i need help drilling 1 inch holes

[AntrimMan]

Heat is your enemy. Enough heat will draw the drill temper (soften) and possibly surface harden the hole in the steel part (given the appropriate chemistry).

Of the multiple ways to minimize heat, these are available to you given a decent drill press and a 1" HSS drill:
Speed... run the drill at 10 to 15 RPM, (ten to fifteen) thats 40 to 60 SFPM.
Feed... penetrate at not less than .006 IPR (a thin chip cannot absorb as much eat as a thick one).
Coolant... secure the part to the table to free up your left hand. Apply cutting oil to the drill with a 1" paint brush.

You need to have your wits about you to properly hand sharpen any drill.
As mentioned in previous posts, you must drill increasing diameters, the chisel point on a typical 1" HSS drill is probably something like 3/32 wide. Way to much to penetrate from solid.

I know, I know, what is this guy spewing?
If you can't comply with the above you will continue to have the same poor results and it will take all day.

A hole saw will reduce the thrust required, but provide a poor hole finish, and burn up just like the 1" drill bit if you run it at the same speed.
I suggest you make your layout, center punch the holes and go to a shop. They can drill 15/16 holes, chamfer the edges and then plunge a 1" endmill through and then chamfer the back side edges. The holes will be very nice to work with. It might cost $30,(a guess) for 12 holes, everybody needs to eat.

Let us know how you make out.
All the best,
Martin

edit: Looks like I picked a bad day to quit amphetamines.
150 to 230 RPM is 40 to 60 SFPM with a 1" diameter. I don't know where my mind was at. No excuse, I was just plain wrong. - Martin

 

[MadReferee]

I drill holes 1" and larger all the time. The key to getting it done is to use the right drill bit(s), go slow (about 300 or so rpm), and use a good cutting oil. WD40 is NOT cutting oil and has minimal, if any, properties that make it a good choice for a cutting lubricant.

First of all, go to a machine tool supply house (like KBC Tools) and buy 3 or so Silver & Deming drill bits 9/16", 3/4" and 1" at $5 to $7 each or a whole set for under $50 and a good 3/8" HSS bit. The bits made in Poland will work just fine.

Drill the 3/8" pilot hole first, then using a 1/2" chuck in either a heavy duty hand drill or a drill press or mill, drill the hole in steps. Set the RPM to 300, use plenty of good cutting oil, and apply down pressure. This should take all of a few minutes, if that, for each hole.

Good luck.

 

[R_Redding]

As MikeD said...the easiest way to drill 13-60mm holes is by using a Rotabroach cutter in a slugger type magnetic drill press..
I have an original Rotabroach drill press that I recently used to cut 55mm holes into 32mm steel plate. Each hole took less than 10 mins to cut once the pilot holes had been drilled.

Rob

 

[escavader]

Do you folks think i might be better off,to use mt big Makita 1/2 hand drill,instead of that press? I had already drilled all 12 holes,at 3/8.Ill try stepping up an 1/8th each time,ONE AT A TIME,FIRST and see if i can getter done that way,The cutting oil runs out the hole,,or "burns off".how often do you give it some,on the bit or part?Kinda wish i had kept my pin sizes to 3/4 ,i got a bunch of those bits,those 1 inch bits are pricy.Im gonna keep tryin ,and if i cant get it,im gonna drop it off at a local machine shop,they got the right tools for that job
I told the wife,i posted late last night,ill see if anyone has got an answer for me THIS MORNING.11 people posted already,this is why TBN is so great,thank you all
ALAN

 

[CT_Tree_Guy]

Hi again Alan -

I agree with you, this place is amazing.

Hey, first of all: I'd recommend sticking to the drill press. Drilling holes that size with a hand drill will be a nightmare, especially at that point that the bit just starts to go completely through the other side of the workpiece. When the bit grabs, the torque is going to try to break your arms.

Second, I want to put in one more vote for trying a nice, new hole saw. For your purposes, I think the quality of the hole will be just fine, and you might be surprised at how quickly you can drill each hole.

For what you'd pay someone to drill all those holes for you, might as well try it. A 1" Lenox hole saw should be less than $10, though you might need to get an arbor for it if you don't have one already. They're fairly inexpensive though too.

