Case Repair

Vintage Musical Instrument Cases

Instrument Case Repair

by Steve Kirtley

These are a few examples of instrument case repair, restoration, as well as construction of some faithful reproductions of classic old cases. It's not an exhaustive tutorial, but perhaps will provide some ideas and inspiration.

Index:

1. Latch Repair

2. Installing Split Rivets

3. Case Restoration

4. Constructing a Case from Scratch

5. Examples of Custom-built Cases

Latch Repair

Sometimes the catches break on old cases, and instead of staying closed they just flop around. The cause is a broken internal spring. Repairing these old catches that don't close is actually very simple. These catches contain a flat metal spring. When the spring breaks the pieces usually soon fall out. If you hear something still rattling around, turn the case upside down and shake it until you get the broken pieces out.

Finding a Replacement Spring

You need a replacement spring. The simple option is to find a donor case with similar catches, so you can disassemble the catches and steal the springs. You might check local music stores that have rental programs. They may have old violin or horn cases which they consider junk, but which have similar catches. Plus there's always flea markets and eBay.

Making a Replacement Spring

Making those springs wouldn't be hard. It'd be best to start with spring steel. An easy to obtain source of material are the springs that are used on back of certain picture frames. Once you have some spring material and have cut it to size, you could try bending it cold. There's a risk of it breaking later at the bend since tempered steel is brittle. Another approach would be to de-temper the area to be bent by heating to red hot and letting it cool slowly. After bending you can re-temper by heating it to red-hot and immediately quenching in water.

Spring Catch from an Old Case, Showing the Internal Spring Being Inserted

Picture Frame Clip, a Source of Replacement Spring Material

Installing the Replacement Spring in the Catch: Once you have a duplicate spring, the repair takes 30 seconds. There's no need to remove your catch from the case or disassemble it. Just push the spring down into the slot until it snaps in place. The lip at the edge of the opening will hold it in place. Done.

By the way, I'm certain that when these catches were originally manufactured they were assembled, nickel plated, then the spring was inserted last, just like our repair technique.

Installing Split Rivets

Traditional wood-bodied cases of all types have the latches, handles and hinges held on with split rivets. They hold much better than screws. If you need to install new hardware, you'll want to learn the mysteries of split rivets. Actually, they're pretty simple things.

You may need to remove the old split rivets first. The photo below shows the installation process. Just think of removal as the reverse order. Expose the inside area where the split rivet is anchored by pulling back the case lining. (Step 3, below.) You will need to dig into the wood to pull up the two legs of the split rivet. Use a very small screwdriver, a heavy duty knife, etc. (Step 2.) Straighten the legs by squeezing with pliers and they should pull out fairly easily. (Step 1.)

Now, you'll need replacement split rivets. It's not really possible to reuse the old ones as the legs will usually break when re-bending them. You can buy split rivets as well as latches, hinges, etc. online from many sources. One convenient source for small quantities is eBay. You will need to measure the diameter and length in order to get the right size. Don't buy them too long. Take into account the thickness of the wood plus the metal hardware. As you can see in the photo below, the split needs to be below the surface of the wood in order for the legs to spread properly. In a pinch you can cut the slot deeper with a hacksaw.

There are hand-held tools available to install split rivets, but I find it very easy to do without special tools. I spread the legs with a small screwdriver (Step 1.), curl them around with needle-nose pliers (Step 2.), then gently pound the curled legs into the wood while holding another hammer head against the head of the rivet (Step 3.)

Case Restoration

This is an extremely trashed case. Here's a "before" picture of the unfortunate patient. The covering is worn away on most edges, and most of the seams are unglued. There is missing wood on the bottom edges.

The head end is totally blown out.

Even that's not the worst of it. The two middle layers below are not wood, they are crumbly acid damaged cardboard.

Most of the case is de-laminating. I worked white glue in everywhere I could reach and clamped the layers back together.

I had to make a small form so the head area could be glued back into shape.

The head area was totally broken in half. So I created a patch of strong maple veneer, and cut back the old veneer so everything would glue together like a puzzle.

Clamped up.

Finished head area.

Now to the body of the case. I glued all the delaminated areas possible, then reglued the seams. I'm using carpenters glue.
I work quick by tacking things together with staples, then pull the staples when the glue is dry. Here I'm also adding some thick veneer to replace missing wood.

Donor tolex from an old sewing machine case I got for $2 at the flea market. It's old enough to be similar pattern, although not an exact match.

Applying strips of tolex to the worn edges. I'm using water-based contact cement, although I've also done this with white glue.

When such strips are neatly applied around the entire case the result is not especially noticeable, as many cases have a line along the edge.

Then I went inside to replace the pull ribbon for the accessory pocket, which had worn away.

I ripped the fabric from the back of the pocket lid, pulled the new ribbon through the slot, and glued the ends flat.
Then glued the fabric back. I used white glue, but contact cement would work. (I greatly prefer water-base contact cement.)

Finished pull ribbon.

I also replaced the tattered ribbons covering the hinges. Pulled back the lining, glued down the ribbon, reglued the lining.

