Had a bad day on the CNC:o(

[Powder keg]

The first one was Rigid tapping a 3/8 - 16 thread. The feed rate is supposed to be .0625 per rev. Mastercam had .087" BAM!!!

A little later, Setting up a new part. We do a lot of weldments so most of the parts you have to start somewhere because their all a little different. This means all the parts have different work offsets and tool offsets. I had ran the program earlier so I set the new part up and set the work offset then touched off the tools. I pushed the green button and BAM!!! I Rapided the 1" carbide endmill right into my part. 500 RPM's and around 350 IPM. It turns out when I was setting the work offset. I hit the Z and the X at the same time setting the offset for both. I usually keep the Z at zero. It ended up being 8" or so lower than it should have been.

 

[vlmarshall]

It turns out when I was setting the work offset. I hit the Z and the X at the same time setting the offset for both. I usually keep the Z at zero.

Ah yeah, been there...done that. A little keyboard bounce when hitting "Tool Offset" on the Haas machines, and you've set a Z offset along with X and Y, and are heading for a crash.

 

[Deanofid]

I don't now how you guys ever get up the courage to hit "run" for the first time!

What do you make where you work, Wes?

Dean

 

[RonGinger]

I just put power to a new CNC router about an hour ago and it ran- no smoke, everything seems great. Ive got a lot of test and check to go, but so far so good.

I was looking at my front pannel and thinking about labels and I thought I might label the big red button as 'DAMN!' because thats what I usually say when I grab for it.

Im not even sure why the button is there, because anytime you need it the s*&^ happens before you even get near to it.

 

[Powder keg]

Thats if you can remember where the DAMN button is Ron. LOL

Dean, I help build Snow Blowers Big ones!!! Our biggest one has a 1200 HP motor that powers the Blower head. \o/

 

[Deanofid]

Neat, Wes! Thank you for the link.
Anything to do with Motive Power in Boise, or is it a separate outfit?

I used to see one of these now and then in the winter. I'm a ways north of you, about 75 miles from Lewiston, out here where the prairie meets the mountain.

A private RR ran all the way into our little town, mainly to transport grain at harvest time, and to carry lumber year round. The track was de-commissioned a few years back, but I remember seeing similar plows on the head end after a bad snow and drift winds.

Man! They would really throw the snow. It was neat to watch. You could see the snow discharge from miles away.
It's been long enough now that I can't remember if they used a screw type or rotary blower.

Dean

 

[rake60]

Just another day at the office Wes.

We had a poster of, "You Know You're a CNC Machinist When" quotes.

#1
"You know you're a CNC machinist when pressing the Cycle Start button
and watching that first Z axis rapid move give you the same feeling in your
stomach as cresting the first hill on the Mean Streak roller coaster at
Cedar Point."

It got to the point where I wouldn't even watch it.
I'd just press Cycle Start and hope the machine didn't shudder. LOL

Rick

 

[Powder keg]

The mill rapids at 350 inches per minute. The lathe we have is pushing 900 IPM. We have some service tecs that come around. He was working on a planer? that moved at 2000 IPM. He said it was pretty scary to watch. I went to a show where they were machining at 500 IPM. Everybody looked when they fired that one up.

I've had a real hard time getting used to drilling holes with these things. You are supposed to push the drill hard enough that the chips break.

 

[BobWarfield]

Even a little CNC mill like mine will snap a 1/2" endmill without even pausing. So far I have avoided crashing into a table or vise.

Over the weekend I was making a new engraved panel for some electronics I'm working on. I had the pleasure of discovering a bug in my CAM program as I watched it trench a 1/2" endmill at full rapids through the middle of the panel. Fortunately it was aluminum only a 1/4" thick and it only went about 1/4" inch. Darned thing was supposed to retract. I spent 2 hours trying to figure out why it wasn't retracting and then finally got it to produce the right result by randomly changing the order it did things. Later, I pretty much concluded that if you try to do a helical bore with an endmill that is more than half (but less than the full--LOL) diameter of the bore, it can get confused.

Anyway, that panel has to be completely redone the next time I can get some material delivered.

DOH!

Cheers,

BW

 

[Davyboy]

There's a reason they are called CNC---- Completely No Conscience!!!! :big:

(Signed)
A Veteran
DB

 

[rake60]

I machine I ran was a Mazak Integrex 400.
At 100% the rapid speed of the X ans Z axis was published to be 1496 inches per minute.
That works out to just short of 25 inches per second. It's pretty impressive to see in action,
but it beats the machine up bad. Those machines were usually run with the rapids set
at 50%. Some operations called for a 25% rapid setting. Drilling deep horizontal holes would
be one of those conditions.

Rick

 

[kvom]

I don't now how you guys ever get up the courage to hit "run" for the first time!

I had the same feeling at school on my first parts. The first time you set the rapids to 5-10% and single step the program, possiblty cutting air. The first time to cut metal you set the rapids slow and keep one finger on the stop button.

 

[joeby]

Feedrate override is your best friend when it comes to proving out a program. Most of our VMC's at work are limited to about 400ipm rapids (box way machines), and the HMC is creeping up on 800ipm I think.

That doesn't leave you much time to go looking for the E-stop.

I've gotten in the habit of creeping up at a slow feedrate for the last few inches for every tool when proving out a program. It can run flat out on the second part. That has gotten me a few remarks about being overly cautious; but it's probably saved a good bit in broken tools and machine parts.

Rigid tapping is one operation that I've never gotten used to. Once the cycle starts, on most machines I've operated anyway, the feedrate override is useless.

Kevin

 

[rake60]

Rigid tapping is one operation that I've never gotten used to. Once the cycle starts, on most machines I've operated anyway, the feedrate override is useless.

Picture this:
1"-8 left hand tap programed to tap in the lathe position.
Operator, who will remain nameless, forgets to reverse the chuck rotation in the program.
The lights dim, machine overloads and does an automatic emergency shut down.

Having a ruined work piece and broken tap isn't enough.
I have the head of the CNC department standing there yelling,
"I know EXACTLY what he did wrong!"
In a tapping mode there was no way to stop the machine.

You could stop it in an external threading mode with the Feed Hold button, but you'd
better be in time with the program. If you hit Feed Hold while the tool was rapiding
back for it's next cut everything was fine. Hit it while it was in the thread and you'd
get a grease groove that was not on the print. No Good!

Rick