Beveling a Weld Joint
Taking your welding machines power deeper
Text, photos and video by Tom Hintz
Posted – 2-2-2011
All welding machines have an upper limit in the thickness of the material it can handle properly in a single pass. While excessively thick work pieces are usually more of an issue for the pro welder hobbyists can occasionally run into similar situations. The bevel essentially reduces the thickness of metal for the first pass and that can put it within the range of your machine or your skill level. While the scale may be substantially different, the cure is the same for hobbyist and pro alike.
It is important to know that beveling the edges of a joint in thick material is not uncommon. Welders in many industries routinely use this technique when dealing with large pieces to create a structurally sound joint. The hobbyist welder can use beveling to create a strong bond in material that is too thick for the welding machine they have or their skill level. Using this bevel technique is not admitting defeat but rather being smart about the capabilities of you and your machine.
Why a Bevel?
Grinding a bevel on the edges of two pieces of material to be joined with welding effectively reduces the initial thickness into which the welding machine must burn the puddle. The slanted sides allow you to get a good initial weld in place before adding more beads on top of it to fill the remaining joint. With the bevel completely filled with good welds you can then grind the joint flat without sacrificing strength.
Some instruction manuals that come with welders may suggest welding a thick joint from both sides and that is an option. However, it is sometimes easier to access a joint to lay in a good weld from the top surface. The bevel lets you do the entire operation from one position.
Making the Bevel
While most bevels appear to have 45-degree sides we need not get overly precise with this unless specified by plans or instructions. If it looks like a 45-degree bevel, it is usually close enough. The most important point is that it is wide enough to lay in the first bead comfortably. For many hobbyist welders this bevel may not be large enough to require additional beads to fill the joint. The naturally rounded top of your bead may fill the bevel on the first pass with sufficient penetration.
We also do not want to make the bevel too deep as that can allow the weld to blow out through the bottom of the joint. If your welder is designed to weld 3/16”-thick steel in one pass, use a bevel that leaves roughly that much material for the first bead to penetrate. Here again micrometers are not needed. Eyeball it up and watch how the puddle is developing. You might have to turn the power down or up just a bit to get the penetration you need. A bit of experience doing this goes a long way so practice welding up beveled joints with some scrap first.
If you are still having trouble getting full penetration in your welds you can increased the depth of the bevel to better fit your skills. The crucial thing is to make the bevel deep enough so you can get nearly full penetration in the remaining thickness. This might take a little trial and error initially but once you get used to how deep your welder (and you) normally go making bevels to accommodate that gets much easier.
I use my Bosch 4-1/2”-angle grinder to create these bevels. You can make them with any grinder but the angle grinders most metalworkers have on hand do a good job of cutting the bevel and then grinding the weld flat later.
I like to make the bevels deep enough so t hat I can turn my Lincoln Pro MIG 180 down a bit when I use that machine. That just gives me a little flexibility lat er if more beads have to be laid in to fill the gap.
A Word of Caution
If you are a hobbyist welder don’t forget your common sense when deciding whether to attempt welds in thick material. The bevel helps but you still must apply a good, solid bead or beads to create a joint with the full strength possible. This isn’t a good project to be practicing welds that will be subjected to high loads. I would never weld a trailer hitch or anything that has even remotely similar safety concerns. Using a bevel is a good way to increase your welding capabilities in low stress applications as many of the hobbyist projects are. There is nothing wrong with taking something to a pro or referring a friend there when the job exceeds your skills or your equipment.
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