Home Repairs on Your Cello. Things You Can Do & Things You Shouldn't.

As of this writing, it is March of 2009 and the recession is on everyone’s mind. There’s more thought happening before cellists put their instrument in the car and haul it to the nearest luthier. Many might be tempted to enlist the help of Uncle Fred who, already this year, has managed to fix the toaster and unclog the drain, and always has his tool box with him.

I’ll list various repairs that a person with some tool skills might attempt – with caution!!! – in order of difficulty. This will be followed by a list of repairs that shouldn’t be done by anyone other than a luthier.

1. Changing a string. If you’re comfortable tuning your cello from the pegs, this isn’t difficult: just make sure when you tune, that you’re always listening to the pitch of the string as you tune it , and that you have your target pitch (the pitch that the note is being tuned to) in your ear. You don’t have to be very far above your target pitch before you break the string. If you change a set of strings, change them one at a time. Taking all of them off at once may allow the post to fall, and setting a post is one of the jobs that must be done by a luthier.

2. Making a leaning bridge upright. You can generally tell if your bridge is leaning by lining up the side on your bridge at eye level and seeing if the back of the bridge is roughly square to the top. Over time most bridges tend to lean forward. You may not regularly tune from the pegs, but just the act of initially bringing your strings up to pitch can pull the bridge forward. If you’re dexterous, you can cradle your cello between your knees, endpin in rug, you looking down the front of the cello; place one hand on either side of the bridge with each pinky finger resting on the top, and gently push the bridge away from you with your thumbs. Almost no one does it this way as a few weak, tentative, ineffective pushes are usually followed by more seriously aggressive one causing the bridge to go all the way over, the force of the string tension causing the bridge to hit the top of the cello with a crack loud enough to take several years off your life. A better way is to take a lightweight hammer (described below), and a small piece of softwood, about 5/16” thick, ¾” wide, and about 3” long, or a 3/8” diameter piece of dowel also about 3” long, with leather padding glued onto one butt end of either piece of wood, and gently tap the bridge until it is properly upright. Be warned, a too-powerful blow from the hammer can either knock the bridge down resulting in the trauma described above, or break the bridge. That said, this is actually a fairly easy and safe job if you’re gentle with the procedure.

3. Curing a slipping peg. This usually happens in the dry winter months when the pegs shrink and all the peg dope applied over the years has glazed into a sleeve-type bearing in your pegbox, the kind that cheap electric motors have in order to allow their shafts to spin freely. This repair is simple and requires nothing that you don’t already have. Take the offending peg out of the pegbox and note the two shiny surfaces where it contacts the pegbox. Take your rosin, or better yet that small piece of rosin you saved from the last time you dropped it onto to a hard floor and it shattered into a million pieces of various sizes. Rub the rosin onto those shiny surfaces (most of it will fall off but that’s ok), put it back into the pegbox and twist a couple times to work whatever rosin that managed to stay on the peg into the pegbox. Repeat. Now try it. It should stay without a problem: but be warned: too much rosin in that joint and you may need repair # 7 below.

4. Changing a bridge. Many cellists, especially those in our area, have more than one bridge in order to achieve the proper string height during the varying seasons. It’s possible to do the change at home but don’t attempt it without a bridge jack. If you loosen the strings to enable you to remove the bridge, again, the post may fall. First obtain a cello bridge jack: the larger supply houses have them. Loosen the strings about one full step, put the jack against the back of the bridge, lift the strings high enough to remove the existing bridge, and replace it with the bridge you want to put on. You may have to raise the strings even higher to accommodate the new bridge. Be aware though, if the weather is changing enough to warrant a bridge change, it also means that your post could easily be too tight or too loose and need an adjustment. This, as was mentioned, is a job for a luthier.

5. Straightening a warped bridge. New bridges are expensive but warped ones are not great for sound and playability and will get worse with time. You’ll need a bridge jack, a hard flat surface that you can clamp it to, and a couple clamps. A good flat surface is a piece a quarried and flattened stone. Never use wood. If you live in an area with a quarry and stonecutting shops, there are scrap piles of pieces that have broken or are in some way unsaleable by the stone working firms. Remove your bridge and place a piece of wet paper towel on the back of it until it is quite wet. Then lay the bridge on the flat stone, back down, with the wet paper towel between the bridge and the stone. Clamp gently, especially if the bridge is badly warped (trying to bend it too much in one shot can result in breaking it), placing a piece of wood between clamp and bridge. Usually, if the bridge is warped forward, you’ll need two clamps, one on the top and one on the feet. Leave in clamps as long is possible, minimum three days. If you have another bridge you can put on, leave it as long as a month, every few days checking it to make sure the clamps are tight and that it is flat on the stone. Note: warped bridges that have been straightened will tend to warp again: make sure you keep it straight on the cello.

