Cutting or bending aluminum sheet

[richg99]

I took the flat sheet of decking aluminum out of my old tinny. I want to cut it to fit my new hull. It isn't off by much....maybe an inch or two on each side.

The new hull is slightly tapered. In a perfect world, the old flat sheet would be tapered, too, but, that is not critical.

My challenge is to either cut an inch or two off of both sides, matching the taper of the new hull....or.....bend the old sheet on an angular line to match the new hull. The bending option is complicated by the old sheet edge already having a slight upwards bend along the straight edges.

So....cutting options? #1.Sabre saw;
#2. I can't use a friction type cutting wheel, since one should not cut with friction on non-ferrous metals.
#3 nibbler, but I don't have a air compressor that puts out enough CFM to handle the nibbler or shears that Harbor Freight offers.

I hate that my only cutting option is the sabre saw. This is a large, flat, thin sheet. I'd have to haul a number of saw horses and even buy some 2x4's to support the sheet. I pretty much have to do it at my boat barn, since hauling it home wouldn't easy, unless I haul it in my boat.

Any bending ideas?????

richg99

 

[Fishfreek]

https://www.harborfreight.com/18-gauge-35-amp-heavy-duty-metal-shears-61737.html



I have these and also a 14 ga. cutter that is also electric. Both came from Harbor Freight

 

[CedarRiverScooter]

So....cutting options?
#2. I can't use a friction type cutting wheel, since one should not cut with friction on non-ferrous metals.

richg99

Good thing I didn't know this . . . I trimmed the hull of my jet jon with a cheapo cutoff blade in my cheapo angle grinder. No problems encountered.

 

[overboard]

I cut almost all my aluminum with a carbide blade on either a circular saw or a table saw. MAKE SURE to wear a LS shirt and safety glasses. I clamped a guide on when I used the circular saw so I would get a straight cut. If it isn't a straight cut then you may have to do without the guide.
Cut it from the backside so the curved edge isn't a problem.

 

[CedarRiverScooter]

I have heard you can put the blade in backwards (into a circ saw). It pretty much melts the aluminum, instead of cutting it. Haven't tried it myself.

 

[richg99]

The problem that I read about.... cutting aluminum ....with a normal grinding wheel is that the "glue" that holds the abrasive together can become super heated (due to loading up the spaces in the grinding material) and the wheel can, and does, explode.

I've read enough to make me very wary. Norton does make an Aluminum cutting wheel. The only source that I've found is a package of 25 for $63.00 plus shipping.

Hoping to find another place to buy one or two.

I, too, have cut aluminum with a standard grinder wheel. I am just not that comfortable anymore using a regular cutting wheel after reading about one boater who can't use his hand after his wheel exploded.

richg99

 

[richg99]

Overboard....must say, I hadn't thought of using a carbide blade in my circular saw. If I set the depth very shallow that might do the job. I will still have to haul 2x4's and sawhorses to the barn, but I guess that is a small price to pay.

richg99

 

[DaleH]

Rich:

When I did my transom build of sheet 5052 alloy of 0.090", I cut it using a TiN-coated fine tooth metal cutting blade in a sawzall. Cut like hot knife through warm butter.

When bending, you will need to heat the metal to its annealing temperature before bending, about 650-deg F for 5052H. I have the special 'crayon' or temp-stick that melts at that temp and waved a Mapp gas torch over the area until the stik melted.

You bang it with a large wooden or wood mallet over a wood form/buck to match the radius you need (corner edge actually a tad smaller in radius than as needed and if you need a 90-degree bend, the form must allow bending far greater than 90 due to springback, which wasn't too bad on the large 6+' wide piece I worked.

Note 5052 will work harden as you work it and will naturally re-harden or resume its prior state, so when it stops responding to the hammer - anneal it again. Annealing allows you to bend it without causing cracking or propagating stress risers that will lead to crack formation.

Need to borrow that temp stik?

