There are more words but they are from Tolkien's earlier conceptional periods. Tolkien likely changed these words as he evolved the aesthetics and completeness of the languages. You may even find languages that Tolkien later rejected. Do not mix words from different time periods unless you are familiar with the phonetic developments.
saptha-
verb. to dig, bite into
dol-
verb. to dig
A verb appearing as {dal- >>} dol- “dig” in the Gnomish Lexicon of the 1910s derived from the early root ᴱ√ndolo (GL/30). This root was glossed “delve” in the contemporaneous Qenya Lexicon (QL/65).
Below: Tolkien's Late Period (1950–1973). These are from Tolkien's late conceptual period — his most settled forms of the languages. Prefer these over the earlier ones above when composing new text.
A verb appearing as G. saptha- “to dig, to bite into” in the Gnomish Lexicon of the 1910s based on the early root ᴱ√SAPA “dig, excavate” (GL/67).
Neo-Sindarin: The root √SAP reappeared in Tolkien’s later writings, but for purposes of Neo-Sindarin I would adapt G. saptha- as a basic verb ᴺS. sab- “to dig” to avoid questions of how its phonetics would have changed in later Sindarin.