VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics


Go Back   VAF Forums > Main > RV General Discussion/News
Register FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 06-25-2011, 09:17 PM
macrafic's Avatar
macrafic macrafic is offline
 
Join Date: May 2006
Location: Rochester, MN
Posts: 420
Default 90 Degree Elbow Orientation Problem

I spent some time to day attaching my brake lines to the master cylinders on the rudder pedals, and ran into a problem.

3 of the 90 degree elbows that screw into the master cylinders would not orient correctly (straight up). In fact, one of them would only orient straight down. Others would only hand-tighten at some angle that is sure to cause interference with the rudder pedals themselves.

What are my options here?
__________________
Rich and Cindy Macrafic
Rochester, MN
Flying
Reply With Quote
  #2  
Old 06-25-2011, 09:40 PM
flion's Avatar
flion flion is offline
 
Join Date: Dec 2007
Location: Flagstaff, AZ
Posts: 2,653
Default

Basically, you should get approximately four tuns to hand tight. You then have two to three more turns with a wrench. Within that last turn, you should be able to 'clock' the fittings. Here's a source: http://www.mechanicsupport.com/articleFittingTight.html
__________________
Patrick Kelley - Flagstaff, AZ
RV-6A N156PK - Flying too much to paint
RV-10 14MX(reserved) - Fuselage on gear
http://www.mykitlog.com/flion/
EAA Technical Counselor #5357
Reply With Quote
  #3  
Old 06-26-2011, 01:31 AM
Stoo Stoo is offline
 
Join Date: May 2006
Location: LL10, Naperville, IL.
Posts: 68
Default

Take one of the elbows to the hardware store and get the right size pipe thread die. Lubricate the die with some oil and thread it on to the fitting by hand until tight and then maybe 1/2 turn more. Rinse it off well before trying it in the master cylinder (you don't want any chips in the brake system!). It does not take much material removal, just barely scratching through the anodising in a couple of spots on the thread will give you all you need.

Stewart Willoughby
RV6, finishing.
Reply With Quote
  #4  
Old 06-26-2011, 12:17 PM
szicree szicree is offline
 
Join Date: Jan 2005
Location: SoCal
Posts: 2,061
Default Stress risers!

Aircraft threads are rolled, not cut. Don't use a die.
__________________
Steve Zicree
Fullerton, Ca. w/beautiful 2.5 year old son
RV-4 99% built and sold
Rag and tube project well under way

paid =VAF= dues through June 2013
Reply With Quote
  #5  
Old 06-26-2011, 01:03 PM
sf3543 sf3543 is offline
 
Join Date: Jan 2005
Location: San Antonio, TX
Posts: 1,024
Default

Try a different fitting or swap them to see if you can get the correct orientation. Sometimes it's just trial and error to get a fitting that will orient correctly for your application.
__________________
Steve Formhals
A&P, Tech Counselor & Flight Advisor
RV3B
RV8
Reply With Quote
  #6  
Old 06-26-2011, 02:00 PM
chaskuss chaskuss is offline
 
Join Date: Mar 2005
Location: SE Florida
Posts: 1,499
Default How do they do that?

Quote:
Originally Posted by szicree View Post
Aircraft threads are rolled, not cut. Don't use a die.
Steve,
I'm not a machinist, but I'd like to play one on TV! I know how male threads [like on an AN male fitting] are rolled. I can not envision any way to "roll" a female thread in a hole. What sort of special tooling is used to do that?
Charlie Kuss
Reply With Quote
  #7  
Old 06-26-2011, 03:05 PM
aerhed aerhed is offline
 
Join Date: Dec 2008
Location: Big Sandy, WY
Posts: 2,567
Default

Acme universal aircraft thread roller (deluxe model). Really...if those threads are rolled I'm Jimmy Doolittle.
__________________
Actual repeat offender.
Reply With Quote
  #8  
Old 06-26-2011, 03:18 PM
Walt's Avatar
Walt Walt is offline
 
Join Date: Aug 2005
Location: Dallas/Ft Worth, TX
Posts: 5,686
Default

Quote:
Originally Posted by sf3543 View Post
Try a different fitting or swap them to see if you can get the correct orientation. Sometimes it's just trial and error to get a fitting that will orient correctly for your application.
I agree with Steve, sometimes it takes 3 or 4 different fittings to find one that will orientate correctly.
__________________
Walt Aronow, DFW, TX (52F)

EXP Aircraft Services LLC
Specializing in RV Condition Inspections, Maintenance, Avionics Upgrades
Dynamic Prop Balancing, Pitot-Static Altmeter/Transponder Certification
FAA Certified Repair Station, AP/IA/FCC GROL, EAA Technical Counselor
Authorized Garmin G3X Dealer/Installer
RV7A built 2004, 1700+ hrs, New Titan IO-370, Bendix Mags
Website: ExpAircraft.com, Email: walt@expaircraft.com, Cell: 972-746-5154
Reply With Quote
  #9  
Old 06-26-2011, 06:50 PM
vlittle's Avatar
vlittle vlittle is offline
 
Join Date: Jan 2005
Location: Victoria, Canada
Posts: 2,251
Default

I was told by someone who should know that scotchbriting the threads will allow enough extra turning to solve the problem.

V
__________________
===========
V e r n. ====
=======
RV-9A complete
Harmon Rocket complete
S-21 wings complete
Victoria, BC (Summer)
Chandler, Az (Winter)
Reply With Quote
  #10  
Old 06-26-2011, 10:00 PM
szicree szicree is offline
 
Join Date: Jan 2005
Location: SoCal
Posts: 2,061
Default Do I detect a little sarcasm?

Quote:
Originally Posted by aerhed View Post
Acme universal aircraft thread roller (deluxe model). Really...if those threads are rolled I'm Jimmy Doolittle.
All I know is that a guy who owns/runs a very well-equipped machine shop that specializes in the production of AN style fittings told me that there are very subtle differences between his stuff and the "real" stuff. Chief among these differences was that his stuff was cut rather than rolled. He also explained that the real stuff has a completely different thread profile with round peaks and valleys rather than sharp. Incidently, he also pointed out that the inner diameter on his are larger to flow more fluid, but that this does make them weaker. Finally, he showed me both through a magnifier and the cut one was quite jagged.

Regarding rolling inner threads, I think it is correctly referred to as "forming" when it's an inner thread. I once saw a device for doing it that sort of looked like a tapered tap. Beyond that I have no idea.

I apologize if anything I said is inaccurate, but I was only passing along what I was told face to face by a guy in a shop apron who seemed to be very knowledgeable in this one area.
__________________
Steve Zicree
Fullerton, Ca. w/beautiful 2.5 year old son
RV-4 99% built and sold
Rag and tube project well under way

paid =VAF= dues through June 2013
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 01:45 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.