Mailyour questions here.You will need to get your hands on burnishers for dent work. If you
decide to buy them from the suppliers it will cost good money. I make my own
by grinding, sanding and polishing file blanks. You can get these at a
machine tool shop. This may be hard so to start you should buy one or two
just to see what they are all about.
Burnishing is the process used for smoothing metal between two harder
metals. Not complicated, just takes a little time to get the hang of it.
You probably have already considered buying tapered mandrels. If you do,
buy one for trumpets. This type will work for cornets as well as several
other instruments. It is not important to buy a different mandrel for each
brand of instrument; Bach mandrel for Bach trumpets, LeBLanc mandrel for
LeBLanc trumpets and so on. After awhile you'll find the one which is most
comfortable for you.
Mandrels as well as burnishers must be kept extremely clean. A well
polished mandrel and burnisher does not cause scratches. It is best to get
them hard nickle plated.
Usually, dents are roughed out before being burnished. Putting the horn on a mandrel
and pushing the majority of the dent out before burnishing will greatly reduce the amount
pressure used to remove a dent. It is important to remember that the brassaround a dented
spot has been stretched. The extra material caused by this streching must be taken into
consideration when burnishing. It is important to try and "move" the metalaway from the
damaged spot. By doing this, you will blend the slight amount of extramaterial with the
surrounding surface. If close attention is not payed to this matter,"rippling" or "humping" of
the area may occur. This type of damage is far worse to remove than theoriginal dent.
Annealing is normally necessary to soften the material enough to be reworked.
Lubrication is important to preserve smooth finishes and reduce the frictionbetween the
tool and the horn.I prefer to use ordinary bar soap.Apply the soap to the horn and mandrel
as well as the burnisher. I have found that this will also decrease the chance of scratching the
surface.
Many repairman get along just fine using a roller.Rollers work well most of the time
but do not remove the deepest part of a dent(ie. the crease).Rollers are best used in
situations where preserving the finish is of utmost importance.
Most of the tooling I use is made out of D2 or A1 tool steel. Thismaterial can be made very hard a almost completely scratch resistant. It is cheaper to use oil hardening or water hardening drill rod. You can purchasethis almost anywhere and is easy to harden yourself. Use old files for yourburnishers-grind off the ridges and polish them until there are absolutely no sratches. I recommend taking them to a red rouge type finish (mirror likefinish). Rat tale files work good for me but you may find something else works better for you. After polishing them, take them down to your local Harley dealer and see who does hard chrome plating. This won't be real cheap but you also won't believe how well they work for spinning. Part of your problem is the drag caused by using wood. Lubrication is the answer to usingstuff like wood (try bar soap or lanolin).
Mailyour questions here.