Planning on scrap?

[KC2IXE]

Here's one for the pros out there, from a starting commercial shop

Planning on "scrap"

Obviously, we want our scrap rate to be as LOW as possible, but the inevitable just happened, and I scrapped a part. As the stock is NOT that expensive in this case, and I know WHY it happened, and I can fix things in the fixture for 'next time', I look at it as a "Look dummy, you scrapped a cheap part, you have spare stock, so.."

The thing is, I don't really know that my personal "scrap rate" is right now - Most jobs, particularly one off work so far have had a ZERO scrap rate, but when your making 20-30 of a part that BILLS at $5 each, including materials, you have to make time, and in this case, a piece of swarf jammed in a jig, and offset the part by enough to throw it out

How/Do you plan on a scrap rate? What percentage is considered "normal" to plan for? The biggest hassle on this is I have to go back to step one, and blank out some stock, and redo the who set of setups (it was the next to LAST setup that had the issue - of course) - If I had just made a spare, it would have been "Oh well", but now it means 20 minutes of work (It's one of those jobs - dial in the setup, (N minutes), then knock out the 20 parts at like 10 seconds each, including parts change, then spend N minutes setting up for the next op, repeat

 

[precisionworks]

Most jobs, particularly one off work so far have had a ZERO scrap rate

You're doing a lot better than me

On a part I've never run before, I figure twice the time so that at least one good part will be made after two attempts. If the part has been run before I'll have a working print & usually figure a low scrap rate - probably 5% to 10%. Some parts have a number of callouts that are critical, others have a tolerance of +/- .050", and that makes a huge difference.

it was the next to LAST setup that had the issue - of course

That's the way it always works, either the last op or the next to the last op. Bearing fits are like that, where the entire acceptable diameter range is .0004" - and once the diameter gets smaller than that the part is a paper weight.

Toss it in the scrap can & feel good knowing that you'll get $10 per 100# of scrap steel

 

[KC2IXE]

Well, when you're doing one off jobs, that can't really be replaced (read repairs), a 'figure on 2' doesn't really work, so you really have to take your time

I'm probably charging too little for some of these jobs, but some are dead simple - take the one I did 2 weeks ago, not real tight tolerances - drill and tap 6 holes, drill and counterbore 4 others - Only 30-40 minutes of work or so, BUT a $25 dollar piece of aluminum involved, if you count shipping - I ordered 2, because it's a job where I figure OTHER people are going to want something similar.

So, I bid out the job at $65 + shipping of the finished part - probably a bit low, but

 

[precisionworks]

Only 30-40 minutes of work or so

Every machine gets cleaned after a job is done, and the clean up time is added to the time spent making the parts. A handful of chips takes little time to clean up, but a bushel basket of aluminum shavings that end up everywhere is a different story.

Break the tip off an insert - charge it out. Dull a drill or two during a job - charge out the time to resharpen.

I'd guess that your 40 minute job is closer to 60 minutes if you include clean up, putting away tools & tooling, etc.

 

[KC2IXE]

In that 30-40 minute job, I wasn't kidding - drill and tap 6 holes 5/16-18, drill 4 holes 9mm, and counterbore (in the stock blank as shipped - tolerances for that part were real loose)

Hint - job was laid out with a set of dividers, and one with a drillpress

That one WAS properly bid - I probably spend as much time writing the invoice, and boxing the part as I did actually MAKING that part