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NCLuthierWyatt

allignment pin material

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Hi, I am in the process of building my first violin using an inner mold and would like to use allignment pins for finishing the edge work before beginning thicknessing. I've heard of a variety of different materials being used for allignment pins however I would like to use ebony. Are there any places where I could find ebony pins? If not, how would I go about making them? Any advice or good alternatives to ebony pins would be great! Thank you. 

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I split and shave them from ebony scrap, but I'm a "violin resurrectionist", and have an accumulation of the stuff.  From making strong pins for other purposes, I'd suggest oak heartwood or bamboo, stained black, as alternatives.  :)

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I use steel pins.

... but pull them out after gluing the plates on, and replace them with crossgrain plugs drilled from the plate offcuts to make the plugs as invisible as possible.   Just to be different.

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Nothing beats the old Italian poplar toothpicks I use. :lol:

Seriously, I believe that using a softer wood than the back helps to prevent the possible wedge effect that could cause an open seam, as I put them on the centerline a la Stradivari.

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I use cut off small nails as actual metal pins sharp on one end.  That's just while using the holes and pins for actual alignment and positioning work.  Once glued in place, I pull the metal pin and replace with toothpick or shaped scrap wood.

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19 hours ago, Davide Sora said:

Nothing beats the old Italian poplar toothpicks I use. :lol:

Seriously, I believe that using a softer wood than the back helps to prevent the possible wedge effect that could cause an open seam, as I put them on the centerline a la Stradivari.

To complete the picture I would like to say that obviously I also use steel pins for plates positioning, made from the cylindrical part of drill bits of the same diameter as the one I use to make the holes (1.75 mm) for a perfect match.

The diameter of the toothpick is a little bigger (1.85 mm) so I reduce it with a scraper to adapt it to the hole and of course  I cut the pointed ends making it cylindrical.

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20 hours ago, Davide Sora said:

Nothing beats the old Italian poplar toothpicks I use. :lol:

Seriously, I believe that using a softer wood than the back helps to prevent the possible wedge effect that could cause an open seam, as I put them on the centerline a la Stradivari.

I agree and for work where it will not detract from the desired effect a pin just roughly rounded with a knife is also less likely to cause a crack.

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6 hours ago, nathan slobodkin said:

I agree and for work where it will not detract from the desired effect a pin just roughly rounded with a knife is also less likely to cause a crack.

Guadagnini knew this well....

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On 8/1/2019 at 8:45 AM, Davide Sora said:

Nothing beats the old Italian poplar toothpicks I use. :lol:

Seriously, I believe that using a softer wood than the back helps to prevent the possible wedge effect that could cause an open seam, as I put them on the centerline a la Stradivari.

That would suggest avoiding oak or more importantly ebony which might also compromise the blocks as the softer spruce expands and contracts around the much harder material.  Unless the joining to the top and back prevents structural changes in the block...?

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2 minutes ago, Julian Cossmann Cooke said:

That would suggest avoiding oak or more importantly ebony which might also compromise the blocks as the softer spruce expands and contracts around the much harder material.  Unless the joining to the top and back prevents structural changes in the block...? 

Structural changes take place in any case because the block has a much larger size relative to the gluing surface.

But I believe that if the peg is properly sized and not wedged in, there will be no problems with softer woods.

For hard woods Guadagnini's technique (pin almost squared) would be recommended, because it allows more room for movement.

But you must accept the ugly appearance, at least to my eyes^_^

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33 minutes ago, Davide Sora said:

But I believe that if the peg is properly sized and not wedged in, there will be no problems with softer woods.

That's the important thing... don't hammer them in.  All this worry about relative hardness of the wood I think is a red herring.

There are lots of things going on... endblocks and plates have mismatched grain directions, so there will be pushing and pulling at the glue joint due to humidity changes (not the least of which is when the glue dries), and then there is string tension too.  As long as the plate/block glue joint stays solid (which might not always be true), there should be no significant problem with the pin.  If the glue joints separate, and you have a pin going thru the plate and block... then there is an issue.  Or if you're trying to remove a plate.  My guess is that cracks at the pin are from these two problems, or perhaps a hammered pin... but not those other nits.

