Saturday, July 05, 2008

DIY Upright Piano Repair #1 - Replacement Damper Spring

So a while back, I bought a fairly ancient purple piano, and have since been learning to make some music on it. It's an old John Brinsmead upright, that the previous owner had, for some reason, painted over in purple emulsion - I guess to try and make it look a bit Bohemian and cool. (It didn't work...)

I payed £20 for this thing, which isn't bad I don't suppose, but because of its age (dates back to 1915) I've had a number of recurring problems with it - mainly down to the age of some of the internal action components.

So, says I - instead of wanting to spend £25 an hour for a piano tech. to come out and fix it every time something relatively minor happens, I shall learn how to do a few DIY repairs of my own. I then thought that because it's sort of interesting how pianos work, and probably not many people know how to make simple minor repairs to them, I should document my little voyage of discovery on this blog, in case it's of interest to anyone else out there.

My purple piano - what were they thinking?

Please note that I am not a piano technician of any kind, and usually have about as much DIY skill as a chimp in boxing gloves. The motivation behind ripping my piano to bits is basically twofold: 1) I think it's always a good idea for a musician to understand the mechanics of the instrument they play and 2) I'm too tight to fork out a couple of G's on a decent piano right now, so I'm stuck with the purple thing for a while. (I've actually grown quite fond of it). If you foolishly decide to follow any of the procedures put down here you get yourself into trouble and screw up your piano - then tough, it's at your own risk.

Right then, to the first simple repair.

A common enough fault with old pianos is that damper springs break due to fatigue and age.

To explain what this means briefly: when you hit a key on an upright piano, a push rod (connected through a number of wooden moving parts - I'm not going into the basics of a piano action here) connected to the far end of the key moves up, throws a hammer forward onto the string whilst at the same time pulling back a damper (which normally rests against the string in a steady state scenario - i.e. piano at rest) so that the impact of the hammer against the string causes a note to be heard.

When you relieve the pressure on the key (let it up) the damper springs back against the string in order to stop the string ringing. This is pretty intuitive - we've all plonked on a piano, and as long as you hold down a key, the string will ring - until of course natural decay causes it to fade away. If you release the key earlier, then the sound is cut off abruptly. This is what dampers do.

Now, in order for the dampers to spring back onto the string, they are springloaded with a damper spring, and there is one for each and every key on the piano. (88 keys in the case of most uprights). If the damper spring fails, then the symptom is that a given key (the one associated with the damper) will just continue ringing after you've release pressure on the key. This normally makes the piano fairly unplayable - because every time you hit the offending key, the note associated with that key keeps ringing and causes some fairly horrible modern jazz effects.

Replacing these springs is fairly straightforward.


Here's a step-by-step procedure that I used to do this. Note that some of the photos don't look too good at the size they appear on the page. Just click on any one of them to get a full resolution version!

Step 1. Remove the front of the piano, so that the action is exposed.

This should be pretty easy - but will differ from piano to piano I guess. In the case of mine, it involves flipping up a flap at the top of the piano, and reaching inside to release a catch that holds the front face of the piano in place. Once, you got this panel removed, you then also need to remove the fallboard and nameboard (the bits of wood resting on top of the keys and which will normally have the key lid attached). On my sheddy old piano, these bits just slot out without any latches needing undoing.

A naked piano. The stuff you see exposed is the action.

Step 2. Lift out the action.

Once you can get at the action, you need to lift it out of the piano very carefully and rest it somewhere stable and clean so that you can get at the individual damper assembly that you want to work on.

On my piano, the action is held in place by two little catches on either side, where the action block slots into the main piano frame.

Latches holding in the action, and yes - I think that's bird s@#t on the inside of my piano.

Once these latches are undone, you (I think this is fairly standard on most sensible uprights) tilt the action forward (towards you) and then lift it out. Note, that you should check both sides of the action for connecting rods (dowels) coming up from the pedals. I think that you're actually supposed to disconnect these first, but if you're careful (or don't care about breaking stuff like me) then you should be able to get the action out without needing to do this.

I call this a Chaz 'n' Dave or a Piano Lobotomy. The action gutted from the piano.

Once you have the action out, you'll be able to see it in all it's glory - but remember most of this stuff is just made of wood and therefore fragile. Don't start hitting it with a hammer just yet.

Step 3. Remove the Damper Arm Assembly

Before you can replace a damper spring, you need to remove the damper arm assembly in question from the main action chassis. This is straightforward and simply a matter of locating and then unscrewing the screw that holds the assembly in place - by way of a damper flange which is a little block of wood with two tongues, that has a center-pins running through it at various points in order to allow free pivotal movement of the various damper components.

You can just see the damper flange screw in the center of this rather dubious quality photo.

A damper arm assembly. At the top is the actual damper, connected via a rod to the wooden damper arm, which is held between the arms of the flange. The arm can rotate around a roughly central point and is pushed back into place by the damper spring. (Normally that is).

Step 4. Detach the flange from the damper arm.

If you look at where the flange connects to the damper arm, you will see that there is a small center-pin holding the arm in place, between the arms of the flange. Depending on where the damper spring has broken, then you probably want to detach the arm at this point, so that you can get at the spring seat to remove the "hoop" of the old spring. Basically, you need to strip the assembly down.

Damper flange removed, you can see the arms where the damper arm slots in and the small recess for the seating the spring base. In this photo the center pin holding the arm to the flange is see to the right of the flange.

