bobcat 250 question

[WillieB]

Lets compare steel to aluminum. An aluminum welder must be more powerful to weld the same mass as a steel welder. As you weld aluminum it conducts much of the heat away from the joint. A large piece of aluminum such as an engine block must be heated fast to outrun the conductive properties of the workpiece.

Steel conducts heat more slowly. With a series of beads building up to a larger weld, heat conduction is less important. With steel, rod size is to be considered. Thermal mass of the work is less important, while heat will conduct thruought, you and your electrode are somewhere else by the time that happens. Typically a big weld joint if it were made in one pass would require so much heat it would melt away, blowing a big hole. It must be built up with a series of passes. I have used 5/32" 6011, and 7018, but at present despite dozens of varieties of electrode I have on hand nothing bigger than 1/8" electrode. I'm at about 2/3 of capacity with a Bobcat 250 making the heaviest steel welds.

[gnforge]

bobcat 250 question

Yes both 225 or 250 would work fine on 3/8 steel, no problem there. And you can weld thicker metal with proper preparation and multiple pass. As for fabrication and light repair work those are fine.
For heavy work, carbon arc, suitcase welders you would want trailblazer series and more amps.

[sjohn]

yes I know what you mean. this is what I was trying to find out. that is what I was trying to ask

"If your planning on running 5/32" Rod most of time id go with 250 or larger."

you answer what I was trying to ask

both welders??? you talking about the bobcat 225? and the 250?

[gnforge]

bobcat 250 question

Your missing the point! Just because you have a bigger welder doesn't mean you can always weld something with a single pass. Metal type, type of weld, preparation, strength required, code requirement etc.
Both welders will burn 5/32 Rod with out a problem.
So if You were running 1/8" Rod most of time both welders will work fine.
If your planning on running 5/32" Rod most of time id go with 250 or larger.

[sjohn]

very true I guess I should of said can the bobcat 250 do a single pass on 3/8 plate I know the machine is only rated at 3/8 so with that being said for a good weld with a bobcat 250 I would have to do couple of passes? right? no matter of rod size?

[gnforge]

bobcat 250 question

No. There is a lot to be considered to determine if one or multiple pass is needed. Just grabbing a larger Rod does not mean you can make a quality weld in one pass over a smaller Rod.

[sjohn]

would the 5/32 rod let me do a weld in one pass?

thanks

[raferguson]

Hello

I'am think of getting a bobcat 250 my question is I will be welding 3/8 steel it being a 250 that would be maxing out that machine? wouldn't it? also I have been reading about engine going bad at 3,000 hours? is this true? I will be welding new steel so i'am thinking 6013 1/8 what you all think?

Thanks

If you are running 1/8 inch rod, you will definitely be running under 200 amps, if running 5/32 inch 7018 that could be up to 220 amps, per the Miller stick welding calculator. So you would not be maxing out the machine. 1/8 inch rod would require a few passes to weld 3/8 inch steel, but it would absolutely do the job. 1/8 inch is actually the most common rod size. I would grab 5/32 rod if I had it, to save time. Each rod has a recommended current range, you can look it up. The current required is primarily a function of the rod, but for thicker material you run more on the high end of the current range.

Anyway, a 250 amp machine has plenty of power for what you are talking about. The Bobcat 250 is rated at 100% duty cycle at 225 amps, and 60% at 250 amps, so you are good.

[gnforge]

bobcat 250 question

New steel, 7018 would be my choice. 3/8" steel I would use 1/8" Rod.
Recommend amp range 110-165, your way under maxing that Michine out.
I normally run 7018-1/8 between 115-140 amps. Should be able to run that welder all day long welding 3/8 steel
And you could run 5/32 Rod it's range is 150-220 amps. And I normally run that Rod under 200 amps.

[sjohn]

anyone have any answers to my questions I have ask

thanks

[sjohn]

cross members braces that are there just in case any twisting. hummmm maybe 7018 1/8 would be better?

[M J Mauer]

Welcome to the forum.
The choice of rod depends on what you are building.

[sjohn]

Hello

I'am think of getting a bobcat 250 my question is I will be welding 3/8 steel it being a 250 that would be maxing out that machine? wouldn't it? also I have been reading about engine going bad at 3,000 hours? is this true? I will be welding new steel so i'am thinking 6013 1/8 what you all think?

Thanks