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Reconstructing a Hollow Metal Bow Head
Any thoughts or help would be appreciated on reconstructing a hollow metal bow head.
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Irv
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January 19, 2018 - 11:40 pm
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I just purchased an all steel violin bow (looks to be circa 1930's that is or is similar to that made by L. Mont Allison Patent 1,912,961 of June 6, 1933).  It looks to be (it currently is in transit) in good shape except that it has a hollow metal bow head so therefore the component which accepts the maple tip wedge and the bone tip are missing.  This area takes a fair amount of mechanical loading so I am more concerned with utility than historical accuracy for the repair.

The bone tip is an easily available item which costs a few dollars, so that part is easy.  I found someone selling unhaired carbon fiber violin bows for about $10.  I am thinking about purchasing some of these bows and reduce the outer dimensions of a head to fit inside my bow's (currently hollow) metal head.  I am going to the dentist next week and I was going to see if I could obtain some of his cement used for dental crowns.

Yes, I am aware that the carbon bow is likely to be superior in every way to the steel one so this process is tragic on many levels.

Having never done this before and lacking the original for guidance, any constructive thoughts or comments would be appreciated.

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MrYikes
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January 20, 2018 - 6:57 pm
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You have my interest, but sadly I can offer no help.

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Irv
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January 24, 2018 - 5:46 pm
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I just received the metal bow.  It was expertly packed and received no damage in transit.

The whole shaft and tip area is a steel which attracts a magnet.  It is circular in cross section until a few inches before the frog, where it changes to an octigon cross section.  Upon removal of the frog, it is obvious that they inserted wood inside the steel to receive the wear of the frog connection point.  The metal is extremely thin, about the thickness of a coating of paint.

The bow has no leather thumb grip or wrapping (although there is no paint in this area so it is likely that they were originally there) and it is obvious that there is some salt deposits in the area forward the frog.  There does not appear to be any signs of corrosion, but I did not try to remove the salt deposits.  I hope that this area is ok since the steel is so thin to begin with.  I think that the obvious fix would be to install a piece of surgical rubber tubing to keep sweat away from this area.  The frog does not have any inlay and the ring does not appear to be anything special (although it also has the same type of salt deposit).

The good news is that it is obvious that I don't need to supply anything to the tip.  The wedge takes up the entire tip void surface area, and the wedge is still attached to the hair.  It does not look like there ever was a bone tip lining, although I might be wrong on that point.  

The bow is much lighter than both my wood and carbon fiber bows, and the stiffness is equal or perhaps greater than my carbon fiber bow.  I think that all I need now is to clean it, provide it with a piece of surgical tubing, and rehair it.  I would really like to rehair it with black hair (like a double string bass), but I don't want to waste $50 or more if I don't like it.  I think that it is easily worth what I paid for it ($90).

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AndrewH
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January 24, 2018 - 7:45 pm
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I would not say a lighter bow is better, because bow pressure should depend mostly on gravity rather than arm muscles. Cheap student bows tend to be very light. One of the reasons I like my hybrid bow more than carbon fiber bows is its greater weight.

I would prefer to have a tip plate, whether bone or some other material. If the tip wedge needs to be removable for rehairing, I wouldn't trust it to stay in place without a tip plate.

I notice that the chief advantage mentioned in the patent you cited is uniformity of product, and I further notice that the subsequent citations to that patent are in patents for mass-produced fiberglass bows.

The patent is silent on the structure of the tip ("The hairs are anchored to the tip in any suitable manner"). The inventor does claim a removable weight that may be attached inside the frog, on the screw (Claim 5), but I would question the weight distribution as I see nothing, either in your description of the bow you received, or in the patent document, indicating that weight can be added anywhere else.

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Irv
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January 24, 2018 - 8:59 pm
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Hi AndrewH (and others).  I will have to compare weights of the steel bow with the others that I have with my gram scale.  But it did seem very light to me.  It may also be that the weight is distributed more toward the back (also, the hair is not attached to the tip).

I think that it originally had a tip plate, since the metal had a slight checkered pattern in that area, which must have been to better receive adhesive.