 

[Stumpalump]

Any welding supply will have good disks that can cut aluminum. Once you buy your cutoff disks, flapper sanding wheels and grinding disks from a real store you will only use your harbor freight disks when your neighbor wants to borrow your grinder. That's one of the reasons you dread it. The other is the noise and chips. Wearing a dust mask and hearing muffs when the grinder comes out makes it a lot nicer. Not using the china made disks that are made out of political prisoner body parts is the real ticket. One more tip that most don't know...When the cutoff wheel or grinder starts to chatter it's because the disk is too hot. Back off when it starts to chatter. Bad stuff can happen to a overheated disk. Good luck. I hate those cuts too.

 

[riverbud55]

The problem that I read about.... cutting aluminum ....with a normal grinding wheel is that the "glue" that holds the abrasive together can become super heated (due to loading up the spaces in the grinding material) and the wheel can, and does, explode.

I've read enough to make me very wary. Norton does make an Aluminum cutting wheel. The only source that I've found is a package of 25 for $63.00 plus shipping.

Hoping to find another place to buy one or two.

I, too, have cut aluminum with a standard grinder wheel. I am just not that comfortable anymore using a regular cutting wheel after reading about one boater who can't use his hand after his wheel exploded.

richg99

been cutting aluminum for 50+ years with a abrasive cut off blade with no issues , cant tell ya how many tons we've cut up but its been a lot,,, never heard of such a silly thing, some times just got laugh at things that are written(not at you) ,ya mite have a problem if it 1'' thick plate, get some paraffin wax and run the blade through it every foot or so and start cutting, stops the blade from packing up with aluminum,,,, we actually use bees wax works a little better but not enough to go out of your way for it.. if n ya was near by id come and do for ya :wink: I can bet something else went on with the guy hurting his hand wasn't just cuz he was cutting a sheet of alum,,,, get a metal cutting blade for a skill saw dont try using a angle grinder if your not comfortable with it, much safer the skill saw

 

[richg99]

Guess I'll give the sabre saw a try. See how it goes. I figure I can add a piece of plastic edging over the raw cuts.

My SawzAll looks like it would do the trick quick, too. Just looks unwieldily. The cuts will have to be made in the middle of a parking lot, kneeling on gravel.

richg99

 

[overboard]

:lol: Been there, done that!

 

[bassboy1]

I've read enough to make me very wary. Norton does make an Aluminum cutting wheel. The only source that I've found is a package of 25 for $63.00 plus shipping.

Hoping to find another place to buy one or two.

Here you go.

https://www.lehighvalleyabrasives.c...7-8-a46n-t1-cut-off-wheel-sait-23314-uas23314


FWIW, I'll never cut aluminum with a disc not designed specifically for non ferrous metals. There is a difference, and a very good reason for it, at that.

 

[richg99]

Thanks, Bassboy

That is exactly what I was looking for. No sense taking a chance on screwing up my fishing hands with the wrong tool.

Someone (above) suggested that a welding place would have specialised aluminum cutting disks, so I will take a trip there later today.

richg99

 

[onthewater102]

Any carbide blades for circular saws that I've seen have all said they are safe on non-ferrous metal. Just be extra careful. I used a full face shield rather than just eye protection because the aluminum shavings fly everywhere unlike sawdust. I think you'll get a straight cut with less effort keeping it straight with the circular saw, but if you go slow there is no reason the reciprocating saw can't do it.

 

[Wyatt]

I've cut up plenty of aluminum using a reciprocating saw with carbide tipped blades. I always keep coolant or cutting fluid on hand if it becomes too warm. I'm much better with a reciprocating saw than a circular saw. It would be ideal if you had access to a laser cutter.

 

[riverrat717]

You could probably rent a small plasma cutter from an industrial rental outfit as well.

 

[richg99]

Thanks for all of the help.

Project finished...


Project ( this deck part of it, anyways) is finished. I used the saber saw with a metal cutting blade. The line wandered some, but I am going to finish the decking with vinyl covering and probably some PVC moulding around the sides. I haven't fully decided on that yet.

I never had any compunction about using carbide blades. It was the grinding wheel cutters that I worried about. Guess I won't worry about that anymore for now.

No pix yet, but I'll post some up as I make further decisions and progress.

richg99

 

[onthewater102]

"compunction" - now there's a word you don't see tossed around on forums very often!

 

[richg99]

"compunction"...

Hey! Ain't you got no larnin? Them nuns taught me up good....

Ha Ha

richg99