# drilling steal



## James S (Feb 11, 2006)

Hi folks,

I recently built this for the kids 







The main beam is 12' long and is 2 2x6's screwed and glued together. The instructions said it was fine to use 2 2x6's or 1 4x6. Since I'm truckalogically challenged there was no way I was getting a 12' anything home in the car so I sistered 4 shorter pieces together overlapping 4' in the middle for strength. 

All that done and I'm still unhappy with how much it flexes when the kids are swinging on it. It's probably fine, but as they get bigger it's just going to get worse.

In any case, what I'm thinking of doing is to bolt on a length of steal to reinforce the beam. But to do that I need to drill bolt holes in the thing. I do own a decent drill press but have never used it for metal working before. I will get the proper bits but the question remains about speed and lubrication. Should I drip some oil on it as i go? Should I set the drill to a low speed or a high speed and just go easy on the pressure?

Thanks for any advice!


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## gadget_lover (Feb 11, 2006)

I am not an expert and don't even play one on TV. I've only done limited work with steel but.....

Steel is actually easy to drill with sharp drill bits. In fact, I've been surprised at how easily it drills in the drill press. Yes, you should use lubricant. I use some "cutting oil" that I picked up at home depot. An 8 oz bottle has lasted a year so far. It's stinky stuff.

So the part I can say with authority is that mild steel is well within your capabilities.

Now with no authority at all... Your drill press is rated for a maximum size hole based on horsepower. I've seen numbers in the manuals like "1/2 in hole in steel". Plan to stay within those limits and you should be OK.

I've been following the advice of starting with a smalller hole and moving up 1/8 inch at a time till I get to the final size. This seems to work great as long as you have securely fastened the work to your drill press so it is still in position after changing the drill bit. The idea is to not take such a big bite of steel that it breaks something (like your gears or the bit). A 3/4 inch drill in a 1/2 inch hole is taking off as much steel as the 1/2 inch drill did in the first place.

I watched an online video that showed what was happening mechanically when you drill. It showed the bit penetrating the steel and the chip being formed. It helped me understand that a certain amount of pressure and feed rate are required for drilling steel, otherwise the drill's cutting edges don't penetrate. You get a feel for the right rate of feed about the time the hole is finished.  The centerpunch mark helps keep the drill from deflecting while it's making that initial bite.

Good luck with the project. It looks cool to me!

Daniel


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## ABTOMAT (Feb 11, 2006)

It's less about horsepower than it is speed. Most cheap drill presses don't go slow enough for the idea RPM range. The usual ~500 RPM of a 5-speed import is too fast for 1/2" steel, both from a cutting and mechanical advantage perspective. But if you're careful and the drill has enough power you can get by at a higher speed.

Cutting oil is good, but almost anything will do in a pinch. Oil, WD-40, lard, kerosene, etc. Use a sharp drill press and as much pressure as you can manage without slowing down or stalling the DP. Locate with a center punch, then drill a small pilot hole, then drill the full-size hole. In my opinion 1/8" is way too small a step. Sounds like it would grab and bind too much. I'd keep a much wider range. Usually I just use two bits, sometimes three.


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## chimo (Feb 11, 2006)

Which way is it flexing? Is it sagging from the weight (vertical) or from the sideways force of the swing (horizontal)? 

Flat steel bolted on the side of the beam would help with vertical sag but wouldn't do too much for horizontal flex. 

Have you considered adding a strip of 3/4" or 1" plywood on each side (with staggered joints?) The use of all-weather construction adhesive and lag bolts (with washers) would help make it more rigid. This would alleviate the need for drilling steel.

Paul


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## pendentive (Feb 11, 2006)

a wood-steel-wood sandwich (called a "flitch plate") would have been ideal. But you can get pretty close depending on where you put the steel reinforcement (couldn't find info in your post). 

The general idea is to put a flat piece of steel on the "face"...vertically...to reinforce. Make sense? Not on the bottom, or top...but the front or back (or both, actually, if poss.)

You could get two plates (at least 2 feet, ideally 4+ feet long) and drill matching holes (at least 4) in each. Clamp one to the front, drill through one hole (through the wood), put the other plate on the back and secure a bolt all the way through (use two nuts on the back). Continue with the other holes. If you matched your holes, it'll turn out great.

Use 3/8" carriage bolts with locking washers.



Just MHO, FWIW, YMMV...


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## nemul (Feb 11, 2006)




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## gadget_lover (Feb 11, 2006)

Whew! I was hoping someone more experienced would jump in.  Thanks for the info guys.

Daniel


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## chimo (Feb 11, 2006)

I suggested wood gussets as wood will be easier to work with (especially if the steel has to be cut into long strips and then drilled). 

