Welding without distortion

[XL-C-100]

I just got done welding my hinges. This was my first time welding 4130 tubing. I think it went pretty well and they will be usable but when I was finished the tubes had a slight bend (about an 1/8" over the 12" piece). My question is what is the correct technique to avoid this issue?

[Jlwright]

I am assuming this was welded on both sides and if so did you alternate sides or weld one side complete and then weld the other side. I am a total green horn but if tig welded I would alternate skip welds on both side to minimize the warpage.

[Sam Buchanan]

I just got done welding my hinges. This was my first time welding 4130 tubing. I think it went pretty well and they will be usable but when I was finished the tubes had a slight bend (about an 1/8" over the 12" piece). My question is what is the correct technique to avoid this issue?

Your question has been addressed and I will add that your hinges will work fine. When cut into 1" lengths the bow you see will be inconsequential and you'll want to run a drill through the hinges to clean them up prior to installation.

[scottiniowa]

Welding without distortion for somethings is almost impossible but being able to correct or have something pull back is something you can work on. But as noted when these are cut into small sections and if  you do a trial mockup and actual use with pins in place, you will have very little to notice about.   See below link for actual photos.

But back to the distortion.  if you were to apply heat to the opposite side after your welding, this will often draw back some distortion.   By this I don't mean the opposite side of the weld but of the entire part ( in this case the large tube)  But this gets tough with full implemented welds such as you just did.  In that case refer to above.

Also as noted, you will certainly want to fully clean/drill size the small tube holes.

Lastly, you are making your 1/2 hinge parts, you need to weld the other small tube  on the opposite side and thus when you cut each piece to length and then split...you will have two hinge parts, --  not one and one piece of scrap.  This is clearly shown how it is made and fitted on a aircraft here. https://groups.yahoo.com/neo/groups/IronDesign/photos/albums/916571358


Just suggestions, enjoy your build.


Scott of Iron Design L.L.C.

[scottiniowa]

a few links I hope. 

  hinge CAD detail photo

photo of hinge on tubing

welded in place

[Sam Buchanan]

Lastly, you are making your 1/2 hinge parts, you need to weld the other small tube  on the opposite side and thus when you cut each piece to length and then split...you will have two hinge parts, --  not one and one piece of scrap.

Hinges for the XL are not split. They are slid over the aluminum leading and trailing edges and then riveted into place.

[scottiniowa]

Hinges for the XL are not split. They are slid over the aluminum leading and trailing edges and then riveted into place.

Certainly true Sam,  I was thinking of one aircraft I do, and talked myself into this area... My mistake, well now you guys see the hinge for chromoly baggage doors done easy as I showed it. That wouldn't work very well in this much better way for alum vs steel combination of parts.  Scott

[XL-C-100]

Thanks Scott and Sam sounds like it's a normal issue and nothing to worry about.

[XL-C-100]

Sorry Jim thanks to you too, and to answer your question I did skip weld both sides. Then I came back and ran a bead along the whole length. I was using oxy/acetylene not TIG.

[scottiniowa]

I do have to admit, Joe E's way on using a piano hinge is quick, light and works extremely well.

[scottiniowa]

A CAD hinge so you can see how the bend is made   just another way.. .not saying one or the other is wrong or perfectly right.

Scott

[Sam Buchanan]

I do have to admit, Joe E's way on using a piano hinge is quick, light and works extremely well.

That is nice and clean.

However.......I have had piano hinge eyes break on the RV-6 cowl due to vibration and that is enough to discourage me from using piano hinges for tail surfaces that receive a lot of buffeting.

Having said that, the RV-6 uses piano hinges for the flaps, but the hinges run full span. So how much hinge material would be necessary on the Eagles tails to have sufficient redundancy?

[Jlwright]

I like the idea too and have a bunch of hinge material left over from the RV build. Being so easy to inspect I can't see much of a problem if enough length hinge is used. Maybe by the time I'm ready to do that we will have some air time on them.

[scottiniowa]

I like the idea too and have a bunch of hinge material left over from the RV build. Being so easy to inspect I can't see much of a problem if enough length hinge is used. Maybe by the time I'm ready to do that we will have some air time on them.

Sam B makes a good point. Joe Engleman has flown his with these hinges from Independence Mo to OSH I think 5 times. I did not measure exactly but I think he has three 5" long hinge sets on the rudder. Inspections for all hinging/moving parts are always top on the list...(and always should be with any aircraft)    Cheers!
Scott

[Theodore]

A CAD hinge so you can see how the bend is made  just another way.. .not saying one or the other is wrong or perfectly right.

Cad i see this? ha. thread is dated,,, 2014 yahoo links are gone
there are many grades of metal used with piano hinges, maybe i'll ask a RV6 builder.
Thank you
Theo


Scott