Setting Let-off Wurlitzer

[Dote]

Hi gang,

my Wurlitzer 200A (chopped 206A) is really playing nice, but tonight I felt that I might need to tackle let-off again. Some days ago I did my final pass on leveling the keys and setting lost motion.

I have a very small amount of lost-motion on my Piano, the keys can be depressed only a tiny bit before the hammer moves. It is hard to measure the lost motion, but I guess it is approx. 0.8 -0.6 mm.

Concerning let-off:

some notes (3rd F, F#, G, G# and A) are a bit louder and do have a faster attack, so I guess I need to adjust the let-off distance on these. Do you guys go strictly by feeling/sound or do you acutally measure the let-off distance. If so, how do you measure it, since the hammer falls back very easily even when slowly depressing the key. It seems almost impossible to keep the hammer in the up position to measure the distance between hammer tip and underside of reed. Of course it is very tough to get your ruler inside and to sight down correctly.

So I wonder how this is actually down correctly.

Any help welcome.

Dote

[pianotuner steveo]

You need to make a thin,but firm non conductive strip with 1/16" -1/8" marks that you can slip between the reeds, parallel to the reeds. You then need to press the corresponding key very slowly, and note the distance between the hammer tip and bottom of the reed just before the hammer drops.

Approximate distances are 1/4" in the bass graduating to 1/8" in the treble. Also, I like to make the distance slightly greater to reduce the chance of breaking reeds. If the Let off is way too soon, it will make keys more difficult to play with a lighter touch.

Your lost motion may or may not be too much, but I like to make it as little as possible yet still allowing the jack to fully return.

If you adjust the louder keys and they function better but are still too loud, that is a different issue.

[FixerUpper]

Great tip Steveo. And perfect timing. I've got my electronics all done. I've lubed everything and now I am about to go through the process of adjusting everything. Your tip will come in handy.

[Dote]

Hi Steveo,

thanks for the tip! I will try that.

Best Regards,

Dote

[pianotuner steveo]

You can use a nice card stock or even the back of a business card to make your ruler..just don't drop it in!

In case you are not aware, I sell the let off wrench on ebay...

[Max Brink]

If you would like to make a measurement device my suggestion for making a measuring device I took a plastic ruler that I cut and filed in size and heated up to trim into a 'J/L' shape so that the lip can easily reach between the reeds. As soon as my hammer tip starts to 'kiss' the ruler then I know that it is at the right let off distance and I can make fine tuning adjustments from there.

Additional Edit: Fine tuning will come from adjusting the Letoff, key dip, and lost motion in a way that allows the key to fall back down to a proper at rest position without double striking. All of these parameters work together in the hammer throw and the final catch of the hammer.

[Chris Carroll]

Setting the let off is subjective to how you want your piano to play and sound- At Vintage Vibe we do it by eye, feel and sound, no measurement devices- Before making any Let off adjustments you first want to set your key height, then level your keys, then you want to adjust your lost motion, just enough lost motion that the jack falls back on soft slow play or when the sustain pedal is depressed , and then you can begin your let off. This is assuming your action has all been tightened and you have no sluggish action parts and your keybed has been vacuumed and key pins have been lubricated.  To get the most tone or dynamic throw/responce out of any action/reed the closer the let off the better- Yes, this allows the hammer to hit the reed harder, thus dynamics. I have never had any complaints of broken reeds by our clients nor have I ever broken a reed on my pianos, not to say this can't and does not happen. Personally I would trade one or two broken reeds every once in a while for the right tone if I had to.

As long as the hammer tip is in good shape and does not need to be replaced and as long as the strikeline is optimal, having the least amount of let off without blocking the reed is how we voice pianos at Vintage Vibe- And yes the scale is a graduating let off from bass to treble.

Something of interest in regards to let off on Wurlitzers- Over the years and specifically on the different 200 models The size of the hammer butt and the size of the felt used governed or regulated the throw of the hammer- We often change this felt out to get more throw on our restorations- Wurlitzer was weary of having their pianos known for breaking reeds so they governed this to keep reeds from breaking. But we like them hot as they can be so we change them when and where needed-
Note: in regards to changing hammers out from another piano, this is somthing to consider as they are all not the same size and this will affect how your capstan adjustments are made- they will never look even if you have two different sized hammers in your piano- Instead of changing whole hammers, just refelt and retip your existing hammer-

[pianotuner steveo]

Chris,

Not everyone here has the luxury of having a stock of replacement reeds on hand to "change out one or two" every time they break. They are expensive. They are no longer $2 each like they were when I was a kid.

