ETLB Squawk Forums — Archive

I bought the steel rod shown in attached picture from a home improvement store locally. The label states weld steel. The sales associate was not sure whether weld steel has same characteristics as 4130 steel. I hope it will work. I just made the 4 L shaped pull pins.

I read up on 4130 steel. It is supposed to have good welding suitability. That of course does not mean that all steel with good weld properties have to be 4130.  

https://www.bhpipe.com/4130-steel.htm

Steel alloys vary enormously in characteristics.  If 4130 is specified it would be dangerous to substitute something from a "home improvement store".

Tom

I probably did not word the question correctly.
Is the weld steel you see in the picture likely to be 4130 steel ?
Builders who have worked on metal fuselages like Legal Eagle may have more information.
Thanks

My guess, and it's only a guess, is that it's "hot rolled" steel. Perhaps that's what the "HR" denotes on the tag? If that's the case the tensile and shear strength are likely much lower than 4130.

That being said, I used drilled AN bolts and castellated nuts secured with cotter keys to pin the wings on my MiniMAX.

Lynn

No, it is unlikely to be 4130, which is quite expensive because it is suitable for making spar pull pins from. This is a "do not substitute" component like the AN specified hardware. It needs to be the right stuff.

Quoted from lake_harley My guess, and it's only a guess, is that it's "hot rolled" steel. Perhaps that's what the "HR" denotes on the tag? If that's the case the tensile and shear strength are likely much lower than 4130.
Lynn

Lynn, thanks for that identification of Hot Rolled steel from the tag.
I  have also sent a request to the company for confirmation whether it is 4130 steel or not.
I think I will use these pins for rigging purposes, and substitute later before it gets to flying stage when I get 4130 rod  from Aircraft Spruce. ( Presently it is out of stock ).

I will bet you $100 that it is not 4130.  AN bolts are really cheap....get some.

I may need to operate from a field which has no hangar space to spare (KLIC).
Which means trailering for each flight and assembling the wings.
If hangar space was available, I would have gone with AN bolts for wing attach hardware.

I work in the Tool & Die industry and deal with all types of steel. I guarantee you that is not 4130. Please don’t use it for anything past rigging, not sure if I would even use it for that as the diameter will likely be a little different than the 4130.

1/4" diameter 4130 rod costs $2.06 per foot from Aircraft Spruce.  Chances are what you bought is just mild steel and even the distributor probably has little idea of the characteristics. They are probably just buying the cheapest stock they can find.  The total actual cost of raw materials for aircraft like this is too low to make it worthwhile to buy poor quality.  Most of the cost of your aircraft is going to be in your own labor.  Cost of hardware is insignificant.  The quality requirements are literally "vital".

Tom

Tom, I can assure you cost is not the reason I bought this part locally.  

Iron has a shear modulus of about 9 million psi.  Mild steel, about 11 million psi. The maximum stress on the pin is about 25 kpsi.

Bob, Thanks much for that information. I was just thinking to myself when I cut the rod yesterday to make the pins - from the time it took to cut with an angle grinder with a metal cutting rotary blade,  that even if this is not 4130 , before this fails, the two straps coming from the spars, which are merely AL 2024-T4, those straps will surely give way. I am 99.9 % certain this rod will work, but since I still have plenty of time left while I get other stuff done, I might as well replace it with 4130 just to take away that 0.1 % chance of failure. Actually more for peace of mind than any real practical possibility that such a strong pin will fail. The gross weight is only 550 lbs and that is split along 4 spar pins. Even allowing for sudden gust loading or slight g loading in turns, I don't think each pin will ever be  subject to more than 300 lbs of loading.

Quoted from Keith103 Bob, Thanks much for that information. I was just thinking to myself when I cut the rod yesterday to make the pins - from the time it took to cut with an angle grinder with a metal cutting rotary blade,  that even if this is not 4130 , before this fails, the two straps coming from the spars, which are merely AL 2024-T4, those straps will surely give way. I am 99.9 % certain this rod will work, but since I still have plenty of time left while I get other stuff done, I might as well replace it with 4130 just to take away that 0.1 % chance of failure. Actually more for peace of mind than any real practical possibility that such a strong pin will fail. The gross weight is only 550 lbs and that is split along 4 spar pins. Even allowing for sudden gust loading or slight g loading in turns, I don't think each pin will ever be  subject to more than 300 lbs of loading.

There is nothing more important than peace of mind when your at 3000ft agl and get swatted by a massive midday thermal.  

550 lbs at 4G, sitting on two pieces of  aluminium 1/8" wide.  Moving all  the time, relative to each other. Cheap rusty steel will damage the carry through and wing fittings much faster than the right stuff. My aircraft is now fifteen years old and there isn't any perceptible wear.

Why settle for 4130 steel when titanium is available?
https://www.onlinemetals.com/m.....180&top_cat=1353

Quoted from Bob Daly Why settle for 4130 steel when titanium is available?
https://www.onlinemetals.com/m.....180&top_cat=1353

Bob, by the way how easy / difficult is it to work with titanium  (bend / cut / file etc) ?
Is its hardness comparable to carbon hardened steel like 4130  or is it harder to work with ?

Jolly hard to work with and tends to 'pick up' on other metals.

A friend of mine was using a screw driver to line up his wings while assembling. He forgot about the screwdriver and made his first flight with the screwdriver still in one of the holes.
He is very very lucky it didn’t fall out.

I just received the 4130 steel rod to make my spar pins.  The plans say to bend the rod 90 degrees but not how to do it without weakening the aircraft qualities of the steel.  Do I put the rod in a vice and pound on it?  Heat it with a torch?

Quoted from nathan.bissonette I just received the 4130 steel rod to make my spar pins.  The plans say to bend the rod 90 degrees but not how to do it without weakening the aircraft qualities of the steel.  Do I put the rod in a vice and pound on it?  Heat it with a torch?

Nathan,
Clamp it in a good size vice using some hardwood blocks to protect the rod and pound on it with a hammer. It's been a long time since I did mine but if I remember correctly it will bend without to much trouble and the wood blocks will give you a nice radius.
Dick

Thanks, Dick Rake, I got the spar pins bent and they fit like a glove.  Page 10 of the plans for 1000R show extension springs to hold the front spar pins in place so they don't fall out but I can't find the specific springs listed on the materials sheet or reference sheet.  What do I use and where do I get them?

Just use AN hardware in the front. That's what TEAM is recommending now.

Lowes: https://www.lowes.com/pd/Hillm.....dEAQYAyABEgK_nPD_BwE

I tried using both AN4 bolt and the stock 4130 pull pin. If you are frequently going to assemble and remove the wing ( read trailer operations ), then the stock pin is easier to use as the vertical arm provides good leverage to push the pin in, especially when you have a snug fitting assembly. I had to buy three different springs till I got one with the necessary tension to hold the pin place, ( too tight means hard to pull and loop it around, not taut enough means pin could still slip out ).

I also added a small additional loop to help pull the spring and slide it into place.

I am sure other builders have worked out better and more aesthetic looking set-ups.

EDIT: By the way this thread opened with my question about suitability of a steel rod I purchased at Lowe's. I had to wait about 6 weeks till AcSpruce got the correct spec rod into stock, and I have since replaced the Lowe's pin, with genuine 4130 stock.