How to drill a 1 1/2 inch hole in 16G steel

[Bullseye]

Hey All,

I know it is not a welding question, but all the experienced welders will know the answer. I bought a Delta bench mounted drill and a 1 1/2" thick drill bit from my local metal supply shop ($42). I drill a pilot hole then try to drill through but it gets hung up or just stops. I oil the metal and bit with a Teflon spray. I would go buy a circular drill cutter but I am not positive it will work. Any help would be great or a link to the bit or cutter I should use. My press can support a 1/2" shank. It is a decorative hole so I need it to be a almost perfect circle or I would just cut many 1/2" holes to make the 1 1/2" hole.

Thanks
Adam

[Brett]

16 G ? thats 1/16 thick isnt it?
Id use a bi metal hole saw or for a better finish on your hole a tungsten tipped hole saw.
You'll never get a good 1.5" hole in 1/16" material with a twist drill.

[65535]

I would NEVER buy a spiral drill bit for large holes in material thinner than 1.5" get a hole saw, cheaper and they work better, clamp your piece tightly.

[Qucifer]

Another way is to use these
http://www.harborfreight.com/cpi/cta...emnumber=91201
This set doesnt have the size you need, but im sure you could find the exact size on the internet.

[MAC702]

The PROPER bit for the job is a Unibit. But a Unibit that goes that large is expensive, maybe $80, if even available. My biggest one only goes to 1-3/8" which is the size used with 1" conduits.

[pilebuck]

Id go with a bi-metal hole saw, home dept around $20, I just bought one last week to install some gauges in my sae-300.

[awright]

I second pilebuck's recommendation, however most hole saw tends to wander around a bit before settling into a neat circular groove so if there is a back side to your piece, drill from that side. This is especially true if the pilot hole has been enlarged from the pilot drill size.

If the pilot hole has been bunged up (or just to be safe) you can clamp a piece of scrap to your workpiece to guide and restrain the hole saw from wandring and drill through the two layers.

Use the lowest speed available, use plenty of cutting oil, use the lightest pressure that maintains the cutting action and avoids chatter, and ease off to allow chips to escape VERY often - like every few revolutions. Remember that (in the simple model) the only place for the swarf to go is in the very small tooth gullets. Once they are full you are mostly creating heat, not cuttings. Low speed and pressure, plenty of lubricant, and frequent clearing of swarf will preserve your saw for another day.

Have fun.

awright

[Bullseye]

Wow thanks for all of the responses.. The metal is 16 Gage thick, I need to cut several of them and I plan to make several pieces and sell them to a business (and hope to make more after that). So what would be the best long term solution that will not break my bank (no more than say $250 or so).

Thanks again
Adam

[G3farms]

drill your pilot hole first and then mount your hole saw on the arbor.

G3

[eburgblue]

Use Qucifers post. The punches aren't very expensive and they cut a nice clean hole every time. You can also get them in a hyd version but that's some bigger bucks. These are used by electricians all the time.

[riley mcmillan]

A flycutter with a one quarter inch pilot hole. Some people call them circle cutters. They have a one half inch shank and must be used in a drill press. I've used them for years and cut as large as six inch diameter. They use a one quarter inch lathe bit. Very accurate and a one and a half inch hole is a piece of cake.

[tanglediver]

Just clamp the metal on top of some plywood scrap to back up the metal for the hole saw, if you use a hole saw that is. Plywood is better than 2 x 4's because it will be much flatter.

[Sandy]

An 1½" hole saw will cut slightly larger than an 1½" hole if exactness is a big deal.

[dave powelson]

1-as sandy notes the hole saw will cut slightly larger than nominal 1 1/2" dia.-due to runout and tooth set
2-Hougen Slug cutters--for close tolerance holes--long lasting and fast operation in thin, stainless, thick--these are the way to fly. Hougen makes an 'electricians' set-from 7/8 to
1.5--it was like $240 for the set--but I suspect you could order just a single one with the mandrel.
-must use slow speed, oil and a wood backup under the sheet, plus clamp the sheet down on the drill table
--I love hougen cutters for thick and thin, field use, etc.--I still use bi-metal hole saws for sizes I don't have a hougen cutter for--they just take 5 times longer.

[awright]

Hey, dave:

Thanks a lot for mentioning the Hougen Rotabroach cutters. I didn't know they existed. I checked out the Hougen website and they look great! There goes more of the kids lunch money.

awright

[fogducker]

those Hougen Rotabroach cutters would be ideal....we use them all the time in our mag drills...
another option for the twisted drill would be to stack pile a bunch of the pieces to be drilled

[Joe H]

I'm with Mac on the unibit. They are painless, very fast and precise enough for most things. They make it a breeze to drill a 1" or even bigger hole with a hand drill.

They are expensive, but well worth it. Good ones last a very long time too.

[65535]

I drilled a 1.5" hole in an empty disposable oxygen cylinder the 1.1 cuft type, its about 16 gauge and the hole saw takes the work pretty easily a punch on hydraulics would work better for sheet metal, for repeat work you a splitter type punch on a hydraulic press.

[mooseye]

Originally Posted by fogducker

those Hougen Rotabroach cutters would be ideal....we use them all the time in our mag drills...
another option for the twisted drill would be to stack pile a bunch of the pieces to be drilled

I wouldn't advise this as the bit will still bight the top piece when the cutting edge reaches the bottom of the cut, and hang and probably bend something.

Hole saw for economy, or the circle cutter if you have a drill press.

[sn0border88]

rotobroach cutters are very nice, we use them all the time.

I would also recommend the knockout punches, we have a hydraulic punch and it works very well.

[MAC702]

I thought about this more this morning and also would use the punch set if you can get it. Also, are the pieces big enough to punch a hole without distorting the rest of the piece? I still don't know if the Unibit comes in 1-1/2".

[Joe H]

You're right Mac, biggest unibit I can find is 1 3/8"". Still a bargain at $69.

[aczeller]

do they happen to make a 1.5" step-bit? i've never had a problem with a step bit, but i've never used/seen one that went to 1.5". i'd reccomend one if you can find it. if not, a hole saw would be a good choice. i've never used the punches before, so i can't tell youhow well they work.

good luck
Later,
Andy

[383bigblock]

Bi-Metal hole saw is probably the best bang for the buck and will drill a decent hole. I drilled a 1 1/8 diameter hole in 1inch plate this past weekend for a rubber bushing mount on my lathe and it chewed through it nicely. Didn't drill a pilot hole or anything.

Michael

[DrJim]

Uni-bit, same as a step bit. I've had the best luck with them. Not very cheap and you must use cutting oil with slow rpm. I've also had good luck with hole saws. That would be my next best choice, but not the most accurate, because of the wander, especially on something as thin as 16 guage. And remember once again to use cutting fluid.
Also I would think a punch would be the best for the greatest accuracy, but manually, doing alot of holes could be a problem.

Jim