Sean Couch’s Bench

[Sean Couch]

12 hours ago, MikeC said:

That's looking good!    The second picture, side view can you take a picture with the camera a little bit lower, like halfway between that and horizontal?   I would like to see what that looks like at a slightly lower angle.  I think I got a bit too much recurve in mine in the upper and lower bouts.   

Thanks Mike. Here are some more pictures. Hopefully they show what you are looking for. I don’t know if I have enough recurve so use them at your own risk. I have to redo my contour lines as pretty much all that has changed once I finally got the 6th set. I still have a bit of a pinch in the C-bouts and a few whoop-de-doos to fix, but I think she is as close as she has ever been at being correct.

[MikeC]

Thanks for the pictures Sean,   I was comparing to mine.   I feel like I may have a little to much recurve upper and lower bouts.   I was using the usual 5 cross arch templates from the Titian poster but I also had in mind curtate cycloids.

Your's looks good.   I think mine is ok.   

Here's a picture,  I've done a little more smoothing and refinement since this picture but don't have a more up to date pic. 

 

[Sean Couch]

Yeah, arching really bends my brain for some reason. I am using arching templates from the online manual of “making the violin.” I need to make better ones as mine are paper templates laminated with clear packing tape. I can’t use them like you do and put graphite on them and rub them on the plate to show where to remove material. I hold the template in place and mark where material needs to be removed with a pencil. It is a tedious process.

I do have my mom’s childhood violin here with me, but it is not a very good example to look at for arching contours. It is a poorly made violin with painted on purfling and fairly low arching. My mom will soon be 81 and I think the violin and bow are from around 1920 ish.

When I got the violin a couple months ago you could see that the sound post was at an angle (at least 30 degrees) and there was very little string tension holding up the bridge. I haven’t increased the string tension but I did fish out the sound post. A very gentle squeeze in the waist and it fell right over.

I need to get the bow rehaired and the violin set up with new strings, sound post, and maybe a new bridge. I’ve been pondering if I should attempt the set up or take it to a music shop and have them do it. 

Check out this gnarly little guy. Lol.

 

 

[MikeC]

What I'm using for the templates is paint stir sticks from Lowes.  They are cheap or free,  and just the right thickness.  

except for one of them which is a scrap of violin rib, it's a little too thin.  

[Sean Couch]

Just now, MikeC said:

What I'm using for the templates is paint stir sticks from Lowes.  They are cheap or free,  and just the right thickness.  

Brilliant idea. I may have to go fetch some from HD tonight after having dinner with my daughter.

My next door neighbor is a member of a local “maker’s guild” so I do have access to a laser cutter. I was thinking about having templates cut out of 1/8th inch plywood for my next violin. If I go the laser cutting route, then I will also have it cut out the form and some corner templates if their laser can cut metal.

[Sean Couch]

The contour lines don’t look too horrible. It looks like it is still pinched a bit and I need to extend the C-bout curve profile further into the upper and lower bouts to try and get a bit more oval shaped. Especially on the two highest contour lines. I am going to set aside the back for a bit and flip over to working on the belly.

[Sean Couch]

I took some of the pinch out of the back and I think the arching is pretty much done. Still needs a final scraping and some refining of the edges.

I got the top’s fluting channel depth set, the 6th set, the 5ths all set, so now I am blending them before I start scraping.

[MikeC]

 Looking good,  I need to catch up to you!     I'm slacking off too much! 

[Sean Couch]

21 hours ago, MikeC said:

 Looking good,  I need to catch up to you!     I'm slacking off too much! 

Ahaha, no worries, I’m sure you will catch up. If you didn’t have your kitchen remodel going on you would probably be further along than I am even though I started before you.

For today I worked on getting the 5ths blended and refining the arching by scraping. It isn’t looking horrible and I think it is time to check the contour lines and make them symmetrical.

 

Before I resume work on the top, I am going to take a minute or two and play around with making some varnish. It should be interesting. Below is my setup that I am testing. I already had the controller, SSR, and thermocouple so all I had to buy were a couple of cheap stainless pans and the hot plate. 

 

The recipe and process that I am using is described here:

https://www.ruschil.com/blog/making-violin-varnish

 

[MikeC]

That's a good link, I found that some time back and bookmarked it.  Don't cook it indoors, do it outside, it's a fire hazard. have a fire extinguisher handy.   

[Sean Couch]

17 hours ago, MikeC said:

That's a good link, I found that some time back and bookmarked it.  Don't cook it indoors, do it outside, it's a fire hazard. have a fire extinguisher handy.   

Oh yes, I am being careful. I started it about 3 hours ago. It is cooking away on the back porch. I will probably move it out to the garage where it can do its thing for the next week. It isn’t smoking much and smells nice, but I don’t think I want it in the house.

When I was forging Damascus knives and pens, I did that all in my basement. 2300+ forge and molten salt heat threat at 1500 ish degrees. I have it well ventilated to say the least, but I don’t want the vent fan running non stop for a week. I can hear it when I’m in my easy chair and it annoys me. Lol

[Sean Couch]

Moved the setup out to the garage a while ago. Temperatures are more stable from not being in the wind. Holding 350 +/- 2F. The Colophony is getting darker.

