Ask your WELDING questions here.

Yeah, I prolly shoulda mentioned it's for working on my boat. Plate that's already on the boat.

jigsaw or holesaw. A mag drillpress with an annular cutter bit would be the cat's azz, but I'm guessing it's more than you need/want to pay.

Yes, thank you

Is a decent bimetal holesaw gonna last for a few cuts?

Would a air saw be better then a regular jigsaw?

Anybody make a nibbler or anything that will work that thick?

A few cuts yes, but I've never gotten great life out of them- but I'm usually rushing/bungling some job, drilling at too high a speed with no cutting oil. I think with proper conditions, they could last pretty well.
Don't know about an air saw, but I think a jigsaw with a good blade would handle this easily- not as nice a hole though, and 3" is on the small end for most metal jigsaw blades that I see.

I'd go bimetal hole saw, slow with lube.

thx, that brings up another welding 'related' question: When you are drilling or cutting something in the process of a weld job/repair How do you get the oil off so you can get good primer/paint adhesion especially in nooks and crannies that might be inaccessible now that you welded the piece in there?

(nuther advantage of plasma I guess )

98% argon 2% CO2

Nice mill.

I wish that I had one.

any thoughts on 100% argon for mig stainless?

Please do not take this as gospel as I am sure someone has welded stainless with straight argon. We used to use 90% helium 8% argon 2% CO2 to dip transfer MIG weld stainless. We now use 55% helium 43% argon 2% CO2, based on the high cost of helium. Both mixes work fine, we also have used 98% argon 2% oxygen on heavy 3/8" and thicker weldments with good success.

Good luck

To begin with 1/8" is not considered plate it is sheet metal.
1/2" drillmotor with a bi-metal hole saw of the proper demention for the hole desired. Low speed with lots of liquid coolent.

I would rather cut a 2" hole with a saw than a plasma or torch. No clean up and I would actually get the size I want.

Those cutters are the balls but cheapest was the question. I would only use one in a drill press.

Edit. I got 22 good 7/8" holes with an annular cutter in 1/4" stainless. l flooded it with PB blaster. The last 2 holes were nearly impossible. RPM was about 400.

David

Hey,

How different is brazing from stick welding? Someone's trying to talk me into dabbling in bicycle frame building. If lugs are used, I'd have to teach myself to braze. Is there a good primer on brazing anywhere?

Thanks

If you need to ask here, dont try building bike frames............its not simply a matter of learning how to braze, which is pretty simple.

Brazing is a bond between the metal parts with brass alloy. Welding melts the two metals usually with a filler that has similar properties.

I was under the impression that most lugged bicycle frames were silver soldered NOT brazed.

"silver soldering" is a form of brazing. Brazing is a generic process with multiple possible filler metals, silver solder being one of them. The primary difference between brazing and soldering is temperature.

Yes and uses capillary action to hold the lower melting temperature filler between the two higher melting temperature parent metals.

You can use bronzes, silver alloys, etc as the brazing alloy. But you dont actually melt the pieces being brazed together. There is also arc brazing of steel with silicon bronze where you use a bronze wire in a MIG welder to weld (braze) steel. The auto makers commonly use silicon bronze to weld very thin steel that is too difficult to MIG weld with a steel filler wire. The wire is applied without melting the steel. The surface area of the brazment determines the strength generally, along with the tensile strength of the filler used.

Google search Harris alloys. They have very good info on soldering and brazing.

Or just click the link below.

http://www.harrisproductsgroup.com/en/Products/Alloys/Brazing.aspx

Thanks!