Reader: OK, so I need to build a testing setup of some sort, which will be permanent. That means it will sit in my lab and be ready for use, so I can just walk in and make measurements in a few moments, without wasted setup time. It should be permanent for at least a year or more. My boss suggests I use an Optical Breadboard Bench and set up my components on that. Is this the best way to go, in your opinion, Tony?
Tony: Well OK, in my opinion, NO it’s not the best way to build a permanent testing setup. Unless you need the actual features of a Breadboard Bench, which I discussed in my last post, I recommend you do not use that Breadboard. Why? Several reasons come to mind, which have all happened to me before. First and foremost reason: You just got that testing setup perfected and it works really great. It has been 2 weeks in the lab, left undisturbed and willing and able to help you test stuff. Suddenly, some engineer with way more clout in the company comes in and NEEDS that bench for his testing. Since the boss respects his clout more than yours, your equipment comes off the bench and his goes on. (In companies, clout counts, and not necessarily common sense.)
Second reason, with Breadboards, those evenly spaced 1/4″ x 20 tpi holes seem convenient at first glance, but when you go to install your hardware exactly where you want it, those holes always seem to be in the wrong place. Off by 3/32″ or some other equally dumb amount. Either you have to monkey around with several adapters to get stuff to fit right, or you have to file holes into slots, so they are almost breaking out from the metal surrounding.
Third reason, hardware made for breadboards often rely on post holders and posts to hold components. It’s supposed to be convenient. Well maybe in the university lab it’s convenient to set up some demo or some experiment for teaching principles to students. But in a real-life testing setup, when you’re counting on it to work right every time, not so much. The first time that manager person comes into the lab to show your brilliant test setup to some customers, and bumps the detector (sitting on a post in a post holder) with their elbow, your detector (which took all day to align) is now facing the calendar on the wall instead of the light beam’s axis! Hey, you can easily bump it with your own elbow too.
Reader: Well what am I supposed to do, Tony?
Tony: Get yourself a nice thick piece of aluminum tooling plate which will be as long and as wide as you would ever need. Aluminum tooling plate is pretty flat on both sides, too. Attach your optics, adjusters, electronics, detectors, etc. exactly where YOU want them to be, by drilling and tapping that plate for any size screw you think is appropriate for the task. (Does not always have to be 1/4-20 screws.) YOU are making the decision on where those tapped holes shall be, not some mechanical engineer who is just designing a product to sell. For goodness sake, do use machine screws though. Wait, you don’t know how to drill and tap holes in aluminum? For goodness sake, you had better learn how to drill and tap for machine screws, and soon! Unless you have a good technician or a good machinist who is always at your beck and call, you had better get proficient at drilling and tapping, in aluminum, steel, and soft plastic.
One final thing. To support your optics and equipment, do not plan to use posts and post holders, unless there is a compelling technical reason for using them! Learn how to mount stuff on brackets which are firmly bolted in place and can not rotate or move the first time a person (you or the manager) accidentally bumps them with their elbow. You can buy nice construction components or construction kits, with brackets and cubes, etc. If the equipment is shaped weird or is big and heavy, make your own brackets. Learn how to design and make your own brackets and mounting hardware to suit a specific application. Mount components on that tooling plate rigidly, as though it had to go into space.
Reader: Machine metal? Are you nuts? Tony, I am terrified of using a drill press, much less a mill or a lathe!
Tony: OK. Machine tools are dangerous and you should always get proper training on how to use them, safely! So, in that case, get that good technician or a machinist who is always at your beck and call to fabricate the parts you need. If your company, school, etc. does not have a machine shop and machinist at all, you can design the parts, even if you have to do it on the front of an envelope with a pencil, and take it to a local machine shop in your town, to get a quote. Most machinists can make things like “brackets” to hold optics or components on a plate, without any trouble. By the way, when you find a good machinist and shop you trust, do cultivate their friendship and give them your business. They can be life-savers in industry.
Mount your optical testing stuff on that plate. Do your testing. If that engineer with all the clout comes in and needs the wooden table you have your tooling plate sitting on, (sigh) you and your technician can pick up the plate with its permanently mounted testing setup and equipment, and put it on your desk in your office for a few days, if need be, while that guy does his tests in the lab. Here’s the point my friend: If that tooling plate and its rigidly mounted components are really put together well, you should be able to pick it up, move it to your desk, then bring it back later, and still have it aligned and working fine! Do good work!
Optics Lab Tips and Tricks 