Drilling Square holes...

[SAmadei]

This is not exactly auto related, but I can see some instances where you might want it.

I need to make some 7/16ths square holes in some 1/4 steel for carriage bolts on a project I am working on. My current idea was to drill 7/16th holes then use some kind of angled abrasive to notch the corners, but considering I need to do 6-10 of these holes, that could take some serious time. Plus I am no finding abrasives that will really suit my needs.

I'm seeing different kinds of square punches online, but I assume these need a 100 ton press or something, and most do not list what thickness they will punch through.

If anyone has a good idea, let me know. My backup plan is to use really long lug studs... but they really don't have as much head/shoulder to the "bolt" as I would like.

Thanks in advance.

Edited January 14, 2012 by SAmadei

[wildmanjoe]

Find a machine shop nearby that has a broach. Unless you already have a press or lathe and plan on regularly making square holes, it'll will be cheaper.

[balthazar]

Ask & ye shall receive:

Actually, I ran across this question & link elsewhere last month:

• • •

Otherwise, at the scale you'r working with (7/16), I would be tempted to drill the corners, then the center hole- not as much material removal as straight grinding into the corners... but still a lot of work. Hopefully the bit above is available somewhere & reasonably.

How about some project pics on this, SAm?

[SAmadei]

I'm not sure I see whats going on with the first video. The second video is just mind blowing... I can only assume there is more to it than I'm seeing.

Any idea on pricing, or where one can get one... in general, I can't afford a tool like this right now, but considering I can "standardize" on 7/16ths, I can think of a million uses for a such a tool.

As far as photos, so far its just a big plate of reinforcement steel. I want (hard) carriage bolts for security purposes.

I think I need to wath those videos again... and try a few more Google searches.

[wildmanjoe]

The first one is a Reuleaux bit and chuck. You need a drill press to use one since you aren't going to be holding a hand drill steady enough to use it.

[balthazar]

First vid doesn't illustrate it well, but it's the same principal. Based on the Reuleaux triangle, apparently you need a special chuck that allows the bit's center to revolve on a circle rather than on one point. This shows it:

In poking around online, I've seen mention for drilling in wood & AL, but could not find steel bits available retail anywhere. Actually, I couldn't find any of these bits retail.

Would still be interested in some sort of illustration- can you weld studs on the metal? Otherwise: 5 holes per hole: 4 corners & one center. Watch the overlap.

[SAmadei]

Hmm... so after much searching... Watts Bros sells the drill bits, but they have no website... you have to order over the phone.

To drill a 7/16ths hole, you need...

1 No. 1 or 2 full floating chuck $233-$297

1 7/16 square drill $47.30

1 7/16 Square guide plate $41.69

1 7/16 square slip bushing $14.52

But I'd have to call to ensure the right parts, so those prices likely would change. Not sure this project is worth $350. I think I'm going to have to buy some long lug studs. Hopefully I can find lug studs with a largish head and decent hardness.

[SAmadei]

Speaking of welding... I could tack weld lug studs to the parts, but I can't do it on location... and this project has two parts... one needs only 2 bolts, the other potentially 6-8. I would feel OK with tack weldiing the 2 stud part, as I can likely drill the holes onsite accurately enough to drive it in... but even if I make two trips with the 6-8 stud part, one to drill the holes and one to return with the part with welded studs, I'm afraid that 6-8 studs will be impossible to line up perfectly and get driven in.

I'm trying to think of any other bolts that would work like carriage bolts but not require a square hole... and can be sourced locally.

[balthazar]

Yea- just in looking at the scarcity of the bits, no way was it going to be affordable.

Dude, I could absolute converse on this.... if I had a semi-accurate idea what you were doing.

Can't you weld the 6-8 first (get 'em dead perpendicular) then drill the holes on-site to line 'em up?

"Driven in"... ? Is this thru wood? Can't torque 'em tight enough to call it 'secure'?

Throw me a bone here.

[balthazar]

Just sketching it out: mark out your 7/16" hole, drill 1/8" holes at each 4 corners, then drill a 7/16 hole dead center (step it- but watch avoiding the edges of the 1/8" holes until the 7/16th bit- might have to do a test hole here. 1/8" hole is negotiable, only has to accept the rounded corners of the carriage bolt- but smaller here is better than larger).

A sharp 3/8" wide square file will knock off the tiny bits left after the 5 overlapping holes are drilled. Sized just right & test-fit; you may be able to hammer the bolts in with zero filing.

Shouldn't take all that long with 8-10 holes in 1/4" stock.