The frog had a number of drilled holes with a black material in them (looking from the "hidden" side of the frog which would normally be in contact with the bow shaft).  I would bet that is where weight is added.  Not all of the holes were filled.

I am now thinking that it may have been a good thing that the thumb rest and wrapping was missing.  Unless the steel is of a stainless variety (which it could be because a magnet was only slightly attracted to it), I think that it would be a good practice to wax the shaft on a monthly basis and only utilize a piece of surgical tubing for a thumb rest.  I wonder if I could obtain a piece of black surgical tubing?

In perusing the Violin Repair Guide by Michael Atria, he states that any void in the tip above the wood wedge and hair knot should be filled with powdered rosin.  It would take a lot of powdered rosin to fill the void in this bow (although I really don't have any experience looking at that area in other bows).   

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Irv
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January 24, 2018 - 9:03 pm
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There could have been weight added either as the wrapping or behind the wrapping.  Can't tell you anything about that since it is missing on my example.

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Irv
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January 24, 2018 - 10:04 pm
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A wild thought.  The manufacturer of the steel bow took obvious pains to paint the shaft to approximate the appearance of a wood bow, and looking at it from any distance there is no way to determine if it is steel (once placed in the hand, it is obvious since it conducts heat much better than wood and feels cool).

But it could be plated.  I could see an advantage for a rock or blue grass performer with a chrome or gold plated violin bow.  Not so much for an orchestral player.

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Irv
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January 25, 2018 - 5:51 pm
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I did some measurements of the bow tonight.  It has a length of 27 inches (so it is a 3/4 scale bow).  It has a weight of 48 grams, without the winding and thumb grip of which it did not come with.  The shaft has a diameter of 0.325 inches in the thumb grip area (I did find black surgical tubing and I am going to order 0.25 inch I.D. and hope that I can get it on using alcohol as a lubricant).  The wood insert to the shaft in the frog area is easily removed so I could plate it if I desired.  I removed the salt deposits on the thumb grip area and there was only very slight corrosion, so I think that I am OK.

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AndrewH
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January 25, 2018 - 6:38 pm
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Irv said
I did some measurements of the bow tonight.  It has a length of 27 inches (so it is a 3/4 scale bow).  It has a weight of 48 grams, without the winding and thumb grip of which it did not come with.  The shaft has a diameter of 0.325 inches in the thumb grip area (I did find black surgical tubing and I am going to order 0.25 inch I.D. and hope that I can get it on using alcohol as a lubricant).  The wood insert to the shaft in the frog area is easily removed so I could plate it if I desired.  I removed the salt deposits on the thumb grip area and there was only very slight corrosion, so I think that I am OK.  

That's a very light bow, even considering its 3/4 scale length. Violin bows average around 60 grams, and anything under 55 grams is generally considered unacceptably light. A 3/4 size bow should still weigh well over 50 grams. Also, balance matters; adding weight only at the frog is distinctly unhelpful unless the bow is heavily weighted toward the tip as it is. Ideally the center of gravity should be somewhere between 1/3 and 1/2 of the way down the bow from the frog.

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Irv
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January 25, 2018 - 8:55 pm
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It is much easier to add weight than it is to remove it.  The cavity in the tip is so large I can easily add 10 grams of lead shot mixed with silicone caulk.  I can also wrap thin lead solder under the latex surgical tubing.  But to get the proper balance point, I would have to do the rehair myself since it would be uneconomic for some one else to mess with the weights.  I could get an approximate assuming uniform distribution of mass in the hair and use statics.  It is not like a ship will roll over or something if I calculate wrong.  

I once did similar when my son threw the javelin.  

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Irv
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January 26, 2018 - 12:55 pm
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Hi AndrewH (and others).  Please explain why a tip plate keeps the hair wedge in place.  It would seem to me that the opening in the tip plate would have to be the the entire width and length of the hair wedge in order to have the hair wedge get past it.  In the example of my metal bow, the wedge is so large that I will only have a few millimeters on the sides and back of the tip to secure the tip plate.  I have a lot of room for adhesive on the front of the tip.  

