Trombone Slide SPL
(Straighten, Parallel and Level)

Part 3
Assembly and Soldering


Before we can assemble the horn, we must make sure that all of the connecting joints and brace sockets are clean of the old solder.  Here Dan uses a dremel tool.


Buffing works good too, sometimes.


Before we solder, we check the fit...

When assembling the slide it is best to make sure all the joints fit well. It is important that they fit smoothly and correctly. Not too loose and not too snug as this will interfere with the adjustments made during the soldering process.


In this shop the SPL assembly process is always done in a specific series of steps and in the prescribed order developed by Daniel Oberloh. There is a reason.


make your solder work clean!


Measuring after the first solder and before the second...

The first step is to lay the slide out parallel and level. Make sure the crook is set properly and square with the slide. At this time it is a good idea to double check that the crook is not on backward!  (I've seen it and, well, done it too!)
The first solder is only on the pin (fixed) side of the crook. The other side is the hinge point that will allow for finer adjustments on the cross brace at the other end of the slide.

 A big tip: When assembling the outside slide, do so with the bottom (water key) facing up. This is because when the inside assembly is put together we do so using the outside assembly as a template and by assembling it upside down we are reversing the effects that play on the slide through gravity. In other words, when playing the trombone, the outside slide hangs on the inside assembly that is fixed to the bell. When we are assembling the slide, the inside is hanging on the outside assembly. So by flipping the slide over you are creating an environment that is more likely to deliver better results in how the slide operates just as long as the tubes are straight, parallel and level.

The next solder is at the cross brace.  But first a measurement is made at the far end about three to four inches from the cross brace. Using the caliper, the slide is adjusted to the point that it is dead on with that at the crook end of the slide. You need to go back and forth, end to end, checking and rechecking.

Allow the first solder to cool completely before starting on the next. This helps avoid problems with heat expansion that can throw fine detailed measurements off.

The second solder and then measure again...

...satisfied with the measurements we solder. There is a trick here as well to avoid expansion/contraction issues due to heat but I'm going to leave at least a few mysteries for you to figure out on your own.

The third and final solder on the outer handslide

With the cross brace being soldered we now make the needed adjustment using the magnetic brass sets. There was a slightbow in the middle of the slide that has been corrected using one set. The two on the fixed side are in place to hold the slide stable. The slide is measured again. Having found our slide within .001" we can now solder the remaining joint at the crook, opposite that of the first solder joint made.  The final solder locks the manipulated angle set in the slide tubes using the brass set.  Once the solder is completed and the brass sets removed, the slide will hold the desired dimensions.

Another NOTE:One slight bow of a few thousandths is workable and easy to iron out. If the tubes have more issues than this, you are way ahead of yourself and need to get your butt back over to the leveling stone and back to work getting those tubes straight!


Again, make sure that your solder work is neat!

Yet Another NOTE: Neat clean solder joints at the git-go make cleanup more easy. Sloppy, untidy solder work is apt to present leaks or internal issues.  Not to mention that you will most probably wind up trying to fix it later by heating the solder to wipe away the excess and wrecking the alignment work done so far. Been there, done that, learned my lesson the frustrating way.

We are now ready for the inside assembly!

Part 1 - Evaluation and Preparation for Repair

Part 2 - Cleaning and Dent Removal

Part 4 - Inside Slide

Part 5 - Polishing, Lacquering and Completion



Copyright 2004 Oberloh Woodwind and Brass Works