Warning: saved toolpaths vs re-calculating on the fly almost cost me a $2,100 job

I was running a batch of aluminum parts last week and decided to use a saved toolpath from a similar job 3 months ago instead of re-calculating for the new stock size. Big mistake. The saved path was off by about .015 in one corner and it started chattering bad around pass 4. I had to stop, re-do the CAM, and scrap two parts before I caught it. Now I always re-calculate fresh for every new run, even if it looks the same. Anyone else get burned trusting old toolpaths?

3 comments

3 Comments

adam_nguyen72mo ago

Got bit by the same bug on a batch of 6061 last fall. @adam_hernandez is right about that extra 10 minutes being cheap insurance. I figure it costs me about 15 bucks in spindle time to recalculate versus losing a $200 blank and two hours of setup. The real killer is trusting that "close enough" feeling. Even with the same stock size, tool wear changes the cut dynamics over a few months. Now I force myself to run a fresh simulation before every job, no shortcuts. Saved my ass on a tight tolerance medical part just last week.

ellis.robert1mo ago

Hard disagree here. That exact "cheap insurance" mindset is what eats into my margins every month. Running a fresh simulation on every job adds up fast when you're doing 40+ setups a week, and most of them are fine. Plus, that 15 bucks in spindle time per job times hundreds of jobs a year is real money, not some theoretical number. I save the sims for first runs, new materials, or if something looks off during setup. The rest of the time, proven programs with the same tooling just don't drift enough to justify the overhead.

adam_hernandez2mo ago

Yeah, that "off by about .015" thing got me too on a stainless job last year... now I just suck it up and re-calculate every time, takes an extra 10 minutes but saves way more in scrapped parts.