I have both my own shop made two-step Spurlock style cauls and Pianotek's brass cauls. On this job I used the brass cauls and the Bushmaster, single step procedure, which I finally got to work well and efficiently (used hot hide glue). Even though I have a shop-made .146 pin set, I also have a .146 and .150 Pianotek brass caul set. I prefer the brass cauls to the plastic cauls, and since I bought them, I have always used them to size the new felt with Profelt even if the felt was installed with the two-step plastic caul method.
<friction vs. slop. How does each affect the ultimate feel of the action?
usually my friction levels have been quite low. I am experimenting with higher friction levels, 11-13.5g, as I pin the shanks now at 4-6g (WNG always)...slightly tight, for tonal reasons. I don't do weight balancing metrics aka Stanwood, or even use the data they generate. Rather, the system is low inertia at the hammer, slightly elevated system leverage, minimal lead, usually none starting mid notes of the 30's, all lead in back of the mid point of the front lever, with elevated DW, in the low to mid 60's in the bass graduating to mid 50's in the treble. So...as I usually work to lower friction specs, I can't answer this yet, as I'm gathering data.
<Would you use a heated caul to iron (lay down fibers or compress) cloth or easing pliers (crushing wood fibers)?
Probably pliers, as if it tightened up, and as the felt was minimal (1.0mm), it would indicate I needed a little more room in the mortise.
I measure cloth thickness with a non-spring loaded micrometer. However, I don't read off the felt alone, as that creates a point load and gives a false reading. Instead, I take two 3/16" or so parallel sided wooden shims, and sandwich the felt between them, to take the reading. This avoids a point load. I then subtract the mic reading of the two shims from the total measurement. This gives consistent readings.
Regarding sizing to control wood movement...I size, but not to control movement...wood moves...go with it. I like to size, because I can apply the glue hot (160 deg) and relatively thin, if the wood isn't instantly soaking all the water out of the glue. This way there is no bleed through, and I get consistently excellent adhesion.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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Original Message:
Sent: 01-10-2020 01:38
From: David Skolnik
Subject: Key bushing caul sizes
Here are some thoughts/questions/comments applied to the original post and subsequent responses:
- Jim, what is your source of brass cauls? One reason I ask is that I've found the Spurlock/Erwin teflon/nylon cauls to vary by some thousandths within a set.
- As per Debra's point, what type of wood is the keystick fabricated from?
- Once we get past Mr. Roeder's fanciful bizzaro-world of climate extremes, the approach, and tolerance target depends upon what we know of the ultimate disposition of the piano. Clearly, as long as we're dealing with wood and cloth, an 'ideal' will only exist in some range of variation. Karl's (first/last names used interchangeably) last line - "Do you think there will be enough slack in the system to keep your friction levels where you want them? " - highlights the duality of the issue: friction vs. slop. How does each affect the ultimate feel of the action?
- Jim says he'd "just go back and re-ease at my cost, should the need arise..." Would you use a heated caul to iron (lay down fibers or compress) cloth or easing pliers (crushing wood fibers)? There ought to be some difference, in theory at least.
- Jim also references "choice of the cloth thickness" . What device do you use to measure? I have to admit that I don't own a special spring-loaded mic designed for this purpose, but it would help. Still, careful use of a Starrett 1" caliper, with vernier scale resolving to .0001" suggests significant divergence from the nominal dimensions depending upon the RH conditions. While there's probably a good argument against it, I seem to have had some occasional success using two different thicknesses in a single mortise. This is especially useful when employing the two-caul method, as you can compensate for (small) variations occurring during the first side gluing.
- Would there be any benefit to glue-'sizing' the wood at the front of the key (hide glue or thin CA)? Could that reduce climate-related dimensional change?
Lot's of fun experiments. Thanks Jim
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David Skolnik [RPT]
Hastings-on-Hudson NY
917-589-2625
Original Message:
Sent: 01-09-2020 21:14
From: Jim Ialeggio
Subject: Key bushing caul sizes
The RH in the shop is actually pretty reasonable, for January in NE...low 30's. As this is a mild winter, and I've been keeping the shop colder, in the high 50's, and sealed the air infiltration well this year...the air changes are down, not to mention the heating costs are down as well. In the past, when I was soldering frames, the shop RH was lower, since I had to constantly flush the shop air of soldering gases. So this one is in my favor...but, nonetheless, I will pay attention to the RH question when trying this trick in future keysets.
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 01-09-2020 21:05
From: Jim Ialeggio
Subject: Key bushing caul sizes
Don't know...good questions. However I do know this, that as I really refine my skills, I have always been unhappy with the side to side play in my bushing jobs, and have been trying to figure out how to reduce that slop. I do have several keysets where the tolerances were tighter than my usual, by coincidence, and my own piano is probably the tightest I have done. I have never had a friction issue that I know of on any keyset, so, I'm going to say the chances are good, it will be okay. However, on this experiment job (I experiment all the time of projects), I will mention this possibility to the customer, and just go back and re-ease at my cost, should the need arise...an advantage of having no mortgage or outstanding debt.
Another point to consider, when reducing these clearances, is the choice of the cloth thickness. I always spend some time making sure the cloth I've chosen for a particular mortise is Mic'd, after playing around with different thickness I keep in stock. So the cloth thickness, relative to the mortise size is consistent, and not overly fluffy from the get go.
However, I guess we shall see what we shall see. Point taken!
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
Original Message:
Sent: 01-09-2020 20:12
From: Karl Roeder
Subject: Key bushing caul sizes
Mr. Ialeggio
It's January. RH by you is currently somewhere around negative 12%. Come Spring the RH will return to levels more consistent with carbon based life. When that happens the key wood will swell and the hole that is the mortise will get larger as well. So far so good. The bushing cloth will also get larger but in a more robust fashion than the key wood. Do you think there will be enough slack in the system to keep your friction levels where you want them?
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Karl Roeder
Pompano Beach FL
Original Message:
Sent: 01-09-2020 15:18
From: Jim Ialeggio
Subject: Key bushing caul sizes
I had an interesting experience today, bushing front pins on a 15 yr old European keyboard. I usually, at supply house recommendation, use a brass caul .004" or .005" larger than the pin to bush the front pin. I have been trying to tighten up the front rail bushings when I rebush, to reduce side-to-side slop in the key. Tried sizing the mortise and using thicker cloth. However, I still thought there was more slop than I wanted in a newly bushed key.
I only had a .129" brass caul on hand, for these .129 European front pins, instead of the slightly oversized .031 I would usually use. I figured I'd just use the .129 caul and see what happened. Actually, if this experience repeats itself I may stop using the oversize front pin cauls altogether in the future. Friction came out right on the money, on the whites, 2-3g, after sitting with the .129 cauls & dosed with VS Profelt overnight. Slightly tight on the sharps, but only needed very minor heated caul (used .129) to hit the friction target. Side to side play is excellent.
Any other experience regarding non-oversized front pin sizing cauls out there?
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Jim Ialeggio
grandpianosolutions.com
Shirley, MA
978 425-9026
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