Official Luthiers Forum!

StewMac is pitching this Top Deflection Gage http://www.stewmac.com/shop/Tools/Speci ... Gauge.html

Saying: "Perform bridge work more accurately. By using the gauge and a brace jack to simulate string tension, you can contour the bottom of a new bridge to more closely match the soundboard surface. When you rout the saddle slot, you'll know the bottom of the slot will be flat--that's important for good tone, and critical for undersaddle transducer pickups."

Do you rout your saddle slot in a raised postion as recommended by StewMac? What are the pros and cons of this?

If routing the saddle slot in the raised postion improves undersaddle pickup response (more even & balanced) then it must affect the sound/tone of the guitar even without an undersaddle pickup being installed. Does this follow logically? What is your actual experience?

I have to agree with Todd. There was another thread early where it was suggested that raising the top before gluing the bridge has some advantage. I don't see it. Try flexing a bridge along it's grain, now try flexing it again after it has .120 inches of spruce glued perpendicular to the bottom of it and then another peice of .090 maple glued to the underside of the spruce. That's right, the whole area has become a pretty stiff piece of exotic plywood, with deflection in front of and behind that area but I doubt that there is much deflection AT that area. I am new to building guitars (still, so take my thoughts with caution as they are not from experience) but from a structural point of view this area is pretty darn stiff and rigid and likely will not flex much, certaily along the length of the saddle.

Shane

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Canada

I don't think many of the new tools that Stew Mac is pushing are worth it. A few are but most are shelf dust targets

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Hey John, would you care to elaborate on some of these tools that you have an opinion on? I am not interested in a negative outlook but rather honest opinions from experienced people who either have used tools/methods or can simply see from experience that they are flawed. Many of us look at these tools and wonder. Without enough experience to tell we can sometime waste valuable funds on an empty purchase. Thanks.

I am not a flat top builder but could see the gage as useful for checking top deflection under a given load.
I assume that it could be used for the same purpose on an archtop.
Even if a load was applied with a thumb it might give a feel for how far the top is deflecting.
Would also be good to see how much the top moves when strung vs unstrung.
I'm from the old machinist school where a dial indicator was indispensible so take my comments with a grain of salt.
Nelson

Edit: .......and call the doctor in the morning.

they have a tool that is designed for measuring neck relief that is a bit overkill. I do like the scissor jack but machinist jacks are out there for under $5. Some of the winners are the magnets . Many of the new things are a bit over engineered in my opinion.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

I think this is an interesting idea. There is no doubt that good saddle contact is important. As Shane notes this area is pretty stiff, but how much would it deflect? You probably don't need much deflection to have an impact.

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David White, Toronto

"All my favourite singers can't sing."

Nobody has commented on their experience with undersaddle pickups.

Fishman's written instructions to luthiers has a strongly labeled "IMPORTANT" note saying (Fishman) - "we strongly recommend that before you install any undersaddle pickup, re-mill the existing slot with a plunge router jigged up in an appropriate slot cutting fixture". Fishman claims it makes a big difference in pickup performance and balance from string to string and apparently the average existing saddle slot has proven to be inadequate much of the time since they have this statement as part of their standard installation instructions for undersaddle pickups.

Again, if this is true (that you can hear tonal differences when amplified), I assume the same (harder to hear when not amplified) difference exist for the standard guitar without an pickup. What are your experiences here?

When and how do you rout your saddle slot?

Consider that many factories (And quite a few hand builders) glue flat bridges to domed tops.... There may very well be some flex there...

But... I would be more suspicious about whether the channel was really nicely flat bottomed to begin -- free of tool marks, chatter, grooves, strings of wood, and radiused corners... whatever.... so "Dusting" the bottom of that channel may just be good insurance when someone puts a new pickup into an unknown bridge.

Thanks

John

Gluing a flat bottom bridge onto an arched top is looking for the ends of the bridge to come loose,maybe soon. I curve the bottoms of my bridges a bit more than the curve of the top,to allow for further arching of the top under the steady pull of the strings. Also,to not put the top under tension-you want it to vibrate.

ditto to what Todd does ,

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

Hello everyone
Does any of you guys use a similar home made job for doing neck resets
would be handy for measuring the top while string tension is pulling

I was thinking of getting a stainless ruler and bolting a wee block to the middle
with a stiff screw going down through the block for measuring the height of your bridge
and some shoes of course
havent got round to it though any thoughts or tips ?
Thanks ...tomas

I have to say that this "new" StewMac setup looks remarkably like a portion of the gear that I suggested to them 3-4 years ago for doing top compliance measurements...



aloha,

Dave Hurd
http://www.ukuleles.com

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David C. Hurd
http://www.ukuleles.com

Alice laughed: "There's no use trying," she said; "one can't believe impossible things." "I daresay you haven't had much practice," said the Queen. Through the Looking Glass by L. Carroll

"Since my house has burned down, I have a much better view of the moon"

Thanks for showing the pic Dave
new their must be someone with a home made jig like this
looks like you can use it for loads of things that i didnt think of
anyone know where would you get the likes of that guage from
thanks again