With welding you can reduce but never eliminate the warpage. If it's
critical, weld first, machine second. Sounds like you need tolerances in
the .001" to .003" range, no choice but to weld first. In fact, you
would be well advised to stress relieve the part after welding and
before machining. If you don't, the vibration from use will stress
relive it for you, your mounting flanges will drift.

Terry wrote:

I am building a new hub for a 8" rim I use on my mini chopper. I
turned down a tube to about 3/16" thick, and bored each end to fit a
new bearing. I then CNC machined 2 mounts out of 1/8" thick steel, one
for my rim and one for a disc brake. They each have four mounting
holes on them.

I then attempted to weld the two mounts onto the tube. The mounts fit
very snug on the tube so I was able to get them perfectly square before
I started welding. Though for the hub to work properly, I can only
weld on one side of each mount becuase the other side needs to sit
flush against the rim and the disc brake. This is how the original hub
was designed.

I began by making small tacks 180 deg from eachother. Then I stitch
welded small portion 90 deg apart until I had a bead all around the
tube. But both mounts ended up warping up towards the welded side. So
now my mounts are not perfectly square to the tube, and I have about
.030" run out on my disc brake and rim when spinning on the axle.

So basically I have to start all over again, but I really don't know
how to avoid this warpage while welding on one side of a part. I
could use less heat, but I really want to make sure I penetrate the
1/8" steel. This is a wheel hub which has a lot of weight on it, 100's
of pounds.

Any suggestions in preventing this type of warpage would be greatly
appreciated.

Thanks.