A cracked implement frame has a way of showing up at the worst possible time. It’s never during a slow week in February — it’s the Monday of planting week, or the morning the hay is ready to cut, or the afternoon before a long weekend. And whether you call a dealer, haul it to a shop, or fix it yourself right then is often the difference between getting the job done and losing days you can’t get back.

Catching the outside of an implement on a post when turning just a little too wide happens all too often. After the initial embarrassment of hitting a non-moving object subsides, it’s time to determine the damage. For me, the hardest part is getting the metal back to its original shape so that a proper repair weld can be made. When I break something, I really break it.

Ultimately, this guide walks through how to properly evaluate, prep, and weld a cracked implement frame — the kind of repair that goes wrong when people skip steps, and that holds up for years when done right.

Pro Tip: Before you put any heat on a crack, spend five minutes figuring out why it cracked. A crack in a structural frame member is a symptom, not the whole problem. If you weld over a crack without understanding why it happened, it’ll crack again — usually in the same spot.

Step 1: Evaluate the Crack Before You Touch It

Not all cracks are created equal. Here’s how to read what you’re looking at:

Generally, fatigue cracks start small and grow slowly over time, usually from a stress concentration point — a sharp corner, a weld termination, a hole, or a transition in material thickness. They’re the most common type on farm equipment. They look like a fine line running through the material, sometimes visible only when you get light on them at an angle.

Impact cracks come from a single hit — a stump, a rock, a hard landing. They tend to be more sudden and more dramatic, sometimes bending the material at the same time they crack it.

Corrosion-assisted cracking happens in material that’s been weakened by rust over time. The weld repair is the same, but the surrounding material quality matters — you may be welding next to metal that’s thinner than it looks after rust removal.

Before you weld, look at the whole area. Is there bending or distortion around the crack? Is it a single crack or multiple? Does the crack run through a weld or through the base metal? Is the material thin enough that you’re concerned about burn-through? All of this shapes how you approach the repair.

For example, I have welded the square tubing on Rogator sprayers at the top where the booms attach to the back of the sprayer. That point takes an absolute beating in the field when running booms out at high speed. However, after adding a gusset and a slightly better than factory weld, we have had years of service without issue.

Step 2: Decide Whether to Weld It or Plate It

Of course, a crack that’s caught early — before it’s propagated far through the material — can sometimes be welded directly. But in most structural repair situations, especially on loaded frame members, you’ll want to add a plate. Welding the crack closed without additional reinforcement just puts you back at the same stress concentration point, and the repair often fails again in the same spot.

The general rule:

  • Short crack (less than 1″), first occurrence, in non-structural secondary member — weld it, grind it flush, monitor it.
  • Longer crack, structural member, or known high-stress area — weld it AND plate over it.
  • Full break or severe crack with distortion — assess whether the part needs to be straightened first before welding.

Moreover, a plate doesn’t need to be fancy. A piece of matching material — same wall thickness as the tube or the same plate thickness — cut to overlap the crack by at least 2″ on each side and welded around the full perimeter does the job. It distributes the load over a larger area and gives the repair more than enough strength.

Step 3: Prep the Metal — This Is Where Most Repairs Fail

Field repair gets a bad reputation partly because of how often people skip prep. Weld over rust, scale, old paint, and mill scale, and you get porosity, incomplete fusion, and a repair that looks okay but doesn’t hold. Prep is the difference between a repair that lasts five years and one that opens up in six months.

Here’s the sequence:

  1. Grind off paint, rust, and scale for at least 1″ around the entire crack on both sides of the material if you can access both sides. A 4.5″ angle grinder with a 40-grit flap disc is the right tool. You want to see bright, clean metal — not just ‘less rusty’ metal.
  2. Chase the ends of the crack. A crack has a tip that’s usually farther than it looks. Grind to the very end of the crack, then go a little further. Drill a small hole at the end of the crack (1/8″ or so) before welding — this stops the crack from continuing to propagate during the heating and cooling cycle of the weld.
  3. Bevel the crack for thicker material. On material over 3/16″ thick, grinding a V-groove along the crack (45° on each side, leaving a small root face) allows full penetration through the section. Without a bevel, you’re welding on top of a crack, not through it.
  4. Clean again. After grinding, wipe the area with a clean rag. Grinding dust and contamination sit in the groove and cause porosity if you don’t clear them.

Fun Fact: The stop-drill technique — drilling a small hole at the tip of a crack before welding — has been used in structural repair since long before welding existed. Aircraft mechanics used it in the early days of aluminum airframes to arrest crack propagation. It works exactly the same way on a steel implement frame.

Step 4: Choose Your Rod and Set Your Machine

For structural farm equipment repair on mild steel or low-alloy steel, E7018 is the correct rod if you can keep them dry and your machine runs DC. Specifically, it’s a low-hydrogen electrode that produces strong, clean welds with minimal porosity risk. It’s the right choice for loaded structural members.

