Gouge Help

[ninewgt]

Hey guys... I was gone for a while - The file is not nearly as big as I said (looked at wrong one) I can put it on a floppy =)

Anyway - Ill email it to anyone... I cant figure out the FTP thing and dont really want to post it anyway - were producing this hull soon

Thanks

Tom Mitzlaff
www.mitziskiffs.com

[hardmill]

Send it here

PEACE

[tsalaf]

I’ve recently got my router up and running and started experimenting with VisualMill. There has been some weirdness in the finishing pass in the form of unwanted movements. It would be useful to know what the issue is with nine’s code.

Steve

www.tac-pro.com

[balsaman]

Send it here: cnchomeman@yahoo.com

[ninewgt]

Balsa -

I emailed it to you........


Thanks

[Mortek]

Send it to chiron@qwest.net

[cadcam]

Please send all info to Mastercam@ppcadcam.com
Including the stock size the Pickup location along with the tool list please .

[hardmill]

Send to hardmill@rockhardmilling.com

PEACE

[ninewgt]

I ran the part again. Roughing went fine - got a gouge on the finish. Interesting though - same type of gouge - straight accross, but a little further aft on the part as a percentage of the part ( I scaled it down - my stock was smaller) but i ran same way, speeds, depths etc..... gouge was also a little higher on part, but zero was at top of stock this time, was set at the bottom of stