Rotary Wing Forum  

Go Back   Rotary Wing Forum > Rotorcraft > General Discussion

Reply
 
Thread Tools Rate Thread Display Modes
  #1  
Old 02-06-2017, 07:20 AM
JPAnderson JPAnderson is online now
Magpie
 
Join Date: Nov 2016
Location: Havre, Montana
Posts: 31
Default Unmarked Aluminum Angle

I'm recently bought a Bensen that needed a complete rebuild of the airframe. I'm using Brock KB-2 plans for the rebuild.

I ordered in a 25' of 6061-T6 3/4"x3/4"x1/8" angle from Onlinemetals.com. It came with the Mill Test Reports but it has no die markings designating mill, alloy and batch number like normal. It cuts and files like the 6061-T6 I have with die marks purchased from Wicks Aircraft.

Anyone else ran into this. How can you tie the material to the Mill Test Report without a batch #? Should it be trusted?

Most of the time I order from Wicks.

John
Reply With Quote
  #2  
Old 02-06-2017, 07:37 AM
phantom phantom is offline
Platinum Member
 
Join Date: Apr 2009
Location: Eagle River
Posts: 1,368
Default

I have run into this before, you can check it against a known piece of aluminum with a small ball bearing and a press, put the ball between the known and unknown and squeeze, if the indentation is the same in both parts it is the same if it makes a deeper indentation in the new stuff it's not 6061-t 6 .
Norm
Reply With Quote
  #3  
Old 02-06-2017, 07:51 AM
JPAnderson JPAnderson is online now
Magpie
 
Join Date: Nov 2016
Location: Havre, Montana
Posts: 31
Default

Sounds like fun. I'll give that a try. It cut and filed the same. I have some non-6061 stuff I found on the old airframe. I'll test it for a comparison.

I was wondering why Gyros don't use more 2024-T3 till I compared prices.

John
Reply With Quote
  #4  
Old 02-06-2017, 10:47 AM
phantom phantom is offline
Platinum Member
 
Join Date: Apr 2009
Location: Eagle River
Posts: 1,368
Default

I think if someone is not half deaf like me if you rang two identical pieces you would hear the difference too. As for 2024 t3 cost is not really a factor in the amount to build a gyro and I have used it to build one but quickly found out that it has a severe corrosion problem in its bare form, it has to be well protected from the elements, I'm not talking about surface only , it starts to delaminate .
Norm
Reply With Quote
  #5  
Old 02-06-2017, 11:02 AM
j bird's Avatar
j bird j bird is offline
j bird
 
Join Date: Nov 2005
Location: Cave Junction,OR.
Posts: 1,556
Default

I have bought a lot of metal from Onlinemetals.com and never have had any issues with there products.
__________________
Jay Gunderson

"Wise men talk because they have something to say;
fools talk because they have to say something."

Plato
Reply With Quote
  #6  
Old 02-06-2017, 12:20 PM
AirScooter's Avatar
AirScooter AirScooter is offline
Scott Waggoner
 
Join Date: Sep 2009
Location: Bear Poplar, NC
Posts: 804
Default

I have seen the same thing with square tubing. No markings on the material but the MTR shows 6061 T-6. I would like it better if it had the markings but I used it anyway since I had the report.
__________________
Scott Waggoner
Reply With Quote
  #7  
Old 02-06-2017, 01:30 PM
Brian Jackson's Avatar
Brian Jackson Brian Jackson is offline
Platinum Member
 
Join Date: Jul 2004
Location: Hamburg, New Jersey USA
Posts: 2,414
Default

I am interested in this too as I'm about to order materials and have never done business with OnlineMetals before. I've ordered from Wicks in the past but sent back a scratched tube damaged from poor packaging. Hoping others might chime in on this thread about any issues or favorable experience with OnlineMetals. Didn't know about the lack of markings / identifiers. Hoping that's not normal.
Reply With Quote
  #8  
Old 02-06-2017, 02:17 PM
Gyro28866's Avatar
Gyro28866 Gyro28866 is offline
Gold Supporter
 
Join Date: May 2009
Location: Dickson, Tn. USA
Posts: 1,612
Default

Hello JP:
It is basically the same reason we use AN grade hardware vs a Grade 5 or 8 bolt.
It will yield (bend) not fracture (break) under the load.
Yes; 2024 is stronger, but more brittle and will crack/break/fail and the same component made out of 6061-T6 will deform and bend, but will hold together to get your butt back on the ground.
I do not care if it all looks like a pretzel when it fails, just as long as it stays together to get me back on the ground so I am re-useable!!!
__________________
David McCutchen
615-390-2228
Bensen B7m, 90 hp Mac
Dominator Tandem, 100 hp Hirth
Kolb Mark III Classic, 80 hp Verner
Certified - Advanced Master Beef Producer
EAA Member #0511805
PRA Member #28866
PRA Chapter 16 Member
Secretary & Treasure - PRA Chapter 16
President / Sylvia - Yellow Creek Volunteer Fire Dept.
Chairmen - Dickson County Veteran's Day Committee
Volunteer - Dickson County Airport Aviation Day Committee
2 busy 2 No!
Reply With Quote
  #9  
Old 02-06-2017, 03:03 PM
scottessex's Avatar
scottessex scottessex is offline
Sling-Wing Pilot
 
Join Date: Nov 2003
Location: central, ga
Posts: 10,983
Default

Just an FYI:

2024 alloyed with copper:
High strength structural applications, excellent machinability in T-temper, fair workability &corrosion resistance, alclad combines high strength and corrosion resistance, used in truck wheels, aircraft structures, automotive parts, fasteners, recreation equipment, screws & rivets

6061 alloyed with magnesium and silicon
Good formability, weldability, corrosion resistance, & strength in the T-tempers, good general-purpose alloy used for a broad range of structural applications & welded assemblies, pipeline, marine applications, furniture, agricultural applications, aircraft's, architectural, building products, chemical equipment, electrical and electronic parts, fasteners, general sheet metal, recreation equipment, storage tanks

6063 Stay away! only 49% of the strength of 6061
Pipe railing, furniture, architectural extrusions, marine applications, truck & trailer, recreation equipment, building products, electrical and electronic parts

7075 alloyed with zinc
High strength alloy in aircraft & structures, recreation equipment

6061 has good corrosion resistance and is by far the least expensive of the heat treatable alloys.

