03 January 2012

Drilling leaf springs, made easy

Welcome to 2012, folks.

 Those of you counting down to "ZOMG!! TEH END OF TEH YEAR ON DECEMBER 21, 2012" Should go right ahead and leave. Now. Quietly... or there will be no apologies. ;)

I hope all are doing well after the holiday season. I, for one, feel MUCH better, having it aft of us. I HATE that time of the year, not for philosophical reasons, more for familial stressors and the overarching fact that just about everyone has forgotten the meaning of the season- and no, I'm not referring to strictly the Christian mythos, either... most belief systems have a common goal for the November/December timeframe... but I'm off-mission, there... ;)

So I am STILL working on this darn truck. It pains me to admit I am looking at about 7 months since I've driven it. Long story short, the axle ripped out about June, I wasted a month and a half while a buddy was insisting he'd "get it out in a day or two" while adapting one of my Dana 44 solid axles to replace the back Corporate 10 bolt, I finally said hell with it and decided to just dive in and do the solid axle swap (ie: cut off the factory IFS (Independent Front Suspension)) and convert the whole damn thing to oldschool solid axles out of a Wagoneer) myself.

"Couldn't take more than a month or two, longest". Pfft. Well, yeah- if I'd had bank to back up the goal, no job, more tools, etc, etc... I am wrapping up the project now, though.

One of the things I found after mounting the springs as far forward as I could without fabricating a frame extension, was that I needed to still move the axle 2" forward to clear the back of the fenderwell- I couldn't cut the fenderwell because on this truck the back of the fenderwell is actually the firewall, and if I didn't move the axle forward I'd actually have shortened the overall wheelbase- not something you want to do on this truck, given my goals.

The easy solution would be to completely rework the entire front so I could use different springs off of a YJ (about $400 for springs, plus all my wasted time, etc). No.

Or, I could order some custom springs with the spring pin moved 2" forward. I checked into that and it's about $400 or so, and would bolt in... but might provide it's own problems by way of addressing lift discrepancies front/rear.

Or, I could just drill a hole 2" forward on the springs I have built. Gee, how hard could that be, after all I own a drill press... Go google "drilling leaf springs" and you'll find the following "advice" (all of which proves to take anything you see on the Internet with a VERY big grain of salt...)

-don't EVER drill springs, if you do the stress risers induced in the metal will make the springs fail in short order, and you'll die when the axle comes out from under the truck
>(I should note, I actually saw a highly-degreed fellow (at least, he claimed to be) espousing this approach. Now, I respect the man's education and qualifications- but I feel the need to wax Heinleinian here: "Always listen to experts. They'll tell you what can't be done and why. Then do it. - Robert Heinlein. Yes, I am a bit partial to just about anything Heinlein said or did, as I basically consider myself a Heinleinian Libertartian, but that is Another Discussion Entirely(tm).. and requires alcohol, steak, and a fine cigar). I should note I've actually seen this attitude invoked by people whose rigs look like company advertisements for Rusty's Offroad Products, and anyone who's had a chance to inspect the aftermath of when those products fail should realize that's a pretty big freaking joke. I had a friend (mumbles something about "Absent Companions") whose XJ's lower control arm actually broke at the weld- while backing out of the driveway. Anyway- enough said about that at the moment...

-heat the spring with a oxy-acetylene torch to detemper it, drill the hole in the now unhardened steel, and retemper it. Use your barbeque and a 5 gallon bucket of water to do this.
>Gods, where to begin! First off- your barbeque grill is NOT going to get the steel hot enough to properly detemper/retemper the steel, even if you can get the damn spring to fit into it (how many of you have a 5' long barbeque, hmm?). Likewise, that 5 gallon bucket of water isn't going to quench the red-hot steel, either- quenching steel requires IMMERSING it in a liquid, entirely, and usually oil to boot so you get some carbon transfer from said oil. Thirdly, tempering/detempering steel properly is a rather exacting operation involving heating the steel to a specific temperature and doing so in a uniform matter. While yes, it is done in primitive conditions (notably by Nepalese blacksmiths- see the Gurkhas and their distinctive khukuri blades), those folks aren't depending on the product to maintain safe operation while several tons of force are regularly conspiring against the integrity of said product.

