Vacuum loss auto shut down

[MooreBroCo]

My apologies if this has been covered before but I couldn't find it if it has.

Has anyone figured out how to wire the emergency shut off switch to a vacuum gauge/sensor?

We are machining small plastic parts using a custom gasket spoil board to hold them with a 25"-Hg vacuum pump. See the pictures below.

https://goo.gl/photos/TmZ9zJaQXasuhzP56
https://goo.gl/photos/cBpJ2Hq5nzNm26iFA

It works really well until it doesn't. If one of the parts has a chip under it and jumps off you lose vacuum for all the parts and if you don't catch it right away can trash the rest of the stock and the spoil board.

What I would like to figure out is a way to have a sensor on the vacuum system so that if it drops below a certain level it trips the emergency stop. Has anyone done this? I am sure I can figure it out but would much rather copy someone else than start from square one.


Thanks

Oliver
Moore Brothers Co

[srwtlc]

You could hook up your sensor to an open input and then set that input (VN) to either normal open stop or normal closed stop, whichever is right for your sensor contact type.

You could also put it inline with the E-stop, as long as it is of the proper contact type (Normal Closed for newer tools), but would probably want a way of bypassing it when doing other jobs.

Another option would be to have set as a 'standard switch' input and then in the file, monitor that input and if it is true, it could be told to PAUSE and give you a warning message. More complicated, but should work. Likely that you would loose position with any of these and you'd need to reset. Not a big deal if you set it up at the start and just C3 again.

[MooreBroCo]

Right but a pressure sensor isn't going to be an open/close switch. You need some way of taking the pressure reading from the sensor and setting a limit that triggers a switch. The sensor needs to have a set point at which it triggers the input like you said. I think I can do it with a pretty simple raspberry pi setup but was hoping some one would know of a less custom solution.

[bleeth]

Pretty sure Jerry is talking about a gauge you might find from the following google search.
https://www.google.com/search?sourceid=navclient&aq=&oq=switched+pre&ie=UTF-8&rlz=1T4GGHP_enUS638US638&q=switched+pressure+gauge&gs_l=hp..2.0j0i22i30l4.0.0.0.9873...........0.LkG5 LcHqVH0
I've seen it discussed but haven't seen anyone define what gauge or their source.

[srwtlc]

Yes, wrong terminology. You just need some kind of vacuum switch that will go Open or Closed when the vacuum drops out. Should be easy enough to find one that would do the trick. After that, all you need to do is wire it to an input and set it accordingly in SB3.

[Brady Watson]

Be prepared to spend some money. You'll need a decent sensor (times the number of zones you want to monitor), an arduino (much easier and better suited to the task than messing with a Raspi) and some time to tinker. You can get fancy with an LCD and rotary switch to navigate through menus and set your trigger points. Then, just output a signal and 'listen' for an input (whatever one you have setup) in SB3.

Nobody here that I am aware of has done this, so plan on doing lots of your own research. I suggest checking out Ebay for vacuum switches and transducers, avoiding the cheapest ones, and the Arduino forums for the code. It's best to copy/paste something that is known to work and hack it to fit your needs for testing.

Components have gotten a lot cheaper but it still may be a big number when you factor everything in. Personally, I would not want it to stop the machine, but do some kind of corrective action like shutting off the 'troubled' zone. There are lots of ways to do that but they cost money. For comparison, I think it was somewhere around $1000 to pneumatically control my vacuum zones & that was with me building my own actuators using Gary Campbell's fine example...

If you do wind up doing this project, please post up your findings so that others can follow your lead.

-B

[MooreBroCo]

Pretty sure Jerry is talking about a gauge you might find from the following google search.
https://www.google.com/search?sourceid=navclient&aq=&oq=switched+pre&ie=UTF-8&rlz=1T4GGHP_enUS638US638&q=switched+pressure+gauge&gs_l=hp..2.0j0i22i30l4.0.0.0.9873...........0.LkG5 LcHqVH0
I've seen it discussed but haven't seen anyone define what gauge or their source.

Wow. It always amazes me how close and yet so far you can be with a google search. I figured they had to exist I just couldn't find them. And they popped right up on your search:

http://www.omega.com/pptst/PSW-500.html?pn=PSW-521

Those guys look like they might do the trick.


Thanks for the help.

Brady, I hear you and that was why I was really hoping someone had already done it. For each set up we are only running one zone so I figured a stop and a deal would be my only option.
My brother (and business partner) has been playing with raspi parts making cameras and the tinkering time is significant for sure.


Now to go find some of that spare time...

Oliver

[knight_toolworks]

maybe this is a way to go thats practical. when I built my vac pump for a vac bag the kit had a pressure switch to turn the pump off and off. I doubt it was too much since the only thing was about 100 or so. but all you need to do is hook it up to a flashing light maybe not quite as good but it is a simple solution.

[donek]

I've started on a similar project, but I'm in my busy season, so it will wait until summer. There are a couple of approaches you can take.