I prefer non-structural plugs just to fill the holes after the metal pins are removed, and/or short enough to avoid going into the block, for these issues.

I think the Guad square pins are just 'cuz it's easier to make a square pin using a knife, not some carefully considered structural reason.

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When I fill the holes with the wooden pins I put two separate piece, one that go in the block hole only and one that fill the plate hole only, even if cutting a soft wood pin with an appropriate opening knife it's actually a lot easier than one might think.

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Davide, are your worried that someone will X-ray your violin and want it to look good? :)  I'm not that concerned about an empty hole in the end blocks.

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2 hours ago, Don Noon said:

Davide, are your worried that someone will X-ray your violin and want it to look good? :)  I'm not that concerned about an empty hole in the end blocks.

I'm worried about leaving an empty cavity that could partially be filled with glue, which fragmenting could cause some annoying high-frequency vibration.

I know, I'm paranoid :lol:

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A toothpick from other than an Italian restaurant is sacrilegious. Maybe some of you are making Chinese knockoffs  :P

My toothpicks are a little under 2 mm in diameter. I use a no. 44 drill which is 0.086" = 2.18 mm. I have no splitting issues even if the hole is on the seam. I dip the toothpick in watery hide glue and slide them into the hole.

I soaked them thoroughly in a dark stain of walnut crystals years ago and stored them.

 

 

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I only took the time to look up two species, Picea abies and Acer pseudoplatanus.  Radial shrinkage in the spruce is 4.5%, and 3.9% for the maple.  Based on this very limited sample size I don't think we can assume that a hardwood species shrinks less or more than a softwood.  I've been using hardwood toothpicks for my pins.  Would it would be a better idea to make pins from the cut-offs of the plates so that the pin and plate radial shrinkage are the same?  

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11 hours ago, Jim Bress said:

Would it would be a better idea to make pins from the cut-offs of the plates so that the pin and plate radial shrinkage are the same?  

Unless you plan to use a custom-made plug cutter and cut crossgrain plugs, and then align the grain to match the plate (like I do), you're going to have pin/hole shrinkage mismatch.  I should emphasize that I only do this for aesthetic purposes, and not because I believe it's better at preventing cracks.  Using a toothpick, the diameter of the pin will be controlled by crossgrain and tangential properties, whereas the hole is controlled by crossgrain and longitudinal properties... the same situation as with tuning pegs in a pegbox.  Most pegboxes don't crack... and many have ebony pins jammed into the holes.  How many pegboxes would crack if you didn't jam the pegs in, but glued them in without pressure?  Do you see why I think this stuff is all a red herring?

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12 minutes ago, Don Noon said:

Unless you plan to use a custom-made plug cutter and cut crossgrain plugs, and then align the grain to match the plate (like I do), you're going to have pin/hole shrinkage mismatch.  I should emphasize that I only do this for aesthetic purposes, and not because I believe it's better at preventing cracks.  Using a toothpick, the diameter of the pin will be controlled by crossgrain and tangential properties, whereas the hole is controlled by crossgrain and longitudinal properties... the same situation as with tuning pegs in a pegbox.  Most pegboxes don't crack... and many have ebony pins jammed into the holes.  How many pegboxes would crack if you didn't jam the pegs in, but glued them in without pressure?  Do you see why I think this stuff is all a red herring?

A nice practical explanation. 

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Locator pins in the top seem to cause as many cracks in old violins as poorly fitted saddles. It seems like the idea of a softer wood is a good one, but what about other ideas for avoiding locator pin cracks in tops after 50 or 100 years?

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20 minutes ago, GeorgeH said:

but what about other ideas for avoiding locator pin cracks in tops after 50 or 100 years?

As I stated in a previous post, I believe that pin cracks are due to glue joint failure at the blocks and/or plate removal stresses, and these would all be avoided by having a pin that does NOT go thru the plate and into the block... as Davide does... and/or having a crossgrain plug that fails easily in shear, like I  use.  

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