Drilling a big hole in small steel plate



There's been a wood theme to the answers. My variation is two pieces of wood, with the plate sandwiched in between. If you need to see the plate to line up the hole, pre-drill the top piece of wood. Clamp or screw the pieces of wood together, and stick the mess in your vise. That avoids bending the metal and keeps the drill from pulling it out of your clamp setup. Or, if you have some time to kill, just punch the hole with a nail and file it out to a larger size. (:
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Now we're getting somewhere. Sandwhich the thin stock between two pieces of thicker stock. Wood will work but to really keep the thin plate stock from lifting/burring at all when the drill flutes get a bite on it, I'd use scrap metal (steel or alum) and really pinch the plate tightly.
Also firmly secure the work to your drill press table, forget about the bench vise and the hand drill. If the work is not firmly secured and drilled with a rigid spindle (as opposed to hand drill), the thinner the stock is the more likely you end up with a "triangular" (also under sized) instead of perfectly round hole.
This is the sort of drilling operation that a mill is real handy for but there's no reason you can't do just as well with a drill press, it will just take longer to set up.
Dennis van Dam
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.50 cal BMG and file off the little burr. (Somebody HAD to say it!)

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that's the best one so far...
o

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Use a unibit and a block of wood and clamp it on your table. The .50 raises too big of a burr.

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|

| | The issue is, how do I drill big holes in small plate. I cannot simply | fixate it in my vise, because it would bend. I cannot drill 1/2" holes | and hold the plate with pliers, I know that it is unsafe. Help me | resolve this quandary. I have a regular floor drill press.

Some have suggested a greenlee or similar punch, but I doubt you're doing a lot of holes. Even when I did a lot, I hated that tool because it took so much effort on my part.
I suggest going down to the hardware store and getting a step drill. They come in different size ranges, and once you have one, you'll use it for a million other things. Clean and fast hole, too. Unibit was the first ones to come out with it, and a lot of knockoffs are out there now, but any decent brand will do fine. Home Depot has a variety. Just dawned on me that I don't have one myself and I really orta get me one o' them! I hate to say it, but they start at around $17 and head up. Well worth it, though. I used the heck out of them as an electrician. They sucked in stainless boxes, and I had to use the punch set as a last resort, hence my disregard. You could, however, get hydraulic sets, which were sweet, but they're not for my pocketbook, that's for sure!
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On Fri, 29 Jul 2005 13:13:31 GMT, Ignoramus27279

I used to use a plumber's tapered reamer to make holes for tube sockets. The reamer had a tapered rectangular tang that fit in a hand brace -- as in brace 'n bit. Drill a 1/4" hole and ream as needed up to about 1.5" dia.
Yow, I see that a basic Stanley brace now goes for $79, but they're on Ebay for less, and might be found cheap at garage sales or estate sales.
Uni-bits are available up to 1" dia, work very well in a drillpress (low speed, please) for making nice holes in sheetmetal.
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Greenlee punches are pretty inexpensive:
<http://cgi.ebay.com/GREENLEE-KNOCKOUT-PUNCH-AND-DIE-SET-5-8_W0QQitemZ7533622321QQcategoryZ73116QQrdZ1QQcmdZViewItem
Buy 'em once, use forever.
Jim
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jim rozen wrote:

<http://cgi.ebay.com/GREENLEE-KNOCKOUT-PUNCH-AND-DIE-SET-5-8_W0QQitemZ7533622321QQcategoryZ73116QQrdZ1QQcmdZViewItem
One thing - Greenlee chassis punches are measured using the bottom cutter. e.g. the hole size it punches is the punch size.
Knockout punches by Greenlee - are for the Electrical trade - and are Conduit inside sizes. e.g. a 1/2" Knockout is for tubing with ID 1/2". It punches the outer size that is larger than the marked size of 1/2".
I bought a nice set of Knocks and couldn't use them. 1972. Had a nice handle system...
Martin
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Ignoramus27279 wrote:

Hole saw
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Ignoramus27279 writes:

Screw it down on a scrap of lumber.
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"Richard J Kinch" wrote: Screw it down on a scrap of lumber. ^^^^^^^^^^^^^^^^ This is the best idea in the list, if you juat want tio get the job done easily. Make sure the wood is long enough and slender enough to hold in one hand, to prevent rotation, while feeding the drill with the other.
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If I want a hole much larger than I can drill, this is what I do. Mark the centre of the hole using a centre punch, then score a line around the circumference using a pair of dividers. Then, inside the first circle, score another circle with a radius about 1 mm smaller. Then use a small drill (say 3 mm) and a drill press to drill a ring of holes, nearly touching, inside the smaller circle. Then take the metal plate, put it in a vice and use a punch to knock out the circle inside the small holes you've drilled. Then take a half-round file and carefully enlarge the hole until it meets the first line you scored. You can make quite a neat hole this way if you're patient. I've often used this method to make mounting holes for switches, etc.
Chris
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Leo Lichtman wrote:

On something like that, I make it long enough to hold up against the column. It is far stronger than my hand and won't break under extreme conditions. Martin
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done
hold in one

The hole may still be distorted, though. Much nicer results when the work piece is clamped between 2 pieces of wood (or steel)...
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Ignoramus27279 wrote:

There's Greenlee chassis punches that will do this in a jiffy and leave nice clean edges, downside is that for a couple holes they're outrageously expensive unless you can find some used or surplus. A sheetmetal shop should have punches that size, might take some sucking up/doughnuts/six pack for them to do it at a reasonable cost, though.
Alternative, Unibit stepped bit. Think the company is Irwin-ed now but the major hardware chains carry them now. Also kind of spendy, $14-20 range, but will also cut cleanly and leave fairly smooth edges. Screw your piece to a wood block and drill it that way. Beats getting your hands sliced up when(not if) the drill grabs and you get the whirlaway.
Stan
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Unibit stepped drill bit makes this pretty easy to do if you use the piece of wood behind the metal as was suggested by others. then you are only drilling a small amount with each step.
Doug

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.===snip---
I'd use a hole saw. They sell sets at Harbor Freight on the cheap. Clamp the sheet metal piece in a sandwich of wood on your drill press table using two C clamps. Set drill speed low and feed with frequent backups to clear chips.
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wrote:

I have never seen 0.5" OD hole saws...
i
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On Sat, 30 Jul 2005 21:06:34 GMT, the opaque Ignoramus27279

Spot weld cutters are that size hole saws and come larger/smaller. http://www.tools-plus.com/ast722.html Center pin is spring-loaded. http://setools.com/miva?/Merchant2/merchant.mv+Screen=CTGY&Store_Code=STO&Category_Code=SWC
I have a diamond dust set (Ebay vendor mistake) with a 1/2-incher. Similar to: http://www.toolprice.com/product/7130A
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