Air cylinder speed

If you know anyone that is an electronics hobbyist or ham, they'll probably have an oscilloscope, a counter or both. That and a couple of photosensors or hall sensors would tell you elapsed time between two points quite accurately.

You could get an estimate with a hex nut, a ruler, an assumption and a calculator. The assumption is that the piston accelerates linearly throughout its travel, probably not a bad assumption in most cases.

Orient the cylinder vertically. Put the nut on the piston. Actuate the piston, note how high it shoots the nut assuming that it doesn't hit any sheetrock, skylights light bulbs or pigeons.

The final velocity of the piston in ft/sec is the square root of

2*height*32.2, where height is in feet. Average velocity is half of final velocity, elapsed time is stroke (in feet) divided by avg velocity.

If it moves 4" in 50 mS, avg velocity is 6.667 ft/sec, vmax is twice that (if the assumption of linear acceleration is correct), the nut will reach a height of 33.2 inches or 2.76 feet. OK the ceiling is safe,load one (1) nut and fire for effect. Ready on the left....

If it shoots the nut up 20 inches or 1.667 feet, vmax is sqrt(2*1.667*32.2) or 10.36 ft/sec, vavg is 5.18 ft/sec, stroke is

0.333 feet (4 inches) so elapsed time was .333/10.36 or .064 second.
Reply to
Don Foreman
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Assuming you are controlling this machine with a PLC, you might be able to time the reed switches with the PLC, If the scan time is fast enough.

stan

Reply to
sbaer

This can still work if the cylinder is horizontal. Just hang the weight from a long piece of fishline, like a pendulum, and push the nut with the piston. Use the same equations to convert height to maximum velocity. The mass of the nut and length of the string don't matter. Energy is initially all kinetic (velocity), all potential (height) at max height in both cases.

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Reply to
Don Foreman

"Tom Gardner" wrote in news:E5M0h.16842$ snipped-for-privacy@newssvr29.news.prodigy.net:

Tom, Set up a prox sensor that is just made when the cylinder is retracted and a prox switch at the end of stroke. Use the PLC high-speed timer to determine the time, triggered by the first prox going off and the second coming on. The delays in signal processing should cancel out with this method.

Reply to
Anthony

You're an "out of the box" kinda' guy! I sallute you! (I can afford a nut)

Reply to
Tom Gardner

Keep in mind that it's just an estimate. If there is significant viscous damping (as in restrictions in the airline or exhaust) then vavg would be greater than 1/2 vmax so the elapsed time would be less than the calculations above would indicate.

Another possibility that makes no assumptions:

Materials:

One $3.95 neon circuit checker like this:

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One digital camera that permits manual override of autofocus and shutter speed. Better digicams (not necessarly newer) allow this. If you don't own one, you surely know someone who does.

Stick the little neon bulb on the piston, drive with line voltage. Put camera on tripod, aim at, zoom in on and focus on the piston so the whole stroke is in view. Set camera shutter at 1/2 or 1 second depending on how good your reflexes are.

Operate shutter, actuate piston.

You'll see a bright bulb image at each end of the stroke and a row of dimmer images in the middle. Count the dim ones and one bright one. Each count represents 8.333 milliseconds.

Dang, Tom, I couldn't resist trying this. See

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I just hand-held my little neon bulb and whipped it past the camera after I hit the shutter. I'd say the horizontal row of dashes represents just about 100 milliseconds.

If you can't find such a little neon tester, email me your snailmail addy and I'll send you mine if you promise to send it back in a week or two. Mine is built right into an ordinary 2-prong line plug. I made it years ago so I could see by looking out the window that the cord to my engine block heater outside is live.

Reply to
Don Foreman

God, I hope they keep you locked up, you're dangerous!

Reply to
Tom Gardner

Yea, and thanks a BIG bunch...now I have to go in to the shop tomorrow. I'll have to turn up the heat, make a pot of coffee, play with the cats and unfortunately, I have the camera and the neon.

Move to Cleveland and come play with me.

Reply to
Tom Gardner

According to Andrew VK3BFA :

A Strobotac by General Radio. Here is one of the auctions on eBay at present:

170044077408

This one is the tube-based one -- the later model is transistorized, except for the flashlamp itself.

The replacement Xenon flash lamps are expensive and hard to find, and they darken with use, especially at the higher end of each rep rate range.

