Looking for a bit to drill through 3/8 of iron. It's the bottom flex rail of an old school patio chair. Tried bit made for metal at Lowe's, didn't get past 1/32 before it stopped cutting.
Drill bit for iron
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Use any bit for metal . drill at a slow speed use lots of cutting oil .
because you want a 3/8 hole use a 1/8 to drill a pilot hole
because you want a 3/8 hole use a 1/8 to drill a pilot hole
Do yourself a favor go to a real hardware store and buy a name brand drill bit. Irwin, Hansen, Vermont American. As the prior poster noted drill a pilot hole, go slow and use cutting oil. Some folks like to work their way up in size. Definitely don't overspeed the drill bit as it will work harden the metal.
Harbor Freight and other discounters sell "titanium" drill bits colored gold, many are made of inferior base metal and dull rapidly. I have a large drill index set someone gave me from HF and I will smoke multiple drill bits drilling one hole.
Going cheap on drill bits and cutting tools in general is usually false economy, the money you save up front usually is exceeded by frustration and the need to buy more bits. It the metal is weird, cobalt drill bits available at automotive supply houses usually will cut through anything but they can be brittle.
Harbor Freight and other discounters sell "titanium" drill bits colored gold, many are made of inferior base metal and dull rapidly. I have a large drill index set someone gave me from HF and I will smoke multiple drill bits drilling one hole.
Going cheap on drill bits and cutting tools in general is usually false economy, the money you save up front usually is exceeded by frustration and the need to buy more bits. It the metal is weird, cobalt drill bits available at automotive supply houses usually will cut through anything but they can be brittle.
Buzz Saw
Minister of Fire
The "rail" could be a spring steel. Definitely want a high quality bit with low rpm's and cutting oil.
sportbikerider78
Minister of Fire
Decent drill bits will always cost over $3-5 per drill. If you buy a 20 pc set for $15. They are absolute garbage.
All good advice above.
Look for one with a high value (e.g. 120) angle also for harder materials.
![[Hearth.com] Drill bit for iron](https://www.hearth.com/talk/data/attachments/176/176880-69285a4a5ff7bcb7f4c5ff7bef2a7a4b.jpg?hash=BK_CEnwLVG "[Hearth.com] Drill bit for iron")
Look for one with a high value (e.g. 120) angle also for harder materials.
Buzz Saw
Minister of Fire
Yes, it's the part that sits on the ground and flexes as it aborbs weitght when sat on. It's about 3/8" thick and very dense, chair probably from the 50's.
Buzz Saw
Minister of Fire
![[Hearth.com] Drill bit for iron](https://www.hearth.com/talk/data/attachments/176/176954-9ee8a5dd559ddf94cc4f76a81617b836.jpg?hash=qDoKjdidGa "[Hearth.com] Drill bit for iron")
This is good stuff for cutting and tapping. In a pinch engine oil, or bar oil will work. Cutting oil is designed to lubricate and wash away chips. Engine oil is designed to lubricant and stick to metal(crank shafts main bearings). So in a production setting engine oil will stick to the cutting tool resulting in the tool over heating.
But for a once in awhile drilling use what you've got laying around. Bee's wax or even bar soap is a decent lubricant. Sorry for the loooong over complicated response.
I bought a new bit, titanium, Milkwakee, $4. 135 spread. Dropped some bar/chain oil in and used slow speed. It did nothing!. I ended up using 4 cable ties. The only issue with the chair was on one side the seat border came unwelded from the spring bottom for about 6". It was just enough to fall through and scare you, not make you fall over. The cable ties are holding firm.
Well I guess they made that runner with hardened steel.
There always is the final solution for difficult to machine materials https://en.wikipedia.org/wiki/Electrical_discharge_machining
There always is the final solution for difficult to machine materials https://en.wikipedia.org/wiki/Electrical_discharge_machining
So it had a weld area close by/ on where you needed to drill - therfore that steel became hardend from the heat of welding. the other thing is if you were going at full tilt with the previous bit you likely created a hardened surface a few thousandths thick that you must break through. This can be next to impossible with a hand held power drill, even when using a carbide tipped bit. So what to do - get out the trusty propane torch ( Mapp gas unit better) and try to heat the area to a dull red, then let air cool completely ( you are annealing the area, Removeing the temper) then possibly with a sharp bit and lots of oil and slow speed try again.
Wait...that's counter intuitive, if heating it hardened in the first place, how would heating it again remove it?
Buzz Saw
Minister of Fire
Different temperatures ranges do different things to metals. Low and slow will will take the hardness out. High and fast will put the hardness into a metal(primarily steel alloys). Ever watch "Forged in fire" on the history channel? The blacksmiths use heat to shape the blades and when they are done the blade is quenched in oil. The oil rapidly cools the steel (plus other stuff) and makes the blade very hard.
You made the steel very hot when drilling and it cooled rapidly via air and is now"work hardened". Try annealing it see what happens. Nothing to lose, right?
Yup .
The material for spring steel is generally 60 points carbon .60% or more than half that required for a decent file.
At 60 points carbon the spring steel can be strong/tough enough to make wrenchs and hard enough to make decent axe blades and wood chisels. Pretty hard to drill through for sure.
Anealling the spring will cause it to break trather than bend thus dooming the chair.
The only way to drill it has already been mentioned, carbide tipped bits.
In industry we would use a solid carbide spade bit for this task, for a homeowner the masonry bit is far and away the best choice.
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