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Violin Bridge Carving On PANTOGRAPH - Thoughts?


Thomas Knight
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  Hello MN members and the master level luthiers on this forum, I come from a different background of creativity and have a Deckel Pantograph GK2 that I have wanted to use for some time to do something. I have used my CNC routers to make corner blocks, etc but I thought a bridge should have some personal touches and slight imperfections that would give it character, so I carved one just to see and I want feedback whether positive or negative. All I did was find a picture of a baroque bridge, print it out 4 times larger than an actual 4/4 bridge, set the Deckel to a 1:4 ratio, and traced along the outside of the picture. It cant be as accurate as it will be with a profile template. It also cant be accurate to the picture as the bit is 1/8" (3mm) and I would have to offset the profile 1/8" x .5 x 4 to get an exact copy and do the inside detail work with a .050" (1.2mm) bit. I would use my CNC to make a 4x larger pattern so the bridge would be much more accurate to the drawing as the stylus would run in a channel so little side play would result.  CNC parts are nice but look sterile and lifeless to me so I could make 100 at a time on my CNC machines but have no desire to do so. After the main route is done a chamfer could be added to the edges by using a different bit. The additional advantage would be the carving of a name in the bridge.

  I have listened to the logic on other repairs using machinery and see it is a bad idea for most things. However a bridge, tailpiece, chinrest, pegs, etc are a separate component. Jacob Saunders, Blank Face, Mark, George, Strad O Varius, Brad, Jerry, Bill, Wood Butcher, ViolaDamore, etc whom I respect and have given such good advice or insights, I hope you will give an opinion. Would a set of accessories, bridges, etc made mostly by hand using exotic woods on a hand operated duplicator like the Deckel be acceptable to the true masters out there?

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To be frank, I do not think this is the kind of character you want to pursue.  I know this was just a test, but it would be almost impossible not to do a better job by hand using a knife.  I also think you would save a lot of time if you stick to traditional methods.  Is there a problem with commercially available bridge blanks?  

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What a neat old piece of equipment!  :)

That said, the results look wasteful and appallingly crude.   You should also know that good bridges are made from maple wedge splits which are previously treated with ammonia (to harden them), traditionally from rabbit poop or horse urine.

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4 hours ago, Jerry Lynn said:

Hey Thomas,

 

Why not just use your CNC router to make custom oversized blanks to fit and finish in the normal fashion?  Skip the middle process on the Deckel…

This is a man , who bought a machine, and, he want's to use it, for ....something, garsh darn it! :lol:

well it's neat and all but not a million dollar idea, and I would be the only guy I can think of who would use "exotic hardwoods" and well I make my own by hand, so were' not buying today , but keep on thinking, there's got to be "some thing" that you can do with your machine

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7 hours ago, chiaroscuro_violins said:

To be frank, I do not think this is the kind of character you want to pursue.  I know this was just a test, but it would be almost impossible not to do a better job by hand using a knife.  I also think you would save a lot of time if you stick to traditional methods.  Is there a problem with commercially available bridge blanks?  

Great point. There are plenty of good blanks out there. I am always looking for ways to 'improve' production.

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5 hours ago, David Beard said:

First, such machine work is far less fine that good hand work.

Second, wood choice is not just decorative.

  Thank you for your input. Yes, the top experts out there make a gorgeous bridge. I understand the different woods and their density, weight, frequency response, etc all affect tone. I am always thinking.

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5 hours ago, Violadamore said:

What a neat old piece of equipment!  :)

That said, the results look wasteful and appallingly crude.   You should also know that good bridges are made from maple wedge splits which are previously treated with ammonia (to harden them), traditionally from rabbit poop or horse urine.

Yes, and thank you. Crude is being kind :-) I wanted to try something different and ask those more informed than me about making these. I have hundreds of bridge blanks. They are all boring. I have seen such well made and beautiful bridges that are similar but completely individual so that is my goal.

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5 hours ago, Jerry Lynn said:

Hey Thomas,

 

Why not just use your CNC router to make custom oversized blanks to fit and finish in the normal fashion?  Skip the middle process on the Deckel…

It seems that nearly all the bridges out there look identical with the grade of wood being the difference. I have made a number of unfinished blanks in the past and finished them by hand. You are probably right--I just want something that works yet is identifiable as unique.

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49 minutes ago, jezzupe said:

This is a man , who bought a machine, and, he want's to use it, for ....something, garsh darn it! :lol:

well it's neat and all but not a million dollar idea, and I would be the only guy I can think of who would use "exotic hardwoods" and well I make my own by hand, so were' not buying today , but keep on thinking, there's got to be "some thing" that you can do with your machine

Yes. Not necessarily looking to make $$$ but rather to improve something. In my previous line of work I invented, patented, and developed a product that is currently used by nearly every automotive manufacturer and F1 race team because the industry said 'it cant be done' which caused me to say 'why not?' I have always been one who will 'think outside the box'. This is why I embrace and dont take the criticism personally.

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55 minutes ago, Thomas Knight said:

Yes. Not necessarily looking to make $$$ but rather to improve something. In my previous line of work I invented, patented, and developed a product that is currently used by nearly every automotive manufacturer and F1 race team because the industry said 'it cant be done' which caused me to say 'why not?' I have always been one who will 'think outside the box'. This is why I embrace and don't take the criticism personally.

