I have developed a method for making the square plugs with crowned top that was a common feature in the furniture of Greene and Greene, and I thought that others interested in this type of furniture might find my method useful. Before I begin, I do need to give credit where credit is due. My method is derived from the technique explained by Darrell Peart in his excellent book, Greene and Greene, Design Elements for the Workshop. I have used many different techniques to make these plugs over the years, and none of them were fully satisfactory. Peart's came the closest to providing the results I was looking for, but still came up short in my hands. What I wanted was a technique that was fast, accurate, and easily reproducible, and this is what I came up with.
The challenge with this seemingly simple detail is to produce a gently symmetrical, rounded crown on a square plug. It is this "pillowed" effect as Peart refers to it, that stands proud of the surface and presents a smooth visual and tactile feature that is both subtle and distinctive. I am convinced that this cannot be easily done after the square plug has been inserted. It has to be done before insertion, and this requires precision and reproducibility. The main problem for me with the Peart technique was turning a square rod by hand against a rotating sanding disc at a predetermined angle, even with the jig that he describes. The thought of using a drill to turn the rod against an inflatable sanding drum seemed to be a solution for this problem, and is the basis for this technique.
To start, I take a piece of 3/8" diameter steel rod and cut off four 2" inch sections. I then flatten the ends on the grinder as shown in the photo. I prepare 4 wood blanks (in this example I use wenge), 3/8" square and about 4" long. I check these against the plug recesses which have already been cut, making them very slightly oversized to insure a tight fit. Using medium viscosity CA glue and accelerator, I glue the wenge blanks to the ends of the rod, using a block of wood as a fence to align them accurately. This glue joint is quite strong - Billy Mays would be proud! The steel rod/wood assembly is then chucked in a cordless drill. This is amazingly accurate, with little to no run out of the wood blank.
I mark an index line on the table below the drum to help me visually align the blank to the drum at an angle that seems appropriate. After a few times, the angle becomes almost automatic, and I don't have to refer to the index line. I also deflate the drum so that it is quite soft. With the sander turned on, and the drill running so that the wood is turning in the opposite direction, I make a pass along the drum and back. Voila! A perfect rounded crown! Repeat with the other three blanks.
Now it's over to a flap sander (home made - I'm cheap!) to sand the ends. I don't use the drill at this point, and don't ask why I know this! I hit each piece four times, a ninety degree rotation for each plunge into the flap sander. That finished, it's on to a flannel buffing wheel charged with red rouge, resulting in a polished surface. The next step is to cut off the finished plug from the blank. My past experience with trying to cut off small pieces like this with the table saw is not good, even with an 80 tooth cutoff blade, so I use the bandsaw with a fine tooth blade.
This step is critical, as one needs to cut off the plug to the proper length so that it will stand proud just the right amount, and so that each plug is exactly the same. I decided that the "ripping gauge" recently described by Ernie M. could be used equally as well as a cutoff gauge. I made a small sled for the band saw with a runner that fit in the table slot and a fence at right angles to the direction of cut. I cut a dado in the sled to accept the runner of the gauge. Using a digital caliper, I measure the depth of the recess into which the plug will be inserted, and also measure the height of the "crown" on the plug itself. The sum of these two measurements equals the distance from the blade to the tip of the guide, or in other words, the total height of the plug. Now, it's just a simple matter of placing the blank, with the steel rod still attached, against the fence, advance it to touch the guide, slide the guide back out of the way so that it doesn't trap the cut off piece, and then slide the sled forward, cutting off the plug. Repeat with the other three blanks. Now we have 4 finished plugs and 4 blanks ready to repeat the process.
The first time I tried this, I made 40 plugs in about 50 minutes, and they were all exactly the same, at least as far as I can tell. Since then, I've made more, and am somewhat more efficient. I think that with a minimum of practice, one could make plugs at the rate of about one per minute or less. Once the wood blanks get to within about 1/4 inch of the metal rod, simply remove the remaining wood, and glue another blank in its place, or glue another blank onto the remaining wood stub. The four 4" blanks will make a considerable number of plugs. My recesses were a little less than 1/8" deep, so I was getting about 5-6 plugs per inch, or around 100 plugs out of the four blanks.
