Mechanical Pegs: Pegheds vs. Planetary Perfection vs. Wittner
After a harrowing experience attempting to remove a malfunctioning mechanical peg with the help of my luthier, I posted a query to Facebook’s International Cello Forum inquiring about other cellists’ experiences. This post presents a synopsis of the information gleaned from that helpful conversation. But first, a little background:
I’m a great fan of mechanical pegs and, as an early adopter, have used them for more than 20 years. To ward off the slipping pegs and falling soundposts common in upstate New York’s challenging climate, I even had them installed in all of Cornell’s cellos and have been very happy with the decision. In the last couple of months, however, I’ve run into intermittent problems with slipping Pegheds brand pegs in two different cellos. With traditional pegs this would be no particular concern — any luthier and most experienced players know how to handle a troublesome peg — but the “black box” design of mechanical pegs are a mystery to most players as well as many of the luthiers who install them. While I can’t imagine going back to life as a traveling cellist without mechanical pegs, this wake up call has made me revisit the pros and cons of the various peg designs.
Wittner mechanical pegs have been around for decades. They house an 8:1 ratio geared mechanism in their slightly oversized peg head. In contrast, Pegheds and Planetary Perfection (Knilling) pegs share a different design with 4:1 ratio helical gears in the peg shaft. Unlike the Wittner, these two brands require gluing the threaded aluminum shaft into the pegbox for proper functioning. The gluing and removal procedures are where the problems arose that precipitated this post. Despite more than 100,000 Pegheds circulating worldwide, relatively few luthiers have had to deal with removing them. This speaks well for the generally trouble-free operation of their design, but not so well for the unfortunate few who find themselves needing to replace a peg.
When installing or using mechanical pegs, the first place to look for instructions is, of course, the manufactures’ websites. While the Pegheds brand website is “old school” and offers relatively little information for users (at last check, PDFs were still “coming soon” after decades on the market), Planetary Perfection pegs offer helpful tips HERE at their Australian distribution website. Fortunately, Knilling pegs are identical in function and design to Pegheds so the the linked website is very helpful. Less fortunately, information regarding removal or replacement of the pegs is not available on either website. Curiously, while Knilling advises the use of urethane glue (i.e. “Gorilla Glue”), stating that the use of any other glue will void the warranty, Peghed’s PDF instructions (not linked on the website but available by request from the company) recommend a drop of Super Glue (cyanoacrylate) or urethane glue. Most experienced luthiers who have installed dozens or even hundreds of Pegheds are unaware of Knilling’s instructions and report bad experiences when using Gorilla Glue because it expands and “makes a mess.” It also has a higher melting point than Super Glue, creating additional difficulty if pegs need to be removed.
Why, you might ask, would it be necessary to remove mechanical pegs? In my case, after years of trouble-free functioning, the tapered portion of the peg portion of my Pegheds gradually wore a small ridge and ceased to apply the consistent friction required for reliably non-slip operation. In addition, I noticed a gradual degrading of the operating smoothness of the pegs over time. A small amount of slack appeared when changing directions between tightening and loosening the pegs as well as slight grinding noises in the gears. Pegheds, although not a sealed bearing or airtight system, cannot be lubricated without risking getting grease on the all-important inner edge of the aluminum shaft. As with all grease, even the high quality grease used by the manufacturer slowly degrades and becomes thicker over time. If maintenance is attempted and grease gets on the interior tapered portion of the peg, it is nearly impossible to remove and the pegs will no longer operate properly. Fortunately, I had fine tuners on my cello to compensate for the impaired accuracy of the peg, but slipping (however intermittent) gave me cause to reconsider the peg design.
When Pegheds or Knilling pegs cease to function properly, it is usually one of these three issues (listed in order of frequency encountered):
The glue joint holding the peg into the peg box can break, causing the shaft to turn inside the pegbox instead of the gear mechanism functioning as it should. (This is why most luthiers install cello pegs with 2 or 3 drops of glue instead of the official “1 drop” recommendation.)
A ridge or blemish can develop in the plastic tapered portion of the peg head (see photo below) or, rarely, the helical gear can become loose. (i.e. a problem develops with the head portion of the peg.)
Occasionally, an imperfection can be present at the manufacturing phase or develop over time in the aluminum and steel gear mechanism. Although this is a rare occurrence, it has been known to happen.
While, in my opinion, it is rare to find a product with the high level of engineering and manufacturing quality exhibited by Pegheds, the risk of being stuck in a situation where I can’t tune my cello or replace a defective peg “on the road” has led me to install Wittner brand pegs in my instrument. I now carry a spare peg and know that I can enjoy accurate tuning without that nagging concern of being stranded before a concert. Based on my discussions with expert luthiers as well as Peghed inventor and company founder Chuck Herin, it is my hope that improvements will be made to the design so glue isn’t required and that a removal mandrel will be shipped with all peg sets as a precaution. In the meantime, please read on below the Pegheds images to see the steps my luthier and I took to replace them with Wittners on my cello.
Peghed and Planetary Mechanical Cello Pegs: The Inside Story
The knowledgeable and generous members of the Facebook International Cello Forum shared several methods for removing glued and threaded Peghed style pegs:
Numerous luthiers recommended using acetone or another solvent to dissolve the glue between the aluminum peg and the instrument’s pegbox. We decided to pass on that method for fear of degrading the wood around the peg or dripping on the instrument and damaging the varnish.
Next, at the advice of one or two members of the forum, we attempted to break the glue joint by tapping the end of the peg with a punch. This method didn’t work for us, unfortunately. The glue joint was too strong.
Using a soldering iron to generate heat inside the aluminum sleeve was one of the more frequent suggestions made by luthiers on the forum (see photo above). When we tried it, unfortunately, the varnish on the pegbox started to melt and bubble up before the glue joint broke. Using a pliers and a supportive mandrel, we were able to break the joint, but the ensuing (and scary!) popping sound indicated that the glue joint had not been melted or weakened much by the soldering iron. In retrospect, applying the soldering iron directly to the interior of the outer sleeve may have generated more heat directly on the glue joint, but after our experience with the bubbling varnish we were reluctant to try it.
Finally, and most successfully, we used a 6061-T6 aluminum mandrel I had made the night before on my lathe. I also made a steel mandrel out of a grade 5 half-inch bolt, but that didn’t heat the joint as well. Presumably this is because aluminum has a higher friction co-efficient. If the mandrel method is in your future, we recommend working with a partner so one person can hold the instrument securely and the other can operate the drill. In the event the aluminum seizes up, the spotter may prevent considerable heartache. Also note that one experienced luthier mentioned that he has had some luck making a mandrel out of an old ebony peg. We ran out of pegs to remove and didn’t try that method.
In conclusion, I recommend that mechanical peg users travel with a spare peg (in the case of the Wittners) or a spare peg head (in the case of Peghed or Planetary pegs). Pegheds users should NEVER lubricate the pegs, especially if they start to slip. Lubrication is sure to make things worse. Although I don’t anticipate any problems with my new Wittner pegs, I will be prepared and will let you know how they turn out!
Happy music making!