1. The simplest is likely using a pressure switch from joe woodworker and connecting to an input. You don't want to hit an e-stop as that can result in lost steps and the need to reset your axis locations. A few relatively simple lines of code that calmly stop the machines motion and display a warning is all that is necessary. The part would be:
http://www.veneersupplies.com/products/Vacuum-Pressure-Controller-18-NPT.html

2. A programmable system that gives greater monitoring of other components in your system might include a plc or an adruino utilizing a barometric pressure sensor. This requires more programming and some elctronic experience. but can be used to perform a similar task of machine shut down based on vac pressure or any other sensors you might wish to implement.

[MooreBroCo]

I've started on a similar project, but I'm in my busy season, so it will wait until summer. There are a couple of approaches you can take.

1. The simplest is likely using a pressure switch from joe woodworker and connecting to an input. You don't want to hit an e-stop as that can result in lost steps and the need to reset your axis locations. A few relatively simple lines of code that calmly stop the machines motion and display a warning is all that is necessary. The part would be:
http://www.veneersupplies.com/products/Vacuum-Pressure-Controller-18-NPT.html

2. A programmable system that gives greater monitoring of other components in your system might include a plc or an adruino utilizing a barometric pressure sensor. This requires more programming and some elctronic experience. but can be used to perform a similar task of machine shut down based on vac pressure or any other sensors you might wish to implement.

That is definitely a more affordable option. I will see if I can make it happen.

I started looking through your youtube channel again last night. I really like your press temperature controller. Very slick. We've started batting ideas for something similar. I really like the enclosure that lays flat. Much better than jamming it all in the grey box that is too small. We need to sort something out better than our current temp controllers if we are going to start curing prepregs in house. Our current move is to use an autoclave at another company down street.

I am also super jealous of your edge bender. We are chasing the custom ski dream as well and have dreams of making something like your bender.

[donek]

That is definitely a more affordable option. I will see if I can make it happen.

I started looking through your youtube channel again last night. I really like your press temperature controller. Very slick. We've started batting ideas for something similar. I really like the enclosure that lays flat. Much better than jamming it all in the grey box that is too small. We need to sort something out better than our current temp controllers if we are going to start curing prepregs in house. Our current move is to use an autoclave at another company down street.

I am also super jealous of your edge bender. We are chasing the custom ski dream as well and have dreams of making something like your bender.

The bender is available for sale, at least the mechanical portion. We are currently developing a cam package for it. You are welcome to contact me for details. The programming for that controller is pretty extensive. We have considered offering it as a completed until. We can discuss that as well. Having a full time programmer on staff certainly helps in putting this sort of thing together.

[knight_toolworks]

see you could have the pressure switch activate a solenoid that drops something on your keyboard right over the enter key. see rube goldberg all the way.

[RossMosh]

This is what I'd do. There are some blanks you need to fill in that I can't help you with but I'm sure someone else could as it's pretty simple stuff.

Go buy get a MAP sensor. You can get one off a lot of cars if not, Motorolla make a bunch of them for less than $20. They are very simple. You feed them 5VDC constant and then it outputs a 0-5V signal which corresponds to a pressure. You can either use the formula from the provided PDF or simply use a multi-meter to get a real life reading. Now is the part I can't help with, but I can outline what you need. The first is to get a project board and using off the shelf components setup a pretty basic setup so that when your voltage goes higher than X, it trips a 5V signal which goes to your board, which automatically stops your program. The second is to buy some sort of Arduino board. Same principal. Feed the 0-5V signal in. Program so that if the voltage goes higher than X, a 5V signal goes to your board.

[BrandanS]

MooreBro,

You can buy pressure switches with windowed limits which even have a nice hysteresis feature and response rate adjustment. Set your limits, and wire to an input or E-stop.

Omron sells a version, although perhaps you can get a cheaper one if you look around. The dynamic hysteresis, you can prevent false positives from vacuum fluctuation if necessary.

https://www.ia.omron.com/products/family/506/

http://www.smcusa.com/top-navigation/cad-models.aspx/39459



Have a look at cost vs. requirement.

Good Luck.

**Edit: Just found a price for the SMC version @ $84 USD online from the supplier themselves. These switches may be interesting, even if you're not using them for their switching action at times, but in fact for the actual Readout for your vacuum efficiency ;) .

[Joe Porter]

How about ball check valves such as these http://www.m-powertools.com/products/vacuum/ball-valves.htm or http://www.vacmotion.com/Vacuum%20Components.htm or this http://www.vuototecnica.us/solutions8.php they seem to be pretty specific for holding and not loosing vacuum if the material shifts...joe

[MooreBroCo]

How about ball check valves such as these http://www.m-powertools.com/products/vacuum/ball-valves.htm or http://www.vacmotion.com/Vacuum%20Components.htm or this http://www.vuototecnica.us/solutions8.php they seem to be pretty specific for holding and not loosing vacuum if the material shifts...joe

Those ball valves look pretty cool. I'm not sure if they would work in our current setup as we have around 200 parts in a 4'x3' sheet but they might be really good in the right situation. Thanks for the find.