[MikeC]

Where did you get the rosin?  I'm thinking of getting some from DiamondG,   I have some of their turpentine, it's top quality.  

[Sean Couch]

I bought the rosin off of Amazon. It is the Diamond G brand. I think it was about $15 a pound. It is cheaper on Amazon than on their website.

[Sean Couch]

Worked on refining the contours of the top and some scraping. I think the top and back arching is pretty much done. I still need to refine the edges of the fluting and do the final scraping on both plates.

The varnish is still cooking away. Not much color change in the last 24 hours, but it looks like the next big change will be around the 96 hour mark (according to the source I am following).

[Sean Couch]

I have the top and back pretty much ready for thicknessing. I need to sharpen my scraper and see if I can get the corner areas better, and to try and get rid of some stubborn “hairs.”

The rosin is still cooking away. This morning and just a few minutes ago I noticed that the top layer is congealing around the thermocouple. It dissolves back in if I give it stir. It is like a skin is forming on the top around where the thermocouple is. Maybe it has reduced to the point where the top can’t stay liquid from the localized cooling from where the thermocouple sticks out of the rosin.

[Sean Couch]

The rosin finished its 168 hour cook this morning. It didn’t change much in color from the last sampling:

 

I didn’t want to make a huge batch, so I broke the cooked colophony into chunks after it was cool. I started with 458 grams of pine resin and after the cook, I have 350g. Only about a 23.6% decrease. I was expecting closer to a 50% reduction. Here are the cooked chunks:

 

One of the little pieces back lit with a flashlight:

 

I ran 100g of washed linseed oil with 100g cooked resin, and 10g of mastic at 350 degrees for 2 hours. For the small sample size and because I was using a Pyrex beaker, I used a 1/4” thick aluminum plate as a heat diffuser:

 

Here is a test for the varnish color. I just spread it on with my fingers. I used what was left in the beaker. I haven’t added any siccative, so hopefully it dries. The first picture below is when I first put it on the maple and the next is after I spread it out to form a thin layer. No pretreatment of the wood was used, just bare maple.

 

[Sean Couch]

Working on thicknessing the back. The removal of the bulk material was fairly quick, but now progress has slowed. I am now blending the channels and have a growing distain for my graduation punch. 

[Sean Couch]

Pecking away at graduating the back. It’s down to around 3mm in the upper and lower bouts, 5mm in the center bullseye, and 4.5mm outside of the bullseye. She weighs in at 129g and M5 is at 424 Hz. On to scraping to even things out and get the weight and frequency to my targets. I am shooting for 110g and M5 at 370 Hz.

[Sean Couch]

Getting there. Right now the plate is at 120g with an M5 of 398Hz. My whole center section between the corners is at 4.5mm, so I can take some out to make the bullseye smaller and more centered. I need to go around and take a full set of thickness measurements to identify any areas that need more work and then onto fine tuning.

[Sean Couch]

Not much to show in any pictures, but I have the back plate weight down to 111.75 grams and the M5 is at 376 Hz. I have some thickness to take out in the C-bouts near the ledge. It might give me a reduction of a few Hertz, otherwise, I think the plate graduation is done.  

[MikeC]

It's looking good.  I'm curious how thick are your edges?  I may have went a little too thin on mine.   

[Sean Couch]

9 hours ago, MikeC said:

It's looking good.  I'm curious how thick are your edges?  I may have went a little too thin on mine.   

If I remember correctly, they are at 4.2mm all the way around. I didn’t try to go for the swelling in the corners, maybe next time.

[resonant]

On 7/4/2024 at 12:16 AM, Sean Couch said:

Getting there. Right now the plate is at 120g with an M5 of 398Hz. My whole center section between the corners is at 4.5mm, so I can take some out to make the bullseye smaller and more centered. I need to go around and take a full set of thickness measurements to identify any areas that need more work and then onto fine tuning.

Maybe I missed this earlier in the thread but I'm curious how you are judging the arching for 'correctness'? Comparing to templates/ straight edge and shadows?

Pretty incredible plates for a first violin I must say. 

[Sean Couch]

1 hour ago, resonant said:

Maybe I missed this earlier in the thread but I'm curious how you are judging the arching for 'correctness'? Comparing to templates/ straight edge and shadows?

Pretty incredible plates for a first violin I must say. 

Thanks, I think they are turning out fairly well. Nicer than I expected.

For the arching, I used full templates, not half ones. Paper templates that I printed out and laminated with clear packing tape. They are quite flimsy so for the long arch, I taped in a piece of 0.004” shim stock to give them a bit of rigidity.

They were quite tedious to use since you can’t “paint” the inside of the template with graphite and use it to mark areas that need to be removed. I would hold the template in place with one hand and then mark the areas that needed to be removed with the other. It was not a very efficient way to work, but I finally got there. I spent way more time trying to align the templates than I did removing material from the plate.

If I make another violin, I will do it differently. At the least I will make some “proper” templates, but I have a few ideas rolling around in my head on a better way, for me, to do the arching. I would love to not have to use templates, but I have a hard time visualizing what the arching should look like. The first time I held a violin was about 6 weeks ago.