What material is used for pool equipment o-rings (buna? viton? nitrile? silicone?)

[Danny D]

:)

[Danny D]

BTW, I don't think I've *ever* needed Calculus in my daily life.

For example, I've never taken the derivative of anything in order to do something; nor have I calculated the integral of anything for practical purposes.

I'm sure *you* have, given your theoretical & practical background; but I just never needed it.

Still, it's nice to know the simplest things, e.g., the integral is the area under the curve and the derivative is the change of the output given a change in (usually) time.

That's just about all *I* need to know about Calculus (but now we're straying far too much away from the topic).

[DD_BobK]

DDD-

That's why I figured it was a "cut & paste"

[DD_BobK]

as people could of you but they just go on what your writing reveals.

Of course I knew that...

But you didn't comment on the duplicity of your desires vs your own behavior.....

[DD_BobK]

I tried to help...but you waste people's time. I try to return favors.

[DD_BobK]

Maybe you should have been...might have injected some logic into your problem solving methods. Those labs & report writing can have amazing influence.

Suggestion: Stick with ME courses....more applicable to DIY home repair. Though, welding, wood shop & basic electrical would be more helpful.

Tip: Systems are unstable when poles are in the right hand plane. :)

[Danny D]

You must recall that you said that you live within walking distance of me - and that you could stop by to help me out.

So, all I did was look up where you live in response to your offer (it only took me a few minutes - so I probably responded to your offer within that time frame - although we could just look back at that thread to see the turnaround time).

Turns out you don't live anywhere near me; so I wrote what I did obfuscated, but enough for you to recognize yourself, just to see if I had the right guy - and you didn't respond, so I didn't expend the effort to take you up on your kind offer.

However, I was stunned by your professional credentials. Your technical accomplishments are simply amazing!

PS: I could use some of that explosive talent on my brush piles!

[Danny D]

Naah. All I know about the Fourier series is that this Frenchman figured out that every periodic wave was composed of just sine waves of various frequencies. That's pretty ingenious to figure out.

And, of transform, whew! It's a beast. I've never needed it outside of academia; but it's great for an algebraic reduction of complex differential equations. Luckily, I only took the first year of college calculus, so we really didn't deal with it other than theoretically.

It's used in the EE class I'm auditing though, but again, only at the theoretical level.

Starting in the fall, I'm taking organic chemistry, which should be a lot of fun!

[Danny D]

I have an old arc welder, and oxyacetylene tanks that I picked up at a garage sale. It's night now, but I can snap pictures of them in the daylight for you to see. I haven't used them though, and I don't even know if they work. Haven't even checked the hydro dates on the tanks - but the goal was to be able to weld when/if I ever needed to (my steel water tanks are leaking).

Took wood shop in junior high and high school for far too many years. Now that I'm older, I realize that it's better to take a bunch of different classes in high school than the same class over and over again, because you don't know what you like at that young age.

Read all the SAMS books ages ago on basic electronics, and even built a few 68701 Motorola microprocessor boards as a kid. This was before PCs, of course, when you *had* to build your own boards. But I forgot most of the assembly language stuff long ago (load accumulator A, push and pop data off the registers, etc.). Yuck.

[DD_BobK]

I certainly hope you're a paying customer.......

I pity the instructor & students who will be sharing lecture time / space with you. :( BTDT... the S/N is going to be unbelievably panful.

[DD_BobK]

DDD-

I need help recognizing myself? Somehow I cannot believe that was your motivation...

The problem is....many people cannot appreciate things that they get for free. :(

I mistakenly figured you lived in the foothills of Orange County based on terrain & vegetation.

[Danny D]

Yes. You can't audit without being registered, and, you must take all exams and do all homework.

The only difference is the grade is Pass/Fail (and the fact I'm three times the age of the students, and, often twice the age of the professor!). :)

I have one advantage over some students, in that I have an application in mind when the professor discusses things - and I bring that to the table.

When I show the math, I show everything, down to the last detail - for which I've received kudos for in these classes.

[krw]

Definitions differ. When I was in college (and indeed when I was an instructor at a different, private, college) "Pass/Fail" and "Audit" were completely separate modes. "Pass/Fail" was as you describe. "Audit" didn't require exams, though they were voluntary. Professors couldn't stop someone (indeed didn't know) if someone was taking the course "Pass/Fail" but could and certainly did, if they wanted to audit a course.

[DD_BobK]

IME, as well, aduit is much different than Pass/Fail......

[Oliver Street]

replying to Danny D., Oliver Street wrote: You did the right thing. The choices are substantially butyl rubber, nitrile rubber, BUNA-N, and Viton. The correct choice for an application is driven by cost vs. the resistance to whatever environmental stress is present that will either break down the rubber or penetrate and swell the rubber until it's too soft. Viton is between 1.5x and 2x the price, and has several times the resistance to oxidation salt and chlorine, and swells about 1/10 to 1/4 as much as the others in oil and grease, and less in water. The pecking order would be Viton, Nitrile or BUNA-N, butyl, unstated elastomer.

[makingland]

replying to DD_BobK, makingland wrote: You're a worthless asshole that is attempting to subverting the man's ability to learn. Why are you here?