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With 3 acoustics on the bench with fresh bridges glued on it was time to fit pins and revisit methods.

Having read all the recommendations to cut slots thru the bridge plate to reduce wear, I wasn't really seeing it so thought I'd do a little testing myself. In the past I've always given the string a bend right at the ball to make sure it is tight to the bridge plate and out of the way of the pin and I think that goes a long way to make slotted pins work. But a hundred string changes later by who knows and I expect my regimen would not be followed.

I set up a maple test block and tested slotted and unslotted pins side by side. It was immediately obvious the slot thru bridge method allowed the ball to sit much better on the bridge plate. I was sold, thanks Hesh and all the others here who were pushing the slotted bridge!

I always made enough of a slot in the bridge to provide a smooth path to the saddle with a variety of tools the hard way.

So doing more cutting thru the bridge plate and bridge I wanted better tools to control chipout or damage.

I looked for tools to make it happen and found the saws and files I'd like at StewMac. Saws were back ordered and files were NOT cheap. Bit the bullet and ordered all 5 files. When they didn't come in by Friday I thought I'd see what I could come up with over the weekend. I had all the stuff in the shop already.

Side note -- Anybody else seeing much longer ship times from StuMac??? For years I always got my stuff in 2-3 days, now double that! Ohio to Michigan.

I should get my files by tomorrow but here's what I came up with in the shop for anyone interested.

The homebrew saws/files work really well and I could probably return the files to StuMac but may keep them to dress the slots. Some of the blades needed some grinding to work thru the pin holes and rounding sharp edges and corners to make them safer for the guitar. I wasn't sure if I could freehand grind flats accurately on the 5/32 chainsaw file but held in a vise grip they came out better than expected. Orientation of the visegrip helped keep the sides parallel. I broke a new chainsaw file in half and made 2 from one file. EDIT- In use I had to touch up the two made from a chainsaw file by grinding one edge a bit narrower so the file doesn't stick in the slot, both edges still came in handy during the process.

One more thing, I always put a flat or 2 on handles that are position oriented, gives me some tactile indication the tool is in the right position without eye strain.

Cheers!, Brian

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Brian R, Wood Mechanic
N8ZED

Looks good!

I wrestle with the SM files, especially the thicker one. It always seems barbaric and late in the game to be hearing those kinds of sounds happening over an already buffed surface.


Sent from my iPhone using Tapatalk Pro

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Agreed! I would love to find tools for this job that are aggressive, are easy to control, and leave a smooth kerf.

I appreciate the information you have provided from your experiments, Brian. I may have to look into making my own, too.

If you’re trying these tools for the first time be careful, I have dinged a couple of tops with the StewMac tools. Now I put a piece of cardboard over the area around the bridge for protection plus I’m a lot more careful too.

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Steve Smith
"Music is what feelings sound like"

Mario would and does use a hand held jig saw sitting on top of the bridge

Good stuff Brian we made our own too. I use the StewMac saw but made three files of different widths to clean up the slot.

I'll add for sanities sake stick a towel in the sound hole when using the saws the box amplifies that awful sound of the teeth ripping through the plate, top and bridge.

Also, the files that smooth the cuts can also be used to craft string ramps to the back of the saddle so you guys can take a guitar that needs a neck reset but the economics are not there and create break angle behind a saddle that is nearly proud of the bridge. I do this frequently when setting up an inexpensive guitar that could still provide the owner with some more years of service.

My last comment is the X-acto saw requires some attention and care the blade bends very easily. I use one too at times I just have to pay attention.

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Ann Arbor Guitars

Brad - "I wrestle with the SM files, especially the thicker one. It always seems barbaric and late in the game to be hearing those kinds of sounds happening over an already buffed surface. "

So true! I cover with cardboard too, at that point I don't even want light hitting the top.

Some of those I made cut on the pull stroke and some on the push and different TPI offers up some alternatives on the process.

I start them all with the X-Acto keyhole saw which is narrow and fine toothed and works pretty easily and widen up as necessary.

Hesh, Mario has more balls than me, that's for sure. Don't you use some reciprocating gizmo for filing frets? Maybe you could adapt it.

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Brian R, Wood Mechanic
N8ZED

I have used a hand held jig saw resting on the top of the bridge for years after seeing Sylvan Wells post about it. Mario too.

It works great for me and you actually have surprisingly good control. I do it after the holes have been countersunk and reamed for the bridge pins and make a starter notch with a narrow hand saw. The Bosch blade I use will fit the holes. The larger strings still have to be widened a bit with appropriate files.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

Brian yeah no kidding we never adopted Mario's jig saw method but it's fun to talk about.