-cut the hole with a plasma cutter
>yes, because everyone owns a plas. Nevermind that the plasma operation doesn't transfer *as much* heat into the spring, it is still transferring LOADS of heat into a spot on the spring- to the tune of several thousand degrees.... it's *plasma*, folks. Not real wise.

-cut the hole with a oxy torch
>I'm suddenly glad I have no hair, as it would really suck to be ripping it out right now.

-can't be done, don't even try, you'll induce stress risers into the spring and it will fail
>Yes, if you cut the hole with the wrong sort of bit, with no lube, and "just go at it" on high-speed. NEVER cut steel on a high speed, particularly tempered steel. First off, you'll just harden the steel as you're trying to cut it- you're working against yourself.

-use a carbide/titanium/unobtainium bit. Replace often.. even if you can resharpen the bits yourself. >expensive, and seems a rather "hack" method of operating. Anytime you're using a tool for its intended purpose and then throwing it away immediately, you're probably doing it wrong.

-use a hammer and a punch, do it with the spring at room temperature
>:crickets: Really? Look, if you've done this, I will NEVER give you any trouble, lest you smite me mightily...

-use a step-drill in a drillpress, and it's no problem.
>this sounded like utter bunk to me- my experience with uni-bits (step drills) always seemed to end up regarding them as the adjustable wrench of the drill world. It'll work, kinda, but will cause more damage than it's worth, because it's not the proper tool... plus they're expensive. I did grab a pack of 3 a few months back at Harbor Freight for $10, as a gamble.

Please note, I say it "sounded" like BS. As in, past tense...

Since I am trying to keep this build as inexpensive (read: "Best bang for the buck") as possible, I elected to drill the spring. Read on...

I've been sick with a low-grade stomach flu since Thursday, so the past weekend has sucked to say the least... even so, I managed to pull the spring on Thursday after work and attempt to drill the hole 2" forward of stock. I used a 1/8" drillbit, and even with it being a high-grade TiNitride bit, still had to sharpen it 4 times. I stepped up a couple sizes- and about 1/4 of the way through the pack (of 7 leaves, so not even getting 2 leaves) I hit the wall. I'd been using plenty of oil, moderate pressure, and still it work hardened and I could go no further. I tried for two hours, numerous bits, all freshly sharpened with my Drill Doctor (BUY one, now, if you haven't!) and it was an act of desperation. I tried the step-drill thing yesterday- disassembled the pack, got one of those cheapo step drills, expecting to frag it immediately... setup the drillpress (again, Harbor Freight*, and the second-best $50 item in my shop) shrugged, and spun the feed wheel around- and the damn bit sunk through the steel like it wasn't even there. I am EXTREMELY impressed.

So, long story short- need to drill holes in a leaf spring? Use a good step drill, a drill press set to slowest speed (sub 700RPM), lots of oil. Cut each spring individually. Easy.

*BTW- yes, I know they're cheap tools, made in China, and no I'm not real happy about it. But when I can spend $50 on a chopsaw that will cost easily 4 times the price if it's "made in the USA" (and that's likely a lie- it's likely made in... China) and it lasts me 9 years of just beating the hell out of it while building several jeeps and projects, and then only needs a new set of brushes, I don't mind saying I got my money's worth. Conversely- I bought American- a Hobart (aka Miller) plasma cutter (AC250i, I think it was?) for $800, using it occasionally, and the damn thing flat-out DIED after less than 2 hours' runtime... to the tune of needing a new $670 mainboard which the company would not honor warranty on, and told me "you can't let them sit, they have to be used often to maintain them (unbelievable levels of bullshit, that- and yes I am qualified to judge)... well hell, no "Made in America" for me, thanks. I have a jeeping buddy who uses a cheap Chinese plasma cutter (I want to say the Cut250?) in his shop all the time and it's not given him any problems- and cost less than half of what I wasted. Well, he's using that tool to put food on the table and it's not even hiccupped. I bought mine as a hobby/very occasional use tool, and I now have a $800 paperweight. How smart was "buying American", again?

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