Question about Hall switches that I am planning to use as limit switches.

@will My understanding is that since the Hall switch is electronic there is essentially no bounce. I had the same question and went looking for the answer. Everything I could find that mentioned debouncing said it was unnecessary. In experimenting with the Hall switches I have, I saw virtually no bounce when doing digitalReads of those pins each time through the loop. I don't have an oscilloscope, so I can't say for sure that there is zero, but it seems from my observations it is insignificant if it's there.

@pritchs 

I have since repented anyway, it's an alarm so de-bouncing isn't required 🙂

@pritchs Having that camera anywhere near a dangerous dusty environment is almost guaranteed to destroy the camera in a hurry. If I had to do that I would use a lens in the neighborhood of 100mm and situate the camera as far away as possible. With any luck the entire 4ft? bed is in good enough view you don't need to track it but in any case you certainly do NOT need pan and tilt, just a slider is sufficient.

As well as a 50+ yr programmer, 50+ year photographer, I also once had a full wood shop so I understand what you need.

A 100mm lens 20ft away will have everything between 17ft and 24ft in good focus. 20ft puts the camera out of flying debris range but I would still have a lexan shield in front of the camera since it's about a $3,000 total investment body and lens.

The other option I would give serious consideration to is a security camera. That may still require a slider. If you want to 'up your game tech wise, get rid of the joysticks and use artificial vision to follow the turners hands and position the camera with that input. But start simple.

@pritchs Strange set up, never seen a single rail slider before. I am afraid my camera, battery pack, 100-400 lens would be a bit too heavy for that.

@will HUH, series, I don't see any way to use parallel unless they are on different pins each with its own logic. I have worked with this arrangement both in steel mills and elevators, always in series.

@zander 

The switch is normally open so it doesn't consume any power until the arrival of the carriage presses it closed.

@zander Ron,

I understand your concerns and they are certainly a reality. However, the environment we have is significantly different than that of a woodshop. Depending on the club, woodturning demonstrations are almost always outside of a woodshop environment. In a Woodcraft or a senior center or the basement of a church, etc. Wherever someone will allow a group of (mostly) old guys to meet. There is seldom more than the slightest bit of sanding and many places don't allow it at all. Almost everything else that comes off a lathe is larger than what most people consider dust.

As for debris, yes, I have seen things fly off the lathe during demonstrations. In fact, once or twice I was the demonstrator. 😀 Most things that come off a lathe don't go vertically. Some do, and if they do, they are usually moving at a pretty good clip. I've got around 11K-12K hours in front of a wood lathe, so I've seen most of what it is likely to do. 😆 

My club uses (and most clubs do) a Canon video camera that's in the $300-500 range new. Our needs are HD, and we do share live demos over the internet, but we aren't in the business of producing professional quality material so no high-dollar equipment is required. In addition, the equipment is generally used for a few hours a month and so its time of exposure isn't high.

@will And a piece of flying wood off the lathe breaks the wires rendering it useless. The amt of power a NC uses connected to a pin is ma if not ua and he is connected to a beefy battery pack or plugged in any way.

@zander 

Or strikes the camera. Game over anyway. I much prefer your remote camera with the lexan shield concept.

@pritchs So what is your point? Just mount the camera overhead with a wide enough angle view.

@pritchs What is weight of video camera?

@will I figure the lexan shield covers everything, it only needs to be about 1 ft by 5 ft, 1/8 to 1/4 thick (I don't know breaking strength)

@zander Hey Ron,

I lost track of where this comment came from, but I'll do my best. 

I'm not a professional programmer, but I have been programming computers off and on since I purchased my first one in about 1978. That was when, if you wanted a computer to do something, you had to make it happen. I have dabbled in assembler (ugh), done a fair bit of Lisp, some COBOL, quite a bit of Unix/Xenix/Linux scripting, a bunch of SQL, and some Basic. I spent the last decade of my working career as a systems administrator and IT manager in the Federal Courts. As an SA, I supported a Unix, then Linux automated case management system, then as a manager had that as well as several hundred PCs on a Novel network to worry about. So, some experience, but a professional programmer? Not by a long shot.

I have been an amateur photographer for 40+ years and I do my own photography for my turned artistic pieces. I do a more than a passable job at that IMO, but again, a professional? Nope.

I hope this helps answer your questions.

@pritchs It sounds like you are in USA. I am in Canada, and using a wood lathe in any church or public space would cost a fortune in insurance and would most likely be not allowed in any case. I don't understand what you are doing at all now that I know that.

@zander Ya, a single rail like the guy in the video was using is a little optimistic IMO. My plan was to use 2040 extruded aluminum which I think would do nicely.