To detach the arm, very, very carefully push out the center-pin holding it in place with a center-pin pusher or a very thin gauge center-pin punch. If you can, try and do this without ripping and shredding up the cloth bushing that will surround the center pin. As I've mentioned I'm very cack-handed and not generally any good at this sort of manual stuff, but I found that just being very patient and being very gentle seemed to do the trick. (Think of it like an airfix model).

Step 5. Remove the old spring remnants.

Turn the flange side on, and look at how the damper spring is held in place. You should see a thin line of chord pulled through the sides of the flange and through the eye of the spring, and normally the spring will have a little heel inserted into a hole in the flange recess. Using a pair of tweezers (my wife's eyebrow ones are the ones I used) pull the chord out and then snag out the remains of the old spring.

If you shred the cord (it may be well worn out), then you will need to a narrow (about 1 - 1.5 cm) replacement strip of chord - if not, then you can re-use the old one. (Which is what I did). Keep this chord for the next step.

Step 6. Set the new damper spring.

Making sure that you have the flange oriented the correct way, slot the heel of the spring into the hole in the flange recess, and then wet the chord and pull it through the flange and the eye of the spring so that you end up with something like that shown in the photo below:
New spring in place, almost there.

To make sure you have things the right way around, place the flange on a flat surface, with the edge that connects to the piano facing down. (I.e. as it would sit back in the action frame). Check that the spring forms an arc out of the flange so that it looks like a kids slide. It should be convex in aspect, and not concave. If it is the incorrect way around, then remove the chord, switch the spring around and then re-seat it.

Note - I put a tiny blob of glue at each end of the chord to hold it in place, just to prevent any lateral movement as the spring works back and forth whilst playing the piano. Not sure if this is good or bad practice, just seemed logical to me.

Step 7. Re-attach the damper arm.

Once you're happy with the spring, then re-attach the flange to the damper arm by pushing back in the center-pin (again - very carefully) and then position the spring so that the curved tip at the top of the spring is seated on the felt pad situated about 3/4 of the way up the back of the damper arm. The finished damper arm assembly should look like this:

A finished damper arm assembly, with replacement spring firmly in place. Wife's tweezers can be seen at the top right of this photo.

One thing I noticed here was that the replacement damper springs which I bought were slightly narrower in gauge than the one which I replaced. Because of this, the spring wouldn't seat exactly in the middle of the damper arm. A bit of gentle tweaking with some electrical pliers sorted this out - however if you do this I'd be careful not to weaken the spring by being too rough with it. I think that the main thing you're looking for is that top of the spring moves smoothly over the felt pad (red blob in the picture above) as the arm moves, so that you have a nice seamless action to the assembly.

Step 8. Re-seat the damper arm assembly in the action.

Once you've admired your handiwork for quite some time, as I did - I can tell you, you then need to put the damper arm assembly back into the main action chassis. Hopefully at this point you will remember where it came from, and so re-attaching it is really just a matter of seating the flange against the main action rail (which is the long piece of wood to which all the damper flanges connect).

Be extremely careful here not to over-tighten the flange screw. If you do then you can quite easily strip the thread and have to do some drilling, plugging, doweling and allsorts in order to make good.

The best strategy is to screw things back in quite lightly, and then once the action is back in the piano tighten up a fraction in order to align the damper arm correctly with it's target string.

Step 9. Put the action back into the piano, check alignment.

Nearly done. Carefully, place the action back into the piano, flip the catches to hold it in place (its final resting place) and make sure that the connecting dowels to the pedals are seated on the various rails correctly.

Once the action is back in, stoop so that you're eye-level with the damper that you've replaced the spring on, and press down the key it's connected to a few times. Visually check that the damper is still moving forward onto the correct string in a nice, straight alignment. If it's veering over to one side or the other, then either loosen or tighten the damper flange screw (as in Step 8) a tiny bit so that the arm moves to the left or right. By gentle, and don't rush any tightening or loosening of screws.

Step 10. Put the covers back on.

Slot the various bits of panelling back onto the front of the piano - and voila, a simple DIY piano repair finished in under an hour.

As I mentioned before, I'm not a trained piano tech. or anywhere even close, but hopefully someone might find this useful somewhere, or perhaps someone who actually knows what they're talking about can drop a few comments in to help out with a few tips.

N joy.



8 comments:

Phil said...

Makes me want to go and buy an old piano right now. Just need to build an extension to house it first.

Anonymous said...

I like your approach - slow, methodical and reasoned. You have proved that non technicians can successfully carry out their own DIY piano repairs; saving money whilst also learning about their instrument - Well Done!

Take Note Piano Supplies
www.take-note.co.uk

heavypetal said...

Just ordered a set of damper springs and about £50s worth of tapes, springs and things from Take-Note supplies this evening after reading your blog.

DIY piano action here I come.. uhoh.

Great article.

Anonymous said...

Man ur the dood! Thanks...great details....Peace Jaime

O4thewingsof said...

We have become inspired nearly there now but struggling threading the cord thru the flange and spring as described in your step7. Is there a knack and why dyou need to wet the cord ???

Mark said...

As a piano technician myself i thought this was a very good, detailed description. The only thing i would add is to be carefull of what gauge you replce the spring with as there are differenat thicknesses for bass,tenor and treble sections. If a bass spring is used used in the treble it can make that note feel heavy.

acw said...

At the weekend I threw away a box of assorted piano springs which I've had since April 1976. Well, would you believe it, today a damper spring broke! First time in 36 years. Luckily, they were still in the bin.

Jessica Stier said...

We just adopted a super old but beautiful upright paino today. It needs a little TLC and I think with your detailed instructions I'll be able to do that work myself. Thank you so much for sharing your experience with us! This kind of thing is why the Internet is such a wonderful place!!! Take care!