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What does everyone prefer on their brige pins? a 3 or 5 degree angle?

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Use whatever is easiest for you to get in the quality you want. Include availability of applicable reamers in your decision...

For me - it's the 3 degree because LMI stocks them... And I already have the reamer... (Edit to remove SM which apparently no longer stocks good 3 degree pins)

Edit to add.. Times they are a changing... I corrected the post based on Woodie's post below and a look through the SM website - looks like SM only offers 5 degree pins in "The Good Ones" now.. When I bought pins from them originally - they primarily sold 3 degree pins and the 3 degree reamer.... They offered only a few 5 degree pins which were Martin replacements that nobody else sold..

So then... Pick your poison but make sure you have a good source to get quality pins in whatever taper you use..

3 degree, usually larger diameter at the bottom end, more room for ball-ends.

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

3 degree AND use unslotted, your bridge plates will love you for it.

Love the idea of more room to get the ball end through the bridge.

I'm a big fan of the Waverly Pins from StewMac, but they only come in 5 degree. Where do you like to get 3-degree pins?

We carry three tapers in stock, because both 5 degree and 3 degree pins are common across both vintage and modern guitars, and vintage Takamine and certain other Japanese & Asian guitars use a pin closer to 2.8 degrees or no taper at all (these are retrofitted with tapered pins).

From 1931 onward, Martin used 5 degree taper pins on nearly every style through the 1970's, so the vast majority of vintage and modern Martin guitars as well as many clones such as post-1992 Collings use 5 degree pins. Pre-1931 Martins, most Asian-sourced guitars, many US-made Guilds, Asian-sourced Fender acoustics, and an lengthy list of small shop or boutique builders use something close to 3 degrees, with enough variation to make fitting new pins a bit of a challenge.

A few notes on suppliers:

- All of Stewart MacDonald's bridge pin offerings save the thermoplastic Mighty Mite pins (a match for so-called Takamine 'lawsuit' guitar 2.8 degree pins) are 5 degree pins, as are most of Antique Acoustics' reproduction vintage plastic Martin and Gibson pins.

- Antique Acoustics pins use period specific tapers, so vintage Gibsons from 1930 through the 1970's and Martin pin sets from 1931 through the 1970's are 5 degrees. Selected pin sets are offered in 3 degrees where the prototype pins used that taper.

- LMII offers both 3 degree and 5 degree taper, based on the material and style, but as discussed, they have of late been inconsistent in angle. As Mr. Farmer mentions later in the thread, this is likely a Gurian issue, as LMII sources their pins from that company.

- Stewart MacDonald pins in all materials are remarkably consistent in dimensions, and avoid the issue of having to fit individual pins as is common for pins from some other vendors. While Antique Acoustics pins have a bit more variation between colors and styles, there is very little variation within a set of pins.

Notes on what we do and why:

- For most upgrades following ramping and slotting, we use the 5 degree Antique Acoustics or Stewart MacDonald pins - the Antique Acoustics where a precise match to a specific pin style is needed on a vintage or faux-vintage instrument, and Stewart MacDonald's plastic, wood, or bone pins for everything else. For their plastic pin offerings, Stewart MacDonald and Antique Acoustics use machined hard plastic construction - Stewart MacDonald uses Galalith, a vintage-style non-petroleum plastic material made with milk protein & formaldehyde, while Antique Acoustic uses one or more hard plastic formulations. Both are uniform enough in machining so that any Stewart MacDonald pin (with the exception of the low-end MightyMite thermoplastic and oversized pins) may be exchanged for any other, and the Antique Acoustics pins seldom require further fitting within the same style and period.

- Like others here, we strongly prefer unslotted pins, and usually fit new unslotted pins and ramp and slot as part of the initial set-up on most instruments. The belief in the shop - backed up by both trigonometry and observation - is that the primary difference between 3 degree and 5 degree taper is withdrawal force, rather than pin side-loading as suggested earlier in the thread. For the small angles of taper seen in practical bridge pins, withdrawal force is inversely proportional to the taper, which is to say that a three degree pin will generate greater resistance to withdrawal than a five degree pin, assuming all other things are equal (materials, fitted length, insertion force, etc.). Because the resistance to withdrawal is primarily generated at the top of the pin hole, a little additional insertion pressure evens the force required. Properly fitted pins require just fingertip pressure to remove, so well below any load which would contribute to splitting loads.

