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Q&A Page 1
--How do you remove dents in small tubing?
--Resetting Table Knife Blades
Q. How do you remove dents in small tubing?
A: When you need to remove a dent in small
diameter tubing or a similar small space,
quick and easy dent tools can be made from
"balling" the ends of brazing rod
with a gas torch. These balls can be
shaped very fast by hand or with a belt
grinder, so you can tailor-make them on the
spot for the repair.
I use regular brazing rod
without the flux coating. If it is clean you don't really
need too much flux (borax flux is what I
use).
Pick a diameter size rod
slightly smaller than the ball size you need. Hold the rod
straight up and apply the flame to the
bottom end. As it melts the end will grow in
in size and get round.
Remove the flame just
before it gets so hot that the melted ball falls off. Doing it
wrong a few time will give you a feel for
the right timing.
The ball is better a
little too big than too little. You can file, sand, grind or buff it
down to the correct size. The correct
size will depend on whether the tubing is
tapered or not and such things as whether
it is straight, bent or curved. Much of
the time you have to actually try it to see
how well it works. A lot of dents require
the metal to be pushed out slightly beyond
where the metal should be in order to
spring it out and make it stay in place.
I often hold the opposite end of the rod in
a vise and tug or push on the tubing with
the dent.
As with most other
shop-made tools, this one is open to countless variations. You
can also make them out of steel welding
rod, but the surface usually come out
slightly pitted. One advantage of
using a steel rod for removing dents in
non-ferrous metals, is that you can use a
magnet to see exactly where the ball is
inside the tubing.
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Q: How do you reset table knife blades? A.
The following is the simple version, for just replacing blades that have
already come out of I use Pour-Stone (a rapidly setting, anchoring cement available at all the local hardware stores in Southern California) to hold knife blades in hollow handles. It is manufactured by Custom Building Products of Seal Beach, CA., for anchoring fences, fixtures, bolts, railing, etc., into concrete floors. It sets up in about 15 minutes and according to their information becomes 50% stronger in one hour than fully cured concrete. If you can't find Pour-Stone, try experimenting with whatever Gypsum/Portland based anchoring cement your hardware store carries. Mix and pour a test "puddle" about 3/16" thick and about 3"
in diameter. Let it get hard. It should set up strong enough to require two hands to break it. Make a note how long it takes to set up.
Prepare the blade by making sure it is straight and free of bends, twists, cracks, etc. The tang needs to be free of the old setting compound. Scrape, or wire brush it to clean it down to fresh metal. Prepare the hollow handle by making sure the is enough room for the blade tang to fit easily. A 1/8"metal rod will help flake away loose compound. Carefully chip away the compound from the opening of the handle. The more space the handle has to receive the Pour-Stone, the stronger it will hold the blade. If you use a drill to clean it out, be careful not to let it touch the inside of the handle! Finish this step by washing out the handle. Drain it, but you don't need to dry it. For setting blades in small quantities, a small yogurt cup filled with sand makes a good holding jig. Do a practice run first. Carefully push the handle (open end up) as far into the sand as it will go. Insert the tang into the handle and check to make sure it will sit straight. Also, check to see which way the blade should face, sometimes the knife is engraved on one side. You will notice that the tang has notches formed into it. This is to provide a better grip when the compound sets up. Next, mix the Pour-Stone to a consistency of pancake batter. Start with a small amount of water and mix well before adding more. Small plastic or yogurt cups work great for mixing, you can pinch them slightly to make pouring easier. With the blade out, direct a thin stream of the liquefied compound into the handle. A narrow rod or wood stick helps to break air bubbles that will block the handle from filling. Fill to about ¼” below the opening. At this point, don’t worry about spills. (Note: don't wash this stuff down the drain! It sets up even under water. I use an old basin to rinse everything into. When it sets up you can throw out the water and throw away the residue.) Place the blade into the handle as you practiced previously. If you poured just enough mixture into the handle the tang going in won't force it to spill out. Most of the time it will spill, but that's OK. Now, position the blade likeyou did with the practice fitting. You want to make sure it is straight and centered. Eyeball it from the top and from two or three different angles.Pour out some of the leftover Pour-Stone to make another "puddle" on a scrap of paper. This will help you know how the hardening process is progressing. At this point you can clean the spills off the handle. Use a soft brush with water and carefully clean as much of the compound away as you can without bumping the handle. Anything left will wash off when you do the final cleanup. Remember, your alignment is precarious until the Pour-Stone gets hard. Check the test puddle now and then. When it is close to being hard, carefully remove the assembled knife from the holding cup and sight it like a rifle. If it is off just a little, you can make minor corrections. After makingthem, put the knife back in the cup. Make sure you don't bump or jar the blade because it may ruin the job. Let it sit until the test puddle is hard to break. (Note: If you botched the job, twist the blade and it will come out, so you can start over again. Clean out the inside of the handle with the thin metal rod and wash it out.)Assuming that everything turned out OK and the Pour-Stone is hard. Wash the knife and chip off anything that didn't get cleaned up with when you brushed it with water. A toothpick works good for this. If you have a buffingmachine, carefully buff the knife with jeweler's rouge, wash again and dry with a soft, clean cloth.---------------------------------------------------------------------
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