One way to avoid thinking is to find the optimal location with a "capstan in a boat."
Make or find a very short capstan (I salvaged mine from an a surplus harpsichord jack).
Mount it in a stick of wood about 3/16 inches thick x 2 inches long and a little narrower than a keystick.
Remove the original key capstan, adjust the boat capstan and go fishing. Use double stick tape to attach the boat to the key.
Adjust until you get the ratio you want, comparing a set key dip in a "T" block to the hammer rise. Not a bad idea to try several keys across the action.
Mark the front end of the boat on the key when you find the optimal location. Then pull the key and use the boat to index the capstan location. Remove the capstan and put a pointy screw in the capstan hole, press to mark the spot.
(On a very compromised action, I found it took different capstan lines to get equal action ratio for naturals and accidentals.)
Sorry I can't show a picture, my shop is packed away as a new location is being prepared.
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Ed Sutton
ed440@me.com(980) 254-7413
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Original Message:
Sent: 01-24-2018 08:18
From: Karl Roeder
Subject: Not good at thinking. Could use some help.
Thank you Mr. McMorrow,
This piano isn't that old and not nearly as far off as those year's instruments were. Still the sugar pine cap has real appeal to me in this case. Thanks Mr. Love for clearing up the leverage question. Do you know anyone selling that capstan tool? Mine is homemade and works poorly it would really be worth it to me to buy one that is well made. What kind of cloth did you use to cover the front of the heel? Thanks Mr. Page for the analysis method. I'll use it. A little off topic but your suggestions were very helpful last year on the C7 with the odd rake angle. FWIW it turns out they built it that way because the hammers were super dense and thus would have been way too heavy if made and bored to proper size and angle. Can any one tell me what the theory was behind Steinway (and Stanwood for that matter) angling the capstans?
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Karl Roeder
Pompano Beach FL
Original Message:
Sent: 01-24-2018 04:08
From: David Love
Subject: Not good at thinking. Could use some help.
If you were to move the capstan forward, presumably for the purposes of lowering the leverage, and then angle it back such that the contact point on the wippen heal were exactly the same as it was before, then the leverage will be the same as it was originally. You will not have changed anything other than probably create more friction between the wippen heal and the capstan. The leverage point on the key is a point directly below the contact point on the wippen it doesn't matter if the capstan is angled or not.
If I understand you correctly that you need to move the capstan to lower the leverage then you should just move it forward toward the balance rail the requisite distance and cover the entire wippen heal with a piece of action cloth so that the capstan doesn't contact the wood on the front side of wippen heal, if that's the problem. Done that many times on some Steinways where the key leverage is so poor that you can't move the capstan far enough without it coming off the padded area of the wippen heal such that it's riding on the small wooden area at the front of the heal.
However, measure twice, cut once. Moving the capstan and having it contact the wippen at a different point also changes the wippen lever ratio so be sure that you've calculated it correctly and factored in that both the key ratio *and* the wippen ratio will be changing. Gravagne's program should do that (last I checked, I use my own spread sheet). It's always wise to do one and see before you do them all.
The general method of moving them is to remove the old capstans, fill the holes with either with plugs or a west system epoxy filler (faster and easier if you aren't drilling into the area of the fill--which it sounds like you won't be). Calculate your new capstan location in each section, draw a straight line across the keys marking the spot and use a cross vise clamped to the drill press bed to hold the key and center the mark under the drill bit. For a standard capstan use a 5/32" drill bit (I think) with a countersink attached and just slightly counter sink the holes. Center the hole in the key, don't try and compensate for some weird wippen spacing by drilling the holes off center. Spin the capstans in with a hand drill and a capstan wrench that looks like this. Try and get them started as straight as you can.
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David Love RPT
www.davidlovepianos.com
davidlovepianos@comcast.net
415 407 8320
Original Message:
Sent: 01-23-2018 17:23
From: Karl Roeder
Subject: Not good at thinking. Could use some help.
So I've got to modify a concert grand that has the capstans 5 - 7 mm too far from the balance rail to the top of the capstan. I've run the specs through Nick Gravagne's geometry program and also have 4 other examples of the same model to compare numbers with. What I'm wondering about is whether the action ratio is dependent on the point of contact with the heel of the repetition or on the position in the key. Specifically I'm wondering if I can get a free mm or two by angling the capstans toward the distal end of the key by 15 degrees or so. This might keep me from having to re-locate the stack forward and moving the keyframe farther in. I've only got about 4.5mm from the back of the sharps to the fallboard so minimizing the keyframe repositioning is a concern. One of the few things I'm worse at than thinking is woodworking so any advice anyone would care to share regarding drill bits and or techniques for moving the capstans would be gratefully received.
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Karl Roeder
Pompano Beach FL
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