For the past year I have been working on wood threading. I have been in the machine trades for more decades than I like to remember. I have cut countless thread in metal by many different means, both internal and external. However, wood is a very different medium. Tapping internal threads in wood is a pretty straight forward operation. Cutting the external threads, I soon learned, is an entirely different matter altogether.
My first attempt at cutting external threads was with the old thread box method. It worked, but it was fussy as to the kind of wood used. Maple always chipped the cutter and hard maple was my wood of choice. The cutter was near impossible to get properly sharpened and a new one is $15. It didn’t take long for me to realize that this method was not going to work for my needs.
My research led me to several methods for cutting external threads in wood. One of these methods was the Beall Wood Threader. This tool looked good to me so I ordered a Beall 1 ¼” Big Threader from Lee Valley and paid full price for the tool. I have no connection with Lee Valley or the Beall Tool Company and all of the usual disclaimers.
The threader arrived in a couple of days. When unpacked it was clearly a quality tool. The instructions were clear. I’m not going to waste time going through a step by step setup. Beall gives plenty of information on their website. The directions are very clear and you can view a two part video tutorial by J.R. Beall himself here.
First a nut was made using the supplied tap. I wanted at least a 1 ¾” thick nut so I cut the threads in a 2” thick piece of hard maple. This is a very good tap and a guide plug is included that attaches to the bottom of the tap and helps to guide the tap straight in the hole.
Now on to the ever so troublesome external threads. The Dewalt D26670 trim router was the trimmer of choice. The threader was setup per instructions using this trim router. Then the first of what would prove to be many test cuts was made. The tool cut a very clean thread, but when tried in the nut the threaded dowel would go less than half way into the nut and bind up. When I checked the external threads the pitch was not correct. The 1 ¼” threader produces 5 threads per inch, but when I measured my threads the pitch was off almost 1/16” in one inch. This is why the threads were binding up. Apparently the cutter was not located to the threads in the white plastic bushing properly. Many attempts were made to correct this problem with little success.
The supplied locating bushing must be removed before making any cuts. In order to remove this bushing the router must be removed from it’s base and reinserted into the base. I thought perhaps the locating system between this router and it’s base was not accurate enough for this tool causing misalignment when the router was reinserted into it‘s base. So I purchased a Bosch PR20EVSK trim router which has a much more accurate mounting system in it’s base. With the new router there was still no improvement.
According to the directions thread pitch errors are caused by misalignment of the cutter in the white plastic bushing. I also learned, any deviation from perfect alignment is cumulative. That is, if the misalignment is 0.010” then at 5 threads (1” in this case) the error is 5 times that or 0.050”. That is an error of almost 1/16”. At the 2” internal thread length that I wanted that error would translate to 0.100”. That is a full half thread at 5 TPI (Threads Per Inch).
Now I turned my attention to the locating system provided by Beall. The inside diameter of the aluminum locating bushing was checked along with it’s outside diameter that locates in the white plastic bushing. These diameters were within reasonable limits. Then the hole in the white plastic busing that accepts the outside diameter of the aluminum bushing was checked. This was found to be bigger than it should have been.
A call was placed to the manufacturer and a human answered the phone! I thought I had a wrong number. After talking directly to J.R. Beall, the owner, it was determined that the white plastic bushing was defective and a new replacement would be sent. Two days later I had a new plastic bushing and a new aluminum locating bushing. Using these new parts the tool was again setup and a new maple dowel had 1 ¼” – 5 threads cut into it. When tried in my 2” long nut it was much better, but the threads still would not go all the way through without binding.
Thinking carefully through the entire process I began to suspect that I was asking too much of this tool, asking something that this tool was not designed to do. Another phone call to the manufacturer, and yes the call was again answered by a human, and another conversation with J.R. Beall pretty much confirmed my suspicions. There was just too much opportunity for error in the setup to allow the threads to work smoothly through a 2” long nut. I needed to figure out a way to setup the tool a bit more accurately and to cut down the length of the nut.
Pictured above is the setup method I came up with. First I set the tool up per the manufacturer’s instructions and took a test cut to determine the error. Then a scrap piece of steel was clamped to the left side of the tool against the router base to keep the router from moving side to side as I made front to rear adjustments to minimize the error. This can be clearly seen in the next picture. Now the dial indicator could be used to show precise amounts of router movement front to back. After a couple of tries this setup allowed me to cut a thread that would work freely in a 1” long nut.
The Beall Tool Company threader cut a very clean thread, both internal and external. No chip out was observed in hard maple. This wood was impossible to thread using the thread box that I had tried previously. The Beall has produced the cleanest threads that I have done to date. This tool will work extremely well for nuts under 1” long. If used within it’s design limitations the Beall Threader is a great tool and a lot of fun to use.
The Beall Tool Company’s customer support is the best I have seen in a very long time. The threader is a good tool made and supported by a good company. And even though it didn’t serve my needs I can recommend this tool.