How can I drill a hole across a bolt?

[rnln]

Hi guys,
Might sounds like a silly question to you guys, but I really don't know :lol:
I need to drill a hole across the end of a bolt, size 5/16 . I use the cobalt bit, which is the best and it will work, according to the sales person at home depot. Well, I sat on it for a while, until my hands are sore and it still doesn't go anywhere.
A friend mentioned that I need a drill-press. To me, the drill press is only helping you to keep the drill bit straight, is that right? Or will it help to press hard on it and it will go through easier?
Thanks.

[rcooled]

If that bolt is hardened (grade 8), you'll have a tough time drilling thru it with a hand drill. In any event, you'll want to use a high-speed 1/4" drill and filing a small 'flat' on the bolt where you want to start the hole will sometimes help.

[John Rogers]

For hardened steel like your bolt you would want about 1500 RPM on the drill bit and some drill lube that also removes heat and melts. I generally use Crisco for that unless it is tool steel then I use a special heat absorbing paste. I don't know what speed your drill turns so that could be the problem?

Time to visit Harbor Freight and get one of their drill presses, I use one of their floor models and have almost never used a hand drill for holes since. The advice for a small flat spot is correct but make sure the bit is lined up to go straight through the bolt. Good luck.

[dad911]

What peter said. Drill slow speed with pressure. Bit should always be pulling a chip, if not it's just skimming the surface and generating heat, getting dull.

[Eric Coffey]

You might check to see if there is anything commercially available to suit your needs first. There are likely bolts in the size you need somewhere out there with pre-drilled shanks for cotter-pin/safety-wire applications.
I'd probably check aircraft supply places and auto/MC race/fab shops, as well as McMaster-Carr/Fastenal.

[Baz]

I wonder if this is something you take to the local fabrication shop. Surely they wouldn't charge much and at least you won't have to buy a bunch of equipment you may not need.

[rnln]

Thanks guys,
So basically, it's is possible, but not easy, for a normal steel bolt. What about SS bolts? Forget about it?
Thanks again.

[abisel]

will this help?
Bolts from Aircraft Spruce

[James Brown]

a little "V" block (you can make one out of wood) is helpful. drill press will help keep it straight but it puts a lot more pressure on the job than a drill, make sure the drill is going in the correct direction...

[pksystems]

Lock wire?

I made a jig out of a piece of scrap aluminum to hold the bolt square and in place. Secure it with a clamp, and use a drill press.

I was drilling 10.9+ socket cap screws.

[Jim Bremner]

There are jobs available. Do not bother with non-USA MADE BITS. If you need just one try to buy a predone bolt.

[unclebilly]

Is your drill turning clockwise when drilled from the top? Who sharpened the bit?

This should not be difficult.

[ckelly78z]

Flatten out the thread portion where you will be drilling, and peen the start of the hole. Use pressure and slow speed. I also use a cutting oil to keep the drill bit cool and cutting a nice curl.

[masraum]

I would assume that a good lube and a slow bit would be pretty important for this sort of work.

[javadog]

First you need a good drill bit (technically it's a drill, not a bit, but we're going to go with the terminology most people use.) You say you bought at cobalt drill bit, but given where you bought it, I am suspicious that it's actually what it is supposed to be. A good quality cobalt drill bit will drill through pretty much anything. Then, you need to use the right drill speed. There are charts that you can use to look up the correct speed for a given drill diameter and material. There are also formulas were you can calculate it; bottom line, for small drills most people use too slow a speed. The third thing you need is something to keep the drill cool; most people use some sort of oil that they consider a lubricant. In reality you're just keeping the temperature of the drill down to a point where it is not damaged. You do you want a certain amount of pressure, to give you a certain feed rate, but don't assume that more pressure is always better. Too much, or too little, neither one is good. A drill press helps to keep the drill aligned but it is not 100% necessary. Lastly, if you are going to drill a large hole, drill a pilot hole first. Understand that there are different drill profiles and some of them work much better if a pilot hole is drilled first.

I drill holes through bolts all of the time; hardened steel, stainless steel and titanium. The biggest factor in my success is the quality of the drill bit.

[1990C4S]

A good set of center drill bits is a smart investment. Get the hole started in the right spot and it's easy after that. Center punch the spot, get the hole started with no wobble, no slipping.

https://www.amazon.com/Center-Drill-Inserts/b?ie=UTF8&node=340049011

[vash]

we used a drill press. this was a pro press that had this nozzle that sprayed a mist of liquid the entire time.

we had to cross drill a lot of high strength bolts because we didnt read the rules that all hardware without a visible nut on the end needed to be safety wired!!

[nota]

Originally Posted by rnln

Thanks guys,
So basically, it's is possible, but not easy, for a normal steel bolt. What about SS bolts? Forget about it?
Thanks again.

lots of rigging parts on sail boat masts are drilled and clipped SS
you really do NOT want them coming apart

the bit has to be harder then the work part [SS bolt]
so no big box store china junk drill sets
cobalt or ti
keep the bit from over heating go slow and let it cool recoat with wax
re-sharpen often
expect to break or burn out bits so get a bunch

[sammyg2]

Originally Posted by rnln

Thanks guys,
So basically, it's is possible, but not easy, for a normal steel bolt. What about SS bolts? Forget about it?
Thanks again.

