Topic by davidizquierdo82

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Topic: Fixing Kawai CA97 - GF1 and GF2 actions

Hi all,

I've repaired my CA97 several times, each time different keys.. (sliding PTFE sheet, sticky key)

While watching a CA99 review, the guy mentioned that they were retrofitting any GF2 actions with genuine felt like in acoustic pianos before they sold the piano, because of the very problem mentioned in this thread. That resulted yet in an presumably better repetion..

Minute 13:40

https://www.youtube.com/watch?v=QoS2ghGCgCg

My question is, any thoughts or guesses out there about what that felt exactly is? I'm willing to repair all 88 keys from scratch but this time hopefully with a definite solution.

Regards,
David

P85>Kawai CA97>Numa XGT>FP90X>LX706
Pianoteq 8 Pro (all instruments) + Organteq 2
i7 4790K W11 64bits + UMC1820 + MTM + DT770 pro X
http://youtube.com/DavidIzquierdoAzzouz

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Reply by MeDorian

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  • MeDorian
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Re: Fixing Kawai CA97 - GF1 and GF2 actions

I did look at this action on YouTube in the past, I own the VPC1, which apart from shorter keys is very similar. Thing is though, at the start it's new felt, but in reality you'll be 'modifying' the keyboard. Regulation will be required, key dip especially important.

As for the felt, self adhesive (large piece cut to size) is ok and doesn't create uneven surface due to poor gluing, it's really ideal and easily changed.

The issue will be the thickness, the felt alone will be of less height than the foam pads you want to replace. Small plastic (risers) can solve this, first cut to size, apply felt and place on the key using super glue. Be aware not to damage the wood here, any sanding down will start to cause poor alignment.

The idea is to achieve the same height with both plastic riser and felt as the original foam pad, this way the capstan can be left alone and no regulation required.

My concern is the capstan and it's bad design resulting in damage to the felt, although the GF2 action, with it's longer keys looks less of a problem than the VPC1. I believe the capstan has now been changed in the latest Kawai actions.

If you have as you say done some work already on repair etc, I would still work on the top (88 key) alone, trying and testing different felt until you're sure it is worth the trouble. It might be worth doing only problematic keys instead of the entire keyboard.

Modifying is very time consuming and hard work ,also you might cause damage...top key first might be your best option for now, then put the keyboard back together and forget about it for a while.

Nick

Last edited by MeDorian (01-10-2020 14:23)

Reply by davidizquierdo82

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Re: Fixing Kawai CA97 - GF1 and GF2 actions

MeDorian wrote:

I did look at this action on YouTube in the past, I own the VPC1, which apart from shorter keys is very similar. Thing is though, at the start it's new felt, but in reality you'll be 'modifying' the keyboard. Regulation will be required, key dip especially important.

As for the felt, self adhesive (large piece cut to size) is ok and doesn't create uneven surface due to poor gluing, it's really ideal and easily changed.

The issue will be the thickness, the felt alone will be of less height than the foam pads you want to replace. Small plastic (risers) can solve this, first cut to size, apply felt and place on the key using super glue. Be aware not to damage the wood here, any sanding down will start to cause poor alignment.

The idea is to achieve the same height with both plastic riser and felt as the original foam pad, this way the capstan can be left alone and no regulation required.

My concern is the capstan and it's bad design resulting in damage to the felt, although the GF2 action, with it's longer keys looks less of a problem than the VPC1. I believe the capstan has now been changed in the latest Kawai actions.

If you have as you say done some work already on repair etc, I would still work on the top (88 key) alone, trying and testing different felt until you're sure it is worth the trouble. It might be worth doing only problematic keys instead of the entire keyboard.

Modifying is very time consuming and hard work ,also you might cause damage...top key first might be your best option for now, then put the keyboard back together and forget about it for a while.

Nick

Thank you Nick for the tip, I'll try at first with the higher keys only and will see what's the result after some usage, so I can determine whether to carry on with the rest of the keyboard.

I've ordered exactly what you're saying, a large self adhesive felt pad that I'll cut into little pieces I can use to replace the current cushions on the keys. The good news is that these pads are available in several thicknesses, I've ordered 1mm because I've measured the actual ones and they were between 1mm and 2mm (together with the PTFE sheet).. so I think 1mm will be fine for now, and I can always try with the 2mm if else..

As I'm still waiting for it to arrive (it will take a couple of weeks), I was wondering whether the felt pad pushing the capstan directly without any sliding surface inbetween woudn't make the action sluggish and weird.. wonder whether the felt is as smooth and gliding as the current PTFE is..

Regards,
David

P85>Kawai CA97>Numa XGT>FP90X>LX706
Pianoteq 8 Pro (all instruments) + Organteq 2
i7 4790K W11 64bits + UMC1820 + MTM + DT770 pro X
http://youtube.com/DavidIzquierdoAzzouz

davidizquierdo82's Website

Reply by MeDorian

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Re: Fixing Kawai CA97 - GF1 and GF2 actions

The original PTFE I found was a good material at first, it acts in two ways, first as a cushion (similar to car suspension) and as a good low friction surface. Over time the cushioning effect, due to wear becomes less so, and a ridge/groove, caused by the capstan occurs making smooth playing difficult, when this happens the smooth surface becomes uneven.

My guess is not only felt is used in the latest actions, but a replacement for the capstan also. In your case, some trial and error will be required to see if any benefits are gained by felt (and correct height riser) with the 'capstan'.

Remember the only purpose for the capstan 'adjustment' is 'key dip'! Whatever material you find works, aim for the same thickness, and felt will not compress as foam pads do. Check key dip by holding down two adjacent keys together, they should all go down the same distance. I would leave the capstan alone and re-adjust the thickness of plastic/felt instead.

Main thing though, ONE key first (top 88). Then problem keys only. Then keyboard then put back together!

Remember also though, the top key has less weight and therefore will play better. Felt and capstan might not work well on the lower keys.

If you could find the original PTFE online, then you could simply replace this and NO capstan adjustments would be required.

Nick

P.s the surface under the felt eg, plastic (old cd case possibly) needs to be smooth and scratch free. Felt directly on the key end wood will not be smooth enough.

PPs I think another problem might be if you were to change to felt on a number of keys, then the overall playing might be noticeably different throughout the keyboard. My above seems to be more about modifying rather than just sorting a few keys out. New PTFE would definitely be my recommendation, I never found it in shops or online so ended up going full on mods with my VPC1.

Last edited by MeDorian (01-10-2020 20:21)