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Old Aug 05, 2011, 02:47 PM
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Hawaii
Joined Feb 2003
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Quote:
Originally Posted by jesolins View Post
Hi Gents,
Shawn,
Your post made me question those measurements that were supplied to me. I just made corrections to the towel bar measurements in the Mega Index since I now have towel bars to do so I would appreciate if you or someone out there please check the weight of the Alum tubing you have as that looks a bit light to me too as I'm sure the Trex tubing which I also do have and remeasured should certainly be lighter than that aluminum tubing.

--15mm x .4mm (5/8 x.016in) square Towel bar: 2.35g/in @ $.20/in -Lowes, Home Depot
--13mm x .3mm (1/2x.016in) Alum tubing: 1.2g/in @ $.13/in -http://www.hobbylinc.com/htm/k+s/k+s9413.htm and http://www.metalsdepot.com/products/...ge=tube&LimAcc=

Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index
There is no way that the 1/2" aluminum square tube is lighter than the towel rack.

I just measured mine:

Towel rack 0.627" X 0.627" X .030" wall thickness. A 30" length weighs 94 grams
1/2" aluminum square tube 0.50" X 0.50" X .0625 wall thickness. A 30" length weighs 143 grams.

So towel rack is 3.13 grams per inch (0.110 ounce per inch) and 1/2" aluminum tube is 4.76 grams per inch (0.168 ounce per inch).
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Old Aug 05, 2011, 04:22 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,706 Posts
Aloha SMW,
Hmmm...Aparently not all towel bars are created equally...

The label on the ones I have says that they are Centura 30" Towel bar Only Polished Chrome E8500A-30/102720. Total weight is 70.5g, so 2.35g/in. The outer dimension does only measure .60in by micrometer, or 15.29mm, so a hair shy of 5/8in. The wall thickness of the ones you have by your measurement is .014in thicker.

I agree with you as I stated The 1/2 aluminum square tube weight does seem wrong to me too. However the tubes in question have only a .016in thick wall, not .0625, which should be really light-weight and not 143g? Are those actual measurement weights, or possibly a typo on the store site?? I hope someone will chime in on that.

Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index

Quote:
Originally Posted by SeismicCWave View Post
There is no way that the 1/2" aluminum square tube is lighter than the towel rack.

I just measured mine:

Towel rack 0.627" X 0.627" X .030" wall thickness. A 30" length weighs 94 grams
1/2" aluminum square tube 0.50" X 0.50" X .0625 wall thickness. A 30" length weighs 143 grams.

So towel rack is 3.13 grams per inch (0.110 ounce per inch) and 1/2" aluminum tube is 4.76 grams per inch (0.168 ounce per inch).
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Last edited by jesolins; Aug 05, 2011 at 05:19 PM.
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Old Aug 05, 2011, 04:32 PM
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Hawaii
Joined Feb 2003
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>> Hmmm...Aparently not all towel bars are created equally... <<

Yes, they are definitely NOT created equal.

>>The label on the ones I have says that they are Centura 30" Towel bar Only Polished Chrome E8500A-30/102720. Total weight is 70.5g, so 2.35g/in. The outer dimension does only measure .61in by micrometer, so a hair shy of 5/8in. The wall thickness of the ones you have by your measurement is .14in thicker. <<

Mine have no labels. I just measured another one. It is now 82 grams and has a wall thickness of .025". Outside dimension is .620".

>>I agree with you as I stated The 1/2 aluminum square tube weight does seem wrong to me too. However the tubes in question have only a .16in thick wall, not .0625, which should be really light-weight and not 143g?<<

I re-measured my 1/2" square tube and the wall thickness is .0625". 0.16" wall thickness is awfully thick. That is over 1/8" of an inch! 0.125" is 1/8" .0625" is 1/16".

>> Are those actual measurement weights, or possibly a typo on the store site?? I hope someone will chime in on that. <<

These are all actual measured weight and dimension. I am using my postal scale and venier caliper.
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Old Aug 05, 2011, 04:46 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,706 Posts
Aloha SMW,

Opps....Yep .016 on my towel bar wall thickness...typos in that last post...SBT.
Was the weight of 30" 1/2 square aluminum tubing with a wall thickness of .0625 tubing really 143g?
Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index

Quote:
Originally Posted by SeismicCWave View Post
>> Hmmm...Aparently not all towel bars are created equally... <<

Yes, they are definitely NOT created equal.

