Bridge thickness and saddle depth

ChuckBarnett

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Again... first build...

I am following the lmii plan for this tenor ukulele. I am making a bridge and working on softwood to practice. My question is: how deep should the saddle sit in the saddle slot in the bridge?
The height of the bridge is 7 mm according to the plan with 3mm of the saddle in the slot and 4mm of wood beneath it. My bridge thickness is 6 mm. (I determined this thickness by laying a straightedge across the frets and over the bridge and reducing the bridge thickness until I got between 1 and 1.5 mm between the top of the bridge and the bottom of the straight edge.)
And if I were to ever believe that this instrument would be worthy of amplification, how thick is the pickup that one would install in the bottom of the slot? If you set the saddle onto a pickup strip it is pushed up, so it would need to be reduced in height. What is the minimum saddle that must be in the slot for stability? My concern is that there doesn't look to be a lot of thickness of wood in this bridge.

Also, best I can tell from the plan, the saddle is 2.5 mm thick. I don't have a saddle yet and need to order material for that. I see where somebody said they rout that slot at 3.2 mm and some more and some less. Is there any kind of a standard?

Grateful, as always!
 
No idea about "Standard". I make my saddle slots 4mm wide for a couple of reasons. It gives me lots of room for intonation should I require. It is alsothen possible to drill a 3.5mm hole in the slot if a client asks for an undersaddle pickup. undersaddle pickups are generally 3.2mm wide and becomes very difficult to pull through the same size hole.

I make bridges on my CNC and the slot is 2mm from the bottom of the bridge. They are alsto tilted back 7 degrees off perpendicular but that is probably too advanced for your first instrument.

I make saddles from bone blanks so I can make them whatever size and shape that I like.
 
Thank you, Alan! Great stuff there. 2 mm... that would give me a little bit of wiggle room. So if I put an under-saddle pickup in I would eat up 3 .2 mm of height, right?
 
As a rule of thumb, I'd like 2/3 of my saddle in the bridge, 1/3 above. Or less above, but not more. I don't use an UST, but if I did I'd deepen the slot by that amount.

Make the saddle a fraction wider than the slot, and then thin the saddle until it only just fits. You don't want the saddle to rock fore and aft.

If you want to compensate the saddle you'll want it 2mm wide, 2.5 mm for a soprano. And if you make it wider, that gives you some leeway for fractional misplacement of the bridge or the saddle slot. Thin saddles look pretty though - look at Ken Timms' sopranos, whose saddles are less than 2mm wide. But on a soprano, 7th fret and above on the C string tends to sound pretty thuddy anyway, so intonation there is less of an issue.
 
Most ukulele saddle slots I see are 3/32". I do 1/8". Like Allen, this give me a lot of room for compensation for low g, and I use most of it. With the saddle slot 1/8", I actually drill 2x 3/32" holes in the saddle for two reasons - one to hold them in place when vacuum pressing, and two, the holes for pickups are already drilled, angled on the ends of the slot.

50% is the rule for saddles, meaning, at least 50% of the saddle should be in the bridge. USTs that I install (LRBaggs Element or Five.O) are .050", so my saddles are naturally 50% plus .050" in the bridge. At 7 degrees as well - like Allen stated, that may be too advanced for a first build.
 
So... width of the saddle is a hair under the width of the slot. And saddle blanks are available for ukuleles at 3.2 mm but some, like Allen, cut their slots at 4 mm. I'm missing something.

I'm also missing what I would use to cut the slot. I've a dremel and a 1/8" downcut spiral bit but cannot find anything that will fit the dremel in either 5/32" or 4 mm. Do people use a regular router? I thought I could make a cut and then reposition and widen the slot.
 
So... width of the saddle is a hair under the width of the slot. And saddle blanks are available for ukuleles at 3.2 mm but some, like Allen, cut their slots at 4 mm. I'm missing something.

I'm also missing what I would use to cut the slot. I've a dremel and a 1/8" downcut spiral bit but cannot find anything that will fit the dremel in either 5/32" or 4 mm. Do people use a regular router? I thought I could make a cut and then reposition and widen the slot.

I buy rectangular shaped bone blanks that are 55mm x 6mm x 10m. I can make both nuts and saddles from this size.

I cut my saddle slot with a 4mm bit on my CNC but in years past it was done with a 3.2mm bit in my laminate trimmer and template.
 
On the old Martins they only had a 1/16" narrow shallow slot, but they used to glue the saddles in..so depth didnt matter much.:)
 
I buy rectangular shaped bone blanks that are 55mm x 6mm x 10m. I can make both nuts and saddles from this size.

I cut my saddle slot with a 4mm bit on my CNC but in years past it was done with a 3.2mm bit in my laminate trimmer and template.

All is cleared up. :)

Thanks, once again, Allen, and forum! I'll get on it!
 
I see two choices: look at the parts on other ukes; follow the plans, although your bridge is 1mm too thin - if that really matters. I think the important thing is to have the channel deep enough to make the saddle secure. I've never made a bridge. I've always used ready-made bridges.
 
I see two choices: look at the parts on other ukes; follow the plans, although your bridge is 1mm too thin - if that really matters. I think the important thing is to have the channel deep enough to make the saddle secure. I've never made a bridge. I've always used ready-made bridges.
 
