Author Topic: Restoration newbie - 1975 MkI Stage  (Read 2409 times)

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #30 on: October 20, 2020, 02:39:35 PM »
This evening I finished cleaning all the glue and felt residue that was left on the underside of the hammers - thank you to Tim Hodges for the red spirit tip - worked a charm ;)

Now I have removed all the old punchings and felts from the front & balance rail and replaced them with new ones. This time the balance rail has the proper white felts. I will begin leveling and setting the dip tomorrow.

A couple of things I have noticed. Firstly there are a couple of keys that felt a bit loose compared to the rest. Sure enough when I checked the balance pin holes they were bigger than the others.



Also, I see that not all of the hammers are sitting square on the pedestals - some are off to one side such that they hang a bit over the edge. This is not something I can imagine is easy to adjust since it would likely mean adjusting the position of the action rail and since the adjustment would be quite small it would cause problems with the existing screw holes.

Some positive news is that adding paper punchings on the balance rail helps to remedy the hammers being so uneven when keys are depressed :)

Offline jwc44

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Re: Restoration newbie - 1975 MkI Stage
« Reply #31 on: October 20, 2020, 03:05:53 PM »
The side to side key wobble is most likely from worn key bushings (the red felts that sandwich the pin). You definitely dont want them too tight as the keys will stick with humidity changes as the wood swells. There is a key bush tightening tool that compresses the wood back to size. If you have a lot of keys that are crazy sloppy you may want to consider rebushing.

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #32 on: October 20, 2020, 03:49:33 PM »
The side to side key wobble is most likely from worn key bushings (the red felts that sandwich the pin). You definitely dont want them too tight as the keys will stick with humidity changes as the wood swells. There is a key bush tightening tool that compresses the wood back to size. If you have a lot of keys that are crazy sloppy you may want to consider rebushing.

Yes, you are right, there a a couple of keys that have some side wobble because the bushing felts have come apart but the ones with the bigger holes drilled have side to side and front to back wobble. I may need to investigate this bush tightener and a few keys will need rebushing.

Offline Tim Hodges

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Re: Restoration newbie - 1975 MkI Stage
« Reply #33 on: October 20, 2020, 05:41:02 PM »

Also, I see that not all of the hammers are sitting square on the pedestals - some are off to one side such that they hang a bit over the edge. This is not something I can imagine is easy to adjust since it would likely mean adjusting the position of the action rail and since the adjustment would be quite small it would cause problems with the existing screw holes.


In fact this is actually quite easy to adjust.

First you need to remove the harp and remove the damper bar.

Next using a long screwdriver inbetween the damper comb arms  loosen the big machine screws which hold the aluminium action rail down to the keybed.

Next loosen the 2 big black nuts on each harp support.

Move the action rail and harp supports left or right and line  up the action rail with the majority of the pedestals until you are happy with each key then re-tighten.
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Offline maestro

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Re: Restoration newbie - 1975 MkI Stage
« Reply #34 on: October 21, 2020, 01:42:41 PM »
Some tools should be retired from the piano technicians arsenal, I cite the key bushing tightener because it is a destructive tool which only achieves its intended result by a brute-force, severely inelegant method.  You make inconsistent work for yourself, and you make future key-bushing replacement more frustrating for the next tech who deals with the board. You can replace felts until the cows come home, but it's really hard to achieve consistency on key mortises that have been bashed in by this tool, splintering and deforming the wood in the process.

VS Pro-felt (by PianoTek) can revive keyushings if they're not too far gone (read: threadbare). But getting into bushing work requires specialized tools and experience and you may be better off having a piano tech do the bushings for you, or better yet, replace the lot and give your piano a guaranteed few more decades of bushing-worry-free operation. A piano tech will have a good set of sized bushing cauls (not the spring loaded type) and heat-treating cauls to make each bushing extremely consistent one to the next.

Also, you showed a photo of a key with an out-sized balance hole. This takes some finesse to fix properly. The old style phenolic inserts are not available anymore, although you may be lucky to find a tech with some left overs plus the special installation drill-bit. However, this isn't the best approach as they can add noise to your keyboard. Ideally you outsize the hole, plug it with hardwood and re-drill. Locating the new hole needs to be very precise.  If you're lucky the original holes can be salvaged (I can't tell from the photo), I like to use Chair-Doctor glue to tighten and then a key-bushing reaming tool to widen to the correct size.  Again, you may want to consult a piano tech to help you with this process or give you guidance.

BAH. Not fun work. Good luck!
« Last Edit: October 21, 2020, 01:46:37 PM by maestro »

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #35 on: October 21, 2020, 02:43:04 PM »

In fact this is actually quite easy to adjust.

First you need to remove the harp and remove the damper bar.

Next using a long screwdriver inbetween the damper comb arms  loosen the big machine screws which hold the aluminium action rail down to the keybed.

Next loosen the 2 big black nuts on each harp support.

