drilling 1" (or so) holes

Having been a machinist for 8 years I know very well how to drill holes. I'm well used to drilling/core drilling/ reaming up to 3" in mild steel. Problem is this... I am
no longer a machinist for a living. I don't have access to all the large Bickford/Archdale drill presses like I used to. I need to drill some 3/4 and 7/8 holes in mild steel at home and all I have is a $150 5/8 chuck drill press. I have never tried to drill such large holes with such a poor machine. The way I see it is:
1. Silver & Deming bits. 2. Knock out the chuck and use the #2 MT. 3. Rotabroach style cutter. 4. Flame cut/file. (please don't pick this option)
Can such a machine actually drill with a 7/8 bit in mild steel? I have a feeling that I will break the feed handle. Do I need to go with the rotabroach style cutter? (expensive and I don't know if they work with a regular chuck).
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All I have is a $65 5/8 chuck drill I picked up at a yard sale and I've done it quite a few times using Silver & Deming bits. :-) I usually pilot drill 1/4" or so first and maybe another step in between and I use cutting oil.
Be sure you by quality bits though!
Best Regards, Keith Marshall snipped-for-privacy@progressivelogic.com
"Even if you are on the right track, you'll get run over if you just sit there." - Will Rogers (1879-1935).

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First a little more info is needed. What's the horse power of the drill press? What's the lowest speed setting?
Anyway with those options I'd say rotabroach would be the best option. However with care it's possible to use Silver & Demming bits. A reaming approach must be used. Drill to 1/2" using what ever method you usually use. Then ream in 1/8" increments. Higher horsepower lower speed drill presses can sometimes manage bigger increments.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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The biggest problems I find with the small inexpensive drill presses is the lack of a really low speed, Some of them only go as low as 300rpm. I find this a little fast even for light cuts with the S&D drills. I have a Rotabroach I use in my Benchtop mill which I find works really well. A straight shank holder and a 1" at KBC runs for about $70, the arbor has 3 flats to prevent slippage. You can also get it in a MT2 for a bit more.
Wayne Cook wrote:

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What's KBC?
Machineman wrote:

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knob writes:

Years ago I did exactly that with a Delta floor drill press and import S+D bits when that was all I had, through 3/4" mild steel bars. Use cutting oil.
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You might consider hole saws.

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Rotabroach all the way. I have some that screw onto a standard holesaw arbor.
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Ive drilled 1.25 holes with a similar drill press using S&D type bits. Actually MT3 shanked bits that I OD ground to 5/8 shank
Took a while, and I had to sharpen to a 118' angle and then pecked carefully
Gunner
"There is no difference between communism and socialism, except in the means of achieving the same ultimate end: communism proposes to enslave men by force, socialism - by vote. It is merely the difference between murder and suicide." - Ayn Rand, from "Foreign Policy Drains U.S. of Main Weapons"
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I use my el-cheapo import floor model with S&D bits up to 1" on heavy steel stock. Projects like drilling 3/4" or 7/8" holes in 1/2" stock for trailer hitch balls, etc. Not great, works ok. Biggest problem is that the belts want to slip when the going gets heavy, you really can't always get the full 1/2hp nameplate specs. Use a 1/4" or so pilot drill to match the web, use oil, go slow. Cheap S&D bits may not be ground the same on both sides, the bit may want to wander.
knob wrote:

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Would you rather use morse taper bits or the S&D bits (if given the choice) in such a machine?
RoyJ wrote:

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No question here. The morse taper wins hands down in my book. I've used them extensively in the past. Of course currently I only have S&D bits in the 17/32" to 1" range but if I'm only going to have one or the other then it's got to be S&D. I can use them in hand drills or anything that'll chuck 1/2". Morse taper is limited to my drill presses, lathes, and two large air drills. One of these days I'm going to increase my collection of morse taper bits in this mid range.
Wayne Cook Shamrock, TX http://members.dslextreme.com/users/waynecook
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The Morse Taper bits are a much better choice. But mostly becuase the MT bits are likely to be much better steel and quality than the S&D bits.All production will be done with MT, never with S&D. So all the used ones will be MT. I have no MT bits so I don't even remember what the spindle in my drill press is. IIRC #2 MT???
knob wrote:

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knob wrote:

No contest , Morse . First thing I look for every time no matter what I am drilling . Lucked out and got about 50 lbs with my lathe . No idea what brands and they are old but every one a gem ;-) Ken Cutt
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I think you can succeed with using the Silver & Deming drill bits. However I would recommend you sneak up on the final size in steps, firmly clamp your work piece to the table, and run at low speed using plenty of cutting oil. Good luck, JM
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APT makes a system just for the purpose of drilling large holes with a low power, less than rigid machine. It starts with a 1/2 inch conventional drill. Then switches to a piloted holder with interchangeable spade bit type cutters. Works quite well. I may have a spare set or at least part of a set that I would be willing to part with. Email me at snipped-for-privacy@aol.com if you are interested -- but unfortunately it will be about two weeks before I can check and get back to you.
Mill

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proposed a theory ......and in reply I say!:
remove ns from my header address to reply via email
I am not saure what Silver and Deming bits actually are, because when I searched, there were all sorts of mentions of "Silver and Deming Type bits" etc etc with sets of 8 at $20.00 US.
However, I regularly drill 1" and even 1.25" holes in mild steel, up to and including 1" thick, on a 12-speed(min 200 RPM) moderately cheap drill press. I do have to say it was "moderately cheap" 12 years ago, and I see them now for the same dollars I paid then. So it's propbably better than I realise! <G>
Sharp bit, start with a pilot of maybe 1/4", just to clear the tip of the 1". Use cutting / lubricating material. I use Trefolex, which is grease-based. Messy stuff, but effective.
It's ....well....boring! A bit slow, but it works OK. I get nice long shavings off the bit.
An aside, and I probably shouldn't. To prevent "breaking the handles" I have been known, toward the end of a long afternoon, to hold one handle and rest my forearm on the next closer one for that bit extra.
Crikey! I've done it using a hand drill! Now _that's_ horrible, dangerous and hard on bits!

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    They are sets of bits ranging above 1/2" up to 1" (I don't believe that the sets go any larger than that), all with reduced shanks to fit a 1/2" chuck. If you are lucky, you can even find a set with three equally spaced flats milled on the shanks, to reduce the chance of slipping in the chuck.
    The name may be local to the USA -- I'm not sure. It presumably originates from the first large-scale vendor of such modified bits.
    Enjoy,         Don.
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On 9 Aug 2004 00:43:23 -0400, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

Known as blacksmith's drills in the Empire :-)
Mark Rand RTFM
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On Mon, 09 Aug 2004 08:05:42 +0100, Mark Rand
......and in reply I say!:
remove ns from my header address to reply via email

But I thought they were _Silver and Deming_ in the US.......<G>
I've just known them as reduced shank.
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