Update: I used to eyeball my tool offsets for years until a scrapped part cost me $500 in material

3 comments

3 Comments

That's a brutal way to learn the lesson. Proper offsets are cheap insurance against expensive mistakes. Sometimes you need to get burned to change a bad habit.

alexw751mo ago

Man, I read an article once about how even tiny offset errors add up over multiple tools. Like if your drill is off by just a few thou, then your tap follows it, and your finish reamer after that... you've basically built a mistake into the part. That $500 scrap sounds about right for a nice chunk of aluminum or stainless.

rose_hart22d ago

Is it really the tool offsets that cause the problem though, or is it more about how you set your workholding? I've seen guys with perfect offsets still scrap parts because their vise wasn't trammed in and the whole setup was twisted a few thou from front to back. A drill can be dead center but if your part is leaning, that tap is going to follow the lean, not the spindle. I'd argue checking your workholding squareness and making sure your parallels are clean is a bigger deal than obsessing over offsets to the thousandth.