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Pegbox Repair Question


Thomas Knight
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3 minutes ago, PaganiniGuitar said:

I repaired a guitar head several years ago that had a similar crack. What I did was clean the crack, glue and clamp. After the glue dryied I used a several bowties made out of aluminum inserted deep enough that I could use veneer of close grain to hide the repair. The bowties are so strong it prevented the crack from opening again. 
 

In your situation I would remove the bushing and use one bowtie between the pegholes and one bowtie after the peghole just before the end of the crack toward the ducktail. You can use a dogbone instead of the bowtie method but either method will stop the crack from reopening and if you’re lucky with the selection of the veneer or wood it will almost be an invisible repair.

Interesting idea. Yes the ultimate mechanical lock. I suspect the neck insert will offer the support needed but I will let the experts decide.

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2 minutes ago, jacobsaunders said:

Whats that?:)

Hi Jacob, a while ago you showed us a string with one end over a crack with the other end submerged in a cup of water and the wick effect soaked the crack. I have used your wash system numerous times and the resulting repairs are immensely better than using a brush and warm water because the surrounding wood swells and softens a bit and when hide glue is added the capillary action of the slightly swelled wood closes the crack and when fully dry only the varnish shows a crack. Very ingenious. It is this type of instruction that is extremely valuable to us who are striving to learn.

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39 minutes ago, jacobsaunders said:

Oh, all right. Americanese is such a difficult language:)

Yes it is, even to we Americans. Visit a small town in the Smoky Mountains and the southern drawl combined with their expressions are as confusing as a foreign language. Gullywasher (heavy rainstorm), Yeller Maters (yellow tomatoes), Yesm (yes madam) and on and on. Visit Washington DC and all you hear is legalese, the language of lawyers. Just awful.

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14 hours ago, Thomas Knight said:

  Great ideas. I took it to an expert here in Tampa and the scroll is crooked, the neck is also 1/4" too short, and the standoff way to low at 1.5mm so we are going to do what all the experts have agreed on which is to clean out the cracks and clamp it properly. The graft requires the G and A holes to be bushed anyway, so he is taking me on as a semi apprentice and we will do it right. 

 

That's the best way to go.  And since you're doing a graft you'll probably have no problems getting the cracks together.  

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Ok, the correct pronunciation of Markneukirchen. Is it 'mark-noi-keer-shin,  mark-new-kur-chen, or mark-new-keer-shin ???

BTW, if I was born in Frankfurt does 'Ich Bin Ein Frankfurter' mean 'I am a hot dog'? I had to choose citizenship in '74, so 'Ich Bin Ein Americaner Frankfurter?

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  Many thanks to all of you. Jacob, your wash system worked great. With the suggestions and help of many on MN; Jacob, Phillip, Mark, Brad, George, Jerry, Wood Butcher, Bill, I thank you for the guidance. I grafted a new neck block after securing the cracks. I am out of 11mm maple dowels for the bushings but here it is so far. I made a fixture a while ago to cut the neck blank at 12 degrees, but decided to follow the advice of experts and do the scroll/pegbox completely by hand. I traced the prepared neck blank onto the pegbox walls and took my time. I let it cure, and finished the roughing. The cracks held beautifully. 

  The pictures show the fixture I machined on my old Bridgeport mill. A .625" x .250" bearing centers the .250" router bit and gives a perfect cut as the slots are .626". Two padded clamps hold the neck blank to the fixture which is held in a vice. I know this is unconventional, but it saved me time having the neck blank done in under 10 min. I also routed the neck round area on my router table with a .750" radius cutter before I glued it. 15-20 min in total prep for the neck blank.

  I would encourage any thoughts, comments, criticisms or input.

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Simply put, I think you should have taken more time with this and spent more time with your local expert.  The quality of the finished work is far more important to me than the speed at which something is accomplished.

You clearly know a lot about machining and how to get things done, but from my perspective you don’t know what you don’t know.  Spending time with someone who does know what you don’t, and can guide you through this work in greater detail, is probably the best way for you to improve the quality of your work, if that is your interest.

