I have an old wooden toy sailboat that has a broken wooden mast. It broke in half. I want to glue it back together, but do not know how to do it in such a way that it can be kept straight with a little pressure on it while the glue dries. The broken piece is 1/4″ in diameter. When joined together the piece would be about 14″ long. Can anyone offer me some advice on how to do this?
Edited 3/2/2004 11:01:24 AM ET by Bill9
Replies
Glue it, get it straight and put a rubber band or two around it. I think exterior wood glue would work well and give you a bit of working time.
Mack
"WISH IN ONE HAND, S--T IN THE OTHER AND SEE WHICH FILLS UP FIRST"
Take an 1 inch to 1 1/2 inch square block about 8 inches long and run a V groove down the mid line of one side. Make the groove shallow enough that the edge of the mast will stand slightly above the edge of the block when the mast is set in the groove, this will allow you to easily clamp the mast pieces into the groove.
If you cut a deeper crosswise groove at the midpoint of the long groove, you'll create a space for glue squeeze out from the joint. A couple of spring clamps should provide all the clamping needed.
The best glue would be an epoxy, because it sets rock hard. Let the repaired mast sit in the clamps for 24 hours to achieve close to full strength. Don't use a yellow glue, it would be flexible enough that the joint would be wobbly.
No matter how good the glue, the repaired mast won't be nearly as strong as it was before it broke. You can reinforce the joint by wrapping it with a 2 inch wide strip of cloth or paper that is saturated with epoxy. If you add the reinforcement, do it as a separate step after the mast is glued together and the glue is fully hardened.
Hope this helps, John W.
Edited 3/2/2004 12:34:57 PM ET by JohnW
Edited 3/2/2004 12:40:09 PM ET by JohnW
I would also suggest drilling a small hole straight down the center of each piece and insert a finish nail (cut off the head first) into both ends when you apply the epoxy. This will help stiffen the joint and prevent further breaks at the repair.
Good Luck.
With a piece so small in diameter, I don't know how this technique might work, but I would consider reinforcing the mast at the break with a miniature "dowel" the way chair legs are often repaired.
Of course, the trick is finding a "dowel" that's small enough. But you would drill a hole into the ends of the broken pieces and insert and glue a reinforcement piece that would connect the two pieces internally (in addition to the glue that binds the mast itself). That will help reduce the loss of strength mentioned above.
I'll leave it to you to think about what material you might use and how the benefit might outweigh the risks.
forestgirl -- you can take the girl out of the forest, but you can't take the forest out of the girl ;-)
Another proud member of the "I Rocked With ToolDoc Club" .... :>)
In a piece this small, adding a pin through the joint will add little additional strength. From an engineering standpoint, almost all of the strength in a long column, like a mast, is in the skin of the piece, this is why a hollow tube is almost as strong as a solid bar of the same material. In a chair joint, with shear and torsion forces on the joint, adding a repair dowel does make for a stronger repair.
A second problem with a repair like this is that unless the holes are very accurately placed the joint won't come together properly. Some strength is gained if the broken ends of the mast can be perfectly mated so that the pieces fit together like a finger joint which gives some long grain glue surfaces.
Offhand, a 1/4 inch diameter mast 14 inches long is fairly fragile, which is probably why the mast broke in the first place.
John W.
The best method depends on a few things. First, just how important is this toy to you and/or how valuable ($$$) is it. If the answer is "very important or valuable" then I say you should conserve the piece, not "fix" it. The first rule in conservation is to not do anything that cannot be undone. That would rule out epoxy, yellow or white glue, poly glue, etc. You should use a glue that can be softened and removed. Also a glue that will not affect any paint or varnish that may be on the mast.
The problem with dowling is one of alignment. I can imagine that this old mast is not really all that straight, so a v-block won't be of much use although some alignment device may be. I also cannot imagine how one would accurately drill a tiny hole for a toothpick dowel so that the mast retains it's former alignment. Dowel drilling guides are not readily available, if at all, for such a tiny situation.
Perhaps someone with hot hide glue experience can verify this......I think (no direct experience here) a good solution would be to use hot hide glue. It is fast setting and can be undone. Of course, the fix won't impart significant strength, but certainly enough to keep the toy on display. Only you can answer how strong it must be. If you wish to sail this craft in the mini-America's Cup, then that is another matter.
Why not just replace the entire mast?
Ok, get a 1/4" dowel and put a scarf joint between the existing bottom and a new top.
Ok, get a short 1/4" dowel and scarf it between the existing top and bottom.
you could make the repair look historically authentic by "fishing" the joint. "fishing" involves glueing and binding thin strips of wood arround the mast either side of the break. Done properly it'll be as strong or stronger than the original material. AND it will look historically authentic.
Ian
You could make up a v-groove block as suggested, a few inches long. In the middle, dado out a section perhaps a half inch wide. When assembling, the joint would be above the dado, so the mast would not stick to the jig. At the end of the jig, attach and end plate and thread a machine screw in it. Use the screw, along with clamping the mast in the groove, to apply a little axial pressure on the joint. A sketch is attached.
Hi Bill,
There have been offered some good advice, and if you haven't already attempted the repair, let me ask a couple of questions. I'm a long time ship modeller, (34 years, and build scratch models, not kits)
Questions: Is the rigging still attached? Is the break clean or splintered?
It will be almost impossible to set up if the rigging is still attached. Remove it and re-rig later. If the mast cannot be replaced, then drill a reinforcing hole up the center of each of the mast parts , about 1/8" diam. and go in as far as you can. Insert a wooden pin in the bottom hole (round toothpicks work well or bamboo skewers, whittled to size). If it fits snug and not much play, then remove and add glue and insert in the bottom again. Then glue the top part of the pin that extends out and fit your top part of the mast down over it , match up the splinters. When that is snug in, take some more Bamboo skewers and place them all around the mast, like splints for a broken leg, as many as can fit, and then wrap the whole thing with tape, electric works best but masking will do. Give it plenty of time to dry up and use a razor blade to remove the tape and splints. Yellow carpenters glue will give the strongest joint.
If there are any spilinters that didn't fit in right, or if you feel you would like to, you could then "fish it". Glue on strips of wood all around the mast perhaps an inch long and 1/8" wide and 1/32" thick, and then wrap the "Battens" with line (about the same size as your rigging. There is a way to wrap the line and hide the knots with a whip or seize them , or you could pin or glue the ends.
If you have any problem, e-mail me at [email protected] and I'll help you out.
Bob
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