[pippin88]

Gah!!!!!!
Was just carving out of a board I'd spent ages painting (days to get it done in between the rain!) and half way through lost some steps on the Y axis (about 5cm worth, I think the computer is ****) and that ruined the whole job.
The actual cutting time is less than 30 mins, but the painting :drowning:

[Johnnyboy]

Spent the last couple of days Programming and machining 3 Ops, Went in to QA, First Artical, inspecter Said, "Good to go", But you made it wrong Issue,
i didnt check customer solid Issue to order. Felt a right T**T,

Not only you mate! We all do it some time or another!

[r00t4rd3d]

I was cutting a 3d model, roughly 8 hours in I quickly went inside to grab a drink. Came back out to see the gear popped off my z axis lead screw. A nice big ole fat line right through the middle of the model. Since then I do routine make-sure-****s-tight checks and pause when I go inside to get stuff.

[neilw20]

Choosing a common brand of CNC bob electronics, and finding the only good thing was the website.
It was junk. Two days of wasted travel rebuilding customer's machine.
PM me if you want to know which one it was.
And I almost double posted here as ISP/server errors tempted me to submit this twice.

[Starfire]

Just happened yesterday. Though it wasn't too much time, but forgot to reset the Z depth and gouged right into a piece I was working on.

[SPEEDRE]

Every time I make a miscue I learn something. One of my mentors once said to me,"if it takes more than twenty minutes to correct, start over. It is not worth doing, but over.". That has been the saving grace of my life.

[79TigerPilot]

Was doing the final painting on my BP mill refurb project with some white urethane paint. Looked nice with no runs but before the paint had a chance to set up a swarm of bees flew over raining yellow pollen spots all over the wet paint. Only think I could do was to let it dry sand and recoat the next day.

Craig

[jharvey407]

Reading through these posts made me realize that we all have very similar 'learning experiences' as we use our CNC machines. I have made just about every mistake I see listed above. These mistakes have made me improve my methodology to include the proper checks and double checks to eliminate a lot of stupid mistakes. These days I still make mistakes, but they rarely damage my work or my machine, and most of them are easy to recover from.

One of my biggest time wasters taught me a few good lessons.

A potential customer contacted me about routing some large double sided pieces in full 3D with a lot of compound curves. He sent me an STL file of the part so I got to work figuring out my method for cutting these parts. I spent the better part of a week gluing 2x4s into blanks for test cuts and trying to cut these complex shapes without the machine running into the parts while cutting. Of course there was also the problem of turning the blank over and getting it indexed properly to route the second side. There was also the issue of surface finish, so the final passes had to be done with small tools and a small step-over.

Toward the end of the week I had everything figured out and was blazing through the first part that looked like it was going to be a keeper! The shape was right on, the indexing of the second side was great, and the surface finish was going to eliminate the need for anything but a quick sanding by hand.

For some reason right at the end of the last pass I got impatient and hit the 'stop' button rather than let the program terminate and park the spindle. Safe Z on my machine is 1.5", which typically works well because I 'always' set 0 at the top of the part. Not this time. Because of the complexity of the part I was using the table as 0 and the move to Save Z plunged my cutter straight down into the middle of my freshly cut part!!

Not a huge deal because it was a test piece, but still! So I patched the hole with a dowel and presented it to the potential customer along with an estimate of lead time and cost for the parts. His reply was, "That's much too expensive, but thanks anyway."

So the real mistake was not asking about the budget before I started the prototyping!

[neilw20]

ABC - Accept nothing, Believe nothing, Check everything.
In other works measure twice, cut once.

[CaptainVee]

I'm a morning person.
I found that most of my big mistakes stem from trying to do things that are not yet routine any other moment than in the morning.

That is a challenge as with most learning nothing is routine yet, especially with cnc.

So I now try to get routine before running the actual part with cheap materials and bits and always preparing for it in the morning. I also write up the procedure that I aim to use at the top of the g code file so I do not have to "think" or "remember"

[neilw20]

Try cutting air,soap,wax or wood. It is usually not as hard on the cutters.

[jharvey407]

I'm a morning person.
I found that most of my big mistakes stem from trying to do things that are not yet routine any other moment than in the morning.

That is a challenge as with most learning nothing is routine yet, especially with cnc.

So I now try to get routine before running the actual part with cheap materials and bits and always preparing for it in the morning. I also write up the procedure that I aim to use at the top of the g code file so I do not have to "think" or "remember"

I have the same problem. My mind gets tired before my body. I don't engage in delicate or complicated work past about 4 pm, although I typically work until about 6. I've made too many stupid and costly mistakes, so if it's late and I need something to do, I get out the shop vac.

[Doug E Stop]

How on earth do you guys prevent people from bugging you with inane **** while programming or doing some other complicated op.??

Seems like every time I have a crash (2 in the last year, nothing more than 80.00 e.m. Knock wood x3) there is somebody behind me with a irrelevant comment or question.

Personally if I need to interrupt another operator I stand where they can see me and wait till they acknowledge me, then ask if they can talk for a minute.

Kinda like no one talks to the guy operating the lift at mine, a cardinal offense, firing on the spot I believe.

[nlancaster]

1 hour, 3 $50 router bits, $10 worth of Aluminum.

[Devastator]

Aluminum nosecone mold, $300 in material, 60 hour run. At some time during the file, my machine on casters shifted against the wall causing one of my belt pulleys to rub on the wall and miss a few steps.

[hanermo]

Have made three iterations of the same machine, cost over 30k in parts, last round.
Spent over 8 years, and over 15.000 hours at it..
Now on number 4..
.. And I think I have it nailed. Time will tell, ..

Its definitely getting better, but ..

[Routerfiend]

Did manage to crash a 200mm x 12.35 carbide cutter. Ploughed into the bed because my knob end of a co worker didn`t calibrate it. First day back from my holiday and this is what happens. Now though if I`m not the last person to have used it then I calibrate everything before anything else. Don`t trust anybody............................... EVER !

[Bob La Londe]

I have finished a complex hinged 3D casting mold that took two full days, only to destroy it pressing the hinge pins in on the arbor press. Ouch. Glad I took notes during the cutting process about where I could optimize my code. Recut it in 14 hours on Saturday instead of going fishing.

I'm still trying to figure out my optimum process for that, but one thing I've done is start spiral milling a small over size distance to start the pin.