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Key Dip of 1.1cm. Replace or shim back rail cloth?

Started by lukevintage, May 08, 2022, 04:50:50 AM

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1979 Rhodes Mk1 73 renovation.
Key Dip measures 1.1 - 1.25 so beyond the limits (1.035) across the keyboard.
Keyboard is perfectly level except the top 5 notes, which sit a paper shim higher than the rest but nothing drastic.
Escapement is at maximum.

No shims anywhere else apart from balance rail.
Back rail felt cloth is in good condition but thin. I'd say 1.8mm.
Rather than replace the original cloth (which seems quite expensive for what it is), could I not simply shim the entire run where the cloth isn't glued?

I assume this would reduce the key dip. Would this have any impact on escapement?



It's an aluminium action rail.
What does shimming the action rail actually do?


Shimming the action rail increases the keydip. Use a thicker back rail felt to reduce key dip.
German Rhodes Tech nearby Hamburg / Bremen


Quote from: Tines&Reeds on May 12, 2022, 03:00:41 PMShimming the action rail increases the keydip. Use a thicker back rail felt to reduce key dip.
Thank you so much for your reply. You saved me from 'experimenting'.
Where can I find thicker back rail felt? I couldn't see any on your site.
Is there an alternative? Could I bit a shim under the felt where it isn't glued? I checked my photos and I measured 2mm. I see the green felt measures 3mm. Perhaps I need put a wood shim along the length of the backrail and then reapply the felt.
Perhaps some experiments with different shim thicknesses under a small area of felt will help identify the best solution.


The top 6 keys sit highest when it comes to key levelling. Does this suggest another defect elsewhere?


So my little experiment of folding up A4 paper to shim under the back rail felt was a little excessive and put the key dip to the minimum of 11/32. Useful to understand how it feels: heavy, tinker-toy-like. Tomorrow I'll try my best to get 3/8s and see how it feels.

Is this an acceptable fix? I can get a metre long 1mm wood shim to do the job a little better. Would it be better to unsteam the felt from the wood, glue the shim down and then lay the felt?

I also wonder if I had failed to screw the action rail firmly down in its seat properly. So I will try that first.


Fortunately, I tried the latter and checked the action rail was properly screwed down without any shims. The key dip is perfect: 3/8 with an extra or minus 1/32 here and there.

This is the 5th time I've taken the Rhodes apart (done in 10 minutes) and I am feeling fairly confident about how I move around the Rhodes now. Enough that I've realised that ALL THE SCREWS on a Rhodes are important. How you set them and how tight they sit is as important for the harp support as it is for the grommets. It's easy to think of a rhodes as a wooden case that contains a keyboard. More attention should be given to how every component is set as there is the right way; all the rest is the wrong way. Let me explain about this particular example:

I had tightened each screw that holds the action rail to the key bed frame. However, if you look underneath, the lip of the action rail sits lower than the key bed frame. If both parts are sitting on a workbench, then resistance in tightening the screws will arrive earlier as you are effectively lifting the key bed frame up off the workbench. I assume this is what I had done which meant that the action rail sat higher than it should. Increasing the height of the action rail increases key dip.
I should also mention that special attention should be given to checking that all the hammers sit as central as they can more or less. My first attempt had them sitting all slightly to one side of the key felt. A tiny shift meant they sat perfectly.
I am starting to think that this piano was made exceptionally well but was put together poorly.