Jump to content
Maestronet Forums

Avoiding wiggles when rounding belly edges


Wood Butcher
 Share

Recommended Posts

I often have difficulty with the areas at the corners, and especially the C bouts, where the edge becomes more parallel to the grain. I’m often left with bumps in the winter growth, and a slight hollow between them.
The wider the grain at the edge, the more exaggerated it can become.

Due to the differing texture of spruce, my only solution is to trim the problem grains back again with a knife, after filing the edge to shape. It works, but feels awkward, and can be easy to go too far when rectifying these areas for a smooth edge. Sometimes I use a half round needle file for spot touch ups.

How do others deal with these areas? If you don’t have these problems, maybe it is my technique, so any advice is appreciated.

Link to comment
Share on other sites

Are you feeling bumps on the outer edge or are you talking about deflections in the crest of the edge where it borders the channel? I try to minimize the use of sand paper as much as possible using knife and a flat finger plane to round off the edge and a very sharp scraper to shape the channel leading up to the crest. Some times it is helpful to scrape only the hard grain and let the soft grain take care of itself. If I am looking for a really sharp crest then I wet, dry and rescrape 3 times to avoid grain raising in the channel and use a folded or hard backed piece of sand paper very lightly on the outer edge.

Link to comment
Share on other sites

2 hours ago, Wood Butcher said:

especially the C bouts, where the edge becomes more parallel to the grain. I’m often left with bumps in the winter growth, and a slight hollow between them.

this may read as a wtf moment but really my best advice is to look at other better makers than yourself whose last name/ surname starts with the same letter as your own -  just to see what they did.  it shouldn't matter which country of origin either.

Link to comment
Share on other sites

12 minutes ago, Wood Butcher said:

I’m talking about the shape of the outer edge.

I did try scrapers in the past, but this led to an even more bobbly shape than the files.

Maybe look at Davide Sora video's        

 

Link to comment
Share on other sites

OK I misunderstood what you were asking. As far as smoothing the outline itself I finish up with files of various types with birds tongues or crossing being the most useful in th C bouts. Always the biggest file possible and and often filing only the hard grain. The long grain in the Cs and at the outer extremes of the outs are indeed the places you need to watch out for. I do think that sand paper tends to dig in to the soft grain and use it as little as possible.

Link to comment
Share on other sites

I had this same problem. You have to use your knife as much as possible, and when you do sand, use a backed paper, and for the love of God avoid over sanding, as that will abrade the summer stuff first. 

The last sanding should be very light, just to get rid of the chamfers from turning the edge. 

Link to comment
Share on other sites

Sorry for not replying sooner, I was getting an error message when trying to log in for the last few days.

I agree with Nathan and Nick’s points about sandpaper, I did try this before, and it only serves to make things even worse in a very short time. 
I have had success with using a curved scraper, working from front to back, and as I mentioned a knife. This still feels slow and awkward.

I never have quite the same issue when shaping the outline, only when I round over the edges. I think how the hard grain becomes more curved/pointed during edge rounding is the reason.

Thanks for the advice from everyone, I will continue to persevere and make improvements.

Link to comment
Share on other sites

48 minutes ago, Wood Butcher said:

Sorry for not replying sooner, I was getting an error message when trying to log in for the last few days.

I agree with Nathan and Nick’s points about sandpaper, I did try this before, and it only serves to make things even worse in a very short time. 
I have had success with using a curved scraper, working from front to back, and as I mentioned a knife. This still feels slow and awkward.

I never have quite the same issue when shaping the outline, only when I round over the edges. I think how the hard grain becomes more curved/pointed during edge rounding is the reason.

Thanks for the advice from everyone, I will continue to persevere and make improvements.

Have you seen this video? I think the only trick is to control the pressure of the files and the sandpaper, when working the spruce the delicacy and precision of the "touch" is fundamental.

 

Link to comment
Share on other sites

Thank you Davide :)

My own process is not so different for the rough shaping, but I noticed immediately that my files are very coarse in comparison.

Maybe this can be a source of my problem, my file is cutting too fast, and also unevenly it would seem. Unfortunately they are the only crossing files I have, but I will think now to order a finer cut for the next instrument.

Link to comment
Share on other sites

18 minutes ago, Wood Butcher said:

Thank you Davide :)

My own process is not so different for the rough shaping, but I noticed immediately that my files are very coarse in comparison.

Maybe this can be a source of my problem, my file is cutting too fast, and also unevenly it would seem. Unfortunately they are the only crossing files I have, but I will think now to order a finer cut for the next instrument.

