Welding on pliers

[CarlByrns]

I have to fabricate a special tool, welding steel onto the jaws of a pair of slip-joint pliers (like these https://www.harborfreight.com/8-in-slip-joint-pliers-63818.html ).

I have a MIG welder- should I preheat the pliers jaws first or is that unnecessary?

[Ed ke6bnl]

I have done things like that with no preheat

[J Tiers]

If the welder is larger than the tiniest Lincoln unit, you should be able to do it directly. But if you feel you may lack power, preheat will help.

Even the low power units do OK with smaller pieces of thick material, even if they fail with large pieces. Small pieces heat up so fast that preheat may not be needed with low-mass pliers.

[fjk]

Preheat won’t hurt the welding.
it probably won’t help either, since steel does not conduct heat that quickly.
it might be a problem for the plastic grips though.

[MattiJ]

Preheat won’t hurt the welding.
it probably won’t help either, since steel does not conduct heat that quickly.
it might be a problem for the plastic grips though.

It can be helpful in achieving best possible weld strength. Depending on manufacturer the alloy used in pliers can be borderline high-carbon tool steel.
With Cr-V steel like 6150 it is highly recommended to preheat the workpiece to prevent cracks.

[CarlByrns]

Thanks everyone. I'll preheat just on general principles.

[danlb]

Thanks everyone. I'll preheat just on general principles.

Good idea when doing small work with MIG. The filler is the sacrificial electrode that melts as soon as the arc is struck. The filler melts before the base metal starts to melt so it's easy to get a cold joint at the very beginning of the weld.