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Explain Metal Thickness Limitations to Me

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Explain Metal Thickness Limitations to Me

Postby Chips O'Toole » Mon Apr 17, 2017 5:46 pm

I have had a MIG since 2007, but I am here with a noob question: what exactly do metal thickness limits mean?

My welder is supposedly limited to 3/16". Last year, I considered getting a finger brake kit for my hydraulic press, but it required welding thick parts together. I forget the biggest number, but some of the stuff was at least 3/8" thick, and one part looked to be 1/2" thick. I figured I could not weld it, but people said that was incorrect.

So if I can weld half-inch plate to tubing 1/4" thick, what's the story with the little chart on my MIG that says not to go past 3/16"? Does it just mean 3/16" is the maximum penetration depth?
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Re: Explain Metal Thickness Limitations to Me

Postby cj737 » Mon Apr 17, 2017 6:02 pm

Yes, but there are other factors in the way a machine is rated for thickness. Like for sufficient penetration in a single pass. If you encounter thick pieces outside the range of your gear, you can also bevel, preheat, and mutlipass. Just be darn certain that you know what you're doing, and that you take all care and consideration into account. Test pieces, cut, etched, and bent to know whether they will sustain their load is prudent.
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Re: Explain Metal Thickness Limitations to Me

Postby Otto Nobedder » Mon Apr 17, 2017 6:39 pm

cj737 wrote:Yes, but there are other factors in the way a machine is rated for thickness. Like for sufficient penetration in a single pass. If you encounter thick pieces outside the range of your gear, you can also bevel, preheat, and mutlipass. Just be darn certain that you know what you're doing, and that you take all care and consideration into account. Test pieces, cut, etched, and bent to know whether they will sustain their load is prudent.


That's a good summary. It's something you only need to do once for any given situation, and write down your settings, materials, prep, and procedure. It's like having your own personal WPS for that weld. Not official, of course, but if you've proven it once, you can depend on it again in a similar situation.

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Re: Explain Metal Thickness Limitations to Me

Postby Farmwelding » Mon Apr 17, 2017 7:39 pm

Yeah most ratings are in terms of single pass like the up above said. For 1/8" material I use around 17-18 volts for one pass. If I was doing a root in 3/8" plate with a bevel I use around the same settings. A lot of it is just metal prep. Usually bevel if and a gap is typical procedure.
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Re: Explain Metal Thickness Limitations to Me

Postby Chips O'Toole » Mon Apr 17, 2017 7:50 pm

Check out this brake kit, and tell me if it's reasonable to weld that heavy plate to the tubing with my small MIG (or TIG).

http://www.swagoffroad.com/20-TON-Press-Brake-Heavy-Duty-DIY-Builder-Kit-_p_42.html
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Re: Explain Metal Thickness Limitations to Me

Postby Otto Nobedder » Mon Apr 17, 2017 8:06 pm

I just watched the video on the site.

You can ASOLUTELY build that with a small welder. All the critical welds are on the HF press you are building this for. The welds you are doing are a matter of aligning the die to the base, and the press (jack) to the die. You don't need welds bigger than the smaller part is thick, so you're golden with even a small welder.

I wouldn't be afraid to build that with Harbor Freight's crappiest little 70A stick welder and some 1/16" 7014 rod.

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Re: Explain Metal Thickness Limitations to Me

Postby Chips O'Toole » Mon Apr 17, 2017 8:48 pm

Well I feel a whole lot better. Thanks.
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Re: Explain Metal Thickness Limitations to Me

Postby Just Nick » Tue Apr 18, 2017 1:40 pm

would it be okay to tig weld that swag off road kit or would you stick with mig ?
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Re: Explain Metal Thickness Limitations to Me

Postby MinnesotaDave » Tue Apr 18, 2017 1:57 pm

Just Nick wrote:would it be okay to tig weld that swag off road kit or would you stick with mig ?


Looks to me like mig, stick, tig would just be personal preference.
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Re: Explain Metal Thickness Limitations to Me

Postby Otto Nobedder » Tue Apr 18, 2017 6:59 pm

Just Nick wrote:would it be okay to tig weld that swag off road kit or would you stick with mig ?


I agree with Dave. This one is "welder's choice". Personally, I'd TIG it, because it is "my tool, that I'm building, for me, and I have to look at the welds for a long time." Whatever you're comfortable with will do.

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