I Beam Piercing for Crackheads

[NFH2740]

How might one go about piercing a C channel shape in the web of an i beam with some significant constraints; i.e.-- the beam is a part of a welded assy and no ironworker is available. My...distant...acquaintance doesn't like the idea of torch cutting because of how rough the mating surfaces will be along with the risk of creating an oversized hole. He does have ten ton porta power and having an affinity for the path of least resistance, would like to find a die or some combination of die shapes that would make a C3x5.4 shaped hole.

 

[mogandave]

What is the thickness of the web? In any event, you're not going to punch much with ten-tons.

 

[cvairwerks]

Two thoughts.......Unless this a 24” or larger beam, a hole that size is going to substantially weaken the beam. For punching a perimeter of that size, you are well past 100 tons. He really needs to rethink this and come up with a better idea.

 

[jh87]

I know your acquaintance didn’t want to torch cut, but what if you used a custom guide shaped like your c-channel? Cut it a little undersized and use a die grinder to sneak up on it and end up with a clean hole. Or, use a mag drill to drill a series of holes and then use a cutting disc to connect the holes.

 

[NFH2740]

The web is .188".

As for reduced strength, the desire is to convert a trailer deck to a low profile design. Factory low profile decks are produced this way and presumably have the approval of a PE. The beam size for a given gross weight doesn't change until the main deck is 30 feet or longer.

The idea was to trade labor for a good deal on an otherwise desirable configuration during a time where pricing is high.

 

[mogandave]

I'm guessing 50 tons for a 3X1.5 rectangle an about half again as much to punch the "c".

I would drill the corners and grind it out.

 

[MJD1]

Make an internal " trace " template sized oversized for half the diameter of a plasma cutter tip. 3)16" is nothing for a fairly decent sized plasma. As for the " roughness of a torch cut, that's pretty on the operater doing the cutting. If I was doing this( which I've done before) I would drill small holes at the corners to prevent cracking in the future. A sharp corner is just a place begging for a crack to start.

 

[gearhead1]

Zizz wheel on grinder is another way. (After drilling 4 corners.).

 

[Lassen Forge]

When we had similar challenges we used a diamond core drill and a mag drill motor, tons of cooling water, and go way way slow. Not cheap, but it works and gives a smooth, round, and generally stress free hole. You can rent the mag mount drill motor, you'll have to buy the bit (makes a nice paperweight) but you end up with a hole that's structurally sound. It depends on the level of finish on the hole you're demanding... and how exacting the cut out is. We used to run sleeved pressure lines through bridge superstructure components, so if we effed it up we would have one HELL of an expensive mess to explain.

Of course, before you punch a hole in an I beam, I'm sure you consulted with a structural engineer if you plan to put any sress on that beam...

 

[cvairwerks]

I'm guessing 50 tons for a 3X1.5 rectangle an about half again as much to punch the "c".

If you turn the C shape into an oblong, online punch tonnage calculators show to need above 155 tons, for a .1875"x 11.4" oblong hole, going thru .25" thick material.

 

[purplezr2]

Make a template that accounts for offset of the plasma cutter, and cut it was a plasma.....

 

[PCustoms]

O.188" thick?

Drill, grinder and a file. Done.

Or just cut the channel in half and weld it from both sides, which I assumed you are doing anyways.

 

[speed bump]

Torch with a 00 tip. Or weld a piece on each side.

 

[welder4956]

I don't understand why the channel needs to pass thru the beam web instead of cutting and welding to each side?

 

[marak]

I don't understand why the channel needs to pass thru the beam web instead of cutting and welding to each side?

I believe this would potentially be stronger and certainly easier.

 

[NFH2740]

Boy, you guys sure know how to kick a fella when he down. My associate was really trying to avoid the drill and cut off wheel approach. This is going to take up valuable rock smoking time.

I don't understand why the channel needs to pass thru the beam web instead of cutting and welding to each side?

It is not mandatory. Such an approach is a consideration; the hope was to cut down on man hours and produce a more professional, factory like appearance.

Even crackheads want things to look nice.

 

[PCustoms]

Boy, you guys sure know how to kick a fella when he down. My associate was really trying to avoid the drill and cut off wheel approach. This is going to take up valuable rock smoking time.


It is not mandatory. Such an approach is a consideration; the hope was to cut down on man hours and produce a more professional, factory like appearance.

Even crackheads want things to look nice.

A tight cutout and a nice weld bead on each side will look no different then a **** joint and a nice weld on each side.

 

[mogandave]

If you turn the C shape into an oblong, online punch tonnage calculators show to need above 155 tons, for a .1875"x 11.4" oblong hole, going thru .25" thick material.

I think the oblong has a perimeter of about 46" inches, while the 3" channel has a perimeter of something less than 18", yes?

1/4" is about 33% greater than 0.188", yes?

46/18 X 1.33 ~ 3.4

3.4 x 50 tons = 170 tons

What material did you use?

 

[Jlarson]

Just torch it, don't use the dirtiest messed up tip you can find and you should be getting clean cut edges anyway. If I had to do a lot of em I'd probably make a template for the plasma but just a couple I'd totally straight edge em with the oxy or plasma.

 

[cvairwerks]

Mog: The calculator I ran, just asked for length and width of the oblong. I used .1875" for the width as a guess and .25" for the web thickness. The calculator had 60 ksi as the tensile. For the length of the oblong, I simply unfolded the channel into a flat and treated the cross section as a constant dimension. In relativity, it's probably a close enough approximation to figure out that punching it wouldn't be home project. If someone was capable, they would have a heck of a home fabrication shop!

 

[mogandave]

Mog: The calculator I ran, just asked for length and width of the oblong. I used .1875" for the width as a guess and .25" for the web thickness. The calculator had 60 ksi as the tensile. For the length of the oblong, I simply unfolded the channel into a flat and treated the cross section as a constant dimension. In relativity, it's probably a close enough approximation to figure out that punching it wouldn't be home project. If someone was capable, they would have a heck of a home fabrication shop!

I thought that's what you did, but how did you come up with 11.4" for the unfolded channel? Does C3X5.4 not mean 3" channel 5.4 lb/ft?

I get that the unfolded channel would be ~6"

 

[cvairwerks]

I ran thru a couple of supplier tables and did not find a 3x5.4 channel, so made the assumption that OP was giving actual hole dimensions. I looked at hot rolled channel, MC channel and bar channel and the closest would have been 3x5.0. Jump to a 4" and you can get a 5.4#.

Did have a thought and ran thru the metric tables and a #8 metric is close.....about 80 mm and around 8kg/meter.....

 

[mogandave]

I didn't bother looking up the channel, I just assumed it was typical 3".

In any event, he's not going to do anything with his porta-power....

Of course he could maybe get a 0.75 X 0.18 obround and "nibble" it.

 

[MatBirch]

messing around with cutting and fitting will take FAR longer than just welding a channel on each side. I would also just add a gusset to each side to help tie the channels.

 

[MJD1]

There is a reason for passing the channel thru the main trailer beam frame. It allows for more flexing without cracking. The fully welded channel cross members frequently crack at the welds and then the crack often spreads thru the main beam. Typically the only welds on the cross members are at the very outside channels that run down the sides of the trailer.

 

[RPH]

Carbide hole saw, get the size you need and slow turning with coolant. Should get the 2 holes you need. Done this before as it’s the quickest thing when you need a large hole and your 3,000 miles from the plant.