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2 minutes ago, Mark Norfleet said:

Simply put, I think you should have taken more time with this and spent more time with your local expert.  The quality of the finished work is far more important to me than the speed at which something is accomplished.

You clearly know a lot about machining and how to get things done, but from my perspective you don’t know what you don’t know, and spending time with someone who does know what you don’t, and can guide you through this work in greater detail, is probably the best way for you to improve the quality of your work, if that is your interest.

  Thanks for your reply. My teacher viewed each step before I proceeded to the next. It is very important for me to get better and learn. This is graft #12 for me having practiced on rubbish. I took my time soaking the cracks starting Thurs morn and glued them on Friday about noon. I did the blank during that time and did the fitting and final gluing after midnight last night. After lunch today I rasped the neck profile and scraped it but the neck is not finished at all. It is in the 90's here most of the day and 80's at night. Glue dries fairly fast. Maybe I am rushing it a little because I am starting classes on varnishing in Aug and have a UV box to build, four violins in the white to set necks and scrape, and I am not doing any more to this one for at least two weeks.

  I do listen to instruction from you experts and your input is valued more than it may seem.

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It looks like the graft fits very well to me.

But I am uncertain how you prepared the joint.  As I understand it, you used a router bit mounted in a router and guided by the aluminum jig that you made on the Bridgeport.  Questions:

Did you use the router to make cuts in both the new neck block and the peg box?

Did you use the router to cut the bottom surfaces of the graft or just the sides?

If just the sides, how did you cut the bottom surfaces?

Was the graft joint entirely machine-cut or was there some hand cutting and fitting?

Did you do anything to remove the machining marks from the machine-cut surfaces?

Did the cracks close after you removed the bushings?

I would like to see a picture of a neck blank mounted on the jig.  Also a mounted peg box, if you machined the peg box.

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2 minutes ago, Brad Dorsey said:

It looks like the graft fits very well to me.

But I am uncertain how you prepared the joint.  As I understand it, you used a router bit mounted in a router and guided by the aluminum jig that you made on the Bridgeport.  Questions:

Did you use the router to make cuts in both the new neck block and the peg box?

Did you use the router to cut the bottom surfaces of the graft or just the sides?

If just the sides, how did you cut the bottom surfaces?

Was the graft joint entirely machine-cut or was there some hand cutting and fitting?

Did you do anything to remove the machining marks from the machine-cut surfaces?

Did the cracks close after you removed the bushings?

I would like to see a picture of a neck blank mounted on the jig.  Also a mounted peg box, if you machined the peg box.

  Hi Brad,

  Someone had mentioned that routing the pegbox was probably a bad idea so while I have done some rubbish violins that way I decided this was too nice of a violin to chance the pegbox being damaged, especially with the crack in it. I did that by hand.

  I prepared the new neck with the router only using the highest speed I could with an extremely slow cut pulling the router backward first. then pushing it as the bit is spinning clockwise and makes a clean pass. This is the technique used with a milling machine on aluminum as it grabs the bit and chips can get between the bit and the alloy. So it was a very clean cut as I pushed it in the direction of the spinning bit for a clean up pass and the .001" clearance allowed a nice finish. I then changed to a .625" end router and cut 1.00" in six .150" plunge cuts and two final .050" finish cuts to get the bottom of the insert square. So the entire insert was routed. I took it to my router table with a .750" radius profile shell bit to rough the neck round area. Then I scribed the outline onto the peg box walls and made a fixture out of two wood sections 1" wide by 1/2" thick tapered to fit the scroll into my vice. I used cork gasket between the wood and the scroll and went to work with my chisels. I have a sharpening system with 1k, 3k, and 10k wet paper on glass and a fixture to hold the chisels whiole sharpening.

  Years ago in my early teens my father was Bernadelli of North America and imported their shotguns so I was sent to Gardone for a few weeks to learn stock fitting onto actions using ash. So powder is a similar system to me.

