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Drilling 1/2" hole through stainless

APW

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I have some new fragramatics vacuums I need to drill a half inch hole through for the electrical connection. Last time I used my vari bit but it ruins the bit. Anyone know of a better way to drill a half inch hole through the vacuum?
 

mac

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Here is how I’ve done it successfully for years. First you don’t need real fancy bits, just new sharp ones. With stainless the slower you drill the better. Start with a small bit, around 1/8”. Drill slow with as much pressure as you can without bending the bit. Putting some oil on the spot helps and any type oil will do. Once through move up to a slightly bigger bit using same method. Work your way up to 1/2”. Might take you 4 to 6 steps. When the bit is ready to go through you might need to let up the pressure a bit or it can grab the metal and break the bit or sprain your wrist. With vacs it’s fairly easy as it’s relatively thin.
 

celica

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Mac, I also employ the same idea. Even my cobalt bits have gotten dull, so I use cheap bits and throw them away after.
 

MC3033

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I would start with a small cobalt but, maybe 1/8”. Then finish it off with a 1/2” step bit if you have the clearance on the other side of what you are drilling.
 

Greg Pack

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I've made dozens of holes in stainless with the same cheap off brand step bit. Having said that, I just bought some higher priced dewalt step bits and they cut through the fragramatics doors quickly, even using an impact. I saw a shootout of several brands on youtube on the project farm channel and the dewalt outperformed several other brands. As others have mentioned, I also drill a 1/8" pilot hole. I buy Bosch 1/8" carbide bits and keep several in my bit bag. Slow speed and lots of pressure works best for me to extend bit life. All the bits that I've burned a step on is because I got impatient and ran them at too high of a speed. I probably drill at 100-200 rpm. If you have to install a 1/2" conduit fitting the hole size needed is 7/8"

Bosch 1/8" cobalt bit on Amazon

project farm step drill bit shootout
 
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MEP001

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I would start with a small cobalt but, maybe 1/8”. Then finish it off with a 1/2” step bit if you have the clearance on the other side of what you are drilling.
I also use step bits in stainless for larger holes. The Harbor Freight ones aren't too bad, the biggest problem is that they grab when the steps break through, but they're only $8.99 for a 3-pack. One really good step drill can cost up to $70. The Harbor Freight ones also leave a messy hole, but that's easily solved if you go through the opposite side of where you started for the last step, then use the next larger step as a deburring tool on both sides to clean it up.

I bought a set of Milwaukee cobalt bits which go through stainless (and regular steel) easier and cleaner than anything else I've ever used.

Do NOT use a center punch on stainless. You'll just create a work-hardened spot in exactly the place you want your hole.

FWIW I almost never use oil drilling the starter hole or with the cheap step drills. A 1/8" bit won't get hot making such a small hole even in stainless 1/4" thick, and if you're going the right speed with the step drill the chips will come off blue but the bit will only get warm. I've drilled many thousands of holes in stainless with hand tools usually without oil, but it certainly won't hurt to use it.
 

MEP001

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I saw a shootout of several brands on youtube on the project farm channel and the dewalt outperformed several other brands.
I like his channel - my fiancée complains about his annoying voice. Some day I'll work up the nerve to tell her "At least he doesn't have to hear yours every time he makes a move..."
 

wyatt

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I always drill slow and pour water on it at the same time. You want to see the metal come off as a continuous shaving.
 

mjwalsh

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If you have to install a 1/2" conduit fitting the hole size needed is 7/8"
Some larger hole drilling jobs that we do not want the drill to stall from the recommended "low speed" pressure on the stainless steel ... we have a very powerful Hitachi drill we bought at Lowes that we sometimes resort to. Warning ... how is your upper arm & shoulder strength?

After watching some electricians use their "metal rated" hole saws ... we have drilled holes that way also. Our local Acme Electric sells some special "sulphur containing oil" that seems to help the stainless drilling process ... possibly keeping the drill bit cutting edges sharper & cooler longer ... not sure.
 

MC3033

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Oddly I’ve actually had better luck with step bits that attached to a 1/4” impact vs on a drill
 

MEP001

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I always use cutting oil with either step bits or cobalt bits.
I do if I'm drilling thick material on a drill press, but since the main reason for oil is to keep the tool from getting hot and they don't get hot drilling 12 gauge stainless, I just don't bother. I can get hundreds of holes in stainless out of one 1/8" cobalt bit and one Harbor Freight step drill.
 

Earl Weiss

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I have used 1/2" hole saws but don'r recall the exact type.
 

tdlconceptsllc

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I have some new fragramatics vacuums I need to drill a half inch hole through for the electrical connection. Last time I used my vari bit but it ruins the bit. Anyone know of a better way to drill a half inch hole through the vacuum?
A electricians knockout set will do it on fragramatic vacs and they will be perfect do it all the time
 

STXCW

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It's all about the speed, you want the drill set to a slow speed to keep whatever bit you are using from heating up. I use step bits more than anything but have used a hole saw a time or 2
 
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