Making Holes in Frames

[SCOTI]

I've been drilling some holes for my rear airbags & it's a pain in the rear.

I've drilled the 7/16" holes for the bolts that locate the bags but still need to make the larger (much larger) holes for the 1/2" air fittings. The adapters that I'm installing require a hole that's about 7/8".

It's difficult enough drilling upside down for 1/2" holes. A holesaw isn't going to cut it here because there's multiple layers of steel (c-notch plate + original frame + coil spring reinforcement crossmember). I tried some hardware store 'die grinder' tips from Home Depot & they weren't worth the money spent.

What do you guys/gals use to open up holes in metal w/o killing yourself? Where do you get your grinding bits @ that will last long enough to get the job done?

[shifty]

i use a unibit to make small holes larger. There's nothing to catch anywhere. I will be watching this thread out of interest though, because i need to do the same drilling for my rear.

[rlm316]

7/8 is the standard opening size for 1/2 sch40 pipe. A good quality hole saw will drill thru multiple layers of metal. You can purchase a holesaw and mandrel from either a plumbing supply or an electrical supply store. Two good brands are Lennox and Milwaulkee. Be sure to buy some cutting oil with your holesaws and an extra pilot bit just in case. It would probably be easier to drill your pilot hole with a 1/4" drill bit to center your hole and let the teeth of the saw rest flat on the metal for starting. Don;t press too hard or the saw will take you for a ride and brake the pilot bit. As you drill thru a piece of steel, back out the saw and clean out the plug. this will let the teeth land on the next piece to be cut. You can't use enough cutting fluid, it will improve the life of the saw. I do this all the time and even thru stainless so it will work, just try not to lie directly under the piece you are drilling. Good luck

[Bob D]

Stepdrill or unibit:

[SCOTI]

The uni-bits work on thinner gauge stuff but I don't think it will like the multi layers of steel..... especially that first 1/4".

The hole saw was the method I figured would be most recommended. But keeping the teeth lubed while drilling upside down is quite the challange.

When I used my holesaw to drill some holes through the shock crossmember it was an excersize in patience.....and that was using all my control standing over the steel. When I think of trying the same thing lying under w/limited space..... well, that's why I'm searching for alternatives.

[Hart_Rod]

Originally Posted by SCOTI

The uni-bits work on thinner gauge stuff but I don't think it will like the multi layers of steel..... especially that first 1/4".

A good one will work. How many holes are you talking about?

[rlm316]

I don't know if you know someone in the trades but if you did , you could try and use a hydraulic knock-out punch. I am not sure if it would handle the multi-layers of steel, but it is a possibility if you found one rated high enough. You would still need to drill the 1/4" pilot hole though. If you set the pilot hole far enough out past the holesaw it will center itself. Just try and brace the drill so the torque is absorbed. If you don't press too hard it will cut at a reasonable rate. You are right, it is an exercise in patience.

[SCOTI]

Originally Posted by Hart_Rod

A good one will work. How many holes are you talking about?

Just two.

But, they are 2 holes that are going through a total of 1/2" thick steel once you combine all the layers (1st layer is the c-notch plate @ 1/4"; second layer is the frame @ 1/8~3/16"; 3rd layer is the coil c.member reinforcement plate that's the same thickness as the frame).

[jerm67chevy]

Contact you local snap-on or Mac tools guy and get a set of carbide burr bits. They are about $100 for a set of 4 but worth it. You put them in your die grinder and start burring out the hole until it's the size you want. I am a bodyman and I use them constantly.

[SCOTI]

Originally Posted by jerm67chevy

Contact you local snap-on or Mac tools guy and get a set of carbide burr bits. They are about $100 for a set of 4 but worth it. You put them in your die grinder and start burring out the hole until it's the size you want. I am a bodyman and I use them constantly.

This is what I need but I need a retail source to get them (I don't have a 'tool guy'). Welding supply company or ????

[jimmydean]

I remember 67Fleet talking about those holes. I went with a small cup just to avoid the hassle

The step bits don't do well with multiple layers. They can be a real wrist breaker.

[SCOTI]

Originally Posted by jimmydean

I remember 67Fleet talking about those holes. I went with a small cup just to avoid the hassle

Unfortunately cups are not an option for me.

[jimmydean]

Originally Posted by SCOTI

Unfortunately cups are not an option for me.

If I recall, he used a hole saw and a lot of beer. The beer was for him though, but it might have helped.

[Shane]

I used a 1" bi-metal hole saw for just the area you are talking about Scoti.

You spoke of "lubeing the saw/drill" ... just take your time, stop every 20-30 seconds to let the saw cool, spray a little oil on it and continue on. It actually cut faster than a regular drill did.

