Conversion of the MX991\U flashlight to 3-watt LED

True enough, but its a function of barrel harmonics and should be considered a testable variable.

Gunner

"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences."

- Proverbs 22:3

Stick one on a rifle barrel and shoot it.

Gunner

"A prudent man foresees the difficulties ahead and prepares for them; the simpleton goes blindly on and suffers the consequences."

- Proverbs 22:3

Strain gages are for mountains and bridges. Piezo is for high speed stuff and started in the late 60's into Navigation gear on airplanes.

I have some disks and rectangles from those days.

Martin

Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member

Gunner wrote:

I was imagining something more ambitious, along the lines of characterizing barrel deflection vs. time, as Gunner is suggesting.

Here's a link to the sort of inexpensive piezo film strain sensors I had in mind.

Ned Simmons

This sure looks a lot to me like PVDF2 , polyvinylidene fluoride piezo polymer film.

If you do something more ambitious, I'll certainly be interested in your findings -- and I'll be particularly interested in your methods for getting 200 KHz bandwidth with these piezo sensors.

Yes.

I'm afraid I've muddied the water here. When I said, "I was imagining something more ambitious," I meant ambitious on your part. My interest is purely academic.

I'm not aware of any reason why their high frequency response wouldn't be at least as good as strain gages when mounted on the same chunk of steel. Am I missing something?

Ned Simmons

I kinda wondered that might be the case.

I'm not saying that piezo would be inferior to straingages in terms of high-frequency performance. However, the signal conditioning requirements are somewhat different. Piezo sensors present essentially a pure capacitance while straingages present a low resistance.

Can't do that in my shop/lab, Gunner. We'll get there. Stuff doesn't always work the first time in my lab, but things nearly always work eventually.

So I hear. But see

In order to use a quartz piezo sensor, there must be a hole (pressure port) from chamber to transducer. A foil straingage is not as direct a measure of chamber pressure, but it is non-intrusive. We're more interested in muzzle behavior than chamber pressure, so the strain method is probably even more applicable. We'd use chamber pressure just as a trigger for the scope or datalogger.

I do too. Those make great force, acceleration and vibration transducers, not so good for directly observing strain. Thing is, folks usually worry about strain in static or very low frequency dynamic sits -- as with mountains and bridges.

The PVDF2 thin-film polymer SG's might work nicely here -- but I didn't see much of a specsheet on them, nor a place to buy just a few for a few bux.

Foil SG's are very well-documented, and I happen to have a few on hand. I try to work with what I have unless someone else is paying for the research at market rate. I don't see any purchase orders sliding under the door!

PS, if I lived near you we'd do exactly that: instrument a rifle you might have that you'd loan or sell to me, and then haul my kit to your place to see how she works. Then back to my lab for modifications, and so on... Only rifle I have at present is an ordinary .22 rimfire. If I lived close to where I could fire a "real" rifle other than on a range, I'd surely own a few.

While driving thru the Glacial Ridge region of MN a couple of days ago, I saw some wonderful sites for 500 yard and even 1000 yard shooting. Rolling hills, open country. I'd need to befriend a landowner, but I'll bet my lake neighbors Scott and Zip could help with that. Farmers can use welding and machining services from time to time. Many farmers can weld well enough to get by, but few do it well -- and they don't have time to screw around with welding when there's a crop in the field. I have lots of time.

Idle dreaming, doubt if I'll ever get serious enough about riflery to pursue it. My correspondent friend is very serious, though. New passion! Think prarie dogs at 1000 yards and beyond.

Why not? No 8" pipe?

Gunner

"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."

"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion).

-Buddy Jordan 2001

Yall will have to come out some time. My range is 2700 yards long.

Gunner

"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."

"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion).

-Buddy Jordan 2001

On Thu, 28 Sep 2006 10:18:12 GMT, with neither quill nor qualm, Gunner quickly quoth:

Hey, you never showed me anything which would shoot a mile and a half! Hell, I woulda/coulda stayed another day for that. ;)

P.S: How's the book coming?

You told me you had to leave.

And as I said..you saw the visitors collection.

In the outbox.

Gunner

"If I'm going to reach out to the the Democrats then I need a third hand.There's no way I'm letting go of my wallet or my gun while they're around."

"Democrat. In the dictionary it's right after demobilize and right before demode` (out of fashion).

-Buddy Jordan 2001

No rifle -- and I'd rather not worry my good neighbors.

On Thu, 28 Sep 2006 16:01:24 GMT, with neither quill nor qualm, Gunner quickly quoth:

I ended up home a day early because I didn't stay at my sister's house after all. Wish I'd known that before I left your house.

Yeah, and I was exhausted just looking at all of those.

Bueno, bwana.

-- Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)

--

- Websites for children of ALL ages

On Sat, 23 Sep 2006 09:31:46 GMT, with neither quill nor qualm, Gunner quickly quoth:

Some what? Hell, you're already sending a package to me, include some. I'll take 'em! (What are these, again? ;)