Math Quiz

porsche tech · 03-08-2017, 05:55 AM

I need to fit a piece of PVC over the end of my blower to make a tube to blow out the gutters. My question is: if I take a 2 inch diameter PVC pipe, heat it and squeeze it in a vice to an oval shape, will the ID be at least 2 1/2" wide to fit over the end of my blower? I would think it would but I'm not smart enough to figure it out. Thanks for any input. --Dave

jyl · jyl's Garage

The inside of your squarish oval will have a wide dimension (call it width) and a narrow dimension (call it height). They are dependent on each other, if you squeeze it to a narrow slit, the width dimension will approach 3.15" when the height approaches zero.

Easiest thing to do it try it.

Next easiest is to wrap string around the end of your blower tube, measure length of string, if it is less than 6.3" then the 2" i.d. PVC tube is big enough.

sammyg2 · 03-08-2017, 06:13 AM

Prolly depends on the other dimension.
How "tall" is the oval opening?
(width x height)

aschen · 03-08-2017, 06:19 AM

1. the circumference of the ID or your tube is pi x the diameter (2" i think but measure)

2. Use a measuring tape to measure the outside circumference of the blower nozzel

if 1 is greater than 2 you are good to go

ossiblue · 06:31 AM

Area (open space) of a circle (pipe): A=pi x r2.

Area of an oval (open space of tube): A=pi x r(a)(long radius) x r(b)(short radius).

The value of the area will not change as the shape of the circle is modified. That means, as the circle is crushed, the radius shrinks in one direction but expands in the other so that the area remains the same. Take a measurement of the long and short radii of the blower tube (Outside measurement) and calculate the area. Then, calculate the area the ID of a 2" pipe (3.14 x 1 x 1=3.14 sq. in.) Does the outside area of the blower tube nearly equal the internal area of the 2" pipe?

island911 · 03-08-2017, 06:32 AM

The math is inconsequential. Air flow will adjust.

sucking the leaves out works better. ( There exists nice ShopVac attachments just for that job)

Fast Freddy 944 · Fast Freddy 944's Garage

Just hire a landscaper to clean em' out and be done with it.

aschen · 03-08-2017, 06:52 AM

Quote:

Originally Posted by ossiblue

Area (open space) of a circle (pipe): A=pi x r2.

The value of the area will not change as the shape of the circle is modified. That means, as the circle is crushed, the radius shrinks in one direction but expands in the other so that the area remains the same. ?

Maybe I am missunderstanding what you are saying, but as you "crush a circle" the Area certainty goes down. Think about the extreme case where you crush it to a nearly flat elipsoid or oval, the area is almost zero.

It is the circumference that remains constant, and that is where the interface between the tube is, and the dimension that should be used

ossiblue · 03-08-2017, 07:10 AM

Quote:

Originally Posted by aschen

Maybe I am missunderstanding what you are saying, but as you "crush a circle" the Area certainty goes down. Think about the extreme case where you crush it to a nearly flat elipsoid or oval, the area is almost zero.

It is the circumference that remains constant, and that is where the interface between the tube is, and the dimension that should be used

yep, you're correct. It's the circumference that's constant. (Too early in the morning for this stuff!)

masraum · 03-08-2017, 07:22 AM

Wouldn't this be less about area and more about circumference. ie, circumference of a circle of 2" diameter is 6.28" If you had an oval with a long side of 2.5" what would a 6.28" circumference make the short side length be.

For a VERY rough approximation (without having to look up the formula for an ellipse), you could probably use a rectangle. Since it's not actually a rectangle, but an oval, the dimension would be slightly higher.

2.5x2 + Xx2 = 6.28.

x = ~.75

It does seem like vacuuming would be better. I've had a couple of leaf blowers similar to what's in the picture, and they usually have the vacuum attachment that mounts to the bottom with a bag that goes where the usual nozzle is.

porsche tech · 03-08-2017, 01:25 PM

I like the idea of the string around the end...for my simple mind. Problem is, the sting is 6.5" when wrapped around. The nozzle measures 2.5" across (outside to outside) and 1" up and down (outside to outside). I knew you brainiacs would be all over this! Thanks for the input.--Dave

LEAKYSEALS951 · 03:11 PM

And just to think I almost didn't click on this thread, assuming it was some trick click bait "what is 3+5?" type question that one would naturally assume was "8" but due to some newfangled common core snowflake math came out to "whatever you want it to be."

Fwiw, they have leafblower attachments premade for just such a task. I bought one.
It wasn't worth a darn. There was too much length, not enough leverage, for whatever reason, it didn't work for me.

I have included two pictures- one of my leafblower system, and the gutter to show you how much I like it.

Now I have TWO projects- one to throw out the leaf blower piping, and two, to clean out the gutters.

I hope your project* works better for you than it did for me!

*If you look closely, you can see that not only did I sqaunder $$$ on the project, I wasted precious duct tape and reinforcing trying to perfect the original concept. I lost an entire afternoon on this endeavor. Worse yet, neighbors might have seen me spinning around in circles with a silly leaf blower system blowing me around like some zany cartoon character, or those inflatable things with zany arms that you see flailing about in front of used car lots.

double edit- even if you are not looking for a system to clean the gutters from the ground but perhaps a shorter extension to let you stand on the roof and hit the gutters from above, the stuff still gets jammed under the gutter mounting nails and will not clean out well. Granted- I am cleaning out pine needles, so you might have better luck with real leaves. When I use a backpack mounted leaf blower- it is too much power to safely use while standing on steep inclines, and still gets jammed.

I have put extensive and exhaustive testing in pursuit of laziness. I wanted to share the results.

ckelly78z · 03-08-2017, 05:03 PM

I guess I don't understand why you wouldn't heat, and reshape the rectangular end of your leaf blower to make a nice circular shape.....so much easier to attach a round hose extension, onto a round exit tube.

john70t · 03-08-2017, 05:21 PM

Aluminum gutter would be lighter than PVC.
And even though it has a larger cross-section..theoretically..if everything were sealed up the output would be the same using identical output apertures.

Personally I'd use a power washer attachment.
Been thinking of one myself. Ladders are evil and want to destroy mankind.

No help with your original question sorry.

island911 · 03-08-2017, 06:58 PM

Quote:

Originally Posted by john70t

. Ladders are evil and want to destroy mankind.
.

Yep. ^

again, shop vac and this...

You can thank us later.

porsche tech · 03-09-2017, 01:32 AM

I do have a large shop vac and I see Amazon does have tube kit for about $25. Maybe I'll try that. Amen to the ladder comments! Thanks.--Dave

porsche tech · 03-14-2017, 03:34 PM

Got the shop vac attachment on Amazon. 2 1/2 inch diameter. Heated the end with a propane torch and squeezed it in a vice. Fits great and works great. Thanks for the idea!--Dave

mattdavis11 · 03-14-2017, 03:47 PM

Thanks for the reminder, and the heads up on the attachment. I need to tell the boy that it's time to clean the gutters, and the attachment will be very useful in the future when he won't or doesn't have to do it for us.