[MrShelley]

Like Shane, I also used a bi-metal hole saw. It WAS definitely an exercise in patience even with the frame upside down. My only advice would be lots of lubrication, even though its a pain when working upside down.

[dan468]

plasma cutter to start does the trick for me

[gringoloco]

Scot, I think you're just gonna have to bite the bullet on this one. Hole saw really will be the the most efficient way. Just grab the $8 metal cutting saws frome Home Depot or Lowe's or whatever. A carbide bit will take much more time and leave you with a less finished looking product. Just don't let the hot shavings fall down your collar...

[pissonNOS]

this guy used a hole saw too i put some soap on the hole saw as well not sure how much it helps with cooling but it seemed to work

[Alvin]

bi-metal hole saw here too. Of course my frame was upside down, but it wasn't bad at all. Should only be mildly horrible with a truck together. Keep the rpm down, you'll be able to tell when it's cutting.

[Longhorn Man]

are you starting with a small bit... like 1/4 inch or so, and moving up... or are you just starting out with that big 'ole sucker?

[cdowns]

this guy used a hole saw, whats the big deal with a couple of tiny holes???

[SCOTI]

Wow, a lot of response on this one.

LhM..... Yes I started w/a 1/8" bit & progessively worked my way up to a 9/16" bit (the largest I had).

For everyone that suggested the holesaw.... I can see that working. But honestly.... I knew it was going to kill my freakin arms/shoulder to lie on my back that long trying to drill slow enough not to chew up the blade; yet w/enough pressure to penetrate & cut.

Sooooo . . . ..... I went by the welding shop & they didn't have zilch for carbide bits. They referred me to another welding supply house & same story. I was on my way to a 'tool trader' type place when I passed a 'Fastenall' which carrys lots of various hardware & more importantly, tools.

They had drill bits all the way up to 1" dia w/a 1/2" shank. They weren't cheap but they would get the job done alot faster than a holesaw. I went ahead & bought 3/4" & 7/8" bits & picked up a set of carbide burring bits too. I didn't think I would need the carbide bits since I was spending the $$ for the big honkin' drill bits but I figured..... I needed them now, I'll need them again.

I drilled the hole out on the pass side rail (graduating to the 7/8" size) in about 15mins. It was then that I realized my estimate of the thickness on these combined layers of steel was slightly off. I went to install the 1/2" to 1/4" adapter into the bag & found out the freshly enlarged hole still wasn't large enough for the hex end of the adapter when installed from the bottom of the rail. No problem.... I'll drop the fitting in from the top & thread it in to the bag that way. The adapter is ~ 1" in length. With the adapter dropped in through the top of the lower frame rail, the threads did not extend through the last layer of steel as I attempted to thread the fitting into the bag. So the combined material here is over 3/4" thick!

Glad I decided to pick up those carbide burring bits after all .

It took about another 15mins of opening up the hole to get it nice & symmetrical, but the carbide bit sliced through all the steel like melted butter. A little round filing to clean everything up & the bag w/the fitting attached, bolted right in.

The drivers side should go fairly quick now that I've got the sequence down. Thanks for all the responses & suggestions.

[pissonNOS]

Originally Posted by SCOTI

Wow, a lot of response on this one.

were a "holey" bunch i guess

[7T2]

The best $50 I have spent in the last 10 years was for a set of Unibits from home depot. Right now they have a package deal that has two standard Unibits of different sizes AND A BONUS TITANIUM BIT. This is important, because I have not seen the titanium bit sold separately, and the three bit set actually costs less than the two normal ones sold separately. I have not found anything that would stop the titanium bit yet. It only goes to 1/2", but you can use the larger one to finish the hole up to 7/8".

Don't go to Harbor Freight and get cheap ones, get actual Unibit brand bits. In this case, you get what you pay for. I have drilled about 25 holes in my frame with the titanium bit so far, and it's just like drilling through wood.

[SCOTI]

We use some pretty high quality bits @ work because 99.9% of everything in the building that would be drilled is stainless steel. The large bits that I purchased are the same type..... pricy too.

The carbide burring bit worked quite well to open the hole up. The main down side was all the freakin' metal shavings shooting everywhere.

I got home tonight & drilled all the holes for the drivers side (that last 7/8" hole for the air fitting is a b**ch). It took a couple of days to re-coup from drilling the pass side holes on Sun so I figured if I was going to be worth anything this weekend, I better drill the holes now so my arms/shoulder are good to go.

All that's left is test fitting the drivers side bag & 'trimming' the hole where required.
After that, I just need to shoot the rails from the cab back to the rear end so everything looks presentable & then start on raising the bed-floor.