Move the action rail and harp supports left or right and line  up the action rail with the majority of the pedestals until you are happy with each key then re-tighten.

Thanks again Tim - this worked like a charm  :)

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #36 on: October 21, 2020, 02:47:19 PM »
Some tools should be retired from the piano technicians arsenal, I cite the key bushing tightener because it is a destructive tool which only achieves its intended result by a brute-force, severely inelegant method.  You make inconsistent work for yourself, and you make future key-bushing replacement more frustrating for the next tech who deals with the board. You can replace felts until the cows come home, but it's really hard to achieve consistency on key mortises that have been bashed in by this tool, splintering and deforming the wood in the process.

VS Pro-felt (by PianoTek) can revive keyushings if they're not too far gone (read: threadbare). But getting into bushing work requires specialized tools and experience and you may be better off having a piano tech do the bushings for you, or better yet, replace the lot and give your piano a guaranteed few more decades of bushing-worry-free operation. A piano tech will have a good set of sized bushing cauls (not the spring loaded type) and heat-treating cauls to make each bushing extremely consistent one to the next.

Also, you showed a photo of a key with an out-sized balance hole. This takes some finesse to fix properly. The old style phenolic inserts are not available anymore, although you may be lucky to find a tech with some left overs plus the special installation drill-bit. However, this isn't the best approach as they can add noise to your keyboard. Ideally you outsize the hole, plug it with hardwood and re-drill. Locating the new hole needs to be very precise.  If you're lucky the original holes can be salvaged (I can't tell from the photo), I like to use Chair-Doctor glue to tighten and then a key-bushing reaming tool to widen to the correct size.  Again, you may want to consult a piano tech to help you with this process or give you guidance.

BAH. Not fun work. Good luck!

Yikes - I do not possess the tools needed for this kind of repair let alone the knowledge or craftsmanship. Since it's not many keys I will try to live with it and only tend to the few bushing felts that have broken away and come loose. Getting a pro busher to do a proper job will have to go on the backlog for now I think. Great info though - thanks ;)

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #37 on: October 21, 2020, 02:55:30 PM »
After making the action rail adjustments, as per Tim's wonderful tip, I turned my attention to setting key dip and so removed the top tine to use as a 3/8" measure.

Unscrewing it revealed a completely destroyed grommet that disintegrated in my fingers. It was covered in rust as was the tonebar where the screw had been.



How serious does this look? Can this just be cleaned up or am I looking at having to replace bars in this kind of condition?

Offline jwc44

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Re: Restoration newbie - 1975 MkI Stage
« Reply #38 on: October 21, 2020, 03:25:48 PM »
That stuff is cosmetic.  I went ahead and de rusted, cleaned, and polished all of the tines and tone bars, it had zero effect on tone, I just wanted to do it because Im not into corrosion.  It was a huge pain and time consuming job so unless you are OCD skip that.

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #39 on: October 21, 2020, 03:37:24 PM »
That stuff is cosmetic.  I went ahead and de rusted, cleaned, and polished all of the tines and tone bars, it had zero effect on tone, I just wanted to do it because Im not into corrosion.  It was a huge pain and time consuming job so unless you are OCD skip that.

Hehe, good to know it's nothing to worry about however, like you, I don't think I will be able to stop myself from trying to remove it. I have just ordered the bushing kit, back rail felt and two cheek blocks from the UK so I have some time to spare before I can continue sorting the keys out now.

I know the cheek blocks are just cosmetic but the tech glued a bright green sticker into one of them like a calling card that says "Reborn 2020 KlassikKeys.com" and it irks me when I see it  :D

How did you approach the de-rusting and polishing?

Offline Tim Hodges

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Re: Restoration newbie - 1975 MkI Stage
« Reply #40 on: October 21, 2020, 04:20:07 PM »
Might be worth seeing if you have a metal plater near you, it costs very little to get the original zinc plating with a yellow passivate finish. Platers will usually dip it in an acid bath beforehand so saves you a lot of time in cleaning.

This is a set I had done recently:

https://photos.app.goo.gl/MEnsu1rfyGUSjMKu9
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Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #41 on: October 21, 2020, 04:50:32 PM »
Might be worth seeing if you have a metal plater near you, it costs very little to get the original zinc plating with a yellow passivate finish. Platers will usually dip it in an acid bath beforehand so saves you a lot of time in cleaning.

