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28

3/8" mild (hot-rolled) steel isn't difficult to drill, but any bit will fail if you get it hot enough to melt the cutting edge. Each hole should take no more than a minute. Use a sequence of sizes (1/8", 1/4", 3/8"). This makes for quicker drilling and allows each bit to cool between uses. If you only have "pilot point" bits on hand, use a starter bit that'...


16

Cutting should be easy This is true for generally all tool-bit-upon-steel work. You should cut long, continuous "chips" (strings, really) that come off like pasta, to the point where you sometimes have to intervene to break them, to keep them from rats-nesting around the drill. run quite cool, to where you can disengage the bit from the work and grab it ...


9

For a hole of that size or larger a hole saw might be an easier method as it removes less material and may be more likely to stay centered due to its pilot bit. However using the more standard bit you have is working and you should be able to get all the way through. The type of vibration and unevenness of the hole from that type of bit is not uncommon in ...


7

No. Steel bits need to be very sharp to do their job. In fact, unless you set a depth gauge just barely through the metal, you'll wreck the cutting edge with every hole when you contact concrete and need to resharpen. Concrete bits create holes by pounding and disintegrating the material. They have cutting edges, but that's mostly to focus the impact and ...


5

Yes, that shank is for an SDS-plus chuck. It won't work well in a regular three-jaw chuck. The SDS shank has the advantage of fitting into a simple spring-loaded chuck, so that bits are simply pushed into the chuck without tightening. This shank and chucks made for it are especially suited to hammer drilling with masonry drills in stone and concrete. ...


5

I'd like to elaborate the step drill bit suggestion by @riseagainst IMO the best option by far for drilling medium sized holes in metal with handheld electric drills. Specifically I would recommend a single flute step drill such as this one: The problem with drilling holes in metal with a handheld drill is correctly categorized as a 'speeds and feeds' ...


5

To drill through metal, use a "slow speed and heavy feed". That is, make the drill bit rotate (relatively) slowly, but push hard. Also note that drill bits are directional -- they either cut when rotating clockwise or counterclockwise. You can tell which edge is the cutting edge by gently running your finger along the drill bit's edges. Make sure your drill ...


5

The quickest and easiest way is to take them to a steel fabrication shop. They have hydraulic punches that would make short work of that. The church we used to attend had to build scissor trusses to support a remodel and tried to drill the steel plates. it took forever and was costly in terms of drill bits (Good steel is tough on bits.) They bought a ...


4

When drilling into metal always use a cutting oil, at the minimum use an oil to reduce the friction and heat build up. I know that sounds counter intuitive reduce the friction, however you are not burning through the metal you are in effect cutting through the metal. Since the bit is to be cutting through the metal ; lubricating the bit is what allows it to ...


4

If you mean non-magnetic , eg 304. stainless , you have a problem. I am assuming a limited amount of experience. If the drill turns without cutting , it coldworks the stainless making it even more difficult to cut. I would say get several 1/8" bits and several 3/8" drill bits. The "chisel" at the center of the point scrapes metal away instead of cutting it ...


4

When you're drilling and tapping threads into metal to accept a machine screw, you have to use the precise right size drills and taps. But you don't need to be real precise with lag screws in framing lumber. Without a pilot hole or with a too-small pilot hole the wood may split. If the pilot hole is too large, obviously the fastener won't hold. Look at ...


4

Use a 'speeds and feeds' calculator to determine the ideal combination for the material, diameter, etc. in question. This should help you get a feel for the best possible circumstance and see how close you can get to it with the stuff you have available. Here is an example: https://www.whitneytool.com/SpeedAndFeedCalculator.aspx When you get into this level ...


4

Do not under any circumstances use used motor oil, as has been suggested. As well as being filthy it is seriously carcinogenic and an environmental hazard and should only ever go to your local recycling site. You really need machine cutting oil, which is much more of a coolant than a lubricant, and needs to be supplied continuously in adequate quantity, ...


3

These are indeed very rare. And old. Google image search kept showing old radio sets. After a lengthy search I found one source that should do the trick for you. Microtech Medium Domed Tri-Wing Wrench Tool Bit (bladehq.com)


2

I have had mine for quite some time and have sharpened them many times with a hand file. Just be careful how much you remove on each side and keep the angles consistent for proper cutting. The thin metal of the bits would heat up too much under machine grinding or the angles would not be easy to reproduce, IMO.


