i need help drilling 1 inch holes

escavader · Feb 3, 2006

I need some advise on drilling 1 inch holes in1/2 thick steel,on my thumb project.I got 12 to do,cant even finish one /forums/images/graemlins/frown.gifI started by drilling 3/8 holes,should i go even bigger,or in sucession 1/2 then 3/4?I will go a little ways good,and then my bit must overheat,and wont cut no more.I have reground 3 times,and i cant even get one through.Im using a small drill press,to drill the parts with.I was worried about going too big first,and having the bit not self center.I was trying to keep oil on the bit,with little luck.Should i keep dipping the part in water.Whats the tip? Drilling is the only accurate way for me to make these holes.I might add,i have my press on the slowest speed.Like i said ,i will sharpen the bit,it cuts great for 30 seconds,then it gets dull from the heat i guess.Please give me advise,for proper procedure,in drilling these large holes.
ALAN

countrybumpkin · Feb 3, 2006

I start out with a 1/8" to get everything in the right spot. Then jump up to about 3/8" & then maybe 3/4" then 1". I use a lot of cutting oil and very good bits. Cheap bits just don't hold up very well. At least not for me. I've been watching your project and am starting mine tonight also.

_RaT_ · Feb 3, 2006

Funny you mention this, I have 20 holes to drill in 1/2" steel 1" in diameter that fit over masonry columns with weldable rebar to be attached.
The best way is go slow, the larger the diameter, the slower you must go. Using oil and slow speed is whats key.

Scozz · Feb 3, 2006

I just finished building a quick attach set up for my loader. Also fabricated a quick mount set up for a a snowplow.
I had to drill 4 - 1" holes thru 1" plate and about 14 - 1" holes thru 3/8 plate. I used a little 10" 1/4 hp benchtop drill press with a 1" hole saw and WD-40. Took about 3 hours to get it done ... but its done! ... Scozz

beenthere · Feb 4, 2006

Sounds like your sharpening technique isn't working (that is if you have quality steel bits to start with). With cutting oil (or even WD40) you should not get enough heat to cause quenching the part in water. When you don't get a good curl of steel from the bit, time to sharpen.
I have to assume you know how to sharpen a bit, either by hand on a grinder or you have access to a bit sharpener. The angles are very critical. Some know how to sharpen pretty well by hand but that involves a trick to get the right relief away from the cutting edge. Sure sounds like you don't have that relief.
In that thickness, I'd likely go with an initial hole of 1/4" or 3/8", and then move to a 1/2" or 5/8", and then up to the 1" bit. I would expect very little heat, and a good curl of steel once past the initial shaping of the hole when starting with a larger bit (sometimes get chips rather than a curl).
Wish you luck and finding the key to easier cutting (drilling).

MikeD74T · Feb 4, 2006

I have a magnetic drill press. I start with a 1/8 pilot hole then straight to the 1". Step sizing increases the chance that the hole will drift off center. You could do the layout, drill the pilot , & take it to a machine shop that will finish the holes quickly & accurately. As RaT said the bigger the hole the slower the drill speed. It takes a pretty good drilll to turn a 1" bit slowly. BTW I picked up Black & Decker 3/4" magnetic drill press on EBAY for $125. One of the best buys I've ever made. Just like this: Shortened First Long URL
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CT_Tree_Guy · Feb 4, 2006

Hiya Alan -

Hey, you might want to consider using a 1" hole saw. I've had great luck with the Lenox brand, they really make good stuff. If you use plenty of cutting fluid you just might get twenty holes out of one, and might even be able to resharpen it if you have to.

Good luck, John

ronjhall · Feb 4, 2006

Most small drill presses do not have speeds slow enough to drill a 1" hole in steel.
You have the correct idea of using different sized drills up to the 1".
Get some cutting oil. I use Rigid Thread Cutting oil that I picked up at Home Depot in the plumbing department.
Try flattening out the cutting edge angle of drill. This will leave more metal behind cutting edge to help take the heat away from the sharp edge.
On my drill press I have a foot switch to start drill running. On large size holes I jog the motor to keep speed down. If you use this type of switch make sure you have a over ride switch to shut off power when changing bits.

Egon · Feb 4, 2006

Think I'd also recommend taking it to a shop that has proper equipment. Might even be cheaper in the long run and certainly less frustrating.

Egon /forums/images/graemlins/grin.gif

SkogenMe · Feb 4, 2006

Not having a drill press, all the 1" holes I have done with a variable speed 1/2" drill and a set of turned down shaft bits that I got from Northern a long time ago. I use a 1/4" bit for the pilot and go straight to 7/8" or 1" with a good deal of oil (tho it ends up often just being WD40).
'Course all bets are off if you happen to be using an old snowplow blade for your thumb project! /forums/images/graemlins/crazy.gif I burned up my old cheap Craftsman drill and a bunch of titanium bits trying to put 1/2" holes in a plow blade.....the new Milwaukee can put 1" holes in regular plate no problem /forums/images/graemlins/smile.gif
good luck