He once posted a pic of a Lancelot tool a power, mini chain saw type device that he liked for neck carving

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Ann Arbor Guitars

Whoops I stand corrected Sylvan was ground zero on the OLF for the jig saw idea.

I can see how how it can be safer too especially in the duration of the operation it's fast compared to ripping away at the instrument with saws and files.

One tip I learned for using the files from Dave Collins is to make them longer and only pull them up half way eliminating any chance of coming out of the hole and stabbing the top with it.

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Ann Arbor Guitars

You know Terence, I have a variable speed jigsaw that is really quite controllable. You can slow it down almost to the speed of doing it by hand. I can see making some adjustments to the foot to keep the saw level and some felt padding....and some off guitar simulated practice. Making me think about it more I'm not as freaked out by the idea as I was at first. Thanks

But, there are a lot of fussy guitar ops that I guess I just prefer to do by hand. And I'm old and not in a hurry.

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Brian R, Wood Mechanic
N8ZED

I recently digitized many of my shapes and jigs and added small 1/16 holes in line with the string paths in front of the bridge pin holes. I drill them when I make the bridges on my milling machine and then drill through them after gluing on the bridge. That locates 75% of the slot and the little saw just needs to break through the last bit between the reamed pin hole and the drilled 1/16" hole. Its worked pretty well! I always hated sawing out those slots from scratch after. I deleted any pics I had from my phone but you can see them here if you are interested:

https://www.instagram.com/p/CtscFe2udil/?img_index=3

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Burton
http://www.legeytinstruments.com
Brookline, MA.

Great thread Brian.
Tossing out a thought on jig saw blade tooth-set: - I just measured a skinny 20 TPI Bosch jig saw blade:

Bosch 1101 AO
Blade Stock: .036" thk
Blade and teeth: .042" thk
Blade set .006" (+/- .003")


I wonder if filing that tooth set off, on a diamond plate, would make that blade cut with less chatter? I am definitely going to try it. These blades are made for scroll cuts (combination rip and cross cut). My best Dozuki has zero tooth-set for cross grain cuts, and cut like butter...... which is likely the case with a bridge pin hole.

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Measure Twice,

Karl Borum

That’s the blade I have used for years. No modification of the teeth. It fits if the hole has been countersunk and reamed for the bridge pin especially if you make a small starter notch which is a good idea.

I did file a little off the back to narrow it slightly and would recommend doing that for a little wiggle room.

Practice on scrap

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It's not what you don't know that hurts you, it's what you do know that's wrong.

I find the BOSCH T101AO SOFTWOOD & PLYWOOD JIGSAW BLADES 83MM best for this job - a fine downcut cut 19tpi narrow blade, back ground down to narrow.
Single for the top 3, and doubled, CA'd together for the bottom 3 (long handle for both hands))- Round the slot with burrs in a dremel and refined with a pippin file.

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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.

Update after using a handful of shop made tools and the StewMac files.

As Colin pointed out, you can probably get by with 2 slot sizes and they both needed to be considerably wider than the string as they are wound back on themselves to hold the ball. The ball end windings are not real uniform either. You want the slots wide enough to accept the string with no "hang-ups".

The X-Acto keyhole saw worked very well for initial cuts so I'd want one in my kit and they are cheap. They are also PERFECT for cleaning fret slots or deepening them a bit.

Surprisingly, the 32 TPI Morse hacksaw blade was about the easiest to get started in wood and most controllable and easy to use. You might be able to do them all on a budget with one saw blade and 2 glued together for the 3 larger wound strings.

The white Morse jigsaw blade wasn't the right blade for this, too course and teeth not refined enough.

I was using the Bosch T101A0, a nice blade but a little aggressive for me and about the same width as the hacksaw blade.

The two I made from a chainsaw file worked pretty darn well but needed the back edges tapered so they don't tend to stick in the slot.

I did get the whole set of StewMac files and they were nice for final cleanup and smoothing and you might get away with just the 0.043 and 0.067, though I used them all except the 0.087. The StewMac files could use a little relief grinding along the back in width because they tend to want to stick too.

Thanks everyone for all the input!

Brian

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Brian R, Wood Mechanic
N8ZED

Well I tried it. I used a diamond stone to hone off the tooth set on a Bosch 1101 blade, making it a crosscut blade. Before and after crosscut difference in hard maple was impressive. SO much so, I thinned the blade height at the end and mounted it in a dowel-rod handle. Removing the tooth set reduced the force needed to cut the slot, made a smoother cut and reduced the slight amount of tearout. YMMV Thanks for the inspiration.

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Measure Twice,

Karl Borum