Since the main beam is 12 feet long, one joint is likely near the middle on one side and the other two are likely a few feet in from each end on the other side. That will call for a couple of long pieces of steel (remember the trunk limitation  ) or a bunch of short pieces. 

Paul


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## James S (Feb 11, 2006)

The beam I made is exactly as the image that nemul linked, except for no steal. I actually considered putting steal in the middle as I was making the beam, but the instructions specifically said that it was OK to use 2 boards screwed together. They didn't even recommend glue (I used the foaming polyurethane wood glue and clamped the heck out of it, worked great)

The movement of the thing isn't really that bad, but my daughter is only 5, so she's only going to get bigger and swing higher 

What I was picturing was a couple of those 3" or so wide 1/4" strips that you can buy at HD bolted along the beam, I would probably put one on either side. But it might be easier to try some good outdoor 1" plywood on either side first.

The beam just scribes a little arc as she swings. Mostly up and down, but side to side as well. The beam is much stronger obviously up and down, but I think the forces of the swing are more pronounced at the bottom of each swing than at the ends.

I'll look into some plywood first i guess. It also wont rust!


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## ABTOMAT (Feb 11, 2006)

OK James, it's "steel" s-t-e-e-l. If you're planning on drilling "steal" the cops might have something to say about that. 

Good luck with the mods. I think are aren't going to see much horizontal improvement with going just the steel router, but it should be some vertical help. The way that HD steel drills I don't think you'll have any trouble with that. Might as well be wood.


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## KC2IXE (Feb 11, 2006)

ABTOMAT said:


> OK James, it's "steel" s-t-e-e-l. If you're planning on drilling "steal" the cops might have something to say about that.
> 
> ...snip...



My best drilling "steal" was about 10 years back, when it was still possible to get great Eastern European tools for next to nothing - got a set of of drill bits for like $10 that have heald up like a good USA set

As for drilling steel - I beam type steel (hot rolled) - usually isn't that bad - start with a small hole first (say, 1/4") and enlarge - you do NOT have to go by 1/8"ths - the big one is to drill based oh the web thickness of the drill - the pilot drill is most done to remove the part that would have to be "pushed" by the center web of the next drill

Joke? In serious steel fabrication, most of this kind of stuff is actually punched - been there, done that, so many times - 13/16" whole through an I beam? No problem - put it in the punch, press the trip, and "thunk" it would be done - we used to HATE when the boss bough non American steel - and we could tell, although today "Mini Mill" steel can be just as bad - there was usually either more chome, or more carbon - the steel was harder, and when you tripped the punch, the steel would go "Bang - ringggggggggggg" instead of "thud"


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## HarryN (Feb 11, 2006)

Hi James - you probably do not want to hear this, but I think your problem is a bit larger than just adding stiffeners. For an item like a swing, you really should have a nominal 1 inch of depth in your wood beam for each foot of unsupported length. A box shape that size is better, but not always possible. Certainly the steel stiffener will help a lot, but perhaps it would be easier to just replace the top beam with a rectangular tube of Al or steel in the first place. That way, you can more or less just maintain your current dimensions and be ok.

Since you did not put a paint finish on the wood, I assume it is a rot resistant type. I use those as well, but they do tend to be soft, so you cannot really rely on the wood being strong enough to hold up to the cyclic load without some load distribution on the nuts, etc, such as very oversize washers. Also, the same natural resins that make them rot resistant tend to be fairly acidic, so you might want to oil your bolts / screws to reduce corrosion.

Nice looking setup BTW


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## turbodog (Feb 12, 2006)

Drill press not required.

I have drilled many holes up to 1/2 dia (and 3/4 thick) with my 14.4v drill.

Set it for low speed, press hard, and spray a little oil if you want to be fancy.


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## cmacclel (Feb 12, 2006)

Just pick up a length of aluminum angle iron and bolt that to the top. It will strengthen the structure from flexing both ways. But it would be loads cheaper just to pick up a nice 12' 4 x 4.

Mac


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## gadget_lover (Feb 12, 2006)

OK, it's time to address the subject of "truckalogically challenged". 

I've only had a truck for 10 years or so. Before that I relied on my passenger car to bring home lumber.

An 8 foot board will fit in almost any car. Simply recline the passenger seat , wrap a towel around teh board wherever it touches the interior. Insert through the open pasenger door till it rests on the shelf behind the back seat. Swing the front around till it rests on the dash. Drive carefully.

Need longer? I've successfully brought home 10 foot boards by using the previous method but leaving the front sticking thorough the open passenger window. In Calif, you are allowed to go about a foot WIDER than the car. Make sure you don't side swipe anyone.

Last week a guy left Home Depsot with some fairly long lumber strapped to the side of his car. Ropes tied around the door posts held the boards against the side of the car at window level. He had towels or cushions of some sort between the paint and the boards. I don't know if he made it to his destination.

