To hold trumpets and cornets you can make a wood mandrel or special
holding device. If you go to a unfinished furniture store they will have
spindle type chair or table legs. Many large lumber stores have the same
thing. Take a horn with you and find one which fits snugly into the bell
section of the horn. It should be smooth without any decorative spinning. You
can place this in the vice (get a good vice, preferably a machinist
vice) and use it to hold the instrument while you solder or work on the
slides.
I also use a piece of 2x4 wood stud about 12" long with two 2B drum
sticks glued into it at a right angle(see diagram above). This is where a picture is worth a
thousand words. The distance between the drum sticks is equal to the distance
between the center of the 1st and 3rd valves. This type of holder is great
for use when "Ragging" the valve section of a trumpet or cornet. You must
remove the valves to place the body on the holder. Unlike the wood mandrel,
this holder will not allow the horn to rotate. I make these holders to
accomodate the horn I am working on at the time. It only takes about three to
cover all the different brands. Make them as you need them.
Moremandrel designs available upon request.