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[Theo]

Yes indeed a novel approach. I would still recommend that you start off by taking the restoration process as far as possible as a first step because that will give you valuable insights into the details of  Hohner  design and construction.  That knowledge will then inform your design and making of improved parts. 

[Peadar]

I would just suggest that if you think the box is in any way historically special you log the pitches of the reeds before you re-tune it into a bog standard even temparement A440. In fairnesss Hohnner production models are unlikely to be anything other than bog standard- a tribute to their mass production methods and quality control.

[Gena Crisman]

https://imgur.com/a/HE9p40C

So, I disassembled the keyboard and tested a couple of buttons with our good friend acetone to see if it would take the paint off. The answer is, yes, but it's a time consuming process.

The reward is, of course, miserable brown casein buttons, as most would have predicted.



So, the choice of what to do, if anything, still remains. The suggestion here of spending 1 hour per button does not seem particularly appealing. Is uh, that the reality I should expect? Since they are ostensibly just a 12.5mm diameter, 7-7.5mm tall, slightly domed physical lump, with a 3mm hole in the bottom. They really could be made of basically anything.

Anyway, the mechanism drops little rust bits on everything it touches, going to try and give it a very thorough wire brushing to deal with this. I've also kept each spring with each button, although I believe it would only matter inner v outer row.

In fairnesss Hohnner production models are unlikely to be anything other than bog standard- a tribute to their mass production methods and quality control.

I don't see any reason why a 2 row would be anything but equal temperament. But, I'll be writing down pretty much everything that does or doesn't appear to be the case about the reeds anyway so I guess we can all find out together!

Glue and clamps are in the mail so I figure I'll probably do pallets tomorrow and reed blocks all together when those that need it have been repaired.

[Nigel.H]

You could try a dense paste of Bicarb with a little water to see if it will bring them up.

[Gena Crisman]

So, I left a button to soak for a bit, and found I was able to abrade the outer surface with a finger nail and find a lighter button material deeper inside. So, I decided to just have a go with some 180 grit sandpaper and watch what happened:

Painted, Cleaned, Sanded:


Macro photo of cleaned vs sanded:


So, I think this looks nice enough to not suddenly race off to make new buttons - they don't look dirty to me any more.

I can't really see any reason to not ignore the soaking & just be reasonably aggressive with an abrasive until a reasonable result is achieved. I could chase those deeper cracks but I'm not sure why I would. The appearance is much lighter, despite the deeper cracks - you can sort of see lighter colour cracks on the unsanded button on the left, which are probably still full of paint. Speaking of which, this would let me strip the paint off without dipping each button in acetone 8+ times, too. One of the buttons has suffered a chip to an edge - given I have the keyboard apart I can relocate that button to the knee end of the box.

The 180 grit leaves the button feeling I guess a little fluffy to the touch? This has also reduced the height of this button slightly, the others are around 7.2 or 7.3mm, this one is now 6.8mm high, so, we've lost 0.5mm - another reason not to chase the deeper cracks. I assume finishing the button with a finer paper should make it feel smoother - I might avoid using a polish just so it doesn't get stuck in the backs. Alternatively I could put some clear varnish on them, or something.

[Gena Crisman]

So, funny story; sometimes you write something down and then get to thinking about it;

I've also kept each spring with each button, although I believe it would only matter inner v outer row.

This is something I know only I've read it in posts on this forum shared by very knowledgeable people. But, it might not be something someone who had to repair this keyboard because a spring broke would know. Combine that with:

One of the buttons has suffered a chip to an edge - given I have the keyboard apart I can relocate that button to the knee end of the box.

Now, if I had a problem with my keyboard, and I wanted to stay in action, I'd shuffle my problems down one end of the keyboard till I got it sorted. And, one of the springs had clearly been replaced, right at the end of the row... and some of the keys feel wrong...

So, since I've kept the springs with their buttons, I measured the thickness of all of the springs (in 0.xx of a mm)

Code: [Select]

long arm   56  56  56  56  56  55  51  51  56  51  RR
short arm    50  51  51  51  57  56  51  56  56  52

Perfect consistency, and then a 50/50 split? That sounds suspicious, heh. I guess maybe the 5th button on the short arm/inside row went and then the springs got jumbled? In that case, maybe I just need one spring for the inside row, and too easy to push long armed outside row button I found just needs a bigger spring putting on it.