I hope a few folks have found this helpful.
Matt
The challenge with this seemingly simple detail is to produce a gently symmetrical, rounded crown on a square plug. It is this "pillowed" effect as Peart refers to it, that stands proud of the surface and presents a smooth visual and tactile feature that is both subtle and distinctive. I am convinced that this cannot be easily done after the square plug has been inserted. It has to be done before insertion, and this requires precision and reproducibility. The main problem for me with the Peart technique was turning a square rod by hand against a rotating sanding disc at a predetermined angle, even with the jig that he describes. The thought of using a drill to turn the rod against an inflatable sanding drum seemed to be a solution for this problem, and is the basis for this technique.
To start, I take a piece of 3/8" diameter steel rod and cut off four 2" inch sections. I then flatten the ends on the grinder as shown in the photo. I prepare 4 wood blanks (in this example I use wenge), 3/8" square and about 4" long. I check these against the plug recesses which have already been cut, making them very slightly oversized to insure a tight fit. Using medium viscosity CA glue and accelerator, I glue the wenge blanks to the ends of the rod, using a block of wood as a fence to align them accurately. This glue joint is quite strong - Billy Mays would be proud! The steel rod/wood assembly is then chucked in a cordless drill. This is amazingly accurate, with little to no run out of the wood blank.
I mark an index line on the table below the drum to help me visually align the blank to the drum at an angle that seems appropriate. After a few times, the angle becomes almost automatic, and I don't have to refer to the index line. I also deflate the drum so that it is quite soft. With the sander turned on, and the drill running so that the wood is turning in the opposite direction, I make a pass along the drum and back. Voila! A perfect rounded crown! Repeat with the other three blanks.
Now it's over to a flap sander (home made - I'm cheap!) to sand the ends. I don't use the drill at this point, and don't ask why I know this! I hit each piece four times, a ninety degree rotation for each plunge into the flap sander. That finished, it's on to a flannel buffing wheel charged with red rouge, resulting in a polished surface. The next step is to cut off the finished plug from the blank. My past experience with trying to cut off small pieces like this with the table saw is not good, even with an 80 tooth cutoff blade, so I use the bandsaw with a fine tooth blade.
This step is critical, as one needs to cut off the plug to the proper length so that it will stand proud just the right amount, and so that each plug is exactly the same. I decided that the "ripping gauge" recently described by Ernie M. could be used equally as well as a cutoff gauge. I made a small sled for the band saw with a runner that fit in the table slot and a fence at right angles to the direction of cut. I cut a dado in the sled to accept the runner of the gauge. Using a digital caliper, I measure the depth of the recess into which the plug will be inserted, and also measure the height of the "crown" on the plug itself. The sum of these two measurements equals the distance from the blade to the tip of the guide, or in other words, the total height of the plug. Now, it's just a simple matter of placing the blank, with the steel rod still attached, against the fence, advance it to touch the guide, slide the guide back out of the way so that it doesn't trap the cut off piece, and then slide the sled forward, cutting off the plug. Repeat with the other three blanks. Now we have 4 finished plugs and 4 blanks ready to repeat the process.
The first time I tried this, I made 40 plugs in about 50 minutes, and they were all exactly the same, at least as far as I can tell. Since then, I've made more, and am somewhat more efficient. I think that with a minimum of practice, one could make plugs at the rate of about one per minute or less. Once the wood blanks get to within about 1/4 inch of the metal rod, simply remove the remaining wood, and glue another blank in its place, or glue another blank onto the remaining wood stub. The four 4" blanks will make a considerable number of plugs. My recesses were a little less than 1/8" deep, so I was getting about 5-6 plugs per inch, or around 100 plugs out of the four blanks.
I hope a few folks have found this helpful.
Matt
