Calibrating an Enlarger Laser Alignment tool .

Years ago I made an eyepiece laser alignment tool to adjust my Dobsonian Telescope.
To get the beam adjusted concentric with the holder I would revolve it horizontally on an engineers Vee block and aim the beam at a wall. Lots of tweeking of the screws until spot on accurate.

I am thinking of making a larger version to use for enlarger adjusting.

This time the tubular body will be be butted up against a Vee block and the beam shone onto the ceiling followed by tweeking until square with the base.

With the circular shaped base adjusting is fairly obvious.

What I am wondering is how are laser tools like the Parallel Versalab tool having rectangular or square shaped bases tested and adjusted at home?

The Versalab alignment laser has no user adjustments.

I imagine if you need a confidence check one could put it on the floor and rotate it by hand and check that the spot on the ceiling doesn't move.

Or align the enlarger with the Versalab and then check the resulting alignment using mirrors.

ic-racer Thank you. I am going to print a copy for future use.

Nicolas Lindan, the circular based alignment tools can be wedged against a Vee block and when rotated with the beam aimed at the ceiling, the red dot should stay in one place if the tester alignment is correct.
I cannot do that with a rectangular housing. No way to keep the dot in the same place.
This is probably why the Versalab cannot be checked and adjusted at home. So you could never really be confident in the rectangular based laser alignment in my opinion.

The laser on my Versalab is adjustable.

Any serious laser tool should be precisely calibrated to begin with. Versalab is kinda an entry level thing. Regardless, I recommend double checking everything with a small machined-edge high-quality level - alas, which you won't find at typical hardware stores or home centers. The best alignment concept is based upon a set of semi-silvered mirrors
likened to an optical collimator. Salthill once marketed a fashion of this suited to enlargers; sometimes they still turn up used. Or you could assemble one yourself from components from Edmund Scientific.

It's hard to level anything well unless you have a suitable dead-flat reference surface. A machinist's block would be characteristic. Then they'd level that with a true machinist's level. Then you'd calibrate your Versalab atop that, or something reasonably equivalent. The key is having a high quality level to begin with, with an actual machined edge. There is a Stabilia torpedo level like that for maybe $50 to $70 these days. A true machinist level will cost somewhat more and be fussier to work with.

How did I do this? I was actually a dealer for industrial alignment lasers at the time, so simply borrowed one from work! Yeah, that was complete overkill in terms of needed precision; but why not?

Really nothing needs to be level at all. The lens axis needs to be perpendicular to the negative glass. Laser alignment makes the cumbersome mirror systems obsolete.

Working off actual level tends to be far more precise simply because a good reasonably long bubble level gives you a much longer reference base than a short little laser (whihc is much better than nothing, but who ya kidding?). Most modern enlarger surfaces aren't even really flat. The best you can do for a reference surface is the carrier glass itself, which hopefully is there. And mirror systems are the most accurate of all at a realistic price because they work on the premise of greatly increased dimensional vectors. Combine a mirror system with a serious laser, and you've really got something. But a tiny little laser by itself .... ? Well, I'm glad one is made, and that people are actually willing to use them. But on the cheap, I'd go with a good level and simple plumb bob any day. But yeah, I'm reasonably familiar with portable laser tools - I've sold thousands of them and been directly involved assessing prototypes etc. Uptick the price, and you can have self-leveling ones.