[Peadar]

[quote/] So, since I've kept the springs with their buttons, I measured the thickness of all of the springs (in 0.xx of a mm)

Code: [Select]

long arm   56  56  56  56  56  55  51  51  56  51  RR
short arm    50  51  51  51  57  56  51  56  56  52

Perfect consistency, and then a 50/50 split? That sounds suspicious, heh. I guess maybe the 5th button on the short arm/inside row went and then the springs got jumbled? In that case, maybe I just need one spring for the inside row, and too easy to push long armed outside row button I found just needs a bigger spring putting on it.
[/quote]
Well done you - nominal wire thickness of the heavy springs - which have to be heavier to load the outer row of pallets to the same holding pressure (moment = force x distance and pressure = force/area) established as 0.56mm nominal, and the others as 0.51mm nominal.

.

[Steve_freereeder]

So, funny story; sometimes you write something down and then get to thinking about it;
So, since I've kept the springs with their buttons, I measured the thickness of all of the springs (in 0.xx of a mm)

Code: [Select]

long arm   56  56  56  56  56  55  51  51  56  51  RR
short arm    50  51  51  51  57  56  51  56  56  52

Perfect consistency, and then a 50/50 split? That sounds suspicious, heh. I guess maybe the 5th button on the short arm/inside row went and then the springs got jumbled? In that case, maybe I just need one spring for the inside row, and too easy to push long armed outside row button I found just needs a bigger spring putting on it.

This seems very much that the original springs have become mixed, or partly replaced by the incorrect gauge size.
Hohner springs for Pokerwork/Erica treble levers should be 0.5 mm for the inside row (short lever arm) and 0.55 mm for the outside row (long lever arm). The longer lever arm requires the stronger, i.e. thicker, spring.
Charlie Marshall can supply the proper springs.

[Gena Crisman]

https://imgur.com/a/SZGtYIb

Been busy, although most of that time is going into the keyboard.

Main takeaway is that I do have some rust to clean up on the inside of probably all of the reed plates, but, this is one bank from that separated reed block (which should now be back in one piece):



I guess I'll have to explore fixing that at some point.

[Theo]

Easily cleaned off.  Support the reed tongue with a pice of thin material then remove the rust with a polishing block, as used for manicure.

[Gena Crisman]

How would you approach the rust on the harder to reach 'inside' face of an individual reed? I've read that it's less attached than that on the outer face but I've no actual idea as I've left it alone for now.

I got some 600 grit paper per Steve's advice earlier, although I can always raid more of the manicure supplies.

[Theo]

600grit glued onto a stick will remove the rust, but it will clog up fairly quickly.

For the under surface I use a miniature screwdriver with a good unworn end. Just scrape along the back of the reed while it’s resting on a flat surface.

[Gena Crisman]

For the under surface I use a miniature screwdriver with a good unworn end. Just scrape along the back of the reed while it’s resting on a flat surface.

This approach worked well for me, excepting one of the reeds on an accidental plate from this block, which just seems to have a bit more rust going on, as well as some white corrosion on the zinc plate right next to it. Not sure if it's all that important to rectify, but, I guess, what would you do (if anything) when the screwdriver is not sufficient? I'll get a nice macro-lens photo next time I'm doing some photography.

Turning our attention to the outer side of the reeds, since I happen to already have a fresh nail buffer, I thought I'd look at what that can do for me. It's a 3 stage one in classic flat format that can bring your nails up to a shine, but, the lowest level of it will not take ridges off of, or shape, your nails. The 3m 600 grit paper I got is a fair shake more bitey than the 1st stage of my nail polishing block, so, I suspect this isn't the right kind of polishing block. Than again, I don't think the 600 is nearly as aggressive as some emery boards I've had, which, for reference, are normally what I would have used for shaping and de-ridging my nails.

Having been keeping an eye out, I finally found the one one flat lolly stick I knew I must have somewhere (all the others are round) and made the aforementioned 600-grit-on-a-stick. I tried the 3 faces of my buffer in reverse order and found that they weren't really up to this task, so it's probably not the kind that Theo uses. The 600-on-a-stick, however, did do the job well & quite easily - and if this is an acceptable approach & is not too aggressive, it is likely what I'll do for all my reeds here - how things will clog up for remains to be seen, I do only have so many reeds to clean, and, I did buy branded paper. Plus I guess I can always make another stick.

As an aside, I used an appropriate looking plastic prying tool to support the reed for these tests, which I feel should be safe as I'm working towards the tip. This tool is probably too thick to support the lower sections of the reed safely, but, this should be sufficient for now.

