Unibit on .250 wall?

I gotta drill some 1" holes and I'm wondering if a unibit is up to the task... looking for input.
Thanks,
Billy

You mean a step bit? I drilled six or eight holes trhough 3/16's with one with no ill effects, in fact it still bites well so I'd vote yes.

i've done it plenty of times

Awesome... I'm glad I posted because the manufacturer's website was discouraging... "ideal for thin metals".
Thanks!
Billy

I've even used my harbor frieght cheapy for the same a number of times, no problems and still sharp.

I love my unibits! When you say .250" wall does that mean you are drilling tube or square stock? just wondering because my unibits don't have quite .25" between steps and for .250" plate I have to flip it over and drill both sides, wouldn't work with tube obviously.

Skullvarian said:

I love my unibits! When you say .250" wall does that mean you are drilling tube or square stock? just wondering because my unibits don't have quite .25" between steps and for .250" plate I have to flip it over and drill both sides, wouldn't work with tube obviously.

Click to expand...

I was thinking of my plated frame rails, but I'm sure I'll use them a lot if it's that much better. You have a good point though... I'll try to find one with as many steps as possible.
Thanks,
Billy

Actually what am I thinking? I *did* use it on .250 plate and it worked fine, I did not flip it either, I just went through the steps (which are under .25) slow, easy, and lubricated (don't get excited here Billy).

I do have some of them that are max of 1" where you would not need to flip the plate, if you want a size that is between the max and min then you may need to flip the plate though as most if not all of my bits have around 3/16" between steps if not less. But now that I think about it 1" max is probably very common.
just sort of thinking aloud
good luck

Yes it is possible to use it on as thick of material as you want if you understand how drill speed and feed rate play into tooling life.

Tooling 101 (simplified): The larger the diameter of the tool, the slower the tool needs to be spun to cut the chip load it was designed to cut. So the opposite applies...the smaller the diameter of the tool, the faster it needs to be spun. Chip load and heat also play into tool life and use success. Coolant is good (cutting oil can be a form of coolant).

Feed Rate: Feed rate is extremely important. Feed rate is the speed at which the tool is trying to be pushed through the material. The trick when using a hand drill is to attempt to put even pressure on the tool. Pushing like mad hell won't make the tool cut any faster, it will actually cause it to wear out. To evaluate your feed, watch the chips. Best bet is to avoid blue chips. You're in the money if the chips are yellow. White chips are good unless a part of them is also blue. If this is the case, they're actually hotter than a blue chip.

How this applies to your unibit question: You want to slow down the unibit as it steps up in size to keep it cutting correctly. Using a variable speed half inch drill (typically slower RPM) is keey with this type of tool as you can actually back the speed off as the unbit works through it. If you get the speed/feed right, oil will only be needed initially (each hole) as a little can go a long way.


Unibit Thickness Rating: For the most part, the unibit will only be "recommended" for materials thiner than the step dimension of the drill bit as it can only cleanly drill a hole of that depth or less. Running it from both sides works just fine and effectively doubles the potential depth of the unibit. I agree with the comment about using a pilot bit first. A drill bit is designed to remove the metal chips better and wont work as much on the intial break-through as the unibit.