  I reamed out the bushings and closed the cracks after soaking them with the system Jacob taught us. I was able to clamp enough pressure while also using clamps to hold the pegbox walls parallel by lining both sides of the pegbox wall with .250" x 2" x .625" on the outside and .450" on the inside so I had clamping surfaces at the top and bottom, and cork to protect it.

 I will do another lesser instrument step by step and document it. 

There seems to be shallow angle grafts and very long grafts and do not know which is best. That is a topic I would love someone to comment about.

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So first you machined the neck blank and then you cut the peg box to fit it.  This is the reverse order of the way I was taught to do it (entirely by hand).  I think there must be some good reason why the peg box should be cut first, but I am unable to articulate it.

 

39 minutes ago, Thomas Knight said:

...pulling the router backward first. then pushing it...

Does this mean you did the climb cut first or second?

 

39 minutes ago, Thomas Knight said:

...I then changed to a .625" end router...to get the bottom of the insert square...

Did this make the bottom of the insert parallel with the finger board surface?  Normally there is a slight angle with the insert getting thinner, top to bottom, as it approaches the volute.

 

39 minutes ago, Thomas Knight said:

...stock fitting onto actions using ash...

Can you elaborate on fitting with ash?

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5 hours ago, Brad Dorsey said:

So first you machined the neck blank and then you cut the peg box to fit it.  This is the reverse order of the way I was taught to do it (entirely by hand).  I think there must be some good reason why the peg box should be cut first, but I am unable to articulate it.

 

Does this mean you did the climb cut first or second?

 

Did this make the bottom of the insert parallel with the finger board surface?  Normally there is a slight angle with the insert getting thinner, top to bottom, as it approaches the volute.

 

Can you elaborate on fitting with ash?

 On the other ones I started with the pegbox first but it makes no difference as the cuts are parallel and the fixture holds either the neck or the blank. I have not built a fixture so a scroll already cut off the neck could be routed. That would require adjustable jaws

 The treble side was routed starting from what will be the thinnest end of the blank pulling toward the fat end, then pushing it back toward the thin part as the cleaning pass. The bass side was done the opposite way. Both cuts start by inserting the router with it off into the groove and then turning it on. I used a 1" long router bit (measured at the bearing which is even with the bottom surface of the fixture)

I then turned the blank over to make the multiple plunge cuts which were parallel to the top of the neck so yes, parallel to the fingerboard. I never knew an angle was needed.

Using a welding torch set with only the oxygen on the burning oxy creates a black ash. When used in annealing, you cover the surface to be annealed and add acetylene to a blue flame and heat the metal, alloys, copper, etc until the ash burns off the surface. It is now annealed. In fitting the actions the stock, usually cherry, is hand carved or routed to a close fit, maybe .5mm. The action is then covered in the soot or ash of the oxygen, but not heated. You push it into place and the ash rubs off where contact is made and transfers to the stock so you know where to remove next. The fitting on the most expensive shotguns includes side plates that contain the firing mechanisms and the work is three times as much as you have the main action and the two side plates. Those are called sidelock versions while most you see are boxlock which house the entire firing mechanism in a 'box'. It also explains why some shotguns were $35k in the 1960's and 70's.

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Thomas you did an awesome job to repair the crack and scarf in a new neck… a little more than I would have done. Your biggest concern is over time would the joint hold up under string tension and general moving the violin around. Not sure if you put a dowel in to join the pegbox to neck to firm up the joint. I hope to see the piece joined to the body soon and finished so we can marvel your repair. I know there will be purists out there that will not approve of what you have done but ‘c'est la vie’.

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I was wondering that. 
The cracks that were the original topic of this thread aren’t exactly what I would call closed....
The graft itself looks a bit gappy as well. Why did it need to be done?

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57 minutes ago, rudall said:

I was wondering that.
The cracks that were the original topic of this thread aren’t exactly what I would call closed....
The graft itself looks a bit gappy as well.

Indeed, neither seem to be well done.

This is what happens with amateur repairs, blundering through, with little quality at the end. That such work is applauded by others, who are even worse, is a sad state of affairs. :(

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