Now the glorious restored case. I had also replaced a missing foot, and found a suitable replacement handle from an old suitcase. I also scrubbed the gunk from the latches with some household cleaner and a small stiff-bristled brush. They came out looking much nicer. There was a significant amount of wear to the case plus the repairs, so I sprayed the whole thing with vinyl spray after taping off the metal hardware. This vinyl spray is from the auto parts store and is intended for renewing car seats. It's perfect for cases because it has a nice mat finish, adheres very well, and actually adds a vinyl layer similar to original tolex material. I would not recommend respraying a classic case just to make it "new". It takes away some of the originality and character. It's a reasonable approach in a situation like this where the case been totally trashed and restored.

I also used the vinyl spray to recolor the brown suitcase handle.

The Restored Case

More Case Repair: A Creative Repair Job for Damaged Covering

Here's an old tweed case that has an area at the head of the case which is badly damaged. Repairing the wood is straightforward, using the techniques shown above. But a large area of the covering is also badly damaged. Where am I going to find matching tweed for this early 1940's case? Impossible, you say? I know where I can find some small strips of perfectly matching tweed.

I peel back the plush lining inside the case and cut a few half-inch wide strips, from where the lining laps over inside the case. After I glue the plush back in place no one will ever know. (HINT: This secret technique works equally well with black-cover cases or even guitar amps.)

Then I glue a few of the strips side-by-side to patch in the missing covering at the head end of the case. I carefully match the tweed pattern, to make the repair as unobtrusive as possible.

I used a bit of stain and shellac to tone the repaired area. It's not an invisible repair but it has neat workmanship and it's 200% better than the "before" picture.

Constructing a Case from Scratch

This is not a complete tutorial on case building, but perhaps it will provide some ideas and inspiration.

Sourcing Veneer

The carcass of a wood-bodied instrument case is laminated from thick veneer, usually four layers of 1/16" or five layers of 1/20" veneer to create a 1/4" shell. Poplar, basswood or maple are good materials. The biggest challenge is that veneer this heavy is nearly impossible to find in retail outlets. It's often known as "laminating veneer" and typically used by manufacturers of furniture or other laminated products. As an alternative I've used sheets of poplar "bending veneer" which is 1/8" three-ply material, and more widely available. Try your local exotic hardwood vendor or any industrial connections you may have to find a source.

You'll need forms to create the shell for a shaped case. See the examples below of easy-to-construct forms for a guitar case.

Quick and Easy Mold for the Sides

This is the form for the sides of a guitar case, and the shape is the INSIDE dimension of the case.

Here's the cheap & dirty method I use to clamp the sides onto the mold. Use wax paper between the mold and the veneers. When the heavy wire is twisted as shown it will apply plenty of clamping pressure. When the glue is dry I use wire cutters to remove the "clamps."

Gluing Up the Veneers for the Sides

When clamping the veneers around the side mold. I start at the neck area where it's semi-flat and strength is less critical. I want the joints of the various layers to be offset to avoid a weak spot. So, I lay down the first ply, two inches later add the second ply, and so on. This puts all the joints two inches apart. I glue and clamp the veneers all around the case until I come back to where I started. Then I join up the layers by trimming each veneer to length, so it will meet the starting point.

Veneer Layers for the Sides

The grain of each alternating layer should be at 90 degrees for strength. The start of each layer is offset by a couple inches.

Quick and Easy Mold for Top and Bottom of Case

Here's the mold for the top, made of 3/4'" plywood or particle board. The shape for the hump is ¾" particle board, glued down then carved to shape. You can see I did some correction in the neck area with plaster.

For the female half of the mold I cut a hole the same size as the hump. I laid the male mold on the floor, covered the hump area with a plastic sheet. I laid the female part on top, poured plaster into the space, then laid a second full piece of plywood on that and screwed them together. I also had strategically placed some small nails in "hump area" of this second piece of plywood, so they would sink into the plaster and prevent it from falling out after it dried. The resulting female mold is a double thickness, and the male part is a single thickness of ¾" plywood.

To clamp up this mold I use a layer of wax paper, add glued layers of veneer, another layer of wax paper, then the other half of the mold. I employ several cross pieces of 2x4 on both sides of the mold so I can apply lots of clamping pressure and ensure the veneers completely conform to the mold.

I don't show the bottom mold, but it's identical except the hump is a teardrop shape in the body area of the case, and the hump is only ½" high. (If the bottom hump was a full ¾" high it would rub on the floor and wear the covering in the middle.)

Trimming the Sides

After the sides have been laminated, mark a straight line along the edges, saw off excess, and use a plane to achieve a smooth, straight gluing surface.

Top & Bottom Glued to Sides, Ready to Trim

So that's a quick description of how to laminate the parts. To assemble - first trim the sides to create a smooth gluing surface. You will have created your laminated top and bottom oversize. Now is the time to trim them to just slightly oversize, probably about an inch larger than the sides all around. Rather than using a ton of clamps for assembly I glue and tack the top and bottom on using very small brads or a heavy staple gun. If using brads I leave them protruding so they can be pulled out later with pliers. After removing the brads or staples I trim the top and bottom flush, then round over with a rasp or router. Finally, saw the case open about 3/4" from the top to create the lid and body of the case. Nothing left but applying the covering, hardware, and lining. If only it was as easy to do as it is to describe.