Good luck, John

 

[Farwell]

Rent a magnetic drill and use the shell type bits. All you need is a good center punch to locate the holes. The bits are like very heavy duty hole saws or shell mills. I can drill a very accurate 1 inch hole in 1 inch mild steel in one minute. The bits have a hardened pin that has a sharp tip on them that sits in the center punch dimple and oil is added from a point above the bit and flows from inside the bit. They are not cheap but are worth the money if you want accuracy and have a bunch of holes to drill. My son uses them all the time to bore holes in I beams used in building construction. It is amazing how many holes he can drill in one day using this method.
Check out Grainger's on line site and look up magnetic drills and the information you need should be there.
If you feel that you do not want to spend the money, get some Black and Decker drill bits with the self aligning tips on the bits. Center punch your metal and use tons of cutting oil.
Notice I mentioned mild steel, when you try to drill harder steel the rules change and you may have to use carbide bits to make your holes.
Cutting oil and sharp bits are the most important things when cutting metal. I drill lots of holes and because I use cutting oil, I have not had to sharpen a drill bit in years, in fact it has been so long that I doubt that I even remember how to do it.
Farwell

 

[R_Redding]

As you have already drilled out the holes to 3/8 you will probably not be able to use a rotabroach cutter or a hole saw as they usually have a 1/4 shank...It may be easier to pop to a machine shop on a saturday morning for a quick cash in hand job.

 

[Toolguy]

Since you already have the pilot holes drilled a machine shop or welding shop with a 1" tapered reamer is the best way to go. Reamers are the best for enlarging existing holes. They a little pricey, though. For one time use you could pay someone to do it cheaper.

 

[5030]

I get a charge out of folks terminology here.

What you need is a piloted annular cutter, piloted to the diameter of the hole you already have worried through the metal. I say worried because whether you are using a cheap bit or a good one, an improperly ground twist drill ( and from your description) you aren't sure how to "offhand sharpen" a twist drill so I'm pretty sure that the cutting angles and web are incorrect.

One thing that applies to all twist drills is the proper clearances for chip flow. On larger diameter drills, it is advantageous to relieve the heel of the drill so it takes less power to drive the drill and (shear) the metal from the workpiece. Actually, I relieve the heel on all my drills with the exception of my Hi-Rocs (solid tungsten carbide die drills).

Probably the best way to learn how to offhand sharpen would be to stop in a machine shop and ask and then observe a machinist do the operation. Hopefully, they will let you in the shop (you know, liability issues there, so be real nice and bring donuts, every machinist likes glazed donuts) It takes skill, proper rotation of the wrist and lots of practice to obtain the proper clearance angles as well as web thickness and equality. Once you master the technique there is little difference between good HSS drills and cheap HSS drills.

Maybe when you take your part to a machine shop (as you probably have work hardened the hole through your inability to sharpen a drill properly) you will be able to observe the sharpening process.

A few points:
*Properly sharpened and relieved twist drills.
*Proper cutting speed (don't guess, tables are easily available to match rpm to cutter diameter for all materials).
*Proper feed technique.
*Work clamped down or otherwise secured (so you don't get whacked as the drill breeches the bottom of the hole).
*Cutting lubricant (not cutting oil). The lubricant is to carry the heat generated at the cutting edge away from the edge and prolong its life and to aid in chip flow (not to get on your clothes and everywhere else). Cutting oil is for pipe threading, motor oil is for engines and drain oil is for the re cycler. You need a good fluid for tapping and drilling, preferably synthetic.

These are the basics of drilling with twist drills. A common, readily purchased tool that that the average person uses improperly, don't know how to sharpen and throws away and buys another. /forums/images/graemlins/grin.gif

If I had the money spent on twist drills that were discarded and still perfectly workable after proper sharpening, I could retire to somewhere warm. /forums/images/graemlins/grin.gif

 

[CT_Tree_Guy]

Even if you've already drilled 3/8" pilot holes you can still use a hole saw if you use the drill press and clamp the workpiece down securely. Try it, you'll like it.

John