Is there a standard format for the start of each column in writing Sifrei Torah?

Question

When I looked at a few Tikunei Lakor'im, they seem to follow what appears to be a standard where certain words begin at the top of a column. I did see several Sifrei Torah that seem to follow this format that the Tikkun has. As a matter of fact, sometimes, when we have a Bar Mitzvah in the shul, the rav informs me before Shabbat to make sure that the chazzan takes out this special Torah, as otherwise the Bar Mitzvah boy will be completely confused when he lains.

I know that there is a mnemonic that certain words such as "Mah Tovu" should start at the top of a column. Other than that, it seems that most Sifrei Torah are "randomly" written.

I'm curious if there is a "preferred" format or "standard". Where is the Tikkun getting its standard from?

Main reason I'm asking is that the Sefer Torah for the Bar Mitzvah that meets the standard, may have a large section that cannot be repaired, easily. We may have a 2nd one formatted the same way that also cannot be repaired. I was thinking of taking a section of parchment from one (whole klaf having several columns) and piecing it together to the other one.

Answer 1

Standard Sifrei Torah today have 42 lines in each column. While there are different opinions how many lines a Sefer Torah should be (See Keses Hasofer 13:6), this has not developed solwly out of Halacha.

There's a good article about how this came to be here

Until some 30 years ago, Sofrim didn't really have a good tikkun to copy from. They either used Chumashim, old codices like the Berdichev Codice or another Sefer Torah, until the renowed Sofer Davidovich took on himself to write a Tikkun for others to copy from, arranging all the Torah in Amudim of 42 lines. Now that's the important piece of information - 42 lines. In this arrangement, Davidovich's tikkun had 245 columns ("amudim"), and after some feedback from fellow Sofrim, who said that the lines where too "cramped", Davidovich made a longer, spaced up version of 247 Amudim...

From then on, the 42-lined Tikkun became the standard tikkun all Sofrim used. For that reason, I understood why the Tikkun of 45cm I purchased from my tutor was also made for a 42 lines tikkun - this is virtually the case in all modern Sefer Torahs you will see.

Answer 2

There are two factors determining the start of columns in sifrei torah:

1. Halacha requires that certain words be at the top of the column. The acronym for these words is בי"ה שמו, the mem of which is מה טובו as you noted.
2. Despite the best efforts of earlier poskim including Keset Hasofer, it is traditional for all other columns to begin with the letter vav (this practice is called ווי העמודים). This is so common with modern (post war) sifrei torah that people have asked me if sefarim without it are kosher.

The two standard tikkunim today were both produced by a Rabbi Menachem Davidovich of Jerusalem. In a way he is the preeminent sofer, having practically standardized not only the tikkun but many stylistic details in the script.

The practical part:
Yes, you can salvage a sheet from one pasul sefer in order to repair another and if both have been written within the last 30+ years they are probably standardized to one of two tikkunim. The easiest way to figure out which one your sifrei torah were copied from is to count sheets. A 245 column sefer will usually have 62 yeriot (sheets) while the longer one will have 63. I would guess that the "bar mitzvah torah" is 248 columns long because most tikkunei korim are for that layout.
I would not recommend doing it yourself because sewing parchment can be surprisingly difficult. You may also run into problems because sofrim sometimes end a word or two sooner than the tikkun calls for.