Well do tell, many of us are car enthusiasts'. Well I'm not sure this is a hole that needs to be filled but I wouldn't try to stop you, but I do think the violin{bowed instruments} is something that many people have tried to "improve" or "come up with a better way"  only to never really succeed. I myself make pretty unusual instruments but have never considered them improvements , just my take on it. 

To me there have been very few successful "improvements" over the years, probably string manufacture, fittings , fine tuners , gearless tuners, carbon fiber bows, things like that come to mind. Many would debate if any of that has been an improvement anyway, or at least needed. 

So don't let me discourage you from figuring out something to do with your infernal machine, you've had success in the past so who knows, maybe you can make lightning strike again.

 

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10 hours ago, Violadamore said:

What a neat old piece of equipment!  :)

That said, the results look wasteful and appallingly crude.  

I have never used a pantograph, but I too was surprised at how poor the cut was.  It appears to be a serious machine tool, and I would expect better.  Has the machine been gone thru to check the bearings and adjustments?

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1 minute ago, Don Noon said:

I have never used a pantograph, but I too was surprised at how poor the cut was.  It appears to be a serious machine tool, and I would expect better.  Has the machine been gone thru to check the bearings and adjustments?

He may have been tracing an image printed on paper, moving the stylus by hand. Tracing an actual 3D object would probably offer better precision.

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1 hour ago, Don Noon said:

Yeah, that could be it.  I just went by the photos, and with the shadows, the big picture of the bridge looked like it was a 3D model.

Oh, the long skinny cutter he used looks like it would have a lot of flex, too. Probably jumped around a bit.

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These machines are capable of pretty amazingly detailed work, even when working from a paper pattern.  Intentionally or not, Mr. Knight is not taking full advantage of his machine.  I'll scan and post some examples of what they can do from a Deckel manual or catalog soon.

38 minutes ago, David Burgess said:

Oh, the long skinny cutter he used looks like it would have a lot of flex, too. Probably jumped around a bit.

RPM can be quite high on these machines, so chip load can be low, but yes, that is likely a factor (see above).  They were originally used with single lip cutters and the company made some rather fantastic grinders for making and sharpening them.

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6 hours ago, Don Noon said:

I have never used a pantograph, but I too was surprised at how poor the cut was.  It appears to be a serious machine tool, and I would expect better.  Has the machine been gone thru to check the bearings and adjustments?

Hi Don, the tool is immaculate. I should have set it up for 1:10 as it would have been near perfect, but I did it in a few minutes and the proper way is a rigid pattern with a 1/8" groove that the 3/32" stylus follows. At 1:4 if I am following the outline of the pattern a 1/8" mistake shows as 1/32" which is quite noticable. An identical machine was used to carve the entire Lord's Prayer on the head of a sewing pin by downsizing numerous times. I will do another.

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4 hours ago, David Burgess said:

Oh, the long skinny cutter he used looks like it would have a lot of flex, too. Probably jumped around a bit.

Yes, freehand I was fighting the bit torque. Had I done a rough cut followed by a final cut it would have been night and day. I am so glad to see comments as that was the purpose of the thread.

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OK--not looking for perfection so I cut a 4x bridge out of MDF on a table saw and drill press. 10 min. I stayed with the 1/8" bit and did a one direction trace in the direction of bit spin so chip interference is minor but results in less bit wandering. This allows for making a bridge in any shape imaginable. I would probably go with a 1:6 ratio for more accuracy and two passes with different bits--first a rough cut then a final cut. It took 3 minutes to cut the bridge.

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7 hours ago, David Beard said:

I just don't understand the motivation for this sort of stuff.

Hi David, I guess it is because I never like conventional thinking. It is hard to argue with 300+ years of bowed instruments and the experts that carry on that tradition. Maple is the standard bridge wood and has a Janka Hardness of 1450. Why was/is maple considered the only proper wood for a bridge? Ease of access? Maybe with treatments maple can achieve Janka 1550. My mind says why not try unconventional woods? What happens if we go even harder to rosewood or bamboo? Maybe a different wood will have greater transmittal of frequencies with certain instruments. Maybe a softer wood is better in some cases.

As a former golf pro I worked with building clubs and the shafts were grouped into 3 categories by how much they flexed on a scale with a weight at the tip and the handle end held securely. Then in the early 80's a researcher discovered frequency testing and flex categories jumped in number. Aluminum shafts, fiberglass shafts, titanium shafts, etc were tried. Then composites were developed and can isolate certain frequencies and improve response to certain frequencies that you 'feel' when hitting a golf ball. At the pro level golf is 95% sensory.

I am not a great violinist but was classically trained as a violist and can hear huge differences between two bridges, two soundposts, strings, tailpieces, and within adjustments of all of those. Tailgut lengths, achieving the proper length ratios, etc. It seems there is room for improvement, especially on student level instruments.

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1 minute ago, Dave Slight said:

This style of bridge is destined to fail. With no support between the legs, they will just splay, and could even crack between the dairylea triangle cut out, and the kidney.

Yes, I am certain it will fail. I made it to show the process of how and what can be done, not to actually use it. I am always looking to try something different and ask for response so you are 100% correct.

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