3/4" Holes in 3/4" Mild Steel

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Hey Guys I am building a new logsplitter and will need to drill 36  .75 inch holes in 3/4 inch mild steel.  I have a 1hp floor mounted drill press with a 1/2 chuck.   These will be used to bolt the push plate together......My original  thought was to clamp the steel in position then give them solid tack welds clamp them all down and drill a total of twelve  3/4 inch holes thru  2.25 inches of steel.  This way I can be sure that all of my holes will in perfect alignment ....once I was done drilling the holes I would grind off my tack welds and bolt the push plate together.  Am I way off base thinking I can successfully drill these holes?  What would be the best way to complete this?  Should my drill bit be spinning slow, med or fast?  In the past I have drilled 3/4-1 inch holes in thick plate with the bit turning slow and adding lubricant often. Thanks for your input and advise on this.Greg
Reply:Slow.  You'll be able to tell the right speed by the look of the shavings.  (I know that sounds unlikely, but I'm a complete novice/hobbyist and it made sense to me as soon as I was drilling.)Jack OlsenMy garage website
Reply:36 bolts?  Why so many?  Can't you eliminate some of them by welding?  I have a 13 ton HF logsplitter and it doesn't have half that many bolts as you are planning to use.  Anyway, I agree with Jack, Slow with plenty of oil to cool and lube the bit.  Be sure to drill pilot holes and then work up to the correct size bit.Miller Syncrowave 350Millermatic 252/ 30A spoolgunMiller Bobcat 225g w/ 3545 spoolgunLincoln PowerArc4000Lincoln 175 Mig  Lincoln 135 Mig Everlast 250EX TigCentury ac/dc 230 amp stickVictor O/AHypertherm 1000 plasma
Reply:Originally Posted by DougAustinTX36 bolts?  Why so many?  Can't you eliminate some of them by welding?  I have a 13 ton HF logsplitter and it doesn't have half that many bolts as you are planning to use.  Anyway, I agree with Jack, Slow with plenty of oil to cool and lube the bit.  Be sure to drill pilot holes and then work up to the correct size bit.
Reply:because it makes drilling larger holes much easier since it has to remove less stock350P 30A spool gun cut master 51  syncro 250 other stuff " take a dog off the street and make him prosper and he will not bite you sad the same cannot be said for man" i didnt use punctuation just to piss you off
Reply:What a coincidence.  I just drilled 35 .5" dia holes in a 1" plate.  See pics.  I drilled pilot holes first (about 3/16" I think).  This made the larger holes a lot easier to drill.  As has been said, use a slow speed for the large dia holes.  I used about 600 rpm.  You can go faster on the pilots.....1300 worked for me.You'll know when the speed is right...the drill just bits into the steel and the chips come curling right off the bit.  Use oil....lots of it. Attached ImagesMiller 211 w/ spool gunMiller Dynasty 200DXLongevity 60i IGBT plasmaO/A w/ crappy chinese torch/gaugesSouth Bend 10K latheGrizzly 4029 10x54 millGrizzly 7x12 hor bandsawangle grnders, bench grnder, bench belt sndr7.5 hp 80gal cmprsor
Reply:I did it the 'poor man's' way.  An inexpensive Harbor Freight drill and cheap Harbor Freight bits.  That's one inch steel plate.Jack OlsenMy garage website
Reply:I have my fathers old 1/2" sears craftsman, which is probably 30 years old, and we have drilled thousands of 1" holes with it, and even drilled a few 1 1/4" holes in 3/8" plate, but had to go very slow. Like everyone has said, drill a pilot hole, use lower rpm's, and use lots of oil. We've changed two belts on it after all these years. It can be done with what you have.
Reply:+ on the pilot holes. Just a small amount less in diameter than the web thickness of your 3/4 drill. This will make feeding the big bit easier. Don't want the pilot too big because it may cause self feeding. Plenty of coolant and peck feed to break up the chips. Partial pecking is just letting up on the feed pressure long enough so the chips break. Otherwise they will start to become a whipping hazard. By stacking you are going 4 diameters deep and will need to withdraw the bit (full pecking) a fair amount to make sure coolant gets to where it needs to be.
Reply:3/4" holes are nothing..I do this stuff all the time..Pilot hole is OK if you don't know how to sharpen the drill with a "Split Point"..With one of those pilot holes are not needed..However for the pilot hole I would use a 3/8" bit first..Spindle speed is controlled by the color of the chips..If the chips are blue then you are too fast..Adjust speed accordingly..Oil is too messy I use wax instead..Much easier and it don't spill.....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:The split point keeps a drill bit from walking as it starts the cut, and helps a -little- with cutting in deeper holes, but the split doesn't have the same rake angle as the rest of the cutting edge, and just doesn't cut as easily, so the pilot hole makes much more of a difference.A pilot hole should be sized to be just under the thickness of the bit's web (which is the poorly cutting part of the bit).  If it gets larger than the web, the bit will wobble.Wax is a good lube choice, but I find it smokes more than I like.  MUCH cleaner though.
Reply:what it the best lubricant? just like motor oil? how often should i apply? if the chips are blue should i slow the bit speed down or let up on the pressure? is there a speed guide for drill sizes and metal thickness?
Reply:for small holes like this its not so much lubrication you need as it is cooling.  Just as the primary purpose of ATF is high viscosity cooling, cutting oil is the same.   With our Cincinnati drills (where we have catch pans and circulation) we use a EG based coolant that is almost pure water.  In that case its just sheer volume over concentration.Zap is mostly right about the color of the chips being your guide - what you want is either silver to straw colored chips in either comma or SHORT curl shapes depending on the grind geometry of your bits.  With most factory drills you will get 'curly fry' looking chips.  With the right speed and down pressure these should break easily into short sections.  If they are very fine and "stringy" add more down force, if they are course and wont break ease up a bit.  Having  a pilot hole will also greatly extend the life of the more expensive larger drills by allowing coolant full circulation along the entire cutting surface.
Reply:I have enjoyed excellent results using Tap-Matic as a drilling and tapping lubricant.  When drilling I try to keep the feed and speed adjusted so that I can make the longest curls.