Finished My Calibration Rig And Tested Some Steel

[Tim71]

As one who thinks through this stuff to crazy degrees I think I have a couple explanations for this.

#1. The extra 3/8 of an inch is probably the straw that broke the camels backs so to speak. You were probably very close to this bar yielding to you.

Second, I'd be willing to bet that the 80ds that you bent made a wider bend radius when finished compared to a gold nail. I don't think I'll be able to explain it exactly but the wider the bend radius does change things a little. Any calibration rig applies force at 90 degree angles at the beginning but our hands do not. So on a piece like that, the ends bend inward at a sharper degree and slightly changing the angle. This helps the hands on the kink but works against the calibration.

Same with me, I took an 80d that previously calibrated at 525 down to past 90d degrees but my steel that cal'd at 530 has kicked my teeth in practically. Every time I've tried it, I practically go to the ground and wake up with my wallet missing. The 3/8 of an inch with the wider bend radius somehow translates into an easier kink....or so it seems to me.

Edited September 26, 2014 by Tim T

[Tim71]

I'm using the same chain length because that's what was originally done by Eric, and I believe by Mike. If I were starting this system from scratch I've probably use chains that were proportionately longer, as the stock increases.

No I don't mind calibrating longer stuff, it's just that the difficulty I believe will be harder than what the numbers show.

I believe the head and point do both work against you but I think that very same thing somehow makes things different on 80ds. Example, on a 70d, they always fell harder than a cut bar rated the same. You lose some leverage on the point because the wraps doesn't grab it as good and as you stated, the head is a pain to wrap. However, for whatever reason, on the 80ds - at least the few I've bent - both of those seem to sort of help counter act some of that awkward length.

Lots of science to this leverage of bending.

[Tim71]

I completely forgot to say Tommy, bending an 80d in IMPs is a crazy top of the heap world class bend my friend.

[Frank Pizzo]

Thanks dewd. There are a couple vids of this in my gold nail thread that i never post in anymore.. Lol

I went through that whole thread a while back and was blown away by your bending strength! Bend after bend the videos just get more incredible.

That thread is a real testament to what it takes to be able to bend a Gold nail for sure.

[Tim71]

Lol! Thats pretty funny.

And your absolutely correct. These particular spikes do have more of a U shape than a V shape; more like the gold when bent to under 2".

I had actually considered this last night in my confusion.. Another thing that crossed my mind was that the spike has a huge head on one side, which makes for a loose wrap on that side no matter what. So that also being a factor, shouldnt the spike seem harder, given that that (a loose wrap) translates to a loss of leverage?.. Especially since i can get a tight wrap on both sides of a gold nail.

Lol, or maybe its just that extra 3/8" thats rollin' my pockets inside-out for me.

Anyways i do apologize for sending the gold.. I didnt catch up on this thread until after i had sent the steel. So i didnt see that you had planned to stick to rating 7" bars. That said, did you use different chain lengths on the gold nail since it is longer than 7", or did you use the same length chain as you did on the other gold nail you rated? (Im still in awe it rated that low)

EJ, sorry i didnt respond to that post until now homie. But i am down to try!

One more thing that you have to keep in mind, if you cut 3/8 of an inch off this gold nail, it would calibrated probably at minimum of 525 pounds. Maybe on up to 540ish.

All those little things add up. I remember years ago Ben Edwards sent me what he felt was the world's toughest G5 bolts. A G5 bolt was about my max back then so I tried these and they felt way harder than the 400 pound ones I'd been bending. He even called them the bolt to bridge the gap to the G8. Well, when Eric cal'd them, they hit I believe 385. Send a couple more to him and same thing. We were all blown away and to this day whenever I bend one they feel tougher.

Where the steel binds up, the angle of the bend, how much spring etc.. all makes a difference somehow.

[Tim71]

Doesn't entirely surprise me. Seems like different types of steel also respond differently to keeping the steel moving. If I had cranked much faster would the stainless have calibrated lower? My guess is it would be possible.

I thought the KOASB would be the highest of the bunch so I was really surprised.

[EJ Livesey]

Hey Timmy how long are the chains to the U-Bolts? And do you think that plays a major part in the numbers?

[Tim71]

Yes, that's what I've been referring to on the chain length. 6.5 inches are the chain length now. They were almost twice that long which is when the Gold nail calibrated over 600 pounds. That's the chain length that Eric used.

On the 6 inches pieces it made no difference. On the 7 inch pieces it took 15 pounds off the Red rating and on the Gold length stuff it took 50 pounds off the gold.

[EJ Livesey]

Any theories on why the length would make that big of a difference if the same consistant pressure was applied?

[Tim71]

Hard to explain but the long bar braced benders would probably understand it a little better. If you pull a 20 inch bar around you knee, you are pulling more against the steel. However, if you can imagine pulling a 4 foot bar around your knee, you're pulling more with the motion of the bend. Your arms are shorter in relation to the bar.

Here's another analogy. If you were pushing a kid in a swing with 8 foot chains, the further you push them the more you pull against the chains. In other words, if you have a kid sit in a swing and you decide you want to push them 6 foot straight out (measurements on the ground) it will be pretty hard because the length of the chains means you will have to raise them off the ground quite a bit. If you put a kid in a swing with 100 foot chains on it you could push them 6 foot with one finger practically. You will only have to raise the weight a couple inches for that 6 foot of movement. Same mechanics at work here only in reverse. It's harder for the steel to resist the force with the shorter chains.

I wished I was good at the photo shop stuff and all that so I could take some pics and draw out the angles and all that.

Exactly Tommy that's a nice simple way of putting it.

