So you want to learn how to use a sash fillister?

This question came up recently on one of the woodworking forums I frequent.  I took a few photos demonstrating why you need a sash fillister for sash work.  It doesn't see much work outside of that specialty, but it can come in handy for moldings.


The glazing rabbet



The molding (ovolo in this case)

Sash requires a glazing rabbet and a molding profile.  The molding goes on the inside of the window, the part that faces the interior of the house.  The rabbet is cut on the outside, so that the "ugly" putty and visual heaviness of the square edges goes outside the home.  To achieve a good looking sash, it is important that all the moldings line up perfectly.

A good looking sash joint.

The glazing rabbets are not nearly as aesthetically important, so any potential error (always possible when working with hand planed stock) is thrown to the outside. The only practical way to achieve this is to only work from one face. Because of the importance of the molding, the reference face is always the inside face.  All layout and joinery must be done from this side.

The sash fillister references the front face to cut the glazing rabbet

 To cut the glazing rabbet, therefore, you need a sash fillister. This plane references the inside face, using the fence, and cuts with the inside left corner of the iron to cut the rabbet. It "leapfrogs" the area into which the molding is cut (rabbets are usually cut before the molding, this is just a demo piece that I had made before).

This is why a moving fillister doesn't work.

 A moving fillister can be used to cut the glazing rabbet, if you reference the "wrong" face and cut against the grain.  As you might guess, the molding plane works best when planing with the grain, so the aesthetically important molding demands that the grain run in a friendly fashion for that cut. If you cut with a moving fillister from the back face, you run the wrong way and you risk tearing out.  Admittedly, this isn't all that important, but it sure is easier work to plane the right way.

So, if you want to make sash by hand, you need a sash fillister.  If you just want to buy a neat old plane, you need a sash fillister.  If you want to power abrade your work into submission and set up your dado stack to cut your glazing rabbet, you probably don't need a sash fillister.