And not everyone here has the level of experience that you and I have for making adjustments.
Using a measuring device is a good way to LEARN how to set the let off until one gets the hang of it.

Yes, personal preference is a key to setting most adjustments, but when I say that I increase the let off to avoid breaking reeds, I am only talking about a tiny amount.

I have NEVER had an issue with dynamics with the way I set let off.

[Max Brink]

Chris' answer extremely thorough and is a pretty good elaboration of what I mean by setting the height and "fine tuning from there." And to his defense on the topic of broken reeds, I don't think that you will need to worry about broken reeds with a good bit of intuition.

Most of the broken reeds that I have noticed have been where the hammer is over extending so far as to strike the key before letting off (or having the felt of the hammer tip warn down too far). I think that people's intuition will keep them from setting the let-off into these parameters.

On the topic of dynamics, I would estimate that the best dynamics are on average between ~1/8" from the lower bass to an approximated ~1/16-1/32" on the upper treble. Pay attention as you are setting the letoff to make sure that the hammer is catching after striking the reed and not bouncing!

It's important that if you do set your action to ~1/16-1/32" and you live in a region with season changes like Chicago with cold dry winters and hot humid summers you will want to check your let-off checked every season to make sure that barometric changes aren't causing adverse changes to your action. --And picking up a humidifier this time of year is a very good idea if you don't already have one!

[Chris Carroll]

Very good Point Max- Humidity/moisture and lack there of wreeks havoc on these instruments- You may have your regulation set up and playing like Aces- then along comes rain and humidity or a cold dry spell to change everything you worked so hard at. Depending if you regulated the piano during a humid time or a dry time, once that weather changes wood swells or decompress' you are going to find changes in your lost motion and let off- That hammer rails is sure to rise and shrink with the weather. That is why so many touring bands who leave their gear out in the van over night have such issues- This is absolutely the worst thing you can do to a Wurlitzer. I wonder if  keeping a large Silica pack inside your piano will help regulate the moisture? I bet it would, especially if you changed it out ever couple months, they are cheap, so it's worth a try-

[Max Brink]

I've wondered about an internal humidifier option in the past as well (and this is probably best for another feed since we're getting off topic). But I have always been worried about adding too much moisture with the high voltage pickup rail. Adding too much moisture along with even a very little amount of dust on the pickup could be catastrophic... I wouldn't hesitate throwing something in a Rhodes for a healthy bit of moisture but humidifying a Wurli is something that I am hesitant of.

What does everyone else think about the idea?

[Jezza]

Thanks to all for this insight.  I'll be doing the same on my Wurli 112 once I get a few other things working first...

[DocWurly]

Here's a curve ball for this thread....I considered appending it to a 120 thread, but I think it belongs here.

Let-off on a 120; this would also apply to a 700 (cabinet version of the 120), and to the earlier, transitionary 112A (not the 112).  We all know that the action on these three models, from late 1956 to circa 1961, is different from the others:  A couple of versions of a Pratt-Read Action.  Vintage Vibe has two very helpful videos up about adjusting these:

https://www.youtube.com/watch?v=WQhkLxJWDXk
https://www.youtube.com/watch?v=rkRgRgfWXEo

There is a special tool required to adjust the "butt regulating screw" (112A) aka the "Hammer Let-off Screw" (120 and 700) .  The 120 and 700 manuals talk about it, and they suggest you get a specific let-off screwdriver.

EDIT: I've been informed that a certain ebay seller who specializes in piano and electric piano supplies sells a contemporary version of this let-off tool.  (Perhaps someone else can supply more info.) Check it out!