6. Gluing a seam. If you notice an open seam (we’ll define a seam as the glue joint between the top – or back – and the sides) and feel that you or Uncle Fred is the person for the job, you will first need some tools you probably don’t already have. 1. Hide-glue crystals (don’t use liquid hide glue from the hardware store). 2. a hot water bath and a small glass jar, 3. a thin artist’s pallet knife, 4. spool clamps, and 5. a couple paper towels. 1. Hide glue is possible to find in violin supply house, but make sure it is of high quality. Some grocery stores still sell Knox Unflavored Gelatin, which is food-grade hide glue (which does make you wonder about all that jello you’ve eaten over the years). 2. A sauce pan with hot, but not boiling water will suffice, and a baby-food jar works well. Note: failing a baby in the house, Gerber’s Carrots & Peas are a mildly tasty, if somewhat abbreviated, snack. 3. Most artists supply stores will have pallet knives. 4. Spool clamps are available from violin supply houses including Metropolitan Music in Stowe, VT. 5. Bounty paper towels are probably an egregious environmental disaster but they work really well.

First, very carefully work the pallet knife into the seam opening. If gently working it around causes the seam to open further, that’s ok. Working it around removes dried bits and powder from old glue. Next, prepare your glue by putting about a teaspoon of crystals into a clean baby-food jar. Cover the crystals with cold water and let it soak for 20-30 minutes. Then put the jar into the hot water bath. When the crystals are fully dissolved, remove the jar (this is tricky as things are hot – but if you’re handy enough to do this repair, you’re probably also handy enough to figure out how to remove the jar) and stir the glue. The final product should be slightly thicker than water. If it is too thick (it probably will be), add homeopathically small amounts of water until it is the right consistency. Then replace the jar into the water bath to keep it hot. Note: if this glue preparation seems tedious and time-consuming, and you and Uncle Fred are tempted to short-cut the process by using some other type of glue, your next trip to your luthier may be an expensive one.

Now dip the pallet knife into the hot glue and then work it around in the open seam until an adequate, but not copious amount of glue is in the seam. Put your knife down, press down on the seam, and wipe around the open joint with a slightly damp paper towel. Now put your spool clamps on the cello – about 3/4 inch between them along the length of the open seam - and snug them tight. Excessive pressure is much worse than not enough. Leave dry for 4 hours, remove the clamps and you’re ready to go. By the way, cap the unused hide glue in the baby food jar and put it in the refrigerator. It will keep and be useable for a long period of time.

7. Loosening a stuck peg. When cellos go from the dry of winter to the heat and humidity of summer, and you are doing all of your tuning from the fine-tuners on your tailpiece, the ebony pegs gradually swell and can become immoveable in your pegbox. Warning: this job is not for the faint-of-heart as it involves both tools that you don’t like to associate with cellos and noises that you really don’t want to hear. You will need a piece of hardwood dowel, 3/8 or ½ inch will work if the peg sticks out of the pegbox. If it does not, you’ll need a piece of hardwood dowel with a small enough diameter to go into the pegbox hole on the exit side. The dowel should be about 3” long. Then you will need a light hammer, a rawhide hammer is best but few people have them. Use the lightest weight you can find and leave Uncle Fred’s 22 oz framing hammer with the sharp, waffled head in his toolbox. Lay the cello on a thick towel (dry, please) on a table at a good working height: gently, and accurately place the dowel on the end of the peg, support the pegbox on the other side with your body, and smartly tap the dowel with the hammer. If you hit it hard enough, it really will pop free: if you wimp out – preferable to breaking the pegbox which would only really happen if your dowel was not lined up on the peg and you gave it a sledge-hammer-type blow – either take it to your luthier or wait for next winter.

Here’s what not to do: don’t use excessive force either by hand or with tools in trying to twist the peg free. You will likely end up with a sickening crunching sound, the peg thumbpiece in your hand and the remains of the splintered shaft still in the pegbox. Then you’ll have to remove that with the method I just described and then take it to your luthier to have an expensive new peg fitted.

REPAIRS & OTHER THINGS NOT TO DO. (in no particular order)

1. Anything which requires you to remove all the strings.

2. Setting or adjusting your soundpost.

3. Polishing your cello (even if the bottle says “violin polish”), or doing anything to the varnish other than regularly wiping it with a soft cloth (a micromesh washcloth works well).

4. Putting cool stickers on your cello.

5. Gluing ANY crack in the wood of the cello. It’s expensive for a luthier to repair the crack, but it’s much more expensive if you try it first.

6. Gluing any piece of the cello that has broken off (corners are common). Save the broken piece – wrap it in tissue paper to keep the broken edge fresh – and get the cello to a luthier ASAP before any wear occurs to the mating surface on the cello.

QUESTIONS? Email us your questions – pperleycellos@AOL.com – and we’ll answer the most interesting on this page of the web site.