Yes, overly aggressive files don't work well with spruce. Older files work best for me, the half-round you see in the video has more than 30 years of use. I had to buy back the oval file some years ago, but I remember that when it was brand new I had to be very careful even if it has a very very fine cut, and if the grain of the spruce is particularly tender I still use my old oval file which is the sister of the half-round one (30 years old). Old (worn) files seems to have a "delay" in cutting which helps the smoothness of the cut, although of course they are much slower and require many more passes than very sharp files, and slow down the work. If you don't have files that old, buy the finer you can find.

Link to comment
Share on other sites

One thing I have found useful is to try to use a file or abrasive which fits the radius of the curve, and is not of a smaller radius. A smaller radius is where one starts to have issues with removing more of the soft grain, while a larger radius bridges between the hard grains much better.

Link to comment
Share on other sites

On 4/11/2021 at 6:50 PM, Davide Sora said:

Yes, overly aggressive files don't work well with spruce. Older files work best for me, the half-round you see in the video has more than 30 years of use. I had to buy back the oval file some years ago, but I remember that when it was brand new I had to be very careful even if it has a very very fine cut, and if the grain of the spruce is particularly tender I still use my old oval file which is the sister of the half-round one (30 years old). Old (worn) files seems to have a "delay" in cutting which helps the smoothness of the cut, although of course they are much slower and require many more passes than very sharp files, and slow down the work. If you don't have files that old, buy the finer you can find.

 

On 4/11/2021 at 9:39 PM, David Burgess said:

One thing I have found useful is to try to use a file or abrasive which fits the radius of the curve, and is not of a smaller radius. A smaller radius is where one starts to have issues with removing more of the soft grain, while a larger radius bridges between the hard grains much better.

I think both of these points highlight what I'm doing wrong. My file is too coarse, and also too narrow.
When I bought the crossing files, the only Grobet model I could get was 16mm wide, and I can now see that it's not enough to bridge across many grains, especially in the areas I've been having issues.

Link to comment
Share on other sites

11 hours ago, Wood Butcher said:

 

I think both of these points highlight what I'm doing wrong. My file is too coarse, and also too narrow.
When I bought the crossing files, the only Grobet model I could get was 16mm wide, and I can now see that it's not enough to bridge across many grains, especially in the areas I've been having issues.

If you can find a decent file that's currently available I would be curious to know about it...

 

Link to comment
Share on other sites

12 hours ago, Wood Butcher said:

 

I think both of these points highlight what I'm doing wrong. My file is too coarse, and also too narrow.
When I bought the crossing files, the only Grobet model I could get was 16mm wide, and I can now see that it's not enough to bridge across many grains, especially in the areas I've been having issues.

By shaping a piece of wood, one can make a "sandpaper file" of any radius, and any coarseness.

Did Stradivari do this? I don't know, but he would have most certainly had access to wood, paper, glue and sand.

Could it have been Omobono's job to make or refresh the sand-surfaced tools? If so, that might explain why Antonio got so pissed at Omobono for moving to another city for a time. :lol:

Link to comment
Share on other sites

On 4/8/2021 at 5:28 AM, Wood Butcher said:

 my only solution is to trim the problem grains back again with a knife, after filing the edge to shape. 

I'd use the knife first, then lightly file and finish up using a 1/4"- 3/8" or so diameter round handle of something with sand paper wrapped around and sand in one direction only - 150 to 220 grit pulling or pushing only, not back and forth.

  I don't really worry about the round outer shape of the edge - varnish and such will re-swell it back out, if that makes sense.

Link to comment
Share on other sites

18 hours ago, uncle duke said:

I don't really worry about the round outer shape of the edge - varnish and such will re-swell it back out, if that makes sense.

If you have removed material, it can’t swell back out, it is already gone.
Varnish will follow the texture and shape of the wood, so any depressions will still remain, unless you are using a very thick varnish, heavily laid on.

Link to comment
Share on other sites

On 4/8/2021 at 1:39 PM, Peter K-G said:

1. Good files

2. Sandpaper blocks of different shapes

3. Glue sizing and fine Sandpaper blocks

 

On 4/8/2021 at 3:55 PM, carl1961 said:

   

 

I realize that my post was from memory, learned from Davide Sora online violin making school :rolleyes:

That's what I have done, but recently having had Finnish high density wood with hard winter wood, there is a better solution.

There is sandpaper and new tech "sandpaper", which is not actually sandpaper. I make files and blocks for these types, super effective and takes care of the problem:

ABRANET

https://www.mirka.com/abrasives/abrasives-by-name/

 

 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.



×
×
  • Create New...