[DocWurly]

Now, that said, I'm wondering if anyone has found regulating the bass register of these ones especially devilish.  This is what I am finding, though I hope I am wrong:  It appears that there is no way to set the let-off of the lowest notes so that they respond decently to repeated fast undamped strikes.  It appears to be a unique feature of this early bass reed motion that, when struck, it travels much, much further vertically, up and down, than on later models. I mean, looking at the reed, you can SEE this difference as it rings.  So, if I set a hammer to hit minimally (=let off lower), it will miss an already vibrating bass reed if it encounters it at its upswing peak.  If I set it just a tad higher, it will then stop the reed if it encounters it at its downswing peak (or, nadir).

It seems they dealt with this on later models by having the hammers strike the reed much closer to the screw.  (The taper of the reed probably modified its motion, too.)  I am finding there is no way to move the strike line far enough on this 120 to solve the problem in this way. (Even, theoretically, redrilling a hole).

The other possible adjustment I could imagine would to add shims to the underside of the key (also known as the "aftertouch" on these models).  My auditions of this method did not produced encouraging results.

This only a problem in the bass register.  Am I missing something?

[pianotuner steveo]

Only if you are not sure about key dip. The dip is preset on this model on the white keys ( unless someone messed with it) and there is a screw adjustment under the sharps for dip.


This is (letoff) a tricky adjustment on these pianos. Part of the reason why they changed the design, I suspect.

After touch is the downward movement left in a key after the hammer lets off.

Please read my PM Paleophone, I would appreciate the help.

[Max Brink]

It sounds like you may be able to get better striking in your bass register by shimming the harp on the bass side. Have you tried angling the harp in order to adjust the angle of the hammer striking the vibrating reed.

The 120 is a completely different beast than the later models but like the other models the parameters of letoff and key dip work hand in hand with one another and may need to be regulated at the same time. I recommend removing the strip of felt so that you can add and regulate guide rail felts if you really want to dial in the action to perfection. The biggest secret to getting the 120 action working properly is paying attention to the key travel and the point at which the hammer lets off within the key travel. For instance, if your hammer is letting off too deep or too shallow within the key travel you can adjust the height of the hammer and the letoff again in order to shift it to a new equilibrium at a different point within the key travel. You'll want the hammer to letoff at an even point around (+/-)7/8ths of the travel distance or so.

The biggest issue that I usually come across with the 120 is that the leather on the bottom of the fly becomes so grooved that it is nearly impossible to dial in the action properly. Many 120 pianos need to have some of these replaced in order to function properly. Symptoms of this include when the hammers let off too soon in the key travel which is impossible to overcome with regulation or when there is a clicking/jamming feeling as the key is depressed. This is usually going to be an issue within the middle registers with more traffic, though...

[pianotuner steveo]

There are ways to compensate for the worn leather without replacing it.


Also, the 112A came after the regular 112, not before.

[Max Brink]

What do you recommend for treating the worn leather??? The way that it gets down always seemed like an irreversible process to me... Have you attempted any process on these 120 cams?

[DocWurly]

Also, the 112A came after the regular 112, not before.

Understood.  I meant earlier than the 120, not earlier than the 112. 

Though I've never seen a 112A, it sounds to be the 112 amp, harp and reeds affixed to what will soon be known as the 120 mechanism/action (early version); therefore, a true transitional model between the first and second periods of the Wurly EPs.  Horribly confusing name given how different it is from a 112.

To the best of my understanding, it goes:

100 1954  (prototype/test market)
110 Late 1954
111 1955
112 1955
112A 1956
120 1957
700 1958

with a modified-action 120 later in the 1950s.
Here again is my list....always happy to receive corrections!


http://paleophone.net/?page_id=923

[pianotuner steveo]

Max, there is a method where you actually sew a piece of yarn under the leather to puff it back up. Then, you can polish and lube the capstan tops with Teflon or silicone, I believe. It's a pain to remove the action to do all of this, but it seems to help.
I suppose that if you go this far though, you can actually replace the leather.

[Max Brink]

Does that work? It seems like yarn isn't going to add very much pressure behind leather...

[pianotuner steveo]

Use thick yarn, sometimes 2 pieces. It's better than nothing, it's not a perfect solution.

This is an old piano tech trick originally used in upright hammer butts behind the leather, and on certain types of grand piano knuckles ( not the round, replaceable type)

I did this on 2, 700 actions if I remember correctly.