By: Weld.com Crew on October 19th, 2020

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Grinder vs No Grinder in Multi Pass Welding

Welding and Fabrication

"Grinder and paint makes you the welder you aint"

"Real Welder's don't need a grinder"

We've heard them all. But the fact is, the welders welding to the strictest codes always have their grinder close by.

Today we're going to have a little fun. We're running two test plates.

  • Both will be 3/8" Carbon Steel
  • Both will be 6010 open root, 7018 fill and cap.
  • Both will be beveled at 35 degrees.
  • Both will have a restart in the root.
  • And both will bent at the end 
Mill Scale Removal

Any time you're welding carbon steel the first step should always be mill scale removal. We've talked about it hundreds of times throughout our videos. If you don't build from a solid foundation, you're setting yourself up for failure, literally. 

Test Plate #1:

Let's call test plate #1 our control. On this plate we are going to show you how we normally prep our plates. We start with a 1/4" grinding wheel to remove the mill scale. You don't have to. go. crazy with it, but It's good practice to remove it at least one inch around the weld area. Make sure you take your time to get down to clean base metal.

Test Plate #2:

We're going to call test plate number 2 our variable. On this coupon we are going to rush through it like we've seen many welders do in the past. After we get the bevel on the plate,  the only cleaning tool we are going to use will be our chipping hammer.

All that being. said, we will not be removing any mill scale from this plate.

Beveling

Test Plate #1:

Depending on your WPS (Welding Procedure Specification), you have some wiggle room in how you bevel your plates.

Today, we are going to use a standard 70 degree included bevel. That means each plate will be beveled at 35 degrees. To put that bevel on, we will begin with the same 1/4" grinding wheel that we used for the mill scale removal. Each plate will get a 35 degree bevel. To make life a little easier, here is a quick tip to ensure. you're getting the best bevel:

Bevel a small area on the end of the plate. Check it with your degree finder and once it's dialed in, use that as your guide for the rest of the plate.

Once we get the bevel roughed in with the hard rock,  we switch over to a Tiger Paw to even everything out. This ensures that we have the best bevel surface possible, without burning up our flap disks on rough in.

Test Plate #2: 

With the variable plate we are going to take the easy way out. Instead of finishing the bevel with the.  40 grit Tiger Paw, we are simply going to put the 35 degree bevel on with the 1/4" grinding wheel. This is going to lead to a rougher, less consistent bevel.

Proper bevel and mill scale removalHere's a visual of plate #1 vs plate #2. Notice how the mill scale butts right up on the 

bevel on plate #2 (bad)

Land

Often times land is a personal preference. Lot's of really good welders don't use any land and just slam the plates together with very little (if any) gap. We like to use a 1/8" land and a tight 1/8" gap. Both plates will get a 1/8" land, but there will be a slightly different approach in how we put it on.

Plate #1:

We prefer to use a flap disk when putting the land on. It gives you a little better control than the 1/4" grinding wheel.

Plate #2:

In keeping everything consistent with the beveling, we are. going to use the 1/4" hard rock in order to put the land on.

Weld Out

Plate #1:

The first plate is going to have everything done right. We put a restart in both plates so we can show the proper way to restart. We will also take a bend sample from each at the restart. We feathered out the tacks with a 1/8" grinding wheel. We do this so we don't get any lack of fusion on the backside. After each weld we will use a wire wheel to remove any smoke or slag.

Plate #2:

On the other plate, the only thing we are using is a chipping hammer.

Watch the full video above for results!