But for one-time use, the one in this auction looks pretty good, in spite of the documented damage. One vendor is in love with his. A search for "Strobotac" on eBay will show several others, including the really ancient version shown here:

120045933772

That one is not nearly as bright as the others. I know, because I have one of those as well.

Enjoy, DoN.

Reply to
DoN. Nichols

Not anymore. I'm an old fart scare-easy pussy with my XD .40 and Mary's Walther PPK .380. I scare when a screendoor slams. Well maybe not quite, butI'm definitely a senior now. We're very gentle folks, prudent as seems appropiate.

We're contemplating a trip east next May with our truck camper. Visit Fitch in PA and Jeff in Boston. Might we visit you as well on the way?

Reply to
Don Foreman

Damn clever!

Reply to
Bob Engelhardt

(hope I got the attribute right) If youre comming through Albuquerque stop in for a visit. I 40 is only a few blocks away. ...lew... another old fart :-)

Reply to
Lew Hartswick

I did resist going in to work today!

Most certainly! You can see my rat-hole factory in it's glory. There's lots of neat stuff that I've built over the past 35 years...and some crap. Lunch is on me! It'l be a senior fest.

How do you like the XD's triger? I have done some work on my XD-9, I couldn't STAND the triger. It was long, jerky and muddy. I got the 9 'cuz I can't afford to feed a .40.

Reply to
Tom Gardner

Aw right! I'll ping you by email as our plans come together.

I'm certainly no expert, but I find the trigger OK. I've fired several Glock models, note no significant trigger difference between them and the XD. I think I recall reading that the trigger problem on XD's was peculiar to the 9's. I did recall your previous mention of that while shopping, didn't buy an XD until I'd fired one. The XD fit my hand better than a Glock, other things seemed about the same, so I went with the XD. My accuracy was about the same with both. I'm working on that, making some progress...

Note that the XD is not a target pistol and it doesn't have a target trigger. A longer pull than that of a DA/SA like the M1911A1 is good when adrenaline is up. Muddy and jerky are definitely not good. Longer pull is also good in a lightweight polymer frame as opposed to a heavier all-metal piece like a 1911. Also tried a small Taurus DAO .40. A footpedal would be better than the trigger on the Taurus.

Based on positive input from a friend, I recently bought a Browning Buckmark .22. Its size, weight and "feel" are quite similar to the XD, and the cost was less than I'd spent to date on .40 ammo. I now practice mostly with that, just fire a couple of mags of .40 each visit to retain familiarization. The Browning is an accurate shooter and a lot of fun to shoot, and ammo is very cheap. It is a bit of a nuisance to clean, but not nearly the project that I hear the Ruger .22's are.

The Buckmark is a bit of a "fussy feeder", doesn't like some .22LR ammo (notably Federal) but it seems to be quite happy with CCI and Remington Hypervelocity. It'll probably mellow a bit after a few hundred rounds. Fitch has put a couple thousand rounds thru his Buckmark with no problems.

Jeff Cooper scoffed at the .380 as being underpowered. Perhaps so, but he also has said that any gun is better than no gun. I owned a PPK in .380 for as long as it took to get home from the store and let Mary handle it. It instantly became "hers". Good show. If there's ever a problem here, I'd much prefer her saying BANG than "Oh, dear!" It's also a very nice carry. I tried to like a Kel-Tec, couldn't do it. Piece o' junk by comparison. We'd tried a Kahr 9. Very nice little pistol to hold, but a harsh little bitch to shoot. Reject! The PPK is very enjoyable to shoot. Everyone who has tried mine, male and female, has been grinning when they handed it back to me. .380 ammo is even pricier than .40, go figure! Oh well, I have the .22. I pay taxes to support the cops, buy insurance to cover thefts, and I buy & burn some ammo about once a month.

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Reply to
Don Foreman

For me, every pistol must be a target pistol, I won't carry - I might have to clean it daily! My XD-9 is the 5" Tactical model and I feel it should have the potential to hold very tight groups without a bunch of custom work. I just did the sear and the striker in stages to my liking. Now it can shoot better than I can.

All ammo is priced according to volume and .40 can only get cheaper. Remember when 9mm was like gold? Now it's 9 cents.