2024 and 7075 are the high strength alloys. All airliners are made from 2024 and 7075 series, we don't use much 6061 on commercial aircraft.

2024 is stronger than 6061 but corrodes easily, It does bend and machine very nicely, 7075 is hard and strong. both are expensive.

Then you get into the heat treating, t-3 t-5 t-6 etc. Never use -0 aluminum in a structural application, it is annealed and must be heat treated after forming before you use it.

If you were to build a gyro out of 2024 you could use thinner wall tubing for the same strength as 6061, but it would cost three times as much, and it would have to be properly prepared and treated, I.E. Acid etched and alodined, primered and painted inside and out.

I would never use mast tubing that was not marked as it would likey be 6063.

I have ordered from online metals, as well as Stock car steel in mooresville NC. When I was unable to find the size I needed at Aircraft Spruce.
Stock Car steel was way better on shipping, and it was all marked with the grade.

Aircraft spruce is good too, but I can just stop by and not worry about shipping, but wicks and AC spruce specialize in aircraft so you know what you are getting.
__________________
The government cannot give anything to anybody that the Government does not first take from somebody else.

I prefer dangerous freedom over peaceful slavery.
- Thomas Jefferson


Scott Essex....Flying H Ranch
Reply With Quote
  #10  
Old 02-06-2017, 05:30 PM
JPAnderson JPAnderson is online now
Magpie
 
Join Date: Nov 2016
Location: Havre, Montana
Posts: 31
Default

The Brock KB-2 plans call for 2024-T3 or T4 in couple of places. Some strips along the leading edge of the plywood rudder and the nose wheel assembly. It was the price of the 3/16" material for nose wheel assembly that was the shocker.

I suspect Ken Brock bought the material in the T0 state, formed and had it heat treated.

Thanks for the feedback. I'm going to order more material in the near future. If I order from onlinemetals.com I'm going to call and talk with them. I might call regarding this last order when I run across the paperwork. The material I ordered in the past was marked and usually Alcoa for the mill.

John
Reply With Quote
  #11  
Old 02-07-2017, 02:30 AM
Earthboundmisft's Avatar
Earthboundmisft Earthboundmisft is offline
Junior Member
 
Join Date: Jun 2006
Location: Satellite Beach, (Sea Park),(Original 'Lums Bums' surfer), Florida
Posts: 2,063
Default

Good post Scott, thanks. I'm printing and saving it as a quick reference. 👍
__________________
" Amaze Your Friends, Annoy Your Neighbors"
Reply With Quote
  #12  
Old 02-07-2017, 10:23 AM
JPAnderson JPAnderson is online now
Magpie
 
Join Date: Nov 2016
Location: Havre, Montana
Posts: 31
Default

I sent a message to onlinemetals.com to see what they have to say.

I've ordered materials from them in the past and it was all die marked. It's always been Alcoa in the past. This is supposedly SAPA Industrial Extrusions metal.

John
Reply With Quote
  #13  
Old 02-13-2017, 11:49 AM
Doug Riley's Avatar
Doug Riley Doug Riley is offline
Platinum Member
 
Join Date: Jan 2004
Posts: 6,022
Default

The materials spec sheet that I received in the late 60's with my Bensen plans called out 6063-T5 for all of the angle struts except for the mast-keel braces under the engine and the braces that triangulate the Mac engine mount.

The angle materials in the Bensen kit clearly were of an alloy softer than 6061-T6, as they bent very easily without cracking, were darker and shinier than 6061, and had no structural cross-section, i.e. they had sharp interior corners. The kit contained two sticks of 6061-T6 angle, with interior corner radii, as well.

Most people who've copied or adapted the Bensen plans have used 6061-T6 angle throughout. Bensen, however, used common, commercially-available materials wherever it was safe to do so.
Reply With Quote
  #14  
Old 02-13-2017, 12:26 PM
C. Beaty C. Beaty is offline
Gold Supporter
 
Join Date: Apr 2004
Location: Florida
Posts: 9,018
Default

A long column in compression, such as a strut of aluminum angle, fails by “bowing” (elastic deformation) rather than “crumpling” (plastic deformation) by a short column.

The compression load at which a long column “bows” depends upon its modulus of elasticity. The modulus of elasticity is nearly the same for all aluminum alloys.

https://www.youtube.com/watch?v=SIFf...zJYXMk3WzzUli7
Reply With Quote
  #15  
Old 02-13-2017, 02:10 PM
JPAnderson JPAnderson is online now
Magpie
 
Join Date: Nov 2016
Location: Havre, Montana
Posts: 31
Default

I'm using Brock KB-2 plans and they call for 6061-T6 other than some 2024-T4 in the axles and some plate/sheet.

Good to know that perspective using Young's Modulus and that all aluminum is about the same in long column compression. I'll run that one by an engineer buddy.

I never heard back from onlinemetals. I guess I wasn't too worried. I ordered more material today.

John
Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -8. The time now is 07:57 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Ad Management plugin by RedTyger