I have 7 melody side buttons left to de-paint and sand down to oblivion/acceptable appearance... and I want to do one more rotary-tool-powered wire brush pass on the keyboard mechanism. Then I think I'd be securing my melody pallets & adjusting keyboard to fit the enclosure. The wooden keyboard enclosure has that iffy paint job on it, and has been repaired prior in the form of some wood splits between the buttons, but, I think it will be fine for the time being. If I can do that, then it might actually feel like I've accomplished at least fixing up one part of the instrument - that'll be nice.

[Lester]

To clean up the plates I use these brass wire brushes
https://www.amazon.co.uk/Yuccer-Plastic-Handles-Cleaning-Welding/dp/B07CVJYP6L/ref=sr_1_4?dchild=1&keywords=brass+wire+brush&qid=1584295604&s=diy&sr=1-4
Just brush in line with the length of the plate and Robert's your father's uncle.

[Gena Crisman]

To clean up the plates I use these brass wire brushes

I happen to have just such a brush. I've found it to be effective, depending on what the definition of effective is. When cleaning, there's going to be a 'going too far' point, but, I guess in a way I'm not sure where that is.

album link: https://imgur.com/a/iHP57uh

This reed:


After a pass with the brass brush:

This takes a way a lot of the 'brown'ness, but, there are still a lot of splotches, I guess. Is this in line with your experience, Lester? (or, is this a fairly rusty reed?) (or does my brush/brushing technique suck)

Using the coursest section of my nail buffer after the brushing provides this result:

Especially near the tip there hasn't been much success, and some brown colour has returned where I guess like, some still rusty areas have opened up with the abrasion?

Using the 600 grit stick:

And this absolutely must have taken away some of the reed material in the process, too, but, it's like, shiny, like you wouldn't have known it had really had rust on it. But, I guess my question is, is that amount removed going to be OK?

Also, this is the reed I was referring to, the accidental plate, with the more stubborn rust on the inside edge (including an extra image of the outside edge - the 3rd image below - we're looking at the inside edge of the reed on the left in the first two photos, and the outside edge reed on the right in the 3rd)

[Theo]

Your cleaning work with the 600 grit looks fine. 

The accidental reed will be too once you have it clean. It’s good to get all the rust off the top and bottom surfaces, but the critical area is the edge of the reed which may need to be scraped and the matching edge of the vent with its whit corrosion. I find the best tool for those areas is the tip of a pointed scalpel blade.

[Steve_freereeder]

... The 600-on-a-stick, however, did do the job well & quite easily - and if this is an acceptable approach & is not too aggressive, it is likely what I'll do for all my reeds here - how things will clog up for remains to be seen, I do only have so many reeds to clean, and, I did buy branded paper. Plus I guess I can always make another stick.

I don't bother with the stick. I just use a bit of 600-grit paper pushed about by the tip of my finger. So long as I have a suitable shim support* underneath the reed tongue which is wide enough, it doesn't damage the reed plate.

So long as you have wet-or-dry paper, you can periodically clean it of cloggings using soap and hot water, then set it to dry on a radiator.

*I make my shims from sections of baked beans tins - the small can type which do not have corrugations. The steel is soft enough not to damage the reed tongues nor the kitchen scissors which I use to cut the shims to length and width and then flatten them out. I then thin down the ends to a fairly sharp edges by rubbing on a  diamond grinding plate, but 400-grit carborumndum paper works just as well. Works for me...

[Gena Crisman]

https://imgur.com/a/gy3rz6M

Finally put the treble end keyboard back together, after cleaning it for days. Not sure if I'll approach the bass end keyboard differently - I might seek to dip things in rust cleaner and hope for the best.

I finally got around to ordering things I knew I'd need from Charlie Marshall yesterday. And, I received them today because that's just how good his service is. I can now look at valving and fitting my C row reeds back on their block in the near future. I also need to decide if I'm putting the new reed block gaskets onto the reed blocks, as was, or, onto the fondo.

That does mean, though, that I have a G row block that has reeds on it, and a working keyboard, so, I stuck that in the box, taped up the bass end, and was able to play a tune for the first time: https://youtu.be/SP8BMwbwvuY - Shockingly, I'm no good at playing in the upper octave unless I've planned for it.

[John MacKenzie (Cugiok)]

Well I'd put the Olivisc on the reed block, so that you can swap blocks  more easily.

SJ

[Lester]

https://youtu.be/SP8BMwbwvuY

Think it may need just a soupçon of tuning