For home protection I have two miniature Schnauzers. "Uncle Tom, uncle Tom come quick! There's a leaf moving in the back yard...what do we DOOOOO???? Let's go investigate, HURRY!" The little furbies know the sound of every car in the neighborhood and perk-up to a strange one. I've seen squirrels stand on their hind legs with their paws on the back door glass, looking in the house wondering when the dogs can come out and chase them. Squirrels are so cruel!

Reply to
Tom Gardner

I clean my daily carry weapon..hummm about once a month, sometimes even less.

It will keep all rounds in a playing card at 15 feet, is double action only, shoots .45acp and is as reliable as a good quality ball pien hammer.

Its brutal to shoot when one hasnt shot something like it before, but it points well, has a groove on the top of the barrel instead of fragile and snaggy sights, and is designed for one thing and one thing only. To project a 230gr cupronickle/lead hollowpoint at high speeds at a point of my chosing. When I want it, and only when I want it.

I can drop it into a sump, or a coolant tank, or a bucket of kitty litter, and when I pull it out..it WILL go bang, 6 times.

Its larger brother..my sometimes daily carry weapon...is more accurate, holds more rounds, but is much bulkier. Easier to shoot, has good quality but rugged sights and I can give it the same mistreatment. But is MUCH harder to tuck about on my person, particularly in the summer months.

Having a target pistol is fine. Ive got "several". The more exotics tend to be tempramental, finicky (well..compared to my daily carries) and some even pack the same punch. But not one of those Target pistol will I depend on to use in self defense. Hummm perhaps a revolver..but not a Target Self Loader. My semi daily carry is a Half Target...but was reworked for reliability over accuracy. Though..accuracy is relative between shooters..and mission.

One need only be able to hit an object the size of a paper plate at ranges out to about 20 yrds. Anywhere in that paper plate sized area..is a stopper. Hitting that area a couple times is nearly a sure thing.

Shrug

Better to have it and not need it..then need it and not have it.

Worse is to have one like a thourghbred horse..skitish and worthless unless under controlled circumstances.

I also keep a rifle at hand daily..or close enough to retrieve. Another weapon I can use for a crowbar, yet hit a paper plate out to about 300 meters, after laying in the mud and the crud for hours. Pretty its not. A tack driver it will never be, but its absolutely reliable. And its comfortable in my hands..and I know it and where it shoots, intimately. It gets cleaned maybe once a year. And it always fires two fouling shots, before I store it close to hand. And I wont carry a weapon that cant be treated this way. Life is never under controlled conditions.

Gunner

Reply to
Gunner

If I were tro carry, I'd go with a Chief or Agent or some other wheeler. I don't know why but I still don't like autos as much.

Reply to
Tom Gardner

Its hard to beat a Colt Detective Special, with 140gr Nyclad Hollowpoints..or even the 125s. Controllable, accurate enough at belly gun ranges and packs a punch that does the job well enough in most cases. I carried one for years. Bobbed hammer, "melted" and so forth. Utterly reliable. Heavier than an Airweight or Chief..but it holds a full 6 round rather than 5 of most of the others. Steel frame..so one can shoot a fair amount of warmish street loads without wearing it out. One of the other old favorites of mine in wheel guns, was the old Charter Arms Bulldog in .44 Special.

It would ring like a bell everytime you shot it..and it was a bit soft..but it did the job admirably.

Gunner

Reply to
Gunner

Looks like there have been lots of good suggestions. I just like the ones that don't require equipment that I can't pronounce. :)

Reply to
Dave Lyon

Hi Don,

Are you referring to the Ruger Mark II pistol?

I've had one of their Target 5.5 inch Bull barrels almost since they were introduced. It is really, really nice and I've not had any notable hassles cleaning it. They are a bit stiff the first few times, but part of that is just learning where to apply the correct "english" during dis/reassembly.

Ruger made a model built like a .45 Colt too. I would think that the action and disassembly would be the same though. Could be wrong...

The only problem I have ever had was with the Ruger clips. They have a tendency to gum up (coil spring that slides overtop of a steel pin, if I recall correctly) and then feed the next round a bit slow, thus causing a jam. Once I figured that out no more woes. The clips come apart quite easy.

Mine shot so sweet I couldn't resist putting a scope on it. With a 4x Leupold EER & parallax reset to 40 yards, you can cover its groups with a penny. If you miss, it is your own fault.

Never used the Browning, nor handled one so I can't compare...

Reply to
Leon Fisk

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