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, 201214 yr by SAmadei

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.

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?

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.

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.

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.

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.

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.

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.

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, 201214 yr by balthazar

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.

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, 201214 yr by balthazar

"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.

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, 201214 yr by balthazar

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.

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.

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. :-(

Generator

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. ;-)

I got ya & am living that nightmare unemployed also