>>The label on the ones I have says that they are Centura 30" Towel bar Only Polished Chrome E8500A-30/102720. Total weight is 70.5g, so 2.35g/in. The outer dimension does only measure .61in by micrometer, so a hair shy of 5/8in. The wall thickness of the ones you have by your measurement is .014in thicker. <<

Mine have no labels. I just measured another one. It is now 82 grams and has a wall thickness of .025". Outside dimension is .620".

>>I agree with you as I stated The 1/2 aluminum square tube weight does seem wrong to me too. However the tubes in question have only a .016in thick wall, not .0625, which should be really light-weight and not 143g?<<

I re-measured my 1/2" square tube and the wall thickness is .0625". 0.16" wall thickness is awfully thick. That is over 1/8" of an inch! 0.125" is 1/8" .0625" is 1/16".

>> Are those actual measurement weights, or possibly a typo on the store site?? I hope someone will chime in on that. <<

These are all actual measured weight and dimension. I am using my postal scale and venier caliper.
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Old Aug 05, 2011, 06:35 PM
Registered User
San Marcos, TX
Joined Jan 2010
672 Posts
Quote:
Originally Posted by SeismicCWave View Post
There is no way that the 1/2" aluminum square tube is lighter than the towel rack.

I just measured mine:

Towel rack 0.627" X 0.627" X .030" wall thickness. A 30" length weighs 94 grams
1/2" aluminum square tube 0.50" X 0.50" X .0625 wall thickness. A 30" length weighs 143 grams.

So towel rack is 3.13 grams per inch (0.110 ounce per inch) and 1/2" aluminum tube is 4.76 grams per inch (0.168 ounce per inch).
Thanks for getting that straightened out for us! So, there is a 1.63g/inch difference between the two. If I were going to use 4-12" arms for an X8 that's only an additional ~78g. Do the towel bars just bend or do they crumple because of the thin wall? We need someone to do some testing on that for us, because if the 1/2" is actually stronger then it might be the better way to go. I'll have to go take a look at those towel bars next time at HD.

Shawn

Edit: oops. I started typing this and then left the computer for a while. It would also be cool to know which transmit less vibrations!
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Old Aug 05, 2011, 06:40 PM
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Hawaii
Joined Feb 2003
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>>Do the towel bars just bend or do they crumple because of the thin wall? We need someone to do some testing on that for us,<<

LOL, yes, we need to find some one to do some crash tests.

>>because if the 1/2" is actually stronger then it might be the better way to go.<<

IMHO using the 1/2" square tube is like building a tank. You should be able to handle a bit of abuse with that.

>>I'll have to go take a look at those towel bars next time at HD.<<

The different size towel racks I have on hand are from two different sources from different time. If you buy them all at one place I think you can get a homogenous product.
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Old Aug 05, 2011, 07:28 PM
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United States, TX, Waxahachie
Joined Jun 2011
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Just lookin, would you belive 1.625 grams per inch.

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Old Aug 05, 2011, 07:36 PM
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San Marcos, TX
Joined Jan 2010
672 Posts
Quote:
Originally Posted by jesolins View Post
Aloha SMW,
Hmmm...Aparently not all towel bars are created equally...

The label on the ones I have says that they are Centura 30" Towel bar Only Polished Chrome E8500A-30/102720. Total weight is 70.5g, so 2.35g/in. The outer dimension does only measure .60in by micrometer, or 15.29mm, so a hair shy of 5/8in. The wall thickness of the ones you have by your measurement is .014in thicker.

I agree with you as I stated The 1/2 aluminum square tube weight does seem wrong to me too. However the tubes in question have only a .016in thick wall, not .0625, which should be really light-weight and not 143g? Are those actual measurement weights, or possibly a typo on the store site?? I hope someone will chime in on that.

Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index
I just checked both links and the ones at hobbylinc are not square, there round. The square ones from metalsdepot are .0625, I just confirmed that with my calipers.

