I’ve seen photos and drawings of these Berg “Trident” mortise chisels for a while and have continued to wonder about their use. Recently, I acquired a #930 model and decided to put together this post.
I dug around and found the 1965 Bahco Catalog #2715. On page H-10 was the information I needed. The chisels were used for recessing locks and hinges. They were both designed to clear out shavings from the recesses. To be honest, I’m still trying to envision how to use these chisels properly.
The chisel below is the Berg #930 version. It is all steel and 8″ – 200mm long. The handle looks quite sturdy, but the blade looks rather thin and delicate. It is only 3/32″ – 2mm thick.
Someone obviously used this chisel You can still see wood fibers embedded on the blade. It looks like the serrated portion of the blade grabs wood chips well.
The #930 model number does not appear on the chisel. However you can see “26 – 2,0mm” stamped there, along with the Berg shark with “SWEDEN” underneath it. The 26 indicates that the blade is 26mm – 1″wide and the 2,0mm indicates that the blade is 2mm – 3/32″ thick.
Below is the #930 G version of this Berg Chisel. All of the photos below are courtesy of Randall Nelson, another Swedish chisel fan and frequent contributor to this blog.
The Berg #930 G version is also all steel, but is only 7″ – 175mm long. The blade is the same thickness as the #930 — 3/32″ – 2mm thick.
Like the #930, the #930G model number does not appear on the chisel. On this example you can see “31 – 2,0mm” stamped there, along with “E.A. BERG” above the Berg shark. The 31 indicates that the blade is 31mm – 1-1/4″ wide and the 2,0mm indicates that the blade is 2mm – 3/32″ thick.
Here’s a closer look at that trident-style blade.
As unusual as this style of chisel seems, it’s possible that they were more widely used and seen in Europe. Randall Nelson sent me this photo of a similar looking tool from Germany. Although it’s not Swedish, it’s interesting enough to be included here.
If anyone has actually used this type of chisel on door locks or hinges, I would love to hear more details on how you used it. You can reach me by emailing me at the address shown in the “Contact” area.