Edited January 14, 2012 by balthazar

[SAmadei]

I tried to PM you with some specific details, but got rejected... not sure whats up with that.

The problem with getting 6-8 welded studs is getting them dead perpendicular... I'm never perfect perfect. Its also hard to hit 8 drilled holes perfectly... unless I make up a template ahead of time. And I'd have to drill the holes slightly oversize, whereas I prefer them to be fairly tight.

I drilled the one part today... I was mostly one the mark, but some drill bit deflection caused problems. Plus the final hole missed more than I wanted, so I was doing some filing for awhile... but this was a thinner part than 1/4... I can't imagine doing this 6-8 times.

Good news, after cutting the other squares off the part, I now have a template for future use.

I think the larger part of this project is going to get postponed a bit, as some of the tooling and metal is getting pricy.

[balthazar]

No ideer on the PM scenario.

Drilling thru fast-growth, green wood sucks, esp PT. Plenty of opportunity for deflection. Nice, dry, slow-growth wood drilling is a relative pleasure. Of course, I'm just assuming wood is involved here; you didn't specify.

As for the studs- I would drill the holes & weld them thru the stock, but you'd have to devise some sort of either (2) right angle to clamp them to, or washers/a sleeve to keep them perpendicular. A bit tricky without a dedicated jig.

Ideally, you'd build the studded steel piece first, then drill the holes they'd go thru second.

Edited January 15, 2012 by balthazar

[SAmadei]

"The member balthazar cannot receive any new messages".

Old wood clad in lots of steel.

Yeah, even using a jig, it always seems things end up a tiny bit off. I remember a few years ago, I had a situation where I needed to put a series of equal distance holes in a pipe... all parallel. I made a jig, but even though I triple checked it, it was off by maybe a degree... and the drill deflection cost me a degree or so on each hole... by the time I got to the other end of the pipe, I was off by 15 degrees! What a PITA that was. Finally got some acceptable pipes from a second jig and decided to attack the project a different way.

Thinking about studs, besides getting them straight, I question the strength of the welds... though I've had pretty good success filling holes, I always worry about penetration. (As I write that sentence, I already can imagine the funny comments, so get your minds out of the gutter already. ;-) ). I fear my welder just doesn't have the power.

It would be cool to have a finished project that didn't have any obvious attachments, though.

I imagine I'd have to cut the heads off of some bolts to get studs that fit the snuggest.

[balthazar]

Ooops- my inbox was full. :duncecap: I cleaned it out try again if you have a pic.

You should be able to weld both sides of the bolt and get good penetration if the welder is up to it- what's it's capacity?

You said security, as opposed to structural, so penetration might not be as crucial.

You'll see it in the steel if it's done well. You can always pre-heat the metal with a torch to aid penetration.

Yes- you'd have to cut heads off (not sure what quality threaded rod you can buy)- but the weld will fill the hole; no worries there.

Parallel pipe drilling calls for a milling machine with a feed table to achieve perfection, IMO.

Edited January 15, 2012 by balthazar

[SAmadei]

LOL, so drilling some holes on this project, I found I'm drilling into 3/8ths steel and an inch of concrete. Unfortunately, I don't have a hammer-drill. I think I hit some of the aggregate in the concrete and it stopped me dead. :-( Either that, or I have another layer of titanium/kryptonite in there...

Any ideas drilling a circular hole into the unknown? Unfortunately, it was getting dark, so I couldn't get a visual. I think I'm going to use some chisels on it to see it it'll break up a little.

I can't believe I have another 3 inches of concrete and steel to go.

[balthazar]

You can use masonry bits in a non-hammer drill, but it will go very slow... or hit a rock and just spin.

You can try a masonry/stone 'star' chisel...

...but with 3 inches of concrete, you're going to vastly prefer a hammer drill.

[SAmadei]

I'm reading that using some masonary nails and a BFH should get me further. Luckily, its only two small holes.

Its a shame, I was cutting through the concrete nicely until I hit something... I was hoping there was no aggregate in this part.

Keep in mind, I have patience and no power, so everything has to be hand worked or battery powered. My hammer drill is neither. :-(

[67impss]

Generator

[SAmadei]

I have a genset. Two actually. A gasoline WW2 era one with a flat four and a propane Onan 12K with a cherry low hour Mopar slant 6. Problem is either is overkill and both need work.

In time, I need a portable, little generator... but I hate the idea of buying a crappy gen secondhand for 80% of the price of a new one. I just have not been able to find a good deal. Besides, while not working, if I'm unwilling to buy a battery powered hammer drill, I'm probably not in the market for a generator. ;-)

[67impss]

I got ya & am living that nightmare unemployed also