Shawn
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Old Aug 05, 2011, 07:44 PM
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Hawaii
Joined Feb 2003
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>>Was the weight of 30" 1/2 square aluminum tubing with a wall thickness of .0625 tubing really 143g? <<

Yes, here is a picture.
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Old Aug 05, 2011, 08:21 PM
Tri-Quad-Hexa-Octo-copters!!
United States, TX, San Antonio
Joined Feb 2007
14,706 Posts
OK Gents,
Whew...so to recap this math in public:
--the towel bars I bought at Lowes are 2.35g/in.
--the towel bars in Hawaii are 3.13g/in which shows there are many different types and weights even of these aluminum towel bars.
--the 1/2 aluminum square tubing with .0625 walls is 4.76g/in
--the Trex 12mm x .3mm tubing is 1.3g/in

The good news is that these arm materials can fit on Rusty's frames...
Cheers,
Jim
Quadrocopter and Tricopter Mega Link Index
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Old Aug 05, 2011, 08:27 PM
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Navarre, FL
Joined Mar 2002
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Man, I go off to Panama City for the day and find two pages of towel bar posts when I get back

I just went out and measured the two I have. They were purchased at the same time, and both have E8500A-30 as the part number.

Outside dimensions are quite similar, with variations from 0.616-0.619 inches. I'm bothered by 0.627" measurements I read, but I certainly believe there could be that much variation. So how big to you make the blocks? That's a problem.

Wall thickness is night and day. One averages about 0.026" and the other is 0.034. That makes the thin one 3.0 oz, and the thick on 3.6 oz. Gotta love that quality control.

The main problem I have with the thin wall tubing is that it's easy to crush when clamped, unless you put something inside it. A while back, I offered some plates that were made for these tubes. They used screws through the square arms to apply the clamping force, and even with the surface area of the plates, it was still easy to crush the tubes. With a 1/2" wide block, there will be much less surface area, so the crushing will be worse.

Due to the inconsistent sizing and ease of crushing, I don't think this will be a block size I want to offer.

If someone desperately wants to try this with the Rev-8 plates without blocks, it would be pretty easy to make it work. The current screws have 0.640" between them. If someone were to add a short piece or two of heat shrink tubing to the screws, it should make a reasonably good fit with the towel bars.

The catch is the motor mount side, where there's only one block. I don't think one block would hold the tube this way, and you'd also have to provide some sort of plate for the other side of the tube to clamp with.

Bottom line, this just isn't anything I could recommend.

Rusty
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Old Aug 05, 2011, 08:28 PM
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Navarre, FL
Joined Mar 2002
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Quote:
Originally Posted by jesolins View Post
The good news is that these arm materials can fit on Rusty's frames...
You may have to modify the good news a bit (while I hide)

Rusty (round is good)
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Old Aug 05, 2011, 08:31 PM
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Hawaii
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Originally Posted by 13brv3 View Post
You may have to modify the good news a bit (while I hide)

Rusty (round is good)
Out of all the discussion I only see that 1/2" round is the only alternative. There are 1/2" pultrude carbon fiber round from Goodwind at great strength to weight ratio. There are thin wall aluminum 1/2" round tubes that are good strength to weight.

Towel racks are not designed to be tight tolerance so I am afraid you will get so much variation it will be hard to standardize on a block size.
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Old Aug 05, 2011, 08:40 PM
Going to Plan C
Joined May 2011
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I build a large quad with 1/2 inch square tubing from home depot and while this thing is large with 23 inch mtm and an 8 inch sqaure plateform for fpv gear. Its is heavy and with dt 700 and 10x6 props i get 6 mins on 2200mah batteries. Not the desire flight time i would want but the other day i had a motor mount malfunction and it came to the concrete geound from 7 feet up on the tip of one arm. No damage to the frame and 10 min later was back in the air. This is great for learning but i quickly find a mass decrease for flight time needed.
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Old Aug 05, 2011, 09:41 PM
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United States, TX, Thrall
Joined Feb 2010
1,213 Posts
Hey Mactadpole the towel bar will collapse and or bend to absorb alot of energy in a crash to help save the frame, motor mount etc please dont ask me how I know I just know that several times same result so please nobody waste there time and money this has been tested.
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