Edited September 28, 2014 by Tim T

[Tim71]

Another thing you have to be careful with is the position that the first link is clamped to the bar. Since you clamp it so tight, whatever angle it is at in the beginning of the pull, it keeps it to the end. I'm strongly considering switching to cable to minimize this factor. It's a major pain in the butt trying to keep the clamps at the exact same length from the end of the bar, while also trying to keep that first link at exactly 90 degrees to the steel and trying to tighten it down without it all moving.

No matter if it's a weight system or one like mine, applying the force to the center of the bar is the easy part. It's anchoring the ends that is the challenge.

And EJ, if this is making you think then, as long as your pulling the force from the center of the bar, why could it be different then I will also point out that with the shorter chains, you have to crank a further distance to get it to the degrees because as the bar bends, the line of travel of the chains has more of an arc. Somebody much smarter than me once said that energy can neither be created nor destroyed and it does seem to be true. Just like a pulley setup, the more distance you pull in relation to the object moving, the less force it takes.

That's kind of the bad thing about my setup. Since I'm cranking with one hand and getting such a good view of the steel bending, it allows me to think of all this and try to look at it from every angle (pun intended).

[EJ Livesey]

This is over my head. Hell, I don't even know how they get the peanut butter into a Reese's cup. Length of chains, applied pressure etc etc is over my head. But I really do alpreciate the explination.

So Mike and Eric used chains that were about 12" and you are using 6.5" and getting comparable numbers? The longer the chain, the lower the numbers and easier to calibrate?

[Tim71]

Eric told me in a PM that his chains were 6.5 inches. Are you saying Mike used chains that were about 12 inches?

I will say that when I looked at the pic of Eric's setup I thought the chains looked longer. I believe a slightly longer chain is more consistant so if Mike used a chains that were 12 inches let me know. I have to be very careful with the shorter chain setup because of the sharper angle that it's pulling at the ends.

I'm about tempted to use my own system and use a long parallel setup with cables to take any of that out of the equation.

To get a 100 percent accurage system would require some very expensive equipment and somebody with alot more education than me.

We'll let me ask you a question EJ, that older gold nail you sent me does 575 pounds sound right or would you think it feels more like 600 plus that I would've gotten with my older setup?

[Tim71]

But the bad thing is we're all already used to the effect that the shorter chains with the "V" setup and therefore used to the numbers.

[Tim71]

Well, the best I can do is to figure out the system exactly that Mike and Eric was using. The biggest difference that it makes is on the 8 3/8 inch stuff.

[Tim71]

I'm pretty beat tonight but somewhere I've got some 80ds that Eric calibrated years ago so I may calibrate those and see where it stacks up.

[acromegaman]

Here is his calibration video but I don't know if he always did it.

http://m.youtube.com/#/watch?v=NAynNyllq_o

[Tim71]

Okay everybody hold the phone. I just looked back again through Eric's gallery and when he told me the chains were 6.5 inches, I'm thinking that looks about like the length going down to his weight bar setup.

Now the pic that shows his handle and 2 chain setup wont enlarge for me but it does look longer than 6.5 inches. I've sent him a message to clarify.

If that's the case Tommy, then that gold nail would be a little higher.

I've tried to count the links in the real small pic but if anybody else can take a look at it and tell me your opinion I'd appreciate it. Maybe somebody else's computer can enlarge it.

Thanks for the video link. That will help.

[Tim71]

Okay I just magnified the screen and his chains are 8 links long whereas mine are 5 and the chain is very similar size. I'll buy some more chain tomorrow and give 8 links a shot and see where it falls.

[Tim71]

Okay with the 8 link setup like in the pic of Eric's, the 497.5 gold nail calibrated at 525. I straightened it back out and re-calibrated it and that was the result.

I also switched to 3/8 inch clamps like Eric states that he uses. That shouldn't make any difference but maybe they'll hold up better.

[king crusher]

Wouldn't straightening it out and rebending it make it weaker?

[Tim71]

Eric did that years ago to test his consistency and he told me it didn't weaken, at least not just doing it one time.

If you've every broken any kind of steel or spike, believe me, it feels like it takes forever to get any easier. I think heat treated stuff like grade 5 bolts might not be a good idea to try this way though.

[Tim71]

Wow, tested a crazy 60d that I bought today. I bought a pound of new 60ds that the hardware store just got in and so I decided to bend one real quick between calibrations with my thinnest 60d pads. OUCH. Well, I just thought my hands are too sore to I switched pads to a slightly thicker and bent it but it felt halfway between a G5 and G8 so I cal'd one. 412.5 pounds!! Man I'll be buying some more of these.

Weird thing is they're slightly magnetic. I can dangle one 60d and pull the tip level to the ground with another one of the nails.

[EJ Livesey]

Chain lengths.

Mike/Eric 10inches

Ivan 8inches( he thinks, he is out of Moscow for a week and couldn't check) but bolts at end of bar not .75 in.

Tim 6.5 inches.

I've been getting the materials together to make 3 seperate units and was going to cal a piece on all three from the same stick of R bar and go over everything with you Tim.

[Tim71]

Tim's were 6.5 inches. Now they are 10 inches. Makes almost no difference on 6 inch stuff, added a little to 7 inch. 8 3/8 inch was the big difference as you can see from above.

Thanks for the info on the chain length for Mike and Eric's setup. Looking back at the pic, it looks like the 6.5 inch chains were the ones going to the weight setup.

Another calibration - Sivaco green 80d 538 pounds. Fun spike. This one is actually 8 3/8 inches long.

Ivan seems to wisely be concentrating on 7 inch stock. That would certainly make things easier. I have to say also going out to the ends of the bar would make the initial setup easier.