I'm with cmacclel. Angle iron or angle aluminum may give better stiffness than the equivilent flat steel.

Daniel


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## scott.cr (Feb 12, 2006)

Why not get a piece of iron pipe, lay it the length of the wooden beam (like a "backbone" of sorts) and hold it in place with U-bolts?

You could also screw boards to the top and bottom of the beam to form an I-beam, which would be most resistant to bending in the downward direction in this case. Won't do much for side flex if that's your trouble. You'll probably have to use eyebolts with a longer shank than what's in there now.

Or you can build a cantilever beam. Replace the straight beam with an inverted V-frame, and then where your beam is now, use a cable. Tighten with turnbuckles. That way your downward force is converted to tensile force on the cable.

Yeah yeah so you can guess where my home repair projects usually go in terms of time and budget...


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## gadget_lover (Feb 12, 2006)

I like the way you think, Scott.


I was thinking of a cable stayed design myself. 


Daniel


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## James S (Feb 12, 2006)

ok, first of all, no fair correcting my spealing 

This was one of those kits where they give you all the hardware and funny hangers and stuff and you go out and purchase all the lumber. I did bring home 6 and 8' pieces no problem, but the 12' was going to stick about 5' from the back of the car and even with a red shop towel tied to the back of them I wasn't comfortable driving home that way. With all the weight of a 4x4 sticking that far out the back I felt like the front end was going to lift off the ground  And since the instructions said it was OK I didn't think it would be a problem.

I've seen some amazing things in the HD parking lot as well.

This is that new kind of treated lumber the "yellawood" and you do have to use special screws and bolts as the copper compounds that they soak it in are highly corrosive. You can only use the hot dipped galvanized screws or stainless steel (see! I got it, STEEL, ok no problem. That's the kind of thing that a spell checker wont help you with...) I was not real happy that they no longer sell the arsenic kind, as everyone knows that is safe as long as you wear a dust mask while cutting it and dont burn it. THis stuff doesn't have the scary word arsenic in it, but it has chemical crystals forming on the outside and left a residue on my hands while working with it. I dont like it. It is well known that contact dermatitis in the skin is a very pronounced effect of getting any arsenic compounds on your skin, which is where you'd get them working with the old lumber or playing on an old playset made of it. And since there was never ever a single recorded case of it ever anywhere it simply does not leach out of the wood. But lets ban it because it has a scary word in the ingredients. I guess we've solved all the rest of humanities problems if we can concentrate on that sort of thing 

in any case, yes it does seem to make it kind of soft (and HEAVY when wet!) 

I had looked at the aluminum angle pieces, but they are very expensive! There is no way I am going to replace the beam with a metal box piece, that would indeed be perfect, but it would also be as expensive as the entire rest of the project! This stuff was all on sale at HD the week after christmas so I decided that was a good time to start the project. I've been looking forward to building one of these for the kids since before I had kids 

I'll have a look in the yellapages and see if there is a welding supply house or other place that might have a better selection and better prices on some steel or aluminum stock to experiment with.

Thanks guys!


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## CNC Dan (Feb 12, 2006)

use low speed. You can't go too slow, but if you go too fast you can overheat the bit.

Use two drills, one to start, and one to get to your final size. The first bit should be about as big as the center web of the final drill. Take a look at a large drill and you will see that the cutting edges don't realy go all the way to the center. That central part of the drill is 'crushing' rather than cutting. If you pre-drill a hole that size you will have a much easyer time. For the smaller hole you could use a higher speed to save time. Use some kind of oil to help reduce heat.

good luck.


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## HarryN (Feb 13, 2006)

I have brought home plenty of long boards and 20 ft. pvc pipe strapped to the top of a car. Just tie it to the corners of the car bumper or underneath.

I put a piece of cloth between the boards and roof, and tied each corner with a "main" and a "backup" piece of strong twine (in case one broke).

I have also brought home plywood this way, but only at very slow driving speeds, a it tends to catch a bit too much air.


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## MoonRise (Feb 13, 2006)

James,

You made up your 12 foot length by making a sandwich of an 8'+4' and a 4'+8', right? The whole thing held together with some foaming polyurethane adhesive and some screws/bolts? All using 2x6 PT lumber, the new ACQ stuff because you can't buy the old CCA stuff (except for industry, if there are still mills making it).

Good news, you didn't do anything wrong. The beam shouldn't break or anything. Bad news, although the instructions were followed, doubled 2x6's or a 4x6 (with the 6 inch dimension oriented vertically) will flex and sag and bend both vertically and horizontally, especially when swinging.