This is a set I had done recently:

https://photos.app.goo.gl/MEnsu1rfyGUSjMKu9


Nice - I will make some inquiries ;)

Offline jwc44

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Re: Restoration newbie - 1975 MkI Stage
« Reply #42 on: October 21, 2020, 04:55:08 PM »
What Tim suggested is the way to go, if you can line that up.    There is a product called evap-o-rust that I used on the hardware that worked great but I was out of it so i just used steel wool, simichrome, and elbow grease.  Came out great but you will have sore fingertips for a few days  :o

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #43 on: October 21, 2020, 05:14:02 PM »
What Tim suggested is the way to go, if you can line that up.    There is a product called evap-o-rust that I used on the hardware that worked great but I was out of it so i just used steel wool, simichrome, and elbow grease.  Came out great but you will have sore fingertips for a few days  :o

Excellent - thanks for the info :)

Offline Tines&Reeds

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Re: Restoration newbie - 1975 MkI Stage
« Reply #44 on: October 22, 2020, 03:00:32 PM »
Please make sure you do not get confused by all those technical terms. You are talking about keydip, but what you actually mean is escapement ;-)

Keydip is the travel of a key downwards. The key stops via the stop lock mechanism which is formed by the pedestalfelt and the hammer and NOT by felts on the frontrail pins. I've seen this often but it's wrong.The frontrail felt should only prevent the key to not go too much into aftertouch.

So there are several things that affect keydip.
The first thing is the key rest felt which should be changed in any case cause it's worn out / hardened over the time. If you take thicker felt than the original, you'll reduce keydip.
If keydip is already low and you want to increase it, you can shim the action rail. You already adjusted the action rail. By shimming the rail you'll raise the hammers thus inceasing distance between key and hammer => more keydip.
The last thing is the pedestalfelt itself. Thicker felt gives less keydip.

My very personal opinion is you should take at least a 2mm key rest felt (some pianos require 3mm). I use pedestalfelt which is 2mm thick. The VV felt is great, because it's very flexible. Good if you have the bump mod. But it's only 1.6 / 1.7mm thick.
I'm even thinking of trying 2.5mm... but haven't tried that yet.
 
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Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #45 on: November 28, 2020, 04:00:03 PM »
At last work has died down a bit and I have been able to give some more attention to the piano.

I have successfully fitted some new key bushings to those that needed it - took a few attempts to get the felt to be the correct length inside the holes but after that it was a fairly easy task.

The old back felt that the key pedestals sit on has been removed and a new one installed. The keys and hammer cams have been cleaned smooth from all glue and felt residue and the keys leveled.

Now I have finally begun to re-install the key bump mod. I have done the first key but I am unsure about something. The bump looks to be in the correct position according to the videos. When the key is not pressed the hammer cam sits upon the bump and when the key is depressed the cam is flat against the pedestal without being impeded by the bump in stop-lock.

What I'm concerned about is that sometimes the cam will overshoot stop-lock and remain in this position. The harp has been removed so there is no tine for the hammer to strike. The dampers have also been removed so there is not force acting on the hammer from the bridle straps. If I place my arm above the hammer so that it strikes my arm then the hammer always returns to stop-lock.

I'm just wondering if this overshoot is normal with the harp and dampers removed or if this is something to resolve before I go any further?

I noticed that I can greatly reduce/remove the overshooting by adding extra punchings under the front rail pins. Here is a video to demonstrate the overshoot....

https://youtu.be/YiTrKjm60Rk
« Last Edit: November 28, 2020, 04:01:46 PM by Chi »

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #46 on: November 28, 2020, 04:03:50 PM »

Keydip is the travel of a key downwards. The key stops via the stop lock mechanism which is formed by the pedestalfelt and the hammer and NOT by felts on the frontrail pins. I've seen this often but it's wrong.The frontrail felt should only prevent the key to not go too much into aftertouch.


Thank you for the kind advice ;) Interesting what you say about the stop-lock - please see my post above and see what you make of the video. Would love to hear your thoughts :)

Offline Tines&Reeds

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Re: Restoration newbie - 1975 MkI Stage
« Reply #47 on: December 01, 2020, 01:55:16 PM »
That's normal. We had that kind of issue in one of the facebook-groups recently. If you reinstall the harp, the issue is gone. The hammer will be stopped by the tine and will never move that far.
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Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #48 on: December 01, 2020, 02:34:48 PM »
That's normal. We had that kind of issue in one of the facebook-groups recently. If you reinstall the harp, the issue is gone. The hammer will be stopped by the tine and will never move that far.

Phew! That's great news - thank you so much :)

Offline Chi

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Re: Restoration newbie - 1975 MkI Stage
« Reply #49 on: December 01, 2020, 02:45:07 PM »
I'm feeling quite optimistic at this stage - removing the poorly done miracle mod and starting again is so far showing signs of improvement. Before there was a large discrepancy between the height of the hammers in stop lock - they were very uneven. The keys that I have re-installed the mod to are now much much closer in height at stop-lock. I was concerned before because it seemed like achieving any kind of even escapement would have been impossible - now it looks like I can get in the right ballpark and make finer adjustments with the screws when the time comes  :)

Offline Tines&Reeds

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Re: Restoration newbie - 1975 MkI Stage
« Reply #50 on: December 02, 2020, 07:28:32 AM »
Great! :-)
Keep us posted.
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