i reverse arched a model a spring and had this other spring pack with nice rounded tapered leaves but the bolt hole isnt in the center of them so i need to drill them so after smoking a couple bits i bought the 11$ cobalt "you wont smoke that one" drill bit and it smoked any secrets or do they punch the holes? thanks B.R.
I agree with Unkl Ian but you have probably work hardened the area. Start from the other side or use a die grinder with a carbide bit to rough it out and finish it off with the sharp drill bit and OIL.
I've redrilled them. Like the other guys already said, nice and slow, cutting fluid, and pressure. It does take patience.
Maybe start small and work your way up to 1/4" or whatever your final hole size is. Or you may already be doing that.
I have done it a few times, i now just take them to a local shop and pay $2-$3 a hole, lots cheaper then buying drill bits
Go and But a carbide tipped drill,it what we use at the shop to drill hardened steel .they are pricey but if you dont break it,they work really good on stainless,and aluminum(spin drill real fast and the inside of the hole will look polished)
Regardless of what you're drilling, smoking bits is too fast and not enough WD40/oil/whatever to cool it. Metal needs slower drill speeds than wood, most people think it's the other way around. Still, I'd be wanting a drill doctor on hand for that task, even done right.
The cheap way out on hardened steel is a carbide tipped cement drill. Just remember its a cement drill so id still run it fairly slow with lots of lubrication/coolant. I went to menards and just got a bottle of pipe threading oil/lube/coolant and I use that for drilling and threading.. Dave
Your running the drill too fast. leaf springs are not that hard. I would use a carbide drill at this point , cobalt will only work for a short while and not at fast surface speeds . A new cobalt drill should run around a 100rpm for a .250 or .312 use plenty of lubercant trans oil or motor oil will work in a pinch. I'd use a drill press and clamp the part down if you can. Dan
I used to start off with a new 1/8th and work my way up to 3/8 usually. Been a long time since I have had to do it....
That is a good way to ruin the outer web on your drills, especialy on something as hard to drill as spring steel. Pick your drill size for the hole you need, and use that size drill. I dont see how this could ever work. I drill through concrete a few times a week on my day job, using a carbide tipped masonry drills, in a hammer drill. While these drills are carbide tipped, they have no sharp cutting edge, that whill make chips (shave away) steel. The problem is, ***uming your using a drill press, most lower cost drill presses will NOT go slow enough for this drilling operation. A carbide tipped bit would be nice, but is not necessary. A Cobalt bit is probably a bad idea, unless your setup is extremely rigid, and the cutting speed and feed rates are exactly correct, as cobalt is hard, but brittle and the bit could break. Your best bet is to get a good split tip 135 degree HSS drill, of the exact size hole you need (good means one made by Triumph, Precision Twist, Chicago Latrobe, Norseman, Champion, NOT something you buy at Home Depot, or any big box store, go to your local industrial supply). Set your drill press as low as you can, it reallly depends on the size of the hole you are drilling. Low for what you need to do is probably LESS THAN 500 RPM! SLOW! Use a good cutting fluid, and keep a steady feed on the drill. You dont want it to just spin, and build heat, you want it to be chipping away metal. If you go slow, the drill will cut the hole, and it wont destroy the drill. Heat buildup ruins the hardness of the drill, and causes it to lose its cutting edge very fast.
I've used Concrete Drills on hardened Tool Steel. Better than nothing,but the Carbide tips don't last, difficult to sharpen even with the correct wheel, and the size isn't accurate. Carbide drills are much better,when needed, also a LOT more money. Last time I used one,was drilling a hole through a bearing race. (my Boss wanted to pressure feed a double row ball bearing) Those ****ers are HARD. Worked perfectly.
<HR style="COLOR: #999999" SIZE=1> <!-- / icon and ***le --><!-- message --> Quote: <TABLE cellSpacing=0 cellPadding=6 width="100%" border=0><TBODY><TR><TD cl***=alt2 style="BORDER-RIGHT: 1px inset; BORDER-TOP: 1px inset; BORDER-LEFT: 1px inset; BORDER-BOTTOM: 1px inset">Originally Posted by Nick79 Maybe start small and work your way up to 1/4" or whatever your final hole size is. Or you may already be doing that. </TD></TR></TBODY></TABLE> That is a good way to ruin the outer web on your drills, especialy on something as hard to drill as spring steel. Pick your drill size for the hole you need, and use that size drill. You are the first person I have heard say to start with the hole size on something hard. Could you explain your thoughts on this. I use air drills so maybe thats what I am not understanding.
i have watched many a big truck spring get drilled, and slow is an understatement, you would fall asleep counting the bit go round, lots of good stinky oil, no pilot hole, HSS is all you need.
Working up from one size to the next,all the cutting force and heat, get concentrated on the corner,instead of spread across the whole cutting edge. It will reduce the amount of force required from the operator,but tend to overload the margin. A blind hole also acts as a reservoir for coolant.Drilling through with smaller drills first eliminates this benefit.
In the last 5 years I've drilled at least 50 holes in leaf springs. Your drill press must go no faster than 200rpm. I drill a 1/8" pilot hole and then the final size. Usually 3/8" for a center bolt and 1/2" for teflon ****ons out toward the spring ends. I use regular high speed steel bits and lots of cutting oil. It is necessary to sharpen the bit occasionally.
I bought a set of drill bits from a guy at the LA Roadster Show, they are obviously from CNC equipment, have two different diameters ( a starter and the finished diameter) and they work really well, and he advised running them pretty slow. Pipe threading lubricant (Rigid or similar) is probably the lube of choice.
i would probally take it to someone who has done it before and let them give it a shot. i'm sure that heating it can't really be safe
question is, did you drill a small hole and work your way up. if not.....that may just be your problem. A tiny little drillbit will drill easier than drilling with your bigger bit straight a way. least thats how it's been in my experience.
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