Two Factors that Compromise Bassoon Profilers

Observations from the Way of Cane Bassoon Reed Service

July 23, 2023

In my continuing articles on bassoon reed machine repair and servicing, I want to talk about some of the most common problems I encounter.

Most machines that come through my shop are the profilers; perhaps that’s because they are traditionally the most common one used by most bassoonists. It was the first machine I had when I was a student at Oberlin (a Reedual) and then a Pfeifer single profiler when I got my position teaching at the Shepherd School of Music after I joined the Houston Symphony. The Pfeifer was the profiler my teacher Kenneth Pasmanick used and it was familiar sight on his reed desk.

The profiling blade will show signs of wear sooner or later depending on the type of metal used for its blade. Those signs are: a change in the profile thickness and the difficulty of cutting smoothly through the cane.

Here is a photograph taken through my digital microscope showing the wear on a Rieger profiler’s blade :

You can see the deformed, inwardly curved blade. This is the main cause of the drifting of the profile's thickness as well. The white on the edge of the cutting surface shows light reflecting off the cutting edge. That means the edge is thick enough to reflect light. A correctly restored cutting edge won't reflect any. In this photograph you can see that the far left corner of the blade doesn't catch light.

Pretty much all of the profilers I service (though not the tip profilers) use engineering designs very similar to the Pfeifer's. There may have been German machines that pre-dated the Pfeifer design (such as Sassenberg), but this type of machine all work using similar principles. These are:

1) A carriage to hold the blade and guide it along the cane, following a sloped or tapered (or multi-tapered) reed design pattern.

2) A rotating cane barrel to hold the cane

3) A pattern to set the tip and collar thicknesses and the slope between them (a straight taper or with a secondary taper).

A characteristic of this type of design is that the pattern is located on the side of the machine opposite the pivot of the carriage shaft. This means that the carriage can only be parallel to the base (and hence the cane barrel) at one part of the profile.

[Most tip profilers have the pattern and cutting area on the same shaft and I think this eliminates the problem of an out of parallel carriage we see with profilers. Also the range of thicknesses that tip profilers produce are more limited in range than with profilers for the whole blade].

Factoring into this equation is that when the blade wears enough to effect the thickness of the profile making it heavier because the cutting edge has in effect “withdrawn” due to wear, we often adjust the machine to compensate for that wear by removing shims from a machine like the Pfeifer or dialing down by a different adjustment mechanism (like the MD, Maxwell, Reeds ‘n Stuff, Reed Machines or Butterfield machines). The end result being that the carriage is no longer parallel at the tip and removes more cane from the near side of the machine.

I usually hear from bassoonist who contact me for servicing that the tip corners are no longer the same from side to side and the cane surface is rough along the whole blade. This is caused by the fact that the blade is no longer straight across (it is curved inwardly) and also the very thin cutting edge becomes ragged by cutting through the bark of the cane. The cutting edge of the tip must be quite thin to cut at all and because of that it wears rather quickly; how quickly depends on the hardness of the metal of the profiling blade. A carbide blade will last longer but is harder to sharpen.

I have some bassoonist friends who are also skilled woodworkers and cabinetmakers and they tell me that they typically spend a lot of time sharpening their chisels, planes and gouges. We bassoonists tend to forget about this until our blades are so dull they will no longer cut — or if they do, the dimensions have changed and the surface of the cane is scratched by the rough blade rather than cutting it smoothly.

So we have a double problem: first, the curved, dull blade and second the machine has to be changed to return the profile to where it had been (before the blade dulled to the point of enough change to get our attention). And if we adjust the machine’s thickness settings to offset this wear then the carriage is lowered enough to cause it to no longer be parallel to the base at the tip. It’s also difficult to move the carriage through the cane due to the blade’s dullness (and often we have neglected to oil the moving parts of the machine).

By design, the manufacturers set the machine up so that the carriage is parallel to the base and barrel at the far left end of the carriage's travel (the tip area). The geometry of this involves several factors: that a new, sharp blade is set to the correct depth in the carriage and the pattern is located so that it allows the carriage to be parallel at the tip. It matters much less if the carriage is not parallel at the back of the reed near the collar since that dimension is much thicker than the tip area. Also the cane is much narrower at the collar area of the reed, making any discrepancy of thickness much less of a problem. For example a difference of .004” (.101 mm) because the carriage isn't parallel at the tip would result in one side of the tip measuring .008” (.203mm) and the other side at .004” (.101mm) — half the thickness. At the collar that same difference of .004” would give at .034” (.863mm) and .030” (.762mm) on the thinner side; I doubt the difference would even amount to that much since the cane is narrower. This means a 14% difference at the collar and a 50% difference at the tip.

In this diagram you can see how the profiler's carriage is lower on the right side where the blade meets the cane and heavier on the left side, when the settings are changed to compensate for blade wear.

The distance "A" shows the designed parallel position of the carriage when it is set up properly with a sharp blade and the tip set to the desired thickness.

Distance "B" shows how the carriage is no longer parallel due to wear and the compensating adjustment to restore the desired thickness at the tip. Although this drawing isn't to scale, you can still see how the blade will cut more on the right side of the cane (the side near the user) and less out of the left.

The steps to restoring a machine's performance I follow are

• First I restore the blade's cutting edge (remove the inward curve) then sharpen the blade to a fine edge with diamond plates and from 400 grit 1000 grit and then abrasive films up to 6000 grit.

• The blade is then reset into the carriage according to the manufacturer's design for the projection of the blade below the carriage; Rieger and Reeds 'n Stuff give information on that dimension as well as offer dial gauges to accurately set their machines up correctly— typically around .04-.05mm (.0015-.0019"), in other words just barely projecting. I use those gauges to set up their machines. For the Pfeifer, we can use the limit bar and shims some machines still have, but some bassoonists set these machines by feel, using less projection than Pfeifer recommended (at least according to his instructions he sent with my machine). This is especially important with the Pfeifer double profilers; I've found these machines need a blade projection significantly less than the single barrel machines. For the single machine I used to set mine at a .015" (.38 mm) projection, the double machines seem to work better with about 1/3 of that or .005" (.127 mm). I will now set many of the Pfeifer singles to more moderate projections of the blade.

• Once these two steps are set then I can proceed to set up the profile thickness requests of each bassoonist since the corners at the tip will be the same.

My next post will report on my ongoing progress learning how to sharpen gouging blades.