2

One solution is to buy an adapter and a large set of normal drills. Another solution is to look for hex-shank drill sets Bosch Uneo Adapter Bosch 2608572075 1/4" 1-10mm Keyless Chuck Adaptor (Suitable for UNEO) Suitable for use in a cordless screwdriver and drills with forward / reverse function. Can also be used with the Bosch UNEO drill to allow ...


2

I can't see how they would be compatible. ¼" = 6.35mm ⅛" = 3.175mm


2

Here's what I eventually did to get the screws out: Used a Dremel rotary tool with a metal cutting wheel on it Cut slots across the head of each screw Used a flathead screwdriver to remove them Hope that helps anyone who might come across this issue in the future.


2

To answer your question, based on where you're at, meaning that hole we see in the picture with a drill bit vibrating as you said (which is beyond the point of starting the whole with smaller bits), in my experience (I have since learned my lesson), you should use a drill with high speed, and not make full contact with the metal, kinda keep a certain ...


2

Neither bit will do well in a standard drill. You need hammer action to chop through concrete with any sort of speed. A hammer drill (conventional drill with hammer action) will work for a few holes with some patience. If you need to bore many holes or to work quickly, a rotary hammer is a must, and they only accept SDS bits with the larger, slotted shaft ...


2

I have no idea how to choose your hole sizes, it sounds like you have thought it through, and I am sure some trial and error will be involved. I can only suggest tools to make the holes. In the smaller sizes, drill bits graduated in 1/32" or even 1/64" increments are readily available. No need for super quality drill bits if you're just drilling plastic....


2

One option that you have is to use a mini-drill chuck adapter or mini-drill chuck. I used the latter term in a search and the auto-fill in The Google added adapter, but the results were the same: This image came from The Home Depot and will accept from 0.00 inches to 0.039 inches (1 mm) according to the specifications. You would find other mini-drill chucks ...


2

I'm going to throw out some opinions here that I don't have hard evidence to back up in form of citations. The Wikipedia article you liked kind of mentions this, but the reason hex shank (6 sides) is a thing is most likely because drills normally have chucks with 3 jaws. A shank with 6 sides is a natural result of that. The extendable bits you show with ...


2

You have work-hardened the holes by letting the bit turn without removing metal. Work-hardening can increase the steel strength by 6 times+ ;like from 50 ksi tensile to 300 ksi tensile . One the hole surface in the plate is hardened above 200 ksi , it is too hard for a new sharp bit to cut. Every turn should remove metal or the bit is burnishing/hardening ...


1

If you are unable to return the bit or cannot find a standard bit in that length you can cut the SDS portion off. They still work as a standard masonry bit in a driver/hammer drill albeit not as well. I've done it in a pinch several times. By the way, SDS is well worth the money if you need to drill or chip masonry even occasionally. I've got at least one ...


1

If you're drilling a hole that small near sensitive electronics, you may want to consider a pin vise. They are often available at hobby stores. Here's a picture of one of the first ones I found via Google: Image courtesy of wonkeedonkeetools.co.uk (with a nice description of use), no product reference implied. The top (of some) pivot so you can place a ...


1

Based on your description, I took a guess at the bolt size, and assumed 3/8", which should be the diameter of the unthreaded shank. That would get a 15/64" pilot hole. If the shank isn't 3/8", measure it and check this chart: https://www.portlandbolt.com/technical/lag-bolt-pilot-hole-diameters/. If you don't have drill bits graduated by 1/64". round ...


1

A Steel Step Drill Bit. This is what I have used to drill through steel beams. Mind you this is much cheaper than what I use for commercial use but still works very well and can be found on Amazon or most hardware stores. $10 Amazon.com link


1

If it is possible that you used the drill bit with the electric drill set to the wrong rotation direction, without realizing it, the freshly ground new drill bit will likely be able to drill a hole through the thin steel but at the same time will dull and round off sharp edges so much that a second reverse operation would never start to cut into the metal. ...


1

Buy a step drill bit that is meant for drilling holes in metal with conventional drills. No need for a pilot hole or any other weird ideas. It gives you complete control, no vibration, and won’t create a crater in the material like you have done. You’re going to end up with a 1.5” hole shortly. A carbide hole cutting bit as recommended would also work.


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