I look for the larger sized bits at yard sales and flea markets...I have scored a Silver & Demming 5/8" and 3/4" bit with the 1/2" shank like new,for 1-2 bucks each..beats paying 10-15 bucks at a hardware store,for a bit you may use only a few times...
The two worst drilling jobs I did --one was drilling 3/4" holes on two pieces of 1/2" thick plate that I used to mount a crane base on my flatbed...
I tried using a hand drill,that proved useless after I got up to 3/8" ,it just stalled and hummed..
So I used the drill press, but its a "Companion" ancient Sears one with a 1/3 HP electric motor that stalled about 1500 times even with plenty of lube on the bit and light pressure...the lowest speed isn't slow enough...nor is it powerful enough for holes over 1/2" really..
I dulled my only 1/2" bit about 4 times before I tried using a 3 fluted 3/4"countersink I had found in a pile of scrap made of high speed steel--it went thru the plate a lot easier than the drill did..despite using the drill press,I spent a good 2 hours drilling a dozen holes..
Worse than that job, was installing a receiver hitch on my '82 GMC..
I had one rated for 10,000 lbs that was like brand new off a later GM pickup that was a bit narrower than my frame rails were,so I used some hunks of 6" C-channel bolted to my frame,to have something the hitch could be bolted too...
I had to drill about a dozen 1/2" holes lying on my back,with the hot chips landing on my arms and chest,pushing upwards hard enough to lift the truck up an inch...then had the drill snag and slam my hands against the frame about 50 times,till they felt broken and were bleeding...by the time I got that hitch bolted up and tight,I felt like I'd been run over ten times by the truck..
The final kick in the nuts is the fact I have never towed anything ONCE since I put it on,nor did I ever get around to installing the "T" splice harness for trailer lights...

..but at least it's there,if I do have to tow something now...

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