are tail ribs still available ?

[fairchild1934]

I don't see anywhere they are for sale now--- are they currently being produced all ready formed ?????
I was thinking of starting the tail feathers first while i am waiting on my tubing for the fuselage.
Tim

[fairchild1934]

i e-mailed the new owners and they said no.

So what alloy of steel is everyone using to form ribs out of ? There does not seem to be ANY 1018 sheet steel in existence.....
i was hoping to avoid CrMo because it would resist forming on a die.

Can somebody tell me ?

tim

[rv8bldr]

You could make the original flat ribs and glue on wood airfoil profiles on the top and bottom. That's what I did for my 4pl A model.

[alaskabearhawk]

I went to onlinemetals.com and ordered some .032 4130A sheet. Per Bob you can use mild steel too. I sent you a message with more info.

[geraldmorrissey]

When I asked for 1018 sheet, I was quoted "Commercial grade cold rolled steel sheet .030/ 22 guage". Cheap though, 2'×2' × .030 $23.00. I may buy some for welding practice. Have not really researched this material but on the surface it looks like a possible substitute. Got to check with Bob first though.
Gerry
Patrol #30

[fairchild1934]

i called the company that stocks the sheet steel in the big box and hardware stores. The hillman group.
They said their alloy was 1008. ( .030 inch thick ) they also said its hardness ranged from rc 40 to rc 90. WHAT ????????
The hardest fragile knife blades are mid 60's. So this tells me it is scrap remelt from china. The worst possible quality of steel imaginable.
i just ordered .025 4130 from spruce. Spruce and airparts both used to keep low carbon steel before covid. I remember seeing it. Not now.
i have heard from various metal people- including my welding teacher-- that chinese steel is not properly fluxed - not properly stirred and not even fully melted. So you end up with chunks of things like cast iron or piston rings in the pour that never fully melted and dispersed. That's just a recipe for failure.

[fairchild1934]

Gerald---- who were you asking that of ? and did they say it was 1018 ?

[geraldmorrissey]

No they did not say it was 1018, thats what I asked for but they said 1018 was not a ailable in sheets. Metal Supermarkets in Kent WA.

[SpruceForest]

Seems like the hardness number for your 1008 is likely Rockwell B scale (HRB)... that's the scale typically used for softer steel, aluminum, and brasses, while C scale (HRC) gets used for harder steels. A 70 on Rockwell B is well below any of the C scale values, which bottom out at 15 HRC = 94 HRB.

What I am seeing available is usually 1008, which is what I have, and which in cold-rolled form is pretty decent stuff. Pretty sure the only reason we are using steel there versus 032 aluminum is the dissimilar metal and welding issue, so mild steel is plenty strong enough and pretty ductile for forming. You might pick up some 24" x 48" 20g and try some forming over hardwood forms... not terrible... about on par with hammering 032 2024 for the rib flanges. Cold-rolled steel is usually appearance-grade stuff, so less likely to be made of stuff that ruins appearance (Chinese piston rings!).

[geraldmorrissey]

Talked to Bob today about tail rib matl, he recommends 4130A, .025 thickness.

[fairchild1934]

I have made my 3 rudder ribs now-- out of .030 1008 from the box store. Bent across the grain seemed to do OK.
I also have a sheet of 4130 .025 in case the other steel didnt work. It looks like it is working OK. Might save the 4130 steel for the PA-20 SB918 repair.
Starting on the form block for the formed (counter balance area) rudder rib tonight.

Tim