- To address the issue of pin side force, the difference in angle between fitted pins is half the difference in taper, or 1 degree, assuming the slot in the bridge within which the string sits is precisely fitted such that the string is in contact with the face of the pin for the entire distance through the instrument's bridge, top, and bridge plate. To satisfy this condition, each slot must be cut precisely parallel to the face of the pin, and within .001" or less to insure an interference fit between slot, string, and pin. If the slot is cut too deep or at an angle greater than the 1.5 degree (3 deg pins) or the 2.5 degree (5 degree pins) relative to the axis of the pin hole, the bridge pin side-load becomes a function of string ball diameter and the amount of angu;ar or depth error in the slot.

- An error of as little as 3.5 thousandths in slot depth for a 3 degree taper pin results in identical geometry and identical pin side load as that of a properly fitted 5 degree pin. This further suggests that - if the slot is perfectly made, even minute changes in string size or construction (e.g., the string wrap or gauge of core or style/number of windings) will cause changes in the fit of the pin. A fit that is too tight will require refitting before the pin can be fully inserted, and a fit that is too loose will obviate any of the advantages gained from pin taper or close fitting.

- The consensus here is that most slotted bridges are over-slotted for the reasons suggested above, as well as inadequately controlling saw and file during cutting and fitting. An over-depth slot - and most we see are 10-15 thousandths over-depth - effectively removes pin taper from consideration.

- Use of stiff materials versus soft/distortion-prone plastics for pins and precise, full-length fitting of the pin shaft prevents the deformation of the pin and or pin rotation about the bridge's long axis which results in the conditions necessary to see the string ball damage the edges of the pin holes on the bridge plate.

In summary, we feel that the basis for selecting taper is almost entirely a question of consistency with vintage construction practice (e.g., 5 degree for a 1930's Martin or Gibson repro; 3 degrees for a 1920-1930 Martin repro), choice of shape and material availability versus taper, consistency of manufacture (e.g., degree of interchangeability), and cost. From the point of view of practical structural consideration, pin side loading is not going to be a meaningful consideration unless slotted pins are used, removing the variability in slot depth seen with unslotted pins, and even then, the difference in force is negligible and appears far less important than pin material choice (i.e., no soft, easily deformed thermoplastics).

Note on Edits: Please note this post was edited to correct especially egregious errors in grammar and spelling, as well as to clarify some of the discussion. My apologies for the length of this post!

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A constellation only takes shape when one maps the whole.
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5°

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Pat

A quick method to determine pin taper is to measure the difference in diameter 1" apart on the shaft of the pin...many pins are just over 1" in length, so easy to take measurements at the ends of the shaft and find the difference (or use a digital micrometer and zero after the first measurement and before the second.

5 deg = .087" (difference at 1" stations)
4 deg = .070"
3 deg = .053"
2.5 deg = .044"

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A constellation only takes shape when one maps the whole.
- Beth Brower

Just a heads up to spare someone trouble.

I have no idea what the situation is now that Gurian has changed owners, but the tapers they stated for their pins was incorrect at the time I ordered a bunch of custom, unslotted, wood pins. They insisted pins they sent at 2.8 degrees were in fact 5. Gurian was (is?) a wood pin supplier to other retailers including LMI.
If anyone has the information, I'd be interested if they have brought their tapers inline with the rest of the world.
http://luthiersforum.com/forum/viewtopic.php?f=10101&t=47237&hilit=gurian

One other tiny factoid to add to Woodie G's treatise.
Unlike the rest of the period, in 1938 Martin used a unique "Bakelite" 3 degree pin. I tried to find one once and was unable too. Luckily a convincing copy was not too hard to make.

That was a bit of a long read, but it condensed 15 pages of texts and emails from half a dozen participants into a (slightly) shorter 'what we do and why we do it' document - sorry for the rough sledding!

Fascinating facts about the Bakelite pins, Mr. Farmer - I think I recall them being mentioned on UMGF, but very little other information. Also - your measurements of recent Gurian-provided pins matchs up with our difficulty in getting a good fit for a few pairs of recent customer-provided pins, despite a good assortment of tapered pin reamers. I hope the new owners get things sorted out - I've seen some lovely custom pins on some of the guitars coming through, and it seems as though most of them originate with Gurian.

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A constellation only takes shape when one maps the whole.
- Beth Brower

Thank you everyone for all the great info.

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I knew this was coming as soon as I saw the title of the thread.

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Maybe that's why in real life I was getting 3 degree pins no matter whether I ordered from SM or LMI.... SM may have ordered a ton of pins and they all showed up as 3 degree... And so after some gyrations - they just listed them on their site as 3 degree and went on about life... Looks like SM has the issue solved...

I'm over it now. My journey is complete.....................I swear!

I just ordered both 3 and 5 degree tapers for the reamers. I don't want to worry about it. I already have to worry about every little detail while making them. haha

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