Tension control gun - GIF

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May 7, 2022, 08:14 AM
Altair

Tension control gun - GIF

Tension control gun used to tighten bolts to proper torque then snaps off the spline.

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Previously:

https://www.homemadetools.net/forum/...662#post174526
https://www.homemadetools.net/forum/...410#post161985
https://www.homemadetools.net/forum/...029#post145111
https://www.homemadetools.net/forum/...448#post169829
https://www.homemadetools.net/forum/...229#post165489
May 7, 2022, 06:24 PM
piper184

Not sure I understand this one.
The nut is being turned clockwise to tighten, but is the splined end of the bolt being turned counter clockwise at the same time or just held in place?
What is causing the splines to break off?
May 7, 2022, 06:58 PM
Frank S

Quote:

Originally Posted by piper184

Not sure I understand this one.
The nut is being turned clockwise to tighten, but is the splined end of the bolt being turned counter clockwise at the same time or just held in place?
What is causing the splines to break off?

When the nut reaches the proper torque the splines will twist off. the same principal as using a 4ft long torque wrench to tighten the nut only the torque is applied against the splines of the bolt instead of requiring a long torque wrench handle with some form of torque indicator
May 7, 2022, 09:41 PM
nova_robotics

It's a neat idea, but they've been either removed or banned on most sites I've been on. What you can't see is the head of the bolt on the other side of that steel is completely round and smooth. They're actually designed so you can't put a wrench on them.

1. You can't torque them after the fact.
2. You can't get them off without a torch.
3. You can't do a normal cross-bolting procedure to torque them up like normal, so the first bolts you tighten will become loose as you torque the rest of the bolts. See point #1 why this is a problem.

Anyway it's a good idea to reduce the need for QA/QC on structural steel but the execution is really bad. It would make 100x more sense if they just trusted the guys and put a standard hex head on the bolt.
May 8, 2022, 08:26 AM
Frank S

Quote:

Originally Posted by nova_robotics

It's a neat idea, but they've been either removed or banned on most sites I've been on. What you can't see is the head of the bolt on the other side of that steel is completely round and smooth. They're actually designed so you can't put a wrench on them.

1. You can't torque them after the fact.
2. You can't get them off without a torch.
3. You can't do a normal cross-bolting procedure to torque them up like normal, so the first bolts you tighten will become loose as you torque the rest of the bolts. See point #1 why this is a problem.

Anyway it's a good idea to reduce the need for QA/QC on structural steel but the execution is really bad. It would make 100x more sense if they just trusted the guys and put a standard hex head on the bolt.

That was why on the few sites i've been on where they were used the procedure was to run up every bolt at a much lower torque setting then an intermediate setting and only brought to full twist off torque on the 3rd go round, actually much more time consuming than using conventional A325 fasteners or tattle tail pop-up fasteners. One site specified those Nord-Lock® washers, a 2 piece washer with cam ramps for anti vibration and resistant to loosening, once tightened the only way to remove them was to apply enough torque to snap the bolt or weld the 2 halves of the washer so they couldn't separate
https://www.boltdepot.com/Product-De...ontent=Washers
May 8, 2022, 08:32 AM
nova_robotics

Quote:

Originally Posted by Frank S

That was why on the few sites i've been on where they were used the procedure was to run up every bolt at a much lower torque setting then an intermediate setting and only brought to full twist off torque on the 3rd go round[/url]

Can you do that though? I thought they bound up and grabbed the splines once you started to torque them. I guess you could run the gun in reverse to get them off. Sounds like a giant pain either way.
May 8, 2022, 08:58 AM
Ralphxyz

Quote:

Originally Posted by nova_robotics

Can you do that though? I thought they bound up and grabbed the splines once you started to torque them. I guess you could run the gun in reverse to get them off. Sounds like a giant pain either way.

I "think" the spline is used to hold the round headed bolt while the nut is tightened in place of a wrench on the other side.

Reversing the gun would/might just spin the bolt with out the spline to hold it.

Ralph
May 8, 2022, 12:25 PM
Frank S

Quote:

Originally Posted by nova_robotics

Can you do that though? I thought they bound up and grabbed the splines once you started to torque them. I guess you could run the gun in reverse to get them off. Sounds like a giant pain either way.

You use a pass through ratchet that also holds the spline. cumbersome to have to use the powered torque tool to run up the bolts or to have a dozen of those on a jobsite, and as you said the first bolt torqued if the rest are not already tight that one is impossible to retorque. Even a simple spud wrench and a box spline wrench is preferable to torquing a bolt next to a gang of loose bolts