Cutting 20ga galvanized sheet

[JK22]

I have some of these. Once I figured them out,I was able to cut pretty straight. https://www.homedepot.com/p/DEWALT-18-Gauge-Impact-Ready-Shears-Accessory-DWASHRIR/305609180

 

[spitter]

The key to cutting sheetmetal with a cicular saw is to avoid any vibration wit the metal . Clamp the sheetmetal to your straight edge and have it supported on the bottom just out of the blades way . Slow steady pressure on the saw let it do the work ,avoid stops and starts in middle of cut . Any burs can be removed with flap wheel in a couple of seconds. Your basically just dressing it up . Once you get a few cuts under your belt you'll find it a cake walk. Just as easy as ripping plywood.:drink:

 

[Diggin It]

But again, it's all about the length of each cut. I can make a 12-18" (maybe up to 36") straight, clean cut with those shears in less time than it would take to set up for a circular saw cut. I got to where I only used the saw when I wanted to cut longer (up to 13') panels lengthwise.


Another option you'd have to test on some scrap ... You can score (with a razor knife), then bend and snap 29G roof panels. I don't know if you can do that with 20G Galvanized.

One more thought. With a circular saw blade, you lose 1/8" minimum with each cut. Shears mean no loss of material at all.

 

[Big Barn]

But again, it's all about the length of each cut. I can make a 12-18" (maybe up to 36") straight, clean cut with those shears in less time than it would take to set up for a circular saw cut. I got to where I only used the saw when I wanted to cut longer (up to 13') panels lengthwise.


Another option you'd have to test on some scrap ... You can score (with a razor knife), then bend and snap 29G roof panels. I don't know if you can do that with 20G Galvanized.

One more thought. With a circular saw blade, you lose 1/8" minimum with each cut. Shears mean no loss of material at all.

Totally agree.

And don’t forget there is even MORE material loss if a hand held electric shear is used. Maybe close to three sixteenths of an inch.

 

[chim]

For 20ga, the Harbor Freight shear would be nice. I use a DeWalt shear 18V Cordless 18 Gauge Swivel Head and Shear Kit - DC49KA | DEWALT for some things like that. If you're figuring closely on the material, be aware that each cut costs about 1/4" of material to make the "Spam can strip" of waste. The shears Diggin It used can cut on the line and require no extra material. Cutoff discs, circular saws and plasma do use a little.

Also use a cutoff disc in an angle grinder sometimes. Works best if the disc isn't plunged full depth.

Jig saw works OK, but 20ga is a little thin and the metal needs good support. Works better than a sawzall.

I've had better results using my plasma cutter on black metal. It needs more cleaning / attention when used on galvanized. Plus you shouldn't breathe the smoke.

Disclaimer - If I have time to plan and it isn't a Saturday afternoon project at home that I'm creating something on the fly, I can get the guys to shear it at work.

 

[Aquamoose]

You mentioned that you have air. Whichever route you take, you could benefit from an angle grinder with a debuting attachment (with twist-on pads of various coarseness). I use them all the time for metal work.

 

[deserteagle71]

When in a pinch I use a standard circular saw - with the blade mounted backwards to its normal direction of rotation. Works pretty darned good! Wear a face shield if using a circular saw, regardless of what blade you use.

 

[Big Barn]

48” strips...if you were nearby I would be happy to help.

 

[Aviatordave]

Holy Cow, Big Barn!! I’m experiencing extreme tool
Envy!

Got the sheet metal onto the project table yesterday. It makes a great looking top to the table. Too bad it’s going to get cut up.

 

[Big Barn]

I hope we get to see what it is you are making!

 

[grsthegreat]

I cut 20g with my plasma table and my hypertherm 1000 using fine tip consumables all the time. Slight bowing on real small cuts only. Trick is to use fast cut times. Never tried it with hand torch.

 

[metalbender]

HVAC shops use plasma to cut ducting parts, much quicker than shearing method.

 

[/pine]

HVAC shops use plasma to cut ducting parts, much quicker than shearing method.

LoL...maybe than with hand shears...!

 

[Aviatordave]

The project isn’t that glamorous. I’m making a carriage to sling underneath the camper to load the portable black water tote into. Using angle iron for the framework and the sheet metal to box in the tote so the plastic body of the tote doesn’t take any damage from road debris. I pull with a Chevy Suburban so hauling the tote inside the car or camper was not an option. It’s a bigger tote, about 50lbs, and I’m not a fan of hanging it off the ladder or bumper in back. I’m going to mount it just a little forward of the axels for optimal ground clearance.

I’ll upload some pics when I’m done.

 

[Big Barn]

.Aha You’re just using the sheet metal to line an angle iron frame. Any of the previous suggestions will work to cut your pieces since a perfect edge isn’t paramount.

Drill or punch holes to plug weld the sheet metal to the angle iron. Much tidier than weld beads or burn through.

 

[Aviatordave]

I’m actually just going to drill and rivet the sheet to the angle. I’ll weld aspects of the angle frame together but welding the sheet to the angle isn’t going to give me the tidiness I’m looking for. It’ll be easier to drill the rivets if I ever need to remove it.

 

[Big Barn]

Good idea

 

[metalbender]

LOL if you want. Multiple pieces with curves or angles are done quicker on a cnc plasma table. Sheet stock is only handled once.

 

[zzvyb6]

Well, you are about 3 hrs away to Brighton, but I have a Niagara stomp shear That I'm pretty sure goes 4'

But my message is really that you should try to locate a stomp shear either for sale or rent. Or, buy a used one, use it, sell it after you are done ! I cut windmill blades with one to restore old water pumpers.

 

[Aviatordave]

Well, the carbide circular saw blade worked great. I was able to get a smaller one for my cordless trim saw and the upside to that is that the kerf was only about 1/16”.

I put a sacrificial piece of 2x12 under the cut line, clamped the edges down the 2x12 so it laid flat and set up a fence for the saw to follow. It worked great!
A very clean cut, no deburring needed and nice, straight lines

Thanks for all the good advice. (And even with a full face shield, I managed to get a fair amount of finely cut metal flakes in my hair!) : -D

Here’s some pics: