Drilling aluminum hull

[fishinnut99]

Want to add a thru hull fitting for an automatic bilge pump. Needs a 1 inch hole. What's the best bit to make a nice , neat hole? Thanks

 

[overboard]

I used a hole saw, drill a pilot hole first.

 

[LDUBS]

I used a hole saw, drill a pilot hole first.

+1 on the hole saw. Last time I drilled a 1" hole in steel I used a Bosch bi-metal hole saw. Worked good for me. Another option would be a step bit. Might get a little pricey for 1" capacity.

 

[nccatfisher]

Unibit

 

[beetlespin]

Unibit

Ditto

 

[WALI4VR]

Hole saw... Just DON'T use the hole saw below the water line,

Sent from my XT1650 using Tapatalk

 

[CedarRiverScooter]

Run it slow to avoid it gumming up. I have also heard you can coat it with parrafin to avoid alum pickup in the teeth, although I haven't tried this myself.

 

[richg99]

I run my bilge exit lines OVER the transom. I know it isn't as effective, but it keeps me from drilling holes in my transom or sides.

richg99

 

[LDUBS]

I run my bilge exit lines OVER the transom. I know it isn't as effective, but it keeps me from drilling holes in my transom or sides.

richg99

Huh, common sense and nothing to really go wrong. Might be more effective than you take credit for. I drape my transducer line over the transom because I don't want to drill thru the transom.

 

[DaleH]

Drilled a hole in the stern stem of my FRP boat for an in-hull xducer, 6" off centerline - hull was a 1" thick layup. Then drilled the bow deck for a custom pulpit and bollard - hull layup on the bow centerline was 4" thick! Boat was a Parker - dayum well made boats they were!

Now drilling holes in tin boats is easy peasey ... hole saws work for me! If the metal grabs, I'd chalk the bits, but I'm through the hull in seconds with the good ones that I use. As a former machinist (a real one, not an 'offset' button pusher one ...) I've seen more work butchered by unitbits. They may have a place with others, but not for me.

 

[Bearclaw]

I'm with Dale on this one, I'd use the hole saw. Just be sure to use some sealant on the fitting to seal it off. If your hole isn't as neat as you want it you will never know it after the thru hull fitting is on.
Dale,you saying a CNC man isn't a real machinist? I'm a old handle turner too brother, but have a little of the button pusher to go along with it.

 

[nccatfisher]

I have seen just as many wallowed out with a hole saw with worn out teeth as with a unibit. As for keeping the material from building up in the teeth in a hole saw a squirt bottle with water always worked fine for me.

 

[RiverBottomOutdoors]

Unibit makes the cleanest hole, but you don't need a pretty hole. The through hull is flanged and covers the hole. Drill hole, de-burr, silicon, install thru-hull.

 

[onthewater102]

Any reason why you wouldn't use a 1" spade bit?

 

[LDUBS]

Any reason why you wouldn't use a 1" spade bit?

On Aluminum, the ones with the bat ears work fairly well, but I like the hole saw better.

 

[RiverBottomOutdoors]

Any reason why you wouldn't use a 1" spade bit?

Spade bits are for wood. At least that's what I was taught. The "bat ears" mentioned in the post above are made to cut the wood grain before the bit cuts out the material. This helps prevent the wood from splintering and gives a cleaner hole.

 

[onthewater102]

True - but any saw blade meant for wood cuts aluminum just fine, I've used spade bits for any holes I've needed to bore without issue but wasn't sure if there was a reason I shouldn't be doing this.

 

[RiverBottomOutdoors]

True - but any saw blade meant for wood cuts aluminum just fine, I've used spade bits for any holes I've needed to bore without issue but wasn't sure if there was a reason I shouldn't be doing this.

I'm one of those "if it works, it works" guys. LOL.

 

[LDUBS]

Any reason why you wouldn't use a 1" spade bit?

Spade bits are for wood. At least that's what I was taught. The "bat ears" mentioned in the post above are made to cut the wood grain before the bit cuts out the material. This helps prevent the wood from splintering and gives a cleaner hole.

To be sure you are 100% correct, but they do work on aluminum. Not my first choice for aluminum, but I've used them more than once in a pinch.

 

[.Mike]

I bet a spade bit would benefit from having a backer of some sort, like a chunk of scrap wood clamped in place.