There was a reference made by HarryN to "1 inch per foot of length" for a beam dimension, and that is roughly true for building codes for floor joists and their span, when using #2 2x wood lumber. So if you were trying to have a floor span across the supported edges of a foundation and the perimeter walls were 12 feet apart, then you would use 2x12 #2 lumber floor joists spaced 16 inches on center. That would meet building codes, -most of the time-.

But that is not what you are dealing with here. You have a beam on a kid's swing set that is flexing as the swing is used.

First off, everything flexes. How much time/money/effort do you want to spend and how much flex is acceptable? You can put steel plates on, but steel will rust, especially against that ACQ treated lumber. You can sister some exterior plywood on, which will help some, but that is because you are adding material. You can try putting 1/4 inch thick steel angle iron (don't use aluminum) on the top and bottom corners, again you have to deal with rust.

Doing some quick SWAG and calculations, you're looking at about 1/2 inch of vertical deflection on the beam as is, horizontal deflection I'd ballpark at 1+ inch. To cut those numbers down, you need more and/or better materials. Example: use a 6x6 12 feet long (deflections should go down to about 3/8 inch horizontal and vertical), or doubled or tripled 2x8 lumber, or a steel I-beam (way over-kill), or a steel box beam (4x3x1/4 or 4x4x1/4 would work, deflections would be about 1/4 inch).

Although your sistered beam is OK, I'd just get 12 foot lumber next time. Just rent the truck from HD or Lowes for $20 for the hour+ and load up the truck and bring home some heavy, big, and long things.

Like I said, how much flex is acceptable to you and how much do you want to spend in time and money? Pretty easy to do would be the 6x6x12ft beam, you'd probably have to get longer screws/bolts for where the beam attaches to the vertical 4x4 on the "fort". If you can find an 8x8x12ft beam, that would cut your flex down to about 1/4 inch. If you can't or don't want to go wider with the beam, moving up to at least a doubled 2x8 beam will help some (more so in the vertical direction, the horizontal flex as your daughter swings will be a little less than your current 2x6 beam, but still more flex than if you use a 6x6 or 8x8 beam).


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## James S (Feb 13, 2006)

Mike, thanks for the technical info 

It's not really that I think it's unsafe, it just bugs me! I expended a lot of time effort and sweat (but not much blood, I was careful) building this and I really wanted it to be rock solid.

So I suppose as it the case most of the time I'll probably do nothing and just wait to see what happens. 

HarryN, yes, I've done that sort of thing too, but it was mostly as a kid helping my dad bring such things home. My father was one of those people you see in the HD parking lot strapping WAY too big pieces to the top of the car and making lots of knots to hold it all down. It's his fault really, as it was his joking around as the load shifted on the way home that gave me a bad balancing lumber on the roof of the car imprint


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## MoonRise (Feb 13, 2006)

Oh, you want rock solid, do you?  We can do rock solid.

I'm usually accused of overdesigning things. But when I want solid, I get -SOLID- !

First, take everything apart, then substitute 8x8 posts for those wimpy 4x4 posts you have in there, we'll need 3 cubic yards of 5000 psi concrete, 5 cubic yards of 3/4 gravel, and 6 cubic yards of mulch, ..... :nana: 

Only slightly tongue-in-cheek.

Seriously, to cut down on the beam flexing when the swing is used, you need a stiffer beam up there. Using a 6x6x12ft beam should be pretty easy to do and not all that expensive. Even just adding another sistered 2x6 to your doubled 2x6 will help a good bit, if you want to use 8ft+4ft pieces then stagger the joints from the joints that are in there now.


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## tvodrd (Feb 14, 2006)

The original question was on drilling steel.  For mild steels, a cutter speed of ~100 surface feet/minute (sfm) is typical. (If my frequently-defective memory serves me.) A 1/2" drill has a 1.57" circumference =.13 ft. 100sfm/.13ft= 770 rpm for the drill, but you'll definately need coolant! (Slower is gooder!) The stinky sulfer cutting oils are great for steels. I'd punch it first with a 1/4" drill, followed by a 1/2" and C-clamp it to the drill press's table.

(I wonder who the swing is _really_ for? :thinking:  )

Larry


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## James S (Feb 14, 2006)

> I wonder who the swing is really for?



Well, the kit came with 2 regular swings. But they were only rated for 150 pounds! And i've surpassed that by some small margin...

So I bought one heavy duty one and placed it at the far end of the beam which is good for up to 300  So I can gain 110 120 pounds or so an still safely swing there 

You will notice that I laid out the swings with the highest weight ones on the outside. The 300 pound rated swing on the far side and the tandem swing at the opposite side.

My vestibular system isn't what it used to be and so it takes a lot less swinging to make me dizzy now than it did 30 years ago 

thanks for the specifics, I was pricing steal today and for another $80 or so (plus bolts and enamel paint or something) I could add that angle iron to the beam. But I am still debating the necessity.

Thanks!


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