Holes in steel tubing for weight (vs strength)? (2 Viewers)

[Joe45]

Howdy. Looking to build a frame on the back of my HJ45's bed to mount a pop-up sleeper like the AluCab. I am looking at using 1x2x.065 (16 gauge) steel tubing. I know aluminum is lighter, but I don;t have an aluminum welder, and aluminum is more susceptible to brittleness and other effects. For this application, I don't see the weight savings of aluminum being a good tradeoff for the strength and ease of manufacture of steel.

Anyway...

That being said, I have thought of drilling out staggered 1" holes on the steel, on the 2" side, about every 1.5" to see if that helps a bit. I'm think that will amount to a sack of quarters, which although not a lot of weight, it adds up. The 1x2x.065 (16 gauge) steel tubing weighs 1.3lbs per foot.

Concern is loss of stength/integrity of the steel structure due to the holes. Anyone here delved in this? For this application, would it matter? I'm thinking in a rollover it could matter, and my two dogs will be riding back there (in compartments) up close to the cab.
I've seen the dimple die stuff and it's awesome, but not sure I can use that with that gauge steel.
And yes-I will have AC in the box.


I just think it's an interesting subject..

 

[aztoyman]

I'm pretty sure you can use dimple dies with 16 gauge steel. Dimple die holes would be better than just holes. I don't know if you could do it on tube or if it's worth it or strong enough after the holes. Maybe an engineer will chime in. Safety first.

To add, I wouldn't think 16 gauge anything is going to survive a rollover.

 

[Joe45]

I'm pretty sure you can use dimple dies with 16 gauge steel. Dimple die holes would be better than just holes. I don't know if you could do it on tube or if it's worth it or strong enough after the holes. Maybe an engineer will chime in. Safety first.

To add, I wouldn't think 16 gauge anything is going to survive a rollover.

Looked at some dimple dies. Seems the hole would have to go through both sides of the tube, so I couldn't stagger them.

Like you said, let's see if an engineer chimes in!

Thanks!

 

[e9999]

Aside from the fun factor, is it really worth doing, especially given the likely loss of strength ? I always have way more than what I expect would be your weight savings just in random junk in my truck that I could remove if I were that worried about weight... Or excessive camping stuff. But then maybe you are better organized than I am.

 

[Malleus]

@Joe45
At most, you'll save 30% of the weight of the undrilled tube, and more likely less than 20%. The column strength diminishes as well as the bending strength.

If your goal is to support a popup tent, I'd use Unistrut, or something similar. Three lengths on a side and you're done. Much less work and same result. Nothing that size in any wall thickness is going to be an impediment to gravity in a rollover.

 

[Joe45]

@Joe45
At most, you'll save 30% of the weight of the undrilled tube, and more likely less than 20%. The column strength diminishes as well as the bending strength.

If your goal is to support a popup tent, I'd use Unistrut, or something similar. Three lengths on a side and you're done. Much less work and same result. Nothing that size in any wall thickness is going to be an impediment to gravity in a rollover.

Sounds like it's not worth the trouble. I have three 20 foot 1x2x1/16 steel tubes (rectangle) so was thinking of that. What I will do is build a box that has side hatched and acts like the back end of a troopy/van. The pop ALuCab will then be placed on top as the roof: sort of like a roof conversion from alucab but never had the roof.

Aside from the fun factor, is it really worth doing, especially given the likely loss of strength ? I always have way more than what I expect would be your weight savings just in random junk in my truck that I could remove if I were that worried about weight... Or excessive camping stuff. But then maybe you are better organized than I am.

Yeah, probably won't do it then.
Thanks.

 

[leonard_nemoy]

Go fast holes!!!!! It might be a waste of time but it would look cool.

 

[Joe45]

Go fast holes!!!!! It might be a waste of time but it would look cool.

The frame will be covered to make an enclosed box: the holes will be covered by the outer walls, so no one would see them.

 

[ntsqd]

Holes whistle in the wind. Holes are evil. Avoid holes in anything structural unless you're willing to do the supporting Engineering work necessary.

^That's my motto and I'm sticking to it regardless of what the Internet Engineers say.

 

[Joe45]

Holes whistle in the wind. Holes are evil. Avoid holes in anything structural unless you're willing to do the supporting Engineering work necessary.

^That's my motto and I'm sticking to it regardless of what the Internet Engineers say.

The holes would be covered by the skin of the camper, but I have come to agree with that mindset of not messing with the structural integrity of the steel by making holes. I'm sure an engineer could figure out how to do it, but I'm not skilled at that, so saving a couple of pounds at the cost of safety is not worth it.

Thank you!

 

[WarDamnEagle]

An engineer would design to a load with a safety factor and right size the steel. They wouldn't "upsize" the steel and then drill holes in it. If weight savings were paramount then they wouldn't use steel, they would use aluminum or titanium (or a lightweight composite, etc). I think the unistrut suggestion was a good one.