Dressing both sides of cello ribs when thinning?

[Joe Swenson]

Starting cello #2 and thinning the ribs. The rough cut ribs have little dings in the wood. Easy to clean up one side when thinning.  I tend to just work from one side when thinning and leave the other side alone relegating it to inside the cello to exist unseen.

Any reason not to do this? 

[JacksonMaberry]

Nope. On some classical cremonese instruments (del Gesu) you'll find toothed plane markings.  It's okay to leave the inside of the ribs a little rough if you want. 

[Mampara]

1 hour ago, JacksonMaberry said:

Nope. On some classical cremonese instruments (del Gesu) you'll find toothed plane markings.  It's okay to leave the inside of the ribs a little rough if you want. 

Tool marks tell a story and will keep people from the future guessing how you did it. Just like we now guess and discuss how those old timers worked way back then.

[JacksonMaberry]

21 minutes ago, Mampara said:

Tool marks tell a story and will keep people from the future guessing how you did it. Just like we now guess and discuss how those old timers worked way back then.

Yep! Too much fun

[Conor Russell]

I dont mind the odd blemish,  but I tend to run a plane  over the inside  ribs..

Very rough  open wood can get very dirty,  and hard to clean for repair.  Also,  fissures  and holes can give the worms an easy place to start if the violin ever falls on hard times.

[nathan slobodkin]

2 hours ago, Conor Russell said:

I dont mind the odd blemish,  but I tend to run a plane  over the inside  ribs..

Very rough  open wood can get very dirty,  and hard to clean for repair.  Also,  fissures  and holes can give the worms an easy place to start if the violin ever falls on hard times.

I leave tool marks on both sides of the ribs but actual chips or tearouts can start cracks when bending. Since the bout ribs are bent from both directions better to smooth both sides to whatever degree one uses although obviously the actual look of the inside is less important.

[Mike_Danielson]

Nathan is correct--you want both sides to be defect-free.  From a fracture mechanics standpoint, any defects can initiate a crack during the bending or in later years when the side is subjected to a blow.  The engineering science gives a clear answer.

regards

Mike D

[arglebargle]

Leaving tool marks is one thing. Leaving tear-out is another and I would not leave it for the reasons stated above. What I see in your picture is tear-out and I would get rid of it.

[JacksonMaberry]

My former sensei said that every surface, inside or out, ought to be scraped and burnished to a glass-like finish. I only do that on the outside, personally, but the above posters are certainly right that tearout it a weak point and should be avoided. Texture is one thing, tearout is another.

[Urban Luthier]

37 minutes ago, Mike_Danielson said:

Nathan is correct--you want both sides to be defect-free.  From a fracture mechanics standpoint, any defects can initiate a crack during the bending or in later years when the side is subjected to a blow.  The engineering science gives a clear answer.

regards

Mike D

Yep I found out the hard way. I finished the inside of my cello ribs with a toothing blade set to take the finest cut.

[David Burgess]

I wouldn't worry much about "tearout" which can only be seen under oblique lighting, and is less than .2mm in depth.

 

[Joe Swenson]

 

23 hours ago, Mike_Danielson said:

Nathan is correct--you want both sides to be defect-free.  From a fracture mechanics standpoint, any defects can initiate a crack during the bending or in later years when the side is subjected to a blow.  The engineering science gives a clear answer.

regards

Mike D

 

17 hours ago, David Burgess said:

I wouldn't worry much about "tearout" which can only be seen under oblique lighting, and is less than .2mm in depth.

 

Once again... Thank you! 

Makes sense that the depth of the defect would be key here.  Don't want a point of failure down the road.  

Cheers!  

[Marty Kasprzyk]

23 hours ago, JacksonMaberry said:

My former sensei said that every surface, inside or out, ought to be scraped and burnished to a glass-like finish. I only do that on the outside, personally, but the above posters are certainly right that tearout it a weak point and should be avoided. Texture is one thing, tearout is another.

The sound absorption coefficient of wood is dependent upon it surface porosity and roughness.  It would be interesting to see if burnishing to glass-like inside finish changes an instrument's sound.

[Joey Naeger]

2 hours ago, Marty Kasprzyk said:

The sound absorption coefficient of wood is dependent upon it surface porosity and roughness.  It would be interesting to see if burnishing to glass-like inside finish changes an instrument's sound.

I've wondered this as well. There's a real difference between a highly sanded and burnished surface and a surface fresh off the scraper.

[Joe Swenson]

2 hours ago, Marty Kasprzyk said:

The sound absorption coefficient of wood is dependent upon it surface porosity and roughness.  It would be interesting to see if burnishing to glass-like inside finish changes an instrument's sound.

If a porous surface is good at absorption then it would be poor at producing coherent sound as well. The the question is how much do the ribs contribute to the sound? 

I played the cello once without the end pin, between the calves of my legs at it was clear the overall sound of the instrument was reduced. Which says to me freestanding ribs have a non negligible contribution to the sound of instrument. This confirmed what I felt was a good reason for leaving off the linen squares, that many recommend to be applied to the inside of the ribs. But that's for another discussion... 

So I cleaned up the rib - both sides. Definitely the better choice. Finally learned how to properly sharpen a scraper. Lol... Making nice curls of scrapings. 

[David Burgess]

Sound energy doesn't just disappear. It will be either converted into heat, remain as some sort of sound (radiation?), or some combination of the two.

[baroquecello]

11 hours ago, Joe Swenson said:

I played the cello once without the end pin, between the calves of my legs at it was clear the overall sound of the instrument was reduced. Which says to me freestanding ribs have a non negligible contribution to the sound of instrument. This confirmed what I felt was a good reason for leaving off the linen squares, that many recommend to be applied to the inside of the ribs. But that's for another discussion... 

It differs very much from Cello to Cello, and also how the Sound Adjustment was made. My main modern Cello sounds truly terrible without an end pin, and is also sensitive to end pin choice. My secondary modern Cello Sound ok with or without end pin, and is less fuzzy About the end pin also. My baroque Cello sounds fine without end pin, but I wouldn't know how it sounds with end pin .