Fabricators Corner

[Stairgod]

Side note...anyone here know where the term PK came about in regards to self tapping screws? Both of my older brothers only call them PKs and they have no idea where the name came from.

 

[Slim-Whitey]

Festool just isn't something that's worth it to me.

And seems really overengineered in alotta cases.

On the screws, I think I know that one.
PK is a brand name that's synonymous with a type of self tapping screw. PK is Parker-Kalon I think.

Kinda like OSB was known as Aspenite (Asponite?), or melamine as Masonite by alotta guys.

Edit: I don't know what kind of self tappers that company made. I know we don't call them that here. They're self tappers or deckboard screws (since the long, fine threaded ones are used for semi trailer decks).
Yeah, deck board screws aren't deck screws. Wtf, right?

That's why I'm so particular about nomenclature and terminology. The old colloquialisms made tons of tradesmen sound less than smart.

 

[Arcticelf]

Agreed almost all round.
Minus the thread bit. Maybe I've just never had them tight enough, which is possible, but you shouldn't be deforming the threads on that nut. Because you cannot control that deformation without a specific torque sequence.
Now maybe suspension isn't finicky enough to need that specific sequence like, say, a head or a valvecover.

I don't think the thread deformation is huge, but you can definitely find the exact spot where the nut was on a used ubolt, it gets substantialy harder to turn when you hit that spot, then gets easy again.

 

[Arcticelf]

Grade 2 bolts are low/medium carbon steel. That the closest to "mild" you are going to get.

A 9/16x12 (coarse thread) grade 2 bolts has a minimum tensile strength of 13,000 lbs.
A 9/16x18 (fine) grade 2 bolts has a tensile strength of 15,000 lb.

If you've got 4 of those things per axle end, and your threaded area is equal to the diameter of the bolt, AND your plate is nearly the same grade as those grade 2 bolts, you're talking about a force moment parallel to the bolts of 60,000 lb to start breaking them.

I can't think of a time where a single axle corner faces 60,000lb of force while out wheeling. We're talking a distributed force of 120,000lb across the front axle.

Other shit is gonna break long. . . Long before that.

The shear strength is based more on the plate. You aren't shearing a grade 8 9/16 bolt into a mild steel plate with even 3/4" of "meat" around the outside of the bolts. You'd have to tear that steel out.

Again, other shit is breaking way... Way before that.

Not to mention that the bolts, being bolted downward and tight to the plate, aren't directly encountering undistributed moment load anyway. They're holding the plates in place as the area transfer force.

If be far more worried about those bolts pulling the threads out of the plate under tensile than shearing anything, for exactly the reason you describe.

This is what happens when you don't properly spec thread surface area and strength. https://en.m.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

 

[Slim-Whitey]

If be far more worried about those bolts pulling the threads out of the plate under tensile than shearing anything, for exactly the reason you describe.

This is what happens when you don't properly spec thread surface area and strength. https://en.m.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

That's what I was saying though. A grade 2 bolt is low carbon steel, which is most comparable to the plates we're talking about.

If a 9/16 bolt has a tensile strength of 15,000lb, the piece it's threaded into would be comparable to that strength as well if it is of similar metallurgy.

Now, a guy can get into things like threaded section and pitch to see at what point the threads of the plate will pull out or strip in relation to the bolt, and theres a way to figure out the force required to do that, which I can't remember, but hell, it's relevant, so I'm going to look it up.

 

[Blender]

That's what I was saying though. A grade 2 bolt is low carbon steel, which is most comparable to the plates we're talking about.

If a 9/16 bolt has a tensile strength of 15,000lb, the piece it's threaded into would be comparable to that strength as well if it is of similar metallurgy.

You really shouldn't be pulling threads out of those plates.

design intent is usually to have the bolt break in tension before the threads tear out. Machinery's Handbook has a walkthrough of the calculations for min thread engagement for differing materials on page 1536 (29th edition). I don't feel like doing it today

 

[Slim-Whitey]

Edit: Blender beat me.

When I'm done work I'll dig in and be the boring fucker that goes through it, because I just want to see what's what.

 

[Blender]

Edit: Blender beat me.

When I'm done work I'll dig in and be the boring fucker that goes through it, because I just want to see what's what.

Good. That’s literally my job and i dont work for free.

 

[Slim-Whitey]

Good. That’s literally my job and i dont work for free.

What if I offered a crisp high 5?

 

[Blender]

What if I offered a crisp high 5?

I don't want you to touch me, even through your mittens

 

[Slim-Whitey]

True, you might get maple syrup on your delicate fingers.

 

[Spvrtan]

Finally slowly making progress again..

 

[Slim-Whitey]

I says pardon. . .

 

[Stairgod]

Haven't TIGged in a bit so decided some Ally practice was in order.
My bead consistency still sucks , but got good penetration into the root, so that's an improvement.

 

[Stairgod]

Side note:
I am a natural righty. I can MIG and stick with both hands but prefer gun/stinger in right.
But everytime I set up to weld with TIG I grab the torch with my left hand. Also noticed I feed filler differently between the left and right hands. Anyone else this fucked up?

 

[Slim-Whitey]

Side note:
I am a natural righty. I can MIG and stick with both hands but prefer gun/stinger in right.
But everytime I set up to weld with TIG I grab the torch with my left hand. Also noticed I feed filler differently between the left and right hands. Anyone else this fucked up?

Right handed
Shoot left in hockey
Swing right with a hammer
Left with a sledge
Lefty with a hanger nailer
Righty with a framing nailer
Weld lefty vertical, righty horizontal. Either/or overhead.

Yep.

 

[Dukestaco]

I jerk off with my right.

That's all I got.

 

[Slim-Whitey]

Never switch it up huh?

 

[Duckbutter6]

I look left then right then left again before crossing the street

 

[Chris In Milwaukee]

Ive had a MIG for years but have never used it. Hobart 140. I’ve had and used a Meco oxy/acetylene torch for years and got pretty decent with it. But I don’t want to use it in the basement lest I blow up my house in case of an acetylene leak. So I bought a TIG a couple years back (Lincoln Square Wave 200) and intend for that to be my primary welding tool. As I see those of you who are welding up vehicles, it seems like a lot of on-car stuff would be more easily accomplished with a MIG, especially since you can be a little less picky with fit-up. I guess it’s all a matter of use case. Which process do you use most often. Let’s assume steel for this question. Aluminum is a different animal.