Depends on what kind of stainless you are talking about. There are many.
If it's typical 300 series (316, 309L), it's soft and cuts like butter but galls easily.
If you're talking 400 series it is usually heat-treated and can be pretty darn hard.

[sammyg2]

BTW ......

https://www.mcmaster.com/#catalog/124/3241/=1dgumd8


Page 3241

Steel Wire-Lockable Hex Head Screws

Fully Threaded

Partially Threaded

Wire these screws together through the hole in the head to get more vibration resistance than any other screw (wire sold separately). They are made from zinc-plated Grade 5 steel that’s stronger than stainless steel and provides corrosion resistance in wet environments. Length is measured from under the head.

For technical drawings and 3-D models, click on a part number. For technical drawings and 3-D models, click on a part number.


Lg. Threading Min.
Thread Lg. Head
Wd. Head
Ht. Hole
Dia. Tensile
Strength, psi Specifications Met Pkg.
Qty. Pkg. Each



Zinc-Plated Grade 5 Steel



1/4"-20

1/2" Fully Threaded __ 7/16" 11/64" 0.063" 120,000 ASME B18.2.1, SAE J429 10 90124A537 $11.01 8860K14 $6.10
5/8" Fully Threaded __ 7/16" 11/64" 0.063" 120,000 ASME B18.2.1, SAE J429 10 90124A539 11.24 8860K14 6.10
3/4" Fully Threaded __ 7/16" 11/64" 0.063" 120,000 ASME B18.2.1, SAE J429 10 90124A540 11.24 8860K14 6.10
1" Fully Threaded __ 7/16" 11/64" 0.063" 120,000 ASME B18.2.1, SAE J429 10 90124A542 11.75 8860K14 6.10


5/16"-18

3/4" Fully Threaded __ 1/2" 7/32" 0.063" 120,000 ASME B18.2.1, SAE J429 10 90124A581 13.16 8860K14 6.10
7/8" Fully Threaded __ 1/2" 7/32" 0.063" 120,000 ASME B18.2.1, SAE J429 10 90124A582 13.26 8860K14 6.10
1" Fully Threaded __ 1/2" 7/32" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A583 7.28 8860K14 6.10
1 1/2" Partially Threaded 7/8" 1/2" 7/32" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A587 8.42 8860K14 6.10


3/8"-16

3/4" Fully Threaded __ 9/16" 1/4" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A622 7.28 8860K14 6.10
1" Fully Threaded __ 9/16" 1/4" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A624 7.70 8860K14 6.10
1 1/4" Fully Threaded __ 9/16" 1/4" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A626 8.35 8860K14 6.10
1 1/2" Partially Threaded 1" 9/16" 1/4" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A628 9.00 8860K14 6.10
2" Partially Threaded 1" 9/16" 1/4" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A632 10.03 8860K14 6.10
3" Partially Threaded 1" 9/16" 1/4" 0.063" 120,000 ASME B18.2.1, SAE J429 5 90124A636 11.08 8860K14 6.10


1/2"-13

3/4" Fully Threaded __ 3/4" 11/32" 0.109" 120,000 ASME B18.2.1, SAE J429 5 90124A710 11.71 8860K16 6.51
1" Fully Threaded __ 3/4" 11/32" 0.109" 120,000 ASME B18.2.1, SAE J429 5 90124A712 12.13 8860K16 6.51
1 1/4" Fully Threaded __ 3/4" 11/32" 0.109" 120,000 ASME B18.2.1, SAE J429 5 90124A714 12.64 8860K16 6.51
1 1/2" Fully Threaded __ 3/4" 11/32" 0.109" 120,000 ASME B18.2.1, SAE J429 5 90124A716 13.29 8860K16 6.51
1 3/4" Fully Threaded __ 3/4" 11/32" 0.109" 120,000 ASME B18.2.1, SAE J429 1 90124A718 2.89 8860K16 6.51
2" Partially Threaded 1 1/4" 3/4" 11/32" 0.109" 120,000 ASME B18.2.1, SAE J429 1 90124A720 3.06 8860K16 6.51


5/8"-11

1 1/2" Fully Threaded __ 15/16" 27/64" 0.156" 120,000 ASME B18.2.1, SAE J429 1 90124A798 4.43 8860K21 11.98
1 3/4" Fully Threaded __ 15/16" 27/64" 0.156" 120,000 ASME B18.2.1, SAE J429 1 90124A800 4.61 8860K21 11.98
2" Fully Threaded __ 15/16" 27/64" 0.156" 120,000 ASME B18.2.1, SAE J429 1 90124A802 4.78 8860K21 11.98
2 1/2" Partially Threaded 1 1/2" 15/16" 27/64" 0.156" 120,000 ASME B18.2.1, SAE J429 1 90124A804 5.17 8860K21 11.98


3/4"-10

2" Fully Threaded __ 1 1/8" 1/2" 0.156" 120,000 ASME B18.2.1, SAE J429 1 90124A843 6.58 8860K21 11.98
2 1/4" Fully Threaded __ 1 1/8" 1/2" 0.156" 120,000 ASME B18.2.1, SAE J429 1 90124A844 7.04 8860K21 11.98
3" Partially Threaded 1 3/4" 1 1/8" 1/2" 0.156" 120,000 ASME B18.2.1, SAE J429 1 90124A847 7.60 8860K21 11.98