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View Full Version : Mills and Drills Is a unibit good for drilling 3/16" steel?



Brian Elfert
01-29-2013, 12:03 AM
Is a Unibit a good idea for drilling holes in 3/16" steel, or am I better off buying the correct size twist bit? The holes are 3/4" diameter. I have used my Unibit to make a fairly large hole in steel before, but it was only 1/16" thick.

phil harold
01-29-2013, 1:58 AM
NO
the maximum would be 1/8"
Step Thickness 1/8 in
http://www.cesco.com/b2c/product/322316

Craig Coney
01-29-2013, 9:53 AM
Depends on how many you are planning on making. I've used them before on steel up to 1/4" thick. If the material is thicker than the step you need to drill from both sides of the material to the center.

Keith Outten
01-29-2013, 10:06 AM
Yes
Take a look at the cheap step drills from Harbor Freight, with the three piece set each drill has more steps which provide for deeper drilling in thicker material. I recently drilled over a hundred 1/2" diameter holes in 3/8" steel plate for a pulverizer I was building for my tractor. Today I am using the same drill bit to drill 1/2" holes in 6" heavy wall steel pipe making new supports for my work shop.

http://www.harborfreight.com/3-piece-titanium-nitride-coated-high-speed-steel-step-drills-91616.html

The trick is to find the right size unibit for the job but even if you have to drill from both sides they sure save time.
.

Brian Elfert
01-29-2013, 11:54 AM
Why do Unibits save time? Is it because they have the steps and don't drill the full hole size at once? My only reason for using a Unibit is because I already have one and I would like to avoid the cost of 3/4" drill bit if I can. I need to drill 8 holes.

George Carlson
01-31-2013, 10:15 AM
You didn't mention if you were hand drilling or using a press. One nice thing about unibits is that they make a round hole, even in thin sheet metal. Normal two flute drill bits tend to make triangular holes when done by hand. At 3/4" even 3/16 steel can behave like thin sheet metal.

James Rambo
02-01-2013, 7:30 PM
remember not to let the unibit get too hot. I just used a 1 3/8" unibit to cut a 1" hole in seven peices of 1/2" steel for a rock rake for my tractor. The last hole was a bear to cut because I did not wait for the bit to cool between holes. But it worked quickly and did not have to use several drill bits.