FLW Cabinet - #18 Side Panel Preparation & a Problem

Now that the front and back frames are done, I can measure and cut the sides to their final length.  The bottom will get cut to length later once the sides are in-place.  Both the sides and the bottom have already been cut to final width so that’s done.  Since the sides are about 76” long a crosscut sled is used to make the cut.  Here is what that setup looks like.

Before the sides can be screwed to the front and back assemblies, they need to have holes for the shelf pins drilled.  To make the ¼” shelf pin holes I use the jig below which has precisely spaced holes.  The peg holes can be drilled with either a self-centering drill bit in a hand drill or by using a plunge router with a 3/8” bushing and ¼” router bit.  In the past the self-centering bit in a hand drill has always been used.  However, if you go too fast sometimes the bit tears the thin veneer when starting the hole leaving a bit of a rough edge.  So, to see if the router worked better, I decided to try it on a test piece. 

I will use my small router because the hole is small and I don’t need the power of the large one.  Also, it weighs a lot less which is a plus.  First is to remove the large opening plate on the plunge base assembly and replace it with a plate designed to take a bushing.  Here is the router with the plate designed for the bushing and the bushing.

However, before installing the bushing I checked to see how it fit in the jig.  The diameter fit perfectly but the bushing was too long and protruded out beyond the base of the jig by about 1/16”.  So, the bushing gets removed from the base plate and it's off to the grinder to remove the excess.  Right off the grinder I was left with a rough edge that was not completely true or square.  That’s fixed by mounting the bushing in the lathe then using a file to even up and round over the rough edge as seen here.

There is a little room for adjustment of the router base plate so the bushing can be centered on the router shaft.  To do that this cone shaped brass piece having a ¼” shaft gets mounted in the router then the base is run up snug against the cone centering the base.  All that’s needed then is to tighten the screws.  Now when I mount the bit in the router it will be centered in the bushing opening.

The router bit is installed next.  After that the router is turned upside down, the jig set on the bushing which now is just a tiny bit below the surface of the jig and the depth of cut is set on the router.  Here is all that done.

After clamping the jig and the test piece down I was ready to make a test hole.  The green tape blocks off some of the holes as I am only going to use every third one. That puts the shelf spacing at about 4”.  Without the green tape I can guarantee that I would put a hole where it should not be.  Process is to turn router on then on the back side of the router out of sight a release lever is pushed which unlocks the plunge mechanism and you just push down.  The bushing makes sure the hole is in the right place and the stop controls the depth.  Easy.

Below are the results of the testing.  The hole on the left (D) is made with the self-centering drill and you can see how the edge is a little rough.  Part of that can be taken care of with some light sanding but the edge is still going to be a little rough.  The center hole (R1) is done with the router and the edge is a lot cleaner.  However, I made the plunge a little too fast and burnt the edge of the cut hence the brown ring.  Slowing down the plunge on the right hole (R2) gives me just what I wanted a nice clean hole.

To finish up the test I pulled out a couple of ¼” shelf pins and they fit in the drilled hole but not in either of the plunge routed ones.  What the heck is going on here?  A little measuring with the digital caliper told me what the problem was but not why.  The drilled hole is about a hundredth of an inch over ¼” while the plunge routed ones are a slightly a bit more than a hundredth of in inch less than ¼”.  The shelf pins measure about .001” over ¼” and just won’t fit into the plunge routed ones.  After some thought the why came to me.  The carbide bit I am using is probably 35 to 40 years old and gets sharpened as needed which over that many years adds up to a lot of sharpening.  I use a diamond hone to sharpen it and over time I must have removed enough carbide to make it cut a hundredth of an inch undersize. 

A trip to the local big box store got me a new bit.  I had considered a solid carbide spiral up-cut bit but I can’t sharpen it so instead went with a straight solid carbide bit that I can sharpen.  Using the new bit, I made another test hole and it worked just fine.  The shelf pin fit flawlessly.  Setting the jig in place I am ready to start making holes.

When you get to the end of the jig it’s moved down the board and a pin locks it in place allowing a continuation of the spacing.  The white pin at the left end of the jig is the registration pin.

That process is repeated until you get to the last hole then repeated on the other side ending up with a piece that looks like this.  28 holes done and 84 to go.

The second side went well with no problems.  However, after completing the third side as I was doing a double check on the hole spacing a problem emerged.  For whatever reason and I still do not know why on the second set of holes the first one got off by 1/8”.  Since all the holes are registered from the first one all 14 holes in that line are off and that’s a real problem.  That’s because unless all the holes are in the same plane the shelf will not set flat and will rock.  The fourth side went without a problem.  So now I have to correct this glitch by moving the row of 14 holes 1/8”.  Not something I had planned on doing and that’s where I start in the next post.

Next up – Moving Shelf Holes & Assembling the Case