If you’re working outdoors or with older equipment where the base metal is questionable, E6011 is the more practical choice. It tolerates moisture and contamination better than E7018, runs on AC or DC, and has been fixing farm equipment for 70 years. The weld strength is slightly lower than E7018 on paper, but on real-world repair work the difference rarely matters.

For MIG: run ER70S-6 in 0.035″ diameter with 75/25 shielding gas. Use appropriate voltage and wire feed settings for your material thickness — start in the middle of the range and test on scrap.

Amperage for stick: Run 3/32″ rod for thinner sections (under 3/16″), 1/8″ rod for heavier material. A 3/32″ E7018 runs around 75–100 amps; 1/8″ E7018 runs 100–150 amps. Adjust based on your results — too hot and you’re blowing through, too cold and the bead sits on top instead of fusing.

Step 5: Weld the Crack

With the metal clean and your machine set, here’s how to weld the repair:

  • Tack the crack in place first if there’s any gap or movement. Two small tack welds — one at each end of the crack — hold the joint while you complete the repair.
  • If you’ve beveled the crack, run your root pass first. Get full penetration through the bevel. The root pass doesn’t need to be pretty — it needs to fuse completely. Fill and cap passes come after.
  • Weld toward yourself when possible, keeping the arc slightly ahead of the puddle and dragging back into it. Watch the edges of the puddle for tie-in — you want the puddle to wash up to both edges of the bevel without undercutting.
  • On multi-pass welds (beveled material), chip and brush completely between passes. Slag inclusions in the fill pass are the most common failure mode in thick section repair welding.
  • Do not quench with water. Let the weld cool naturally. Rapid cooling causes cracking in the heat-affected zone, especially in higher-carbon steels like some older implement frames.

If the material is over 1″ thick, or if it is cold outside, it’s generally a good idea to preheat the base metal before welding. Doing so will prevent under-bead cracking. For more information on making sure the weld is a good one, check out How to Read Your Weld Bead (And Fix What It’s Telling You)

Step 6: Apply the Plate (If Needed)

Cut your reinforcement plate, commonly called a fish plate, from matching material — same wall thickness as the tube or same plate thickness. Round the corners (no sharp 90° corners on weld terminations — stress concentrations start there). Size it to overlap at least 2″ past the crack on all sides.

Tack it in place, check that it’s sitting flat with full contact, then weld around the full perimeter. No gaps, no skip welds — a partial-perimeter weld is worse than no plate because it creates new stress concentration points at the weld terminations.

If you’re plating a square tube, weld all four sides of the plate. If you can only access one side, cover as much perimeter as you can and make sure both short ends are fully welded.

If needed, cut a hole in the face of the plate and add a plug weld for extra reinforcement. This is good practice on higher-stress equipment, or on plates you can’t weld around on all sides.

Pro Tip: When plating a cracked frame member, use a piece of material that’s the same thickness or one gauge heavier than what you’re plating — not thicker. A plate that’s much heavier than the parent material creates a stiffness differential at the plate edges and can initiate a new crack right at the edge of the plate. Match the material.

Step 7: Finish and Inspect

Afterward, once the weld has cooled, grind the repair smooth — not flush with the base material necessarily, but smooth enough that there are no sharp notches, undercut areas, or crevices that will trap moisture.

Paint or prime the repair area. A weld repair you don’t protect will start rusting within a season, and rust will eventually work its way back into the repair.

Then put the implement back into service and check it again after the first day of use. Run your hand over the repair area and look for any new cracking at the edges of the weld or plate. A repair that’s going to let go often shows early signs within the first few hours of loading.

When to Call It

However, not every cracked frame is a weld repair. Know when to say when:

  • If the crack has propagated through the full section and the part is bent or twisted, straightening before welding may be necessary — and that requires heat and force that can introduce new problems.
  • If the base metal is severely corroded around the crack, the repair material may not be sound enough to hold. Sometimes the honest answer is a replacement part.
  • If the part is a safety-critical component — a hitch receiver, a three-point arm, a steering component — get a second opinion before welding it back into service. Some repairs need to be done by a certified welder or inspected before use.

The Bottom Line

Cracked implement frames are a reality of hard-use farm equipment, and the ability to repair them in your own shop is one of the most practically valuable skills you can develop as a farm welder. In fact, the repair process isn’t complicated — it’s just unforgiving of skipped steps.

Prep the metal. Chase the crack ends. Choose the right rod. Let it cool. Plate it if it needs it. Inspect before you put it back to work.

Do it right the first time and the repair lasts longer than the original weld. That’s the goal.

SEE ALSO: Our Stick Welding 101 guide covers electrode selection and amperage settings in more detail.

Written By
Jeff

Jeff is a pipefitter by trade, certified through the United Association in MIG, Stick, TIG, and orbital welding, with 10 years of experience completing critical welds that required X-ray inspection and CWI approval. Alongside his trade work, Jeff has spent the last 20 years helping his father-in-law run and repair equipment on the family's row-crop farm — the kind of practical, no-room-for-error welding that doesn't show up in a textbook. He started First Pass Welding to bring that same standard to farmers and DIYers who need welds that hold the first time.