Metal Fab questions

[Todd.Brock]

I am building a new gate frame from 1x1.5" .083 (14 ga??) steel tubing and attaching it to a 4 " square tubing 3/16" wall, gate post. I am basically making a rectangle with a z brace, attaching two weld on hinges and then painting it and hang some fence boards. Gate frame will be about 65" by 48-50" tall. The steel is all raw, with some flash rust.

This will be my first venture into an actual welding project. What grit assortment of flap disks, grinding stones/discs, etc would I need to prep and finish the metal? Lehigh Valley abrasives seems to be a good place to stock up

My goal is to knock off flash rust, grind down welds and prep surface for a spray paint finish, maybe a DTM paint, or a roll on bedliner type finish.

Thanks for any suggestions !

 

[RickP]

For knocking off the flash rust and the initial paint prep, I've had good results using the 3m soft abrasive discs on a grinder. They're not as aggressive as a stone, and they last a really long time if you let them float on the surface and don't press down to hard.

 

[kazlx]

I'm partial to 120 flap wheels for most work. That's probably my most used wheel, but I'll use a hard wheel to knock down bigger welds. But on 14g your welds shouldn't be very tall. Decent flap wheels will take the welds right down.

The hardest part is always inside corners. You can usually get in there close enough with a hard wheel and follow with the edge of a flap, it just wears out the edges pretty quickly, but if it's your first project and you don't have a lot of volume then it's fine.

I second the 3M soft flaps on initial prep.

There's also these for inside corners:
http://www.lehighvalleyabrasives.co...7-flat-80-grit-t27-lva-fwd4-5-80cx-fd4-5-80cw

 

[texasranger]

I've been happy with the Lehigh brand 40 grit flap wheels welding heavier rusty stuff. Both standard and heavy duty (long life, whatever they're called) They leave a surprisingly smooth finish even for 40 grit. I'd suggest getting a 5 pack of 40/80/120 each so you can see what works best.

Like others have said, inside corners you'll have to start with a wheel. Having a second grinder with a wheel on it saves a lot of time changing between wheel/flap disc/cut off wheel.

 

[customh]

benchmarkabrasives.com has excellent prices as well for everything mentioned, they don't have those fancy fillet weld flap discs that LVA does though.

 

[Todd.Brock]

Thanks all for the feedback. at 3 ish bucks a pop, I can afford to get 4 or 5. I will need to grind down my booger welds

 

[kkroger]

I get pretty much all my personal abrasives from Roark Supply, I like the Pearl brand Flap Disks I use the Type 27 (flat) ones. 36 and 120 Grits. I like the CGW (Camel Grinding Wheels) Cut Grind Finish Disks as well. Search around and you can find a discount code for him that gets you 10% off, the CGW wheels run about $1.49 each and shipping is free over $99...

 

[LXCam]

For the rust get a course wire wheel. For making the welds look pretty I'd go with a 60grit for the majority and clean it up with a 120.

 

[tarbellb]

^^^ Agreed, you will burn up a couple pads trying to get that flash rust off. Just use a wire brush or even a 5" orbital and 80grit pads.

For general weld fab you could easily get away with (Flap disc) 80grit for fast removal, and 120grit for clean up.

At this point I dont even use a standard stone/disc. Its all flap disc, cutting disk (.045"), and my newest 6" fiber resin pads.

 

[lostmymanual]

I also save my 60 grit flap discs that are worn edged and smooth and finish them off by using them as surface prep wheels. Buying the good ones gets expensive but the up side is that they don't deteriorate like any of the cheap ones I've used.

My grit discs effectively live two lives before being tossed.

For knocking off surface rust, I have had good luck with wire wheels. Then don't dig into metal without forcing them and don't wear out like grit pads do. They will; however, quickly let you know you are climb grinding the wrong direction and kick back like a mule on anything if you are using them in the wrong direction. They are infamous for grinder bites.

Also make sure if you use a wire wheel not to be lazy with keeping the guard adjusted between you and the wheel. Especially with square tube or anything with an edge.
The stray bristles hurt like heck when they launch off the wheel.

