Raising saddle action: why not???

[kkmm]

I have read in this forum, thousands times, saying that one should not turn the thumb wheels to raise the action while the strings are up to pitch (maybe detuned 1/2 step before doing this forbidden act).
Is there any reason for not doing this? Just curious.

[Br1ck]

I think you want to avoid any more downward pressure on the top than necessary. Raising the bridge will put more pressure on the top. Why risk this when you will need to slacken the strings anyway as they will go sharp. Depending how much, you may need to adjust bridge position to intonate anyway.

[Fretbear]

Is there any reason for not doing this? Just curious.

There are a couple of reasons. One is that as Br1ck says, it will increase the string pressure, which all things being equal, can be assumed to be already tuned up to pitch (and at full tension)
It is never a good idea to put more pressure on a top than it was designed for.
The second is mechanical; while those threads are certainly adjustable, they are not designed to be turned while fighting against all that downward pressure of the strings. Some luthiers will fashion a small wedge that they insert between the saddle and base to relieve some of that pressure and to allow a few turns of the adjusting wheels, and some just jam a big screwdriver in there, which can mar both the saddle and the base. There is a very real possibility of actually stripping the adjusting wheels or post threads by raising the saddle at full tension. You can also think of it as a small jack placed between your strings and the top; would you like to keep cranking away at it until you hear a loud crack? You might get away with it a hundred times, but is it really worth the risk when you are going to have to re-tune it anyways?

[Dale Ludewig]

The concern is that turning the thumb wheels under full string tension is that you could strip the threads on either the thumb wheel or the post. There's a lot of pressure on the bridge and, hence, the threads. It never hurts to slack off the tension a little bit when raising the action. Frankly, the same pressure on the thumb wheels and posts is in action when you lower the action. The grinding action works both directions, but people, it seems, only think of it when going higher.

Edit: Fretbear posted before I hit send. I will say this: the increased pressure on the top from raising the action shouldn't be a concern on a well built instrument. You'd have to raise it a lot, hugely, bigly, really really tremendously, before that would be a concern.

[kkmm]

Thanks for all the explanations. These do make sense. I learned some thing new today.

[Atlanta Mando Mike]

I make small changes under full tension all the time. Half a turn here and there- I'm constantly adjusting my action for optimal volume and playability. There's never been an issue and it's not a big deal. My Heiden has a bridge that can just turn at full tension. Others that are tighter, I use little plyers.

[Mandoplumb]

If the post and nut are steel you will probably be alright although that is questionable. For full strength the threads of the nut should be at least the length of the diameter of the post, this is rarely so with mandolin bridges. Also most are brass which is not as strong as steel. You may adjust them under pressure a hundred times with no problem or the first time you attempt it the saddle may come crashing down. Why risk it for the couple of minutes you save.

[Roger Moss]

Before I knew anything about mandolins (last night) I used to try to raise the bridge by turning the thumbscrews under full tension. I never could. The downward pressure of the strings was too great.I guess she was trying to save me from myself.

[multidon]

Both the Original Brekke Bridge and the Traditional Brekke Bridge are designed to be adjusted in either direction under full string tension. And Weber states that it is perfectly all right to do so. In both cases the required tool gives one the additional leverage needed.

[George R. Lane]

Don,
You're right about the Webers being adjusted under tension, but the wrench they provide for the traditional bridge is substandard. I took an old 5/16 wrench from my toolbox and ground the sides down till it would fit between the saddle and the base. I then put it in a vise and bent it slightly upwards so the wrench could never touch the top, that was one of my concerns with the supplied tool. It now works just fine.

[GTison]

I can't turn those knurled nuts. Some mandolin builders used to use hex nuts that you could use a wrench on. I just stick a large (padded with electric tape) screwdriver between the bottom and the top and twist, then turn the nut in or out to set it. I hope that doesn't freak yall out too much, seems safe enough to me. Be careful though.

[pops1]

I try to make sure the fit on the adjusting wheel is as good as I can get it, then rub a little paraffin on the saddle. If everything is right I can raise the saddle with my fingers and there is no way I am strong enough to strip the screw threads with my fingers. If they are tight I will use something to take just a little pressure off the wheels and like Atlanta Mando Mike I have been doing this for decades with out stripping a post. A few times I have used small pliers, but prefer when it is tight to use a wedge. It's not like you are lifting it up a 1/4", but just a tad usually because the top has dried with weather changes and I like a low action.

[fscotte]

A full contact bridge will be easier to raise under tension than a traditional 2 footer bridge.

[Dale Ludewig]

Why would that be? Full contact at the top has nothing to do with the downward pressure on the saddle and the thumbwheels.

[JeffD]

I am peripherally aware of the ins and outs of mandolin set ups, as I have not ventured to actually do it though I have read up.

It seems that adjusting the height of the bridge has to happen in conjunction with a bunch of other things, things that are better done with less string tension. Is it not kind of rare, in the real day to day practice of setting up a mandolin, that the only thing needed is a jog to the bridge height?

[mandroid]

Turning little thumb wheels against all that string load Takes a strong Grip to force them around
& the bridge upward.

[Stompbox]

Agreed, full contact footer just distributes the load across the mando top. It does not change the point load pressure being placed on the two posts.

[Ivan Kelsall]

From Don - "...the required tool gives one the additional leverage needed.". Correct - it does. But,as i pointed out in a previous thread in which Verne Brekke himself joined in,the small wrench is hard steel,the small thumscrew hex. is soft brass. One slip & your hex.is starting to get a tad 'round'. Verne agreed with me that something needs to be done regarding that possibility,& i'm sure that he mentioned that he's working on a new bridge design.

The hex.on the Weber bridge is very shallow, & great care needs to be taken when adjusting it. These days on any of my mandolins,i slacken the strings to raise the action. I think that doing it that way,you can gauge the movement of the thumbwheels much better by 'feel'. Slackening the strings to raise the bridge saddle only adds another few minutes to the job, & it also prevents the possibility of the bridge flipping over & marking the mandolin top - i'll take the safe option every time,
Ivan;)

[Atlanta Mando Mike]

I think everyone who doesn't do it would be shocked at how much difference in volume and playability a small change in saddle height makes -and no, small tweeks don't require other set up moves 95% of the time. Again, needle nose pliers and small moves up or down are fine up to tension. I do it all the time. I may fiddle and do it 10 times in a few days if weather changes. Or if I'm recording vs. playing live. If I'm looking for volume in a jam vs. playing on stage. If I want to be different stylistically-more traditional I'll move the saddle up a little, more modern and fast mood, move it down. And you can do it on the fly. ANd with a new mandolin that I'm trying to find the sweet spot for-I'll make changes through the first month constantly.

[fscotte]

Why would that be? Full contact at the top has nothing to do with the downward pressure on the saddle and the thumbwheels.

My experience has been that a full contact bridge feels easier to raise, in most cases. You aren't just raising the saddle, you are pushing down on the top as well. At any point in the base of the bridge, there is less 'ground pressure' in a full contact than a two footer. There's a definite difference in how tension is being applied to the top of the mandolin between a 2 foot bridge and a full contact, most notably if you look at the deflection that occurs at the f-holes, there will most likely be more with a 2 footer.

I'm still trying to figure out the differences in a full contact bridge and a two footer and how it relates to tone and tension. A full contact is putting more pressure on the center of the top, so less tension is being placed over the tone bars, and subsequently less tension to the ends of the tone bars. I think its something worth more investigating. Perhaps full contact has more advantages with an X braced mando.

[Timbofood]

A well respected luthier showed me the "padded screwdriver as a lever" to just relieve some pressure on the thumbscrews and make small tweaks. Just as "MandoMike" does. Thirty odd years of doing it, never inflicted any serious damage, no gouged top, no stripped threads. Be careful, go SMALL adjustments, I'm not wild about the pliers use but, different techniques work better for everyone.