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Loose screws in piano

Hi,

I've purchased a very old piano, which is very sound musically, the the outer shell, which is essentially a piece of furnatue) has a great number of screws that have completely lost their threads. (The piano lid has hinges, plus there are some other metal parts.)

I'm looking for the best way to fix this. By best, I mean most reliable and most durable. This is the first time this problem arose for this piano in over 100 years and I want the solution to last another 100 years.

The opinions that I have heard are:

  1. Put in a toothpick and put the screw back in.
  2. Use wood putty.
  3. Use plastic wood.
  4. Glue the screw in with Gorilla glue

All of these sound iffy to me. So what is the best way?

Thanks!!!

Aaron

Reply to
aaronfude
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I would go to new, slightly larger screws. Get a countersink if you need to go through any brass.

Reply to
Lee Michaels

Drill out the holes, fill with a dowel, replace screws.

Reply to
Bill B

Most of the screws used in older musical instruments are odd numbered sizes (#7, #9, #11. etc.). With care, they can be replaced with even numbered screws (#8, #10, #12, etc.). You may find it helpful to insert FLAT toothpicks in the holes with a little Titebond or Elmer's carpenter glue before inserting the new screws. The drawback to using glue is that it could make the new screws harder to remove. Screws in a piano must be removable for repair purposes.

Musical instruments are typically made of both soft and hard woods. Care should be taken when trying to set slight larger screws to avoid potential spitting. Do not attempt to increase the grab by using longer screws. They were sized by the designer for each specific joint.

____________________ Bill Waller New Eagle, PA

snipped-for-privacy@comcast.net

Reply to
Bill Waller

Does this approach work w/o removing the hinges first?

Reply to
aaronfude

Piano restoration is a very different business than general furniture building/restoration.

IMHO, you need to ask these questions of someone in the piano restoration business.

Lew

Reply to
Lew Hodgett

What kind of countersink and what's the exact pupose: to widen the hole or to create a bigger bed for the hat?

Reply to
aaronfude

If you need to enlarge the hole, you do that with a drill.

The purpose of the countersink is to make a larger tapered area for the screw to fit into. This would be what most brass has, a tapered part at the top of the hole, so that way, the screw tops are flush with the hinge. If you were to use a larger screw, it may stand proud of the hinge surfce. Hence the countersink bit.

You may need to slightly enlarge the hole in the hinge as well. Use a regular bit for than.

Reply to
Lee Michaels

*Before* going larger with the screws, go *longer* with the same size. Add about 1/2" to the existing screw length as long as you're sure the point isn't going to come out the other side. If the screw may protrude in a visible area, only then, go with a larger diameter screw.

I'd also try the glue and couple/three toothpicks before going to a larger screw. Dip the toothpicks in yellow glue and insert them in the hole - break off flush with the surface. Drive the old screw into the hole about 1/3 to 1/2 way and leave it until the glue sets. After that, drive the screw in the whole way and only tighten to snug down the parts. You may have to back the screw out to break any glue bond with the screw before driving it in completely.

Reply to
Fly-by-Night CC

Hmm? Apparently you mean the holes have enlarged in the wood and the screws don't hold tight. If you really mean what you said (the screws lost there treads), you just go buy new screws.

The best way is to purchase a book on furniture and house repair and then pick 1,2,or 3 above and do it.

Reply to
George E. Cawthon

As I have stated before on this forum, Toothpicks, matchsticks and wood filler are a waste of time and effort to repair screw holes. Drill out the old holes carefully without going clear through the wood. Glue in a hardwood dowel with waterproof glue and trim it off flush, then reinstall the screwsif they are in good shape, otherwise use new screws. Bugs

Reply to
Bugs

I've done the dowel thing on replacing butt caps/pads on gunstocks. It seems to me to be far the best approach. I use a small carving tool to dress down the dowel and remove any excess glue. I've never had any luck with the toothpick thing. I have used the wood putty approach (fill hole, let dry, drill pilot hole) with door hinges.

Reply to
professorpaul

I was the chief piano designer for a major American piano company for 27 years. Whenever our assembly people would strip out a screw by overtightening it, we would require that the old pilot hole be drilled out with a larger bit (same depth as original pilot hole) and then a hardwood dowel (usually 3/8" dia. for screws in the #8 to #10 range) glued in place with Franklin Titebond until completely cured (about 4 hours), trimmed flush with a hand chisel, then a new pilot hole of the same original size (0.196" for a #10 screw) be drilled into the center of the dowel, and then the screw re-installed. Takes a little time, but it's the best and most long lasting method. Occasionally we would catch them using wooden matchsticks or toothpicks, but that's a very short term solution.

babygrand

Reply to
babygrand

Hi,

Thank you for all the responses. I think that the first approach that I'll try would be the dowel.

I that respect I have a few questions:

  1. Do dowels come in all sorts of diameters - or should I drill for a particular size? Also, if the diameter of the dowel is Xmm, should I drill with an Xmm bit or next size down to allow for the glue?
  2. Do they come in more than one type of wood? If yes, how do you choose a best?
  3. Can this be done w/o removing the hinge? Suppose I only want to replace one screw.

Thank you!

Aaron Fude

Reply to
aaronfude

Reply to
George E. Cawthon

"Bugs" wrote in news:1145587427.813042.286400 @i39g2000cwa.googlegroups.com:

That works if the screw doesn't carry any significant load. If the screw has to support any degree of tension, the dowel will just split lengthwise along the grain, and you'll be left with toothpick sized splinters glued to the side of the hole.

If you have a plug cutter, cutting a long plug so that the grain runs across the hole, instead of along it (as in a dowel) is much stronger.

Stronger yet is filling the hole with a putty of epoxy and sawdust (or one of the fillers made for use with epoxy).

All that said, Lew's right, musical instruments are special, and and probably shouldn't be screwed with by the average woodworker. At least, not if you want to preserve it's value.

John

Reply to
John McCoy

I'd strongly advise against using bigger or longer screws for numerous reasons--splitting the wood, changing the appearance are the two that immediately come to mind

I'd suggest taking a block plane to a scrap of the same wood to make come nice curly shavings. Coat them with liquid hide glue, curl them up and and glue those into the stripped holes with the same liquid hide glue. Or start with veneer instead of making your own shavings. That will fix the problem with minimal change to the original piece.

Problems with drilling the holes larger, gluing in dowels and then drilling those for the screws is you'll be screwing into the endgrain of the dowel and the dowel will be corss-grain with respect to the part. Neither is desureable.

If the shaving method doesn't work you can go on to try other methods. But there is no going back from the dowel method.

Reply to
fredfighter

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