Broken weld on backhoe frame

[Longbeard]

Still fighting my welder. I got it running but its not running well. It's not giving me much of an arc, probably because its not running right. Anyone know how to flash the DC field? Its a Lincoln 225/210 Weldanpoer.

[Shield Arc]

This is how you do a SA-200, but it may work with your welder, I've done the same thing with AC generators.

Flashing the exciter field consists of passing current through the fields using an external source of 6 to 125 volts of DC power from a storage battery or DC generator. If using a DC generator, keep the generator turned off except when actually applying the flashing current. To flash the fields:

Turn the welder off. Raise one exciter brush off the commutator.
On Lincoln welders, attach the positive lead from the external DC source to the right hand brush holder.
Carefully holding an insulated section of the negative lead from the DC source, touch its lug or clamp to the left hand brush holder for five seconds. Pull it away quickly to minimize arcing.
Remove the lead from the right hand brush holder, replace the brush on the commutator, start the welder and the generator voltage should build up.

There are two schools of thought on how to do this, here is the second way.

At the bullet nose of the machine, under the cap you have 2 exciter brushes, one on each side of the exciter armature.
Each brush has a screw stud that the pigtail of the brush connects to.
The right hand brush (black wire) is positive
The left hand brush (red wire) is negative

With a automotive or lawnmower battery AND THE MACHINE ****NOT**** RUNNING, connect the positive cable from the battery to the positive (right hand) brush screw stud. Attach the negative cable from the battery to the negative screw stud of the brush (left hand)

[Longbeard]

If I put a patch on both sides of the weld repair should both patch plates be as thick as the material being patched? I'm picking up a carburetor kit for my welder tomorrow so I'll be able to flash it once I have the carb straightened out.

[Johnp33]

Welding anything is a choice, if you reinforce it to much it will not flex and absorb shocks as it was designed. Then it breaks something else, because the shock load is still there it is just transfered. I have welded quite a few frames on class eight trucks, and never fish plated them, never had one break either. The most common fault people do is they want the weld to look good so the end up grinding the frame away, You are welding the crack, gouge it out, fit it, do not overheat it, that means chip it clean and spray with a water bottle, I use to use an air chisel with a shortened flat blade to chip and stress relieve the weld, clean with a wire brush, then weld again, clamp scrap steel to the other side to keep in place, and act as a heat sink. Then grind the back side clean, and weld that up. You have to set your heat and speed so you do not undercut. I was never into grinding the weld off, unless it was an area that had anouther piece bolted to it, then only where it overlaps.
Just a thought!

[Shield Arc]

spray with a water bottle,

Unless you know for a fact the carbon content of the base material is low, I'd be real careful doing this.

Carbon content, steel classifications, and alloy steels - Metals/Materials Tech Cell - TheFabricator.com