control too many things at once, with no reference to maintain perpendicularity other than our own feeling. I'm not saying it's not possible, but it's certainly more difficult and less reliable. Furthermore, having a single tracer for each curve allows us to repeat the same one exactly without changing the measurement. So you can modify the arching and redraw the erased lines to evaluate progress. This kind of tracer is my own idea, born from the frustration of trying to use the Sacconi compass without success. Then I discovered that those who said it worked actually never used it.

[Brian in Texas]

3 hours ago, Davide Sora said:

Is the one with the 100 mm opening for a violin/viola alone, and the 150 mm is for a cello? Because the compass I'm using has an opening of almost 230 mm. No wonder I'm having a hard time.

[Sean Couch]

I used to use my rigged up thickness caliper measuring frame to draw contour lines, but it has a rounded anvil and was difficult to use. I always meant to make a set of contour line tools like Davide has, but I am lazy. My set up is simple and only took a few minutes to cobble together. My system probably isn’t as efficient as what Davide uses, but I only make about one violin a year.

What I use is a square stick of scrap wood about 19mm square, drill a whole through it for a pencil and drill another small hole perpendicular to the pencil hole for a screw to hold the pencil in place. I place the stick and pencil on top of a 123 block, clamp it to a flat surface (my work table) and set the zero height of the pencil. Then I have a bunch of 1.5mm thick plastic shims that I put under the 123 block until I have the desired height/thickness of the isoline that I want to draw.

All you have to do to trace the contour lines is slide the plate gently under the pencil point. Just make sure the surface of the plate and table are free from debris. Resetting the zero as the graphite wears away is easy and so is adjusting the height of each individual isoline.

Below are a couple pictures that will hopefully explain it better. If my little drill press that I use as a graduation punch had a larger table, I would probably use that. I could use my mill/drill but that is in the basement and my shop is on the second floor, so too many stairs for my lazy self to navigate. lol.

Top view with a stack of shims next to the 123 block:

Side view with 4.5mm of shims:

[Davide Sora]

48 minutes ago, Brian in Texas said:

Is the one with the 100 mm opening for a violin/viola alone, and the 150 mm is for a cello? Because the compass I'm using has an opening of almost 230 mm. No wonder I'm having a hard time.

The 150mm one is needed to draw the highest contour lines on the violin and viola (I usually draw two). If the arch is lower, one of these will probably suffice. I also use the 100 mm and 150 mm also for the cello, for the isolines where they can correctly trace along the entire perimeter, limiting the use of the longer one only for the isolines where the smaller ones do not reach.

[Davide Sora]

16 minutes ago, Sean Couch said:

I used to use my rigged up thickness caliper measuring frame to draw contour lines, but it has a rounded anvil and was difficult to use. I always meant to make a set of contour line tools like Davide has, but I am lazy. My set up is simple and only took a few minutes to cobble together. My system probably isn’t as efficient as what Davide uses, but I only make about one violin a year.

What I use is a square stick of scrap wood about 19mm square, drill a whole through it for a pencil and drill another small hole perpendicular to the pencil hole for a screw to hold the pencil in place. I place the stick and pencil on top of a 123 block, clamp it to a flat surface (my work table) and set the zero height of the pencil. Then I have a bunch of 1.5mm thick plastic shims that I put under the 123 block until I have the desired height/thickness of the isoline that I want to draw.

All you have to do to trace the contour lines is slide the plate gently under the pencil point. Just make sure the surface of the plate and table are free from debris. Resetting the zero as the graphite wears away is easy and so is adjusting the height of each individual isoline.

Below are a couple pictures that will hopefully explain it better. If my little drill press that I use as a graduation punch had a larger table, I would probably use that. I could use my mill/drill but that is in the basement and my shop is on the second floor, so too many stairs for my lazy self to navigate. lol.

Top view with a stack of shims next to the 123 block:

Side view with 4.5mm of shims:

This is the system I started with; the concept is the same, that is, using a reference plane corresponding to the plane of the plate, with the pencil held perpendicular to it. The drawbacks of this system are the inconvenience of setting it up every time for each measurement and the possible mismatch between the reference plane and the plate plane. Also, moving the plate instead of the tracer is a bit trickier to get the right and even pressure of the tracing pencil.

But it works.

[MikeC]

Davide, that's a great idea to have a flat surface under the pencil.  I have a small post under the pencil and I think that causes the problems I have.  It's hard to maintain the pencil perpendicular with a post under it.   I'm past that stage on this build but next time, I'll remove the post from my marker and try it your way.  

[Brian in Texas]

I just want to say that I really appreciate everyone for weighing in on this. This sort of exchange of ideas is exactly what I need to be absorbing in order to become a better maker.

[Davide Sora]

3 minutes ago, MikeC said:

Davide, that's a great idea to have a flat surface under the pencil.  I have a small post under the pencil and I think that causes the problems I have.  It's hard to maintain the pencil perpendicular with a post under it.   I'm past that stage on this build but next time, I'll remove the post from my marker and try it your way.  

For the longer one I made for the cello, I included a removable post so it can be used for both the isolines (without the post) and for the thickness (with the height-adjustable post). For the violin and viola, I have one with an adjustable post dedicated to thickness only.