Welding Tips and Tricks

What is the best method for welding 4140 Chromoly steel ? The piece I'm working on will be already pre heat treated to about 32 on the Rockwell scale.

I'm making a wheel sleeve nut for a 3 inch spindle. The nut has 2 pins coming out of the face to accept a wrench for tightening down the nut. Rather than mill out the pins fom a solid piece, I'm going to drill out the holes for the pins and weld them in place. The finished thickness of the nut( minus the pins) will be roughly 3/8 of an inch.

Drill the holes completely through. Cut the pin length less 1/16 inch. Place the pins in the holes and weld from the back side filling the space left by the recess with the GTAW process. Weld at low amperage and you should not have a problem with your heat treatment. Do not allow too much weld convexity and sand flush with back of wheel nut.

Thanks!

I'm planning on using oil hardened drill rod for the pins. Will that pose any problems with the 4140?

Hey,

Becareful with the rod you select. If you can, select one that is meant to be welded. No good choosing an ultra hard one that will be the best for the job if it snaps after welding. I have seen pins snap off simply from being knocked because they were the wrong material.

Mick

Hey Mick,

You're right about the rod, I've used drill rod for locator pins and several other things and although it is very strong and hard, they can also be very brittle under the right conditions.

For this project, I decided to scrap the pins in the spindle nut altogether and just drill the holes in it. That way I can use an adjustable pin spanner wrench on it instead.

Steve

Hey ,

No worries mate. Hope all goes well.

Mick

It works great. I'll post some pictures of it, even though it was really a machining project rather than anything I welded. The company I called wanted about $700 for this nut. I made it myself with a $20 piece of 4140, about $50 in tooling and about 4 hours on the lathe to bore it and cut internal left handed threads.

Steve

Hey,

That sounds like a win.

Mick