Chuck, just more info if you didn’t already have it.
LRBaggs Element Install instructions.
https://static1.squarespace.com/sta...d20c5/1475619465706/element_active_manual.pdf

The measurements are SS guitar, but the basic concepts of ust installation still apply.
Note: I don’t know anyone who installs any saddle with a forward lean.

Redundant, but the Rick Turner Tilt Back Saddle is how it’s done. If you search Fishman advanced undersaddle pickup install guide, you’ll see the concept, and more info that may help. Also posted in my Ouside the Box thread somewhere in here.
 
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I chuck a 1/8" router bit into my drill press and put the saddle blank into a cross vise. I like to take 3 or 4 passes to achieve the desired depth. I then bandsaw the curved part and finish the shaping with the oscillating sander.
 
Let's see if I understand. Figure 6 in the LR Baggs PDF and the accompanying instructions say that the saddle should fit loosely, if not sloppily, so that a forward lean is created?? I was understanding Allen to say that 7 degree back lean is a good thing although we did not talk about why that is so. If I am creating a 7 degree back lean of the saddle and if the saddle is snug but not tight in the slot, I don't see how there can be any forward mean. Not only that, the routing done at a lean should leave the floor of the slot at an angle. That would mean that if the pickup were sitting flat against the floor, it is already angled to match the bottom of the saddle squarely. So it seems that the question is how loosely or sloppily should that saddle be fit into the slot. Clearly, the drawing is an exaggeration?
 
In my nind if you are installing an under saddle pickup it should be loose to the point that the full downward pressure of the strings is transfered onto the pickup wire and no looser. Sp of you were to turn the instrument upside down the saddle would almost fall out of the slot but not quite. Your machining needs to be done well to insure very even contact along the entire saddle or you will have a string that does not have even volume and tone.

Allen i believe is talking about something different when he taks about milling the saddle slot back 7 or so degrees. Doing so has some increase in downward pressure of the saddle but probibly not much.
Baggs is showng you something different,that you should mill the bottom of the saddle to match the natural forward lean of the saddle under tension. Thus keeping the bottom flat to the bottom of the slot. This angle; depends on how deep the saddle is in the slot and what the forward angle is in relation to the bottom of the slot.
 
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Let's see if I understand. Figure 6 in the LR Baggs PDF and the accompanying instructions say that the saddle should fit loosely, if not sloppily, so that a forward lean is created?? I was understanding Allen to say that 7 degree back lean is a good thing although we did not talk about why that is so. If I am creating a 7 degree back lean of the saddle and if the saddle is snug but not tight in the slot, I don't see how there can be any forward mean. Not only that, the routing done at a lean should leave the floor of the slot at an angle. That would mean that if the pickup were sitting flat against the floor, it is already angled to match the bottom of the saddle squarely. So it seems that the question is how loosely or sloppily should that saddle be fit into the slot. Clearly, the drawing is an exaggeration?
Sorry if I wasn't clear when I mentioned "I don't know anyone who installs a saddle with a forward lean." If you take that aspect out of the instructions, there's reference to 50%, which is what this thread was about. And it goes into different techniques that apply to the Five.O and MiSi (since they both use the same UST). And yes, the drawing is exaggerated. Please, don't get wrapped up in this one. In fact, suggestion, let it go.

I use 1/8" Tusq blanks for saddles, and I cut with a 1/8" spiral bit. Its snug, bordering tight. It takes effort to come out of the slot. Works for me.

Next suggestion, look up the Fishman instructions, which does entirely the opposite of LRBaggs, but also references saddle depth. Rick Turner developed this technique (hence, the Rick Turner Tilt Back Saddle). Its what Allen does, and more than a few others.

Here's a vid I did a while back.
 
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Okay, I stopped into a music store and looked at some ukulele bridges. I learned some things. Here is a photo of one (the only one like it out of mebbe 18 or more.)

bridge style.jpg

I didn't understand the LMI plan and somehow thought I was to drill a hole for the string ends and then open that up to the bottom of the bridge. Now I see it is just a hole -much easier!

bridge plan lmi.jpg

This saddle slot has open ends and the saddle is scalloped on each end. That seems both simpler (for the creation of the slot) and quite attractive. I don't know why that wouldn't work. What advantage is there to closing in the ends of the saddle?

I also bought some Aquila Nylgut strings with the low G. Don't know what I'm doing but having fun...
 
Rule of thumb is what is above is also below...but if someone adds a pickup down the road you lose about 1 mm so its best to have the slot deeper. I make mine about 5mm deep to start but i curve the tops of my bridges (even if i don't have a radiused fingerboard) so I lose depth on the edges.
 
Like Beau, I make my slots so there's more under than above, because I just assume a UST is going in (and its already drilled for it anyway).

This saddle slot has open ends and the saddle is scalloped on each end. That seems both simpler (for the creation of the slot) and quite attractive. I don't know why that wouldn't work. What advantage is there to closing in the ends of the saddle?

You sort of answered your own question. Straight through saddle slots are easier to make, closed ends takes a little more effort, read: selling point. Mostly for me, you can't see the ends of the UST in a closed end. Also, if you end up adjusting action with a shim, you can't see that either. I've done that once on a repair, a while ago; not my ideal method.

Glad you liked the clip (and the references?). Hopefully stuff you can use sometime. Beau actually has an upgraded version of the saddle slotting jig, which is adjustable for him. Good stuff.
 
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