Machine or weld First?

[dan s]

The round shown below, needs to be tapped, & welded into the flat. The small diameter is 1", the large is 1.25", & the thread size is 3/4-10.

Is it better to weld and then tap, or vice versa?

http://img291.imageshack.us/img291/256/21603272jb2.jpg (http://imageshack.us)

http://img255.imageshack.us/img255/4945/86237649ed2.jpg (http://imageshack.us)

[macona]

Always weld first if you can. Because stuff moves a lot when you do.

[Andrew_D]

Definitely weld first. The heat will cause everything to expand/contract. Depending how exact it needs to be, you may need to re-machine after welding too.

Andrew

[torker]

Yup...what they said.
If you mean you still have to drill out the round...then tap it...you will shrink the round when you weld it in place.
Of course you can run the tap in again but why do it twice?