Snare Drum – Parting Off, Layout & a Problem

Before I parted the drum from the mounting assembly I did one last check on the dimensions because I wanted to make really, really sure I had everything right since once the shell is cut off I cannot make any adjustments.  With everything checking out I started the process of parting off or cutting the drum shell away from the mounting fixture.

This shows the cut about half way through.  The pencil marks at the bottom of the cut gives me a reference mark so I can gauge how fast I am removing material.

Parting Off Operation in Progress

The closer I get to cutting the drum shell free the more paranoid I get.  What I don’t want to happen is to have the shell come lose, hit the lathe, the wall or me and damage the shell or me.  When I got to where I had less than a sixteenth of an inch left I shut the lathe off.  Because the mounting ring is made from construction lumber it is fairly soft and I could hold the parting tool in one hand and turn the shell with the other hand cutting the remainder away.   Here there is a very thin swiss-cheese looking band of material left holding the shell on, in fact when I looked inside I could see the light shining through it.

Shell Just Before Removing from Mounting Fixture

At this point a little tap on the shell caused it to release.  As you can see that there just was not much holding it on.  There is also some little bits of the base still on the shell that I will need to remove, but at this point everything looks good.  The real test came when I measured the diameter.  The result is good news, the thickened edge was within a few thousands of and inch and the overall diameter is right on.  All the measuring and checking paid off, what a relief! 

Shell Removed from Mounting Fixture

My next step was to clean up the parted edge removing the remaining bits of the mounting ring.  With that done I could do a test fit with the top and bottom drum heads and hoops held in place with 3 of the mounting lugs.  At this point it looks almost like a drum.   One thing I noticed was how light the shell felt, when I set it on the kitchen scale I was surprised in that it only weighed just under 3 pounds.

Test Fit of  Hardware

Lug Test Fit into Scrap

There are 10 lugs that hold the top and bottom hoops in place.  My first step was to do a test fit on a scrap to verify the center to center mounting distance of the holes and their size.   With that done I could lay out the hole locations on the drum shell.

To lay out where the lugs go I needed to make a template.  The starting piece was the top layer of MDF from the mounting fixture.  Since the mounting fixture was held together with screws I could easily take it apart.   The 10 lugs get evenly spaced out at 36 degrees between them.  To do the layout I drew a circle the diameter of the drum, used an Incra protractor to get the angles then measured the distance between the points where the lines intersected the circle as a check.

 

Completed Lug Spacing Jig

With the template made I could mark on the drum the lug spacing.  From there I added blue painters tape to use as a marking surface and extended the vertical center lines of the lugs onto it.

 

Center Lines of Lugs on Blue Painters Tape

Because I had only a few thousands of an inch tolerance in the spacing of the lug hole locations I used a marking gauge with a knife rather than a pencil.  The knife cuts a line far finer than any pencil.  Also, the cut in the tape will act as a guide when I use a center punch to create a dimple for the drill bit.

Marking Gauge

With the gauge set I marked the center line of each hole location.  Both the top and bottom holes were marked off the same reference edge for consistency. 

Marking Gauge Cut 

Lug Mounting Problem

As I was marking the next to last hole it dawned on me that the holes seemed to be pretty close to the bottom edge of thickened rim.  With that in mind I was afraid that the hole might come through the transition area between the thickened rim and the thinner central part of the drum shell.  If so, this would cause a problem in that the screws holding the lugs on had washers over ½” diameter and they would not lay flat if one edge was in the transition area.  A little measuring confirmed the problem.  The bad news was that I had the hardware in hand and the holes all marked.  The good news was that I had not drilled any holes in the drum shell.

I sent the client a drawing illustrating the problem and in a video conference we came up with several ideas, the best two were:

1. Get lugs with a shorter center to center attachment distance.  This will move the screws and washers more toward the center and out of conflict with the transition.
2. Get lugs with a single center mounting point.  This moves the screws and washers to the center of the shell completely out of the way.

We decided that Option 1, lugs with a shorter center to center attachment distance would be the first choice and center point lugs would be the second choice.  A day later I got a note from the client saying that after reviewing the available options he had ordered single point lugs.  With that problem out of the way and while waiting for the replacement hardware to arrive I moved on to milling the bearing edge.

Next Up – Bearing Edge, Jigs & Mounting Hardware