 

[Todd.Brock]

Thanks for the info. I will have some flap disks enroute shortly.

Can you guys help me with another question? I am trying to determine what wall thickness steel I need. I am building a gate frame 65" wide and about 48"ish tall. I am just attaching some poplar board to make it look like a Ky board fence.

Metal Supermarkets has either .120 1x1.5" or .065 wall 1" square. I was thinking .83 1x1.5"would work, but they don't have it. Should I just keep shopping?

 

[LXCam]

Go with the .120 wall. It's much more forgiving to weld and will last a hell of a lot longer lent alone much stronger.

 

[Ole Slewfoot]

I just built about that with .120, and it sags about 1/8 when I hang from the end.
I weigh about 140, and i think its mostly the 4x4 steel post flexing.

I got 50' of .120 x1.5" for $130 walking in at a local ag fab shop

 

[Ole Slewfoot]

Oops pic

 

[Todd.Brock]

Thanks for the feedback. I have a 4x4 3/16" wall section of tube for the post. I was hoping I was eliminating flex by using a steel post

 

[Todd.Brock]

Oh. Re-read- when YOU stand on the gate. I thought it meant your gate weighed 140lb.

 

[Ole Slewfoot]

When I get teh wood on it, it will be a little more than that probably.
I think I will fill the post with concrete to reduce flex and keep water from building up and rusting from inside.

 

[PugetDude]

^^^ Agreed, you will burn up a couple pads trying to get that flash rust off. Just use a wire brush or even a 5" orbital and 80grit pads.

For general weld fab you could easily get away with (Flap disc) 80grit for fast removal, and 120grit for clean up.

At this point I dont even use a standard stone/disc. Its all flap disc, cutting disk (.045"), and my newest 6" fiber resin pads.

+1

The flapper discs are pretty pricey and don't last that long, especially on fillet welds. I've been using 5" fiber pads with a rubber backing pad in my angle grinder lately for weld prep (40 grit) and cleanups (80 grit). You can do a quick follow with a 120 grit flapper for a finer finish.

Good luck and post pics of the finished gate!

 

[ovrrdrive]

I usually use 36 or 40 grit for just about everything. They actually leave a pretty smooth finish if you don't press hard. then when you need to press hard the grit is there to do the work.

I agree with going to 1/8" wall on the tube if you're a new welder. Nothing ***** worse than doing stitch welds to fill the holes you blew out. The thicker wall is much more forgiving to weld on. I built my plasma table out of 3x3x1/8 inch and it went together very easily.

 

[tarbellb]

Have you tried to find a local metal supplier? Is Metal Market a online supplier, seems like a very expensive option.

Dont be intimidated by the metal suppliers, they want your money and will usually walk you through the purchase. And you seem to know what you want....

As for wall thickness, you will have plenty of strength from the .065" wall, agreed .083" would be best. But others bring up a excellent point, that .065" will be frustrating compared to the .120"

 

[Todd.Brock]

Tarbell - Metal supermarkets is a local place, but I think they are a franchise. I wanted the 1.5x1" as I thought it would have a little more strength vs 1" square. I am not opposed to .120 wall, but at 1.8 pounds per foot, it seemed like my gate would be heavy. With my gate post, I imagine it won't be an issue. I need to call around a few other places as I still think 14ga would be sufficient for what I am doing. Fortunately my welder is only a little craftsman 120 v, so I'm not sure it's hot enough to even blow through!

 

[hippie2cams]

If not mistaken .120 is 14 ga.

 

[Tinner]

You're mistaken.

http://www.custompartnet.com/sheet-metal-gauge

 

[Todd.Brock]

14 ga is .083 if I recall. I finally got a quote for 14 ga. It was about 35% more than the .120 wall. He said they have never sold it.

I ended up with 1x2" tube in 14ga. It weighs less than 1x1.5 120 wall. I pick it all up on Tuesday. Then the bird nesting can begin!