Repairing spruce tear outs after taking off top

[TedN]

Inevitably, when you remove a spruce top, the soft chunks of winter grain tear. What's the best way to repair this type of damage?
 

 

-I'm wondering if small bits of spruce should be inserted in each one of these holes. That sounds pretty difficult and tedious.

 

-I suppose you could also plane down the edge beyond the holes and then glue in a new piece of spruce along the entire edge. Getting a perfect joint might be tricky using this method.

 

-Putting in wood putty is probably a shoddy approach. I would imagine it's looked down upon, even though I'm not a restorer.

 

 

I don't have the Weisshaar book yet. I am curious what he says to do about this type of damage.

 

 

[MaestronetLurker]

Lay strips of damp paper towel over the ribs to soften the glue, then carefully remove the bits and glue them to the top. Fill missing pieces with dap wood filler, then level

[Jeffrey Holmes]

After anything that can be saved is glued back, I tend to use a method I adopted/developed to inlay summer grain wood in the remaining voids...  there are a couple other methods we've used in Oberlin as well. One, introduced by Joe Grubaugh, involved quick casting of a void, making a negative cast, and pressing softened summer grain. I like to avoid filler when I can.

 

inlays after installation uncolored/colored

 

[TedN]

Thanks guys.

 

Jeffery, I like the idea of inlaying summer grain. I will try this on a test piece to see how it goes. Never thought of that. Thanks!

[jezzupe]

After anything that can be saved is glued back, I tend to use a method I adopted/developed to inlay summer grain wood in the remaining voids...  there are a couple other methods we've used in Oberlin as well. One, introduced by Joe Grubaugh, involved quick casting of a void, making a negative cast, and pressing softened summer grain. I like to avoid filler when I can.

 

inlays after installation uncolored/colored

 

underedgeun.jpgunderedgetouched.jpg

Garsh darn it you're good. This is the type of repair work that impresses me, I think new builders obviously have lots of skill, but stuff like these invisible repairs are just on a different level. Great work.

[TedN]

Wet towel trick gets 5 stars. Amazing.

[Jeffrey Holmes]

Damp paper towels are our friends.  

 

I'll be able to monitor, but won't be posting on, MN for a few days... but if Jerry Lynn sees this thread, he might be kind enough to walk you through the summer grain inlay process.

[MaestronetLurker]

Wet towel trick gets 5 stars. Amazing.

Usually works nicely. I use scotch tape to hold them in place so you can flip it back, apply glue, then put it right back where it belongs. Best to use stronger glue(as opposed to the somewhat weaker glue that you'll use in the seam) here so future seam openings want to stay in the seam rather than pull your shavings loose.

[~ Ben Conover]

How to get a top off without splinters....if the last person to stick it on used strong glue ? 
Solomon once told me to use a syringe with alcohol for weakening the bond, but to get it in there  ?
I have a tendency to brute force but actually prefer not to use it. 

 

[arglebargle]

I've found that often the splinters/ tear outs are a result of the varnish from the ribs not releasing from the top, and pulling a piece of spruce of with it. 

So, with a sharp knife I score the seam all around the top before starting to remove it. It helps, and makes retouching the underside easier.

[~ Ben Conover]

Good tip, thanks. 

[Jerry Lynn]

 

I'll be able to monitor, but won't be posting on, MN for a few days... but if Jerry Lynn sees this thread, he might be kind enough to walk you through the summer grain inlay process.

If I get a chance after my son goes to bed tonight I'll post some pics of the process.

[TedN]

Oh, a sharp knife to score. That might work well. Just as long as you're very accurate with the tip. Wouldn't want to slice into wood. I might try that next time.

[arglebargle]

No you wouldn't. Go Slowly.

[MaestronetLurker]

How to get a top off without splinters....if the last person to stick it on used strong glue ? 

Solomon once told me to use a syringe with alcohol for weakening the bond, but to get it in there  ?

I have a tendency to brute force but actually prefer not to use it.

I use a insulin syringe to apply the alcohol at the leading edge of the knife. Works well. I think it also helps to use a very thin knife followed by a 1mm knife alternating advancing one and then the other. I use a hacksaw with the blade ground like a opening knife to get at the upper block without much risk of the end of a long blade wandering. It's niche that you can get two hands on the hacksaw and work the blade into the hard to reach area. I've been thinking of doing the same with a bow saw for cello and bass, but haven't gotten around to it. I think a slow, careful top removal usually pays off with fewer splinters.

[David Burgess]

How to get a top off without splinters....if the last person to stick it on used strong glue ? 

Solomon once told me to use a syringe with alcohol for weakening the bond, but to get it in there  ?

I have a tendency to brute force but actually prefer not to use it. 

 

Once the opening knife is inserted, I dip a small retouching brush in alcohol, and then touch it to the opening knife. The alcohol wicks into the joint quite safely and controllably.

[Jerry Lynn]

Damp paper towels are our friends.  

 

I'll be able to monitor, but won't be posting on, MN for a few days... but if Jerry Lynn sees this thread, he might be kind enough to walk you through the summer grain inlay process.

 

 

A few years back I threw together a VERY QUICK picture tutorial on how to use summer growth to rebuild an under edge to send to a colleague.  It was so quick that I redid it for real later.  Here it is:

 

 

Starting in the upper left and corner and moving down that column and then to the top of the other column.

 

Step one is harvesting appropriate summer growth.  Soft and squishy is the best.  I've found a supply of very soft engleman guitar tops that I use frequently for this purpose.  The tool being used is a 1mm no. 11 sweep gouge.  It is available here: http://www.traditionalwoodworker.com/Straight-Micro-Carving-Deep-Gouge-10mm-by-Two-Cherries/productinfo/512%2D1110/ (it's also useful for graining on external surfaces) A small veining tool would also work, it just has to be small enough to get in between the reeds. 

 

Step two is soaking the strand of summer growth in a small dish of water for a few minutes to make it pliable and squishy enough to fill voids.

 

Step three is applying adhesive.  At Oberlin I was shown to use thinned out tight bond (original, not no. 2).  It gives more working time when lining up several strips next to other and minimizes the chance of the moisture in hide glue causing a strip to come loose.  You can use hide glue if you wish. Either way if half-edging should occur in the future the added pieces will get planed away.  Likewise if you wish to soak the pieces out you can do with either adhesive (provided the tight bond was put on thin). 

 

Step four is lining up and clamping with plexi. For a lot of replacement you may need to do several gluings.  Too many become difficult to control if you are trying to line up directly on grain lines.  A cast is not necessary... nice to use if you have one though. 

 

Step five is trimming the added pieces level.  

 

 

If your replacements are going to be visible from the outside, lining up the grain line and color matching makes retouching very easy.  If the pieces are not going to be visible from the outside It is not crucial:

 

Like wise, if you do not wish to have to color the replacement wood, harvesting wood from a dead scrap fiddle (or baking it!) can be useful:

 

 

There are other methods of filling voids using summer growth.  Two years ago at Oberlin Joe Grubaugh showed us a method that he and Sigrun developed using casts made from friendly plastic to press pieces of summer growth into exact shapes that fit the void.  Likewise, one of our participants uses 3d scanning and a cnc mill to make drop in ready replacement pieces.  

 

If anyone has any questions, I'd be happy to try to answer. 

 

Jerry

[TedN]

This is great! Thanks Jerry. I will experiment on some scrap tomorrow.

[HongDa]

A quick way to aggressively get a lot of repair grains if the person before you was just as aggressive in removing a top and passing the work on down to you.
Then use a chisel or plane to get the grains off. I lay out various pieces on a towel to choose from while working.

[shaun fosdick]

On scoring the varnish, some varnishes seem to want a sharp knife tip to be more cut while others seem to want a more rounded tip and the feel is more like scoring glass.

 

Dropping alcohol on the opening knife with a brush is way more controlled than a syringe.  I have had the rubber on the plunger stick then let go in a not so controlled manner before.

 

With an old style butter knives ground to wedge and the blade twisted  slightly I can get most neck blocks free from violin through cello to bass.  The slight twist allows just enough wiggle room to maneuver without cutting into the wood.