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Old 05-04-2017, 11:48 PM   #1
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What drill bit does one use to drill through ceiling

So I have decided to leave my ceiling in my 1996 Bluebird school bus up, now I am facing the Dilemma of trying to get my studs into the metal ceiling, moreover the part of the metal ceiling where the two panels meet where all the rivets are. I've tried a Milwakee 5/8 inch what they claim to be Cobalt drill bit and the darn thing just keeps breaking, the ceiling can't be that hard can it? Really need some good solid guidance on what drill bit to purchase.
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Old 05-05-2017, 12:20 AM   #2
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"where the two panels meet" is where the roof ribs are located so you are drilling through two pieces of sheetmetal then something like 10 gauge (probably galvanized) steel. That said, any decent drill bit should make it through.

But, start with a smaller bit. If you need a 5/8" hole you should begin with something like a 1/4" pilot hole.

I gave up long ago on Big Box and hardware store bits. Try to find a real "Tool Supply". You will pay a little more but the difference in bit performance is amazing.

Best of luck.
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Old 05-05-2017, 12:30 AM   #3
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1/4" Norseman drill bits from Fastenal have done better than any other bit I've tried, and they're less expensive than the Milwaukees, too. I've been using them to drill through the sheet metal I'm reusing from my ceiling panels and 1/4" thick steel bar that I used on my roof raise. They will have no problem whatsoever getting through two layers of sheet metal plus the rib underneath. Do try to avoid drilling into the rivets, though. The drill goes through, but the screws don't like them at all, pilot hole or not.
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Old 05-05-2017, 08:06 AM   #4
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I swear by step bits for thin metal like you described. Standard bits catch and then break. Step bits seem to cut better. IMO Also when using standard bits, a slow speed is better.
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Old 05-05-2017, 09:25 AM   #5
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Drilling rivets is an expensive way to remove rivets. You're going to get some really strong arms doing that ceiling too.

Why not use the punch and chisel method? Use the punch to push the center mandrel out the back of the rivet. Put the punch in the middle of the rivet and hammer the mandrel up into the ceiling. After the mandrel is out the remaining rivet is much easier to chisel off.

That said, at this time all five of my drill bit sets are missing a certain size of bits. It's much easier to punch and chisel the rivets off than it is to drill them. You can use hand tools or air tools.

When you're replacing your ceiling, after insulation, you'll accidentally hit an old rivet hole in a rib occasionally. That still snaps off drill bits.
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Old 05-05-2017, 11:07 AM   #6
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Cobalt is real hard. Unfortunately they're also brittle; breaking easily comes with the territory. That bus metal is just mild steel, so a normal HSS (high speed steel) drill should do fine. Don't run it too fast or bear on it too hard; those both make heat which causes the drill to lose its cutting edge quickly.
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Old 05-05-2017, 02:26 PM   #7
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And of course drill straight.

I do not look forward to all the rivet removal. I do recall that MuddaEarth was using a pneumatic drill for the exterior rivets.
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Old 05-05-2017, 09:21 PM   #8
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Thankfully I decided to not remove the ceiling panels, but still have to screw in the studs. Thanks for all the responses
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Old 05-05-2017, 09:38 PM   #9
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You don't want to remove rivets until you temporarily loose 50% of your hearing? But why?
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Old 05-05-2017, 09:41 PM   #10
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You don't want to remove rivets until you temporarily loose 50% of your hearing? But why?
Haha! Funny! This decision was purely financial and time based.
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Old 05-06-2017, 12:43 AM   #11
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I swear by step bits for thin metal like you described. Standard bits catch and then break. Step bits seem to cut better. IMO Also when using standard bits, a slow speed is better.
I marrying one of these, if I ever have the chance:

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Old 05-06-2017, 03:32 AM   #12
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Try these...

These sturdy fasteners can be drilled right through your stud and into the metal in one fell swoop! They're a God-send when lumber-framing in a bus.

https://www.lowes.com/pd/The-Hillman...Screws/3036242

(I picked a random length for the link.)
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Old 05-06-2017, 09:42 AM   #13
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I LOVE my step drills. If you gotta work on sheet metal...you gotta have one...or several.
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Old 05-06-2017, 09:55 AM   #14
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Where you put the 5/8 hole is also a problem as you have to locate it to suit the rib size.
Off a little and your either hitting the hat side going up to roof panel or falling off the rim.
Why such a big hole?
Gonna use wing bolts?
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Old 05-08-2017, 05:08 AM   #15
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When I attached my framing to the ribs I just used long self tapping screws, worked like a champ.

I did drill pilot holes to screw in my wood ceiling, and I just used a regular drill bit, nothing special.
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Old 05-08-2017, 07:16 AM   #16
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I marrying one of these, if I ever have the chance:
I have one of those. Have you used it on the rivets yet.
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Old 05-08-2017, 07:19 AM   #17
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Where you put the 5/8 hole is also a problem as you have to locate it to suit the rib size.
Off a little and your either hitting the hat side going up to roof panel or falling off the rim.
Why such a big hole?
Gonna use wing bolts?
Mark stuff.
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Old 05-08-2017, 09:47 AM   #18
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If lots of drilling is in your future, invest in a drill bit sharpener. I have the Drill Doctor 750X (it replaces an older DD 700 that was stolen last year) which works very well. It's nice to be able to sharpen bits to as-new condition in less than a minute, and with the price of decent USA-made bits these days the sharpener will more than pay for itself. If I'm drilling in harder materials such as stainless steel or the very tough 90,000 PSI steel that Crown used for their buses, I resharpen the bit after just one or two holes to keep it in perfect condition. You can also adjust the relief angle for better chip removal if drilling through sticky materials like copper and brass. It's an indispensable tool for me.

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Old 05-08-2017, 10:04 AM   #19
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Quote:
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If lots of drilling is in your future, ...
What are you using for bits? Cobalt, tungsten, Kriptonite? I'm not even sure what materials they are using these days. And will your Drill Doctor care?
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Old 05-08-2017, 12:50 PM   #20
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I mostly use plain HSS, but US-made bits wherever possible. For the tougher stuff I either use sulfured cutting oil, or use cobalt bits with cutting oil, and they seem to sharpen as well as the HSS. I've never tried to sharpen carbide bits - I don't want to risk damaging the DD's diamond grinding wheel. Maybe when the wheel is worn out and needing to be replaced anyway I could experiment with a carbide, but that's not any time soon because the grinding wheels last a very long time.

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