Drilling (or burning) large holes???

[Shield Arc]

J J I use to have a circle burner like the flangewizard, guess someone needed more than I. I do have one for the plasma, (haven't used it yet). The one I made is fixed, works great on the rotating table, but somewhat cumbersome any other place, because you can't spin the torch around the center point very easily!

 

[Deere Dude]

I have wondered about that. I know they make gouging electrodes but don't know anything about that either. What you are saying is just use standard electrodes (say 6011??) and start burning? I should be good at that, as I have burned lots of holes (accidentally!) Seriously, you just start burning at a high amperage? Any precautions I should take other than the molten metal?

Exactly. I burn bigger holes than that just trying to weld. :laughing:
I have an old box of 1'4" 7014's and use them for cutting off heavy stuff that I don't need super straight, but I can always touch the ends up with a grinder. Any lighter rods will just heat up and turn to crap. If I had some heavy 6011's laying around I would try them if they are heavy. Also I soak them in a bucket of water for 10 minutes first. They seem to last longer that way. I have a chop saw now for bad ends, but for holes I would use the rods, unless you can find a gouging rod. I heard about them and that sounds good. Just start out at high amperage and other than the normal precautions for the sparks and a little molten metal, it will work. I googled your welder, that's a nice one.

 

[JCByrd24]

7/8" holes and up so far I use hole saws. Lennox, Milwaukee, and Rigid bi-metal all seem to work fine. For 1-1/4" and below I use my drill press, above I use my craftsman 1/2" drill (reduction gear, variable speed) because I can turn slower RPM (or if the piece is too big for the drill press). Keep it cool with oil and they last well enough for hobbiest use, i.e. I haven't bought the same size twice. They cut a pretty decent hole if the arbor and center drill is good. A tip I haven't tried yet is to drill the center hole with separate 1/4" bit and just put a 1/4" rod in your hole saw arbors, though I just bought a center bit recently and it was a little pricey, so maybe next time.

 

[travis potter]

I have drilled large holes using a small bit drill holes all the way around then go back with a larger bit and re drill the holes it isn't pretty but you can go as large as you need this way. The other way up to 1/2 is use a HF step drill 3 for 7 or 8 $ but first drill a pilot hole the step will last a lot longer. I have never had any luck with the gold (expensive) bits just the common bits.

 

[Soundguy]

I've drilled 4" holes in 1/4" plate with some good Lenox BiMetal Holesaws. Nice accurate & clean holes.
Option 2 would be Plasma.

I've done the same.. a hole say, if a good hard one, and kept oil , or emulsion cooled when drilling should be good for quite a few holes in mild steel.

as for drilling otherwise. I almost never drill anything over 5/8.. and even on 1/2 and 5/8 I sometimes torch them.

to the OP.. how many holes to make? more than a hole saw will do?

no torch huh? got a 240v stick welder? if so.. do the holse need to be perfect or will you de able to clean up / hide with a washer / grinder and welding?

if they can be rough, you can burn them with the stick welder and chamfer rods. uglier than a torch.. but DOES work.

soundguy

 

[rankrank1]

Believe it or not technique for using an arc welder welder to cut metal or pierce holes in metal is covered in most Lincoln AC-225 buzzbox manuals or Miller Thunderbolt buzzbox manuals.

In short, they recommend kind of a sawing motion with the electrode after punching through. Diagrams and techniques are in the manuals available for free download.

6010 (DC only) or 6011 (AC or DC) are the best rods to use for improvised cutters because they penetrate deep, and deposit very little metal in the process. A rod like 6013 or 7014 would not be the best to use, because they will deposit more metal and are not deep penetrators. Of course any rod will burn through if you crank it up high enough and the metal is thin enough.

Generally speaking you are not going to want a 1/4" diameter electrode unless you have a really powerful welder. You will usually run the rod at 2 to 3 times the setting you would weld with so with only 200 to 250 amps I am thinking 1/8", 5/32", 3/16" would be a real stretch and about the limit for practical cutting with decent results with the amp supply at your disposal.

With practice it is possible to get semi-decent with cutting and piercing holes. Cuts will not be plasma quality, but can often be good enough for a backyard farm shop. It is relatively cheap to use as a cutter - no doubt.

There are also, special cutting electrodes for small arc welders offered, but they can be pricey (I have never tried any of these special electrodes due to high cost. I save my old damp slightly rusty 6011's for cutting duty).

Gouging with something like an ArcAir gouge takes a really big industrial welder and a really big air supply and is not precise tool at all. Very noisy and extremely messy too. Primarily only useful for cutting out bad welds in thick metal.

Of course if the hole needs to be precise then lots of good recommendations have already been made. Another alternative option is annular cutters. These work sweet but must by used in either a mag drill, drill press, or mill. I do not own any of these but have used them on occasion at work - much better than a holesaw but cost is more too - but still reasonable as they will last much longer than a holesaw. Annular cutters have been covered on TBN before so useful threads available with a search.

 

[rswyan]

Dave, I assume you do this on your drill press at low speed with lots of cutting oil?? Could I get through 1/2 plate?

I've used Lennox Bi-Metal hole saws to drill thru 1" plate using my Crapsman 17" drill press .....

Yup - lots of cutting oil ... slow speeds and correct pressure/feed ... :thumbsup:

I think the largest one I've done in 1" plate was 1" ..... and 2" or 3" holes in 3/4" plate ....

 

[Bison]

I use a torch to cut large holes,helluv a lot faster than all the other options.
I got a whole stack of diff sizes old bearing races ,i usually can find a size to suit and tack it on the plate i need to cut a hole in and use the ring edge as a guide for the torch tip.
Simple and efficient.

 

[grsthegreat]

Id check out craigslist for a good set of used cutting torches. You'll need them sooner or later anyways. Before i purchase my cnc plasme table, i was always cutting holes with the torches. Also, if you need to bend metal, a nice heating (rose-bud) tip on the oxy/acetylene tanks works great.

 

[mjncad]

Since I don't have a torch or plasma cutter, I use bi-metal hole saws from Milwaukee, Lenox, or Rigid. I've gone as big as 3" or 3-1/2" with my Jet 17" drill press. At its lowest speed of 200RPM, it's still faster than recommended per Milwaukee's speed guide; but feed slow, use plenty of oil, clean the chips away frequently, and wear hearing protection as those hole saws will scream bloody murder, especially when the cut is first started.

Another trick I use with my Jet is to use both hands on the quill down-feed, or one hand on one handle, and my elbow on another. This evens out the pressure applied to the quill and multiplies the force you exert on the workpiece.

1/4" mild steel.

A new hook I made for my LandPride quick-hitch made from 1" plate. The large radius cut at the base of the hook was done with a hole-saw, and the pin holes were done with drill bits. The hook itself was cut with a 14" Wilton metal cutting vertical bandsaw.