Timed relay control

Hey Tom,

Always a problem to get anything electronic to "delay" AFTER the power is removed. But an air-check armature type will. I have a handful of Allen-Bradley 115 VAC, if you want to give me a snail-mail and you can wait long enough for them to get there, they will be free.

I think if it was me, I'd be leaving the air on to the nail-guns and setting the nail guns to "bump-fire".

Take care.

Brian Lawson, Bothwell, Ontario.

Some guns we used, notably Bostich, were very slow to respond. If a customer felt it was in their best interest to stay with the Bostich we would add a small poppet valve right on the gun, and just use the brief trigger pulse to fire the valve which fired the gun; this was much more reliable. When using other guns we always made sure the firing valve was as close to the gun as possible (1 to 2 feet) and this was always enough to get fast firing times (while the guns were in motion by the way). The small poppet valve was a Humphry and supplied by Bostich. The main firing valves we used were ARO 3/8".

Although you don't mention specifics, another idea Engineering came up with was to use a coil of vinyl tubing before the item you wanted to delay the return of. The idea was to delay the movement of the cylinder until the entire coil/reservoir/cylinder pressure had dropped sufficently to allow the assembly to move. It worked fairly well in non-critical applications.

Good luck.

dennis in nca

Thanks, I graciously accept your offer and will gladly trade you some brushes. I can't bump-fire as we have eliminated the safeties and modified the noses to fit in between rows of wire. see:

for an address. I'll need yours.

If it were me, I would parallel the NC contacts on the limit switch with a set of NC contacts on a pressure switch that senses the pressure on the triggers. Your holding relay would then not drop out until you achieve full pressure on the trigger line. This setting can be set high enough so that the trigger operates before this setting is reached thus giving you a delay. If needed, you could put a restricter in the line to the pressure switch to tune the timing.

Trying to wrap my mind around the difference between on and off delay here, but just happened to be looking up this little beast for my work today.

Other than being the opposite 'on-ness' think it is about what your looking for. A local supplier claims to have them in stock for around $32.

We have a small automatic router that was built in house years ago and uses several of these timers. (Simply cuts a rectangular hole in the top of small plastic boxes) Yours truly been tasked with building a new one... Hopefully a bit less kludgie than the original:)

The old timers have held up well despite the rough treatment they have received so I plan on using the closest one still available in that series.

Ron wrote in news: snipped-for-privacy@yahoo.com:

That was also my thought on a solution to the problem.

I would post this in alt.engineering.electrical to see if a capacitor wired parallel to the air solenoid might give you the added time.

The ohm reading of the coil and working voltage would also be helpful if you post there.

The capacitor value would determine the time so it might involve some trial and error to synchronize the timing.

Just a thought.

Use a spring to push the trigger for a longer push or use a flow control valve in the push side of the cly for slower action...

Yes, an off delay would do the job, I read Off delay, retriggerable, one shot to mean: after the trigger is removed, the relay waits a period before releasing, this period can be reset by supplying a pulse to the relay before it has reached off time, and one shot means the relay only needs a pulse, not a continuous trigger.

Other options might include using a limit with a long flexible stick to trigger the air guns just before the lift tops out, thereby letting the last tenth of a second of lifting be your delay. Or triggering the down action by a pressure switch triggered by the exhaust port of the nail guns, thus ensuring that the guns have cycled before letting the completed assembly down.

Stuart

"On delay" means "Delay before turning ON"

"Off delay" means "Delay before turning OFF"

Some relays need an electrical signal to "re-set" Some re-set themselfs.

All gun manufacturers manufacture "remote triggers" for their guns, Many of these triggers replace the mechanical trigger parts. Some "remote triggers" are mounted in other pos- itions. All mechanical triggers I'm familiar with are dis- abled by the installation of the "remote triggers."

Rarely I've seen "remote triggers" actually move a mechanical part in order to fire the gun, all others are plumbed to valving within the gun.

dennis in nca

dennis in nca

Hey Tom

OK. Got the street address. I'll send some. How soon do you need them? Actually, no doubt about it, better if I send them from Michigan late Friday or early Saturday. I have to go to a meeting for NAMES in Ann Arbor, so it's very easy for me to get them across the border rather then the goofing around with US Customs Forms sending from here. So, forget I asked.

I'll box up a few and send them..how?? USPS, USPS Priority, UPS, DHL, Fedex.........whaaaaaatttt???? Lemme know soonest.

Take care.

Brian Lawson ps...they are free to you. I got a bunch I didn't even bid on at an auction a week or so ago. Didn't even realize there were any of this type in the drawers until I was sorting through all the crap I got. We used these same ones on older elevators, so they were a surprise but familiar type.

XXXXXXXXXXXXXXXXXXXXXXXXXXXXX

Send me your e-mail address and I'll send you my UPS and FedEx numbers tomorow, I forget them and I'm at home now, having a cup of shade-grown coffee...Mmmm!

Hey Tom,

Too late. I'm off to Detroit right now, so it will be either UPS or FedEX, depending on what office I get to first.

Brian. XXXXXXXXXXXXXXXX

Sorry, I didn't get in to the office until late, I'll send a check, send me your address. THANKS!!!

According to Tom Gardner :

[ ... ]

First off -- if your relay controls are DC powered and not AC powered, there are relays from old phone systems which would serve you well. The normal relay has one or two coils wound on the center soft iron core (about 3" long IIRC), and that one is quick both in pick and in release. The ones which I am describing below were made by Automatic Electric and Claire -- among others.

Then you take one of the two-coil ones and replace one of the coils with a slug of copper occupying the same space. If the copper slug is closer to the moving arm of the relay, it will be slow to pick, and only slightly slow to release.

If the copper slug is closer to the base of the relay, then it will be only slightly slow to pick, but quite slow to release, which is what you want.

Ones made to be slow in both have the copper as a thick-walled sleeve around the core with the winding around that.

Now -- there are other ways to do this. That copper slug is a shorted turn. You can get some of the same effect (a bit less delay) by putting a short circuit across the terminals of a second coil -- at the base if you have a choice. And to make it still as quick pick up but slow release, use a spare pair of contacts to short the second coil's terminals only once the relay has actuated.

Or -- you can connect a capacitor across the coil's windings, with a diode to isolate it from the control power when the relay turns off. (Again, you need DC relays for this.)

Or -- get a relay with a dashpot which can either be slow to pick or slow to release, depending on the design. Those can be DC or AC.

That is an electronics description of the behaviour which you want. It will need steady power independent of the control signal. The "one shot" is a circuit which goes through its time cycle once per input pulse. The real question is whether it can be adjusted to turn off quickly enough so it does not slow your production.

Good Luck, DoN.