I am strongly thinking of attempting to rehair the bow myself.  I just bought two violin frogs with black horse hair already installed in them ($9 each from China, and the company made a special auction for me on eBay since they only offer violin frogs with white horse hair.  It took them only a couple of minutes to respond to me after my email to them, complete with a photo of the frog with the black hair attached.  A very impressive vendor).  Onward to Youtube to learn how it is done.

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coolpinkone
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What a very interesting bow and project. I like reading about this.  I believe my bow is in the 60 grams for weight.  I can't remember.  So 48 sounds light, but if it plays nicely...   I think it is nice to have something unique.  Especially if you have the knack for making changes and messing around with it.

I have my first bow that I will someday have to take in for hair as it is the only bow I have that has been worthy of a rehair.  I am sure I have time on my side for that.. but I won't be doing it myself.

Good project.

Vibrato Desperato.... Desperately seeking vibrato

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AndrewH
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January 26, 2018 - 4:19 pm
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The wedge isn't supposed to "get past" the tip plate -- the tip plate is removed every time the bow is rehaired. Luthiers use a bone glue that melts at a low temperature.

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Irv
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January 26, 2018 - 5:08 pm
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Thank you AndrewH for posting.  I had no idea that was how it was done.  Certainly makes sense.

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MrYikes
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January 27, 2018 - 8:31 am
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I suggest you buy some hair from china to use as a test. I needed a couple of tries to get it right. Its tough to get the hair just right without any crossings of hair. It is easier if you know you can just cut it off and try again,,,and its kinda nice to see hair hanging around. My wife comes in and steals some once in a while (she uses it as whiskers on the stuffed rabbits she makes).  You tube is your friend, I liked the Japanese guy, but he skips over some stuff.

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Ferenc Simon
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January 27, 2018 - 8:49 am
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Yea I liked his version the most as well.. mainly because he's limiting it to doing stuff with his hands and ordinary objects, instead of requiring elaborate equipment and rigs.

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Irv
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January 27, 2018 - 11:32 am
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Not a fan of the Japanese guy.  He coyly uses camera angle to keep you from seeing how he does things, and openly states that he will not show things because they are trade secrets.  

I have attended many seminars where consultants state that you need services, but you need them to do the services.  I tend to like to do them myself.  

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Ferenc Simon
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He shares more than enough.. you can literally learn how to build a violin from start to finish just by watching everything he uploaded.. It will take you forever to watch them though as he drags everything on for a very long time... 

Now when it comes to his actual trade secrets which are pretty much the 'signature' methods for master luthiers, I completely agree with him not sharing those... as well as all the stuff that has to do with recipes.. like his own rosin... or the way he makes the strings.. etc.. 

But in any case, his videos are aimed at amateurs and violin shop owners / teachers.. and he shares more than enough for them to be able to handle most problems. 

Of course I understand you're not a fan... I'm not really either.. especially when he keeps on dragging time instead of getting to the point and pushing that really conservative mindset you briefly touched on aka: "I'm the violin maker, don't question me" 🙂 But.. fact of the matter is that you can't really find other proper master luthiers sharing even a fraction of the information he has there. And some random guy buying set of powertools then experimenting in his garage and making tutorial videos doesn't quite equate to someone sharing his lifetime of violin-making experience in my mind.. (I'm mentioning this, since mainly that's what you can find online... random DIY tutorials by random people which reminds me of an episode of Rocket City Rednecks rather than violin-making 😀 ) 

Anyway.. his bow re-hair video is quite nice and he does it from start to finish in front of the camera, even explains what kind of hair to get... so I didn't have a problem with that particular one 🙂 

Cheers!

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Irv
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January 27, 2018 - 9:59 pm
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The tip I learned from him that I really like is that he puts a "belly" in the center of the violin bridge for greater strength, and really thins the g string and e string edges in a smooth radius.  That makes a lot of sense to me, and I have been very happy with the results.

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Irv
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January 28, 2018 - 12:30 am
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I just looked at Daniel's violin bow rehairing video.  It was wonderful.  You got to see everything he was doing and it was just the way I like DIY videos.  He must have been off his meds when he made that one.

He did not remove the bone tip before he removed the tip wedge and Rosa String Works did not on his video on rehairing either, so I am thinking that AndrewH is joshing me on that point.  Perhaps it was necessary on antique bows?

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