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Howdy We have begun to spec some yellow zinc plate on some mild steel components. We have had a few batches of parts looking less yellow than others, and there was some report of some "white corrosion" from our finished inventory recently. Looking at what I should be expecting from the...

Hot Rod: Surely understand how it is in the bridge design world; those designs are "permanent" and as you state, people's lives are on the line. I wish I could say more, but you all probably want to be somewhat anonymous here as well.... The answer to what would happen if it slid, is probably...

CVG yeah exactly, with a static coefficient a mere 0.06 higher than the dynamic one given, we meet our goal.... We know the design is acceptable, but we have to do a 3rd party PE approval and the assumptions can't be made to satisfy them. Got to be a published number. I even found an old...

JAE SAID "Look through this document - you might have to dig a bit but I bet it's in there. https://apps.dtic.mil/dtic/tr/fulltext/u2/270810.p..." Haha, yeah that's the same document that I linked to above. It only has dynamic values of friction though.... For now, we are rolling with what we...

Guys Thanks much for the replies, my apologies for being absent it's been a busy week. All good ideas, we realize that a friction modifier will do the trick easily, but prefer not to rely on it if we don't have to. Nearly anything is better than just steel. Wood blocks are often used...

JStephen, Thanks and agreed. Not the most homogeneous surface.... That paper observed as much. Still, seems rather certain a static value (if one exists) will get the job done. Last resort we're looking at contracting a test lab. Can always specify that rubber pads be used as a friction...

Howdy: Have searched quite a bit trying to find this. Closest I have come is this document: https://apps.dtic.mil/dtic/tr/fulltext/u2/270810.pdf The only coefficients in the document are for dynamic friction, based on testing for landing experiemental aircraft on asphalt and dry lake beds...

Wow. I guess so! Looking forward to learning a bit more. I'm guessing that all of the flow drill sizes are tap drill sizes. The trick will be getting our beginner CNC programmer to figure it out. I'm sure someone out there has done this. We will see about the tapped thin holes for this...

Oh wow. Thanks bad servo! I have seen assemblies with tapped holes created by such a feature and I didn't know how they were formed. And my memory being what it was it sure didn't come to me for this thread. I like the rivnuts, but the more work that can get done in our Haas without having...

The Riv-Nuts are just about perfect! Plenty of thread depth. I will have to check that out. The welded plugs are a good idea, but we are trying to take some of the manual manpower out of our manufacturing. We are getting busy and don't quite have the space to start another line so are...

Yeah, I thought about changing the screws to #10 and then add a few extra, but as I said we are already using 1/4-20 successfully. The weld nuts are the same thickness but likely harder. Assembly guys use cordless impact wrenches where they shouldn't, and this is what I'm worried about. It's...

Thanks. Well, You might be right. We do use some rivets on existing equipment in other places.... What makes me think they won't just vibrate loose, is the fact that we already do this today and don't seem to have trouble. If torque is such a poor way, then why does it seem to be the primary...

Howdy I've got a 1/4-20 fastener into a .188 thick wall in square tubing. I normally like to run with thread depth = diameter x 1 but in this case, there's nothing much I can do. I have 6 fasteners total holding on a stout trailer fender on an equipment trailer I'm designing. Were I...

Howdy Brad, and all Exactly. It's being abused. GVW seems heavy, but the frame is about 700#, the tongue is 250#, footprint is about 9 x 9', there is a lead acid battery bank, a large hydraulic mast/boom, Solar, etc... So it's every bit of 4000#. Small company. Boss has not defined a goal...

Brad I have seen that as well, I'm talking about fully jackknifing to contact, and then not caring at all, just stomp on the gas and then blame the manufacturer when this significant piece of steel breaks. The reason that it's more plausible than it sounds, is because like I said, there is...

Brad805 Generally, yes. The front of the trailer is square but I don't think that really matters. Jackknife - yes, that's what I mean. It's slightly more complex than that - the trailers travel in pairs, with the rear trailer connected to the frame of the front trailer. They are, as you...

PAstructural08 (Structural) 16 Dec 14 20:10 Correct, if you were only worried of jackknifing (horizontal forces) than you would increase the width of the tongue. Thanks. When you distill it down, that's what this thread was all about. I had my chicken scratches here on my desk, but needed...

CELinOttawa (Structural) 16 Dec 14 19:41 Also there are times that adding side plates to an existing beam is the right way to go, and results in significant strength increase. You have also provided a partial restraint to the putter flanges, thereby negating a failure mode that governs many...

jayrod12 (Structural) 16 Dec 14 19:44 Ah crap, I made a mistake in my previous post and used 3/16" wall thickness for the 4x4 as well. See below for updated numbers. And remember, due to manufacturing tolerances, the actual section properties of the supplied steel may differ from...

jayrod12 (Structural) 16 Dec 14 19:25 I is related to stiffness. That's what Pastructural was trying to tell you. S is related to strength. Your section modulus for the 3x6 in the weak direction is only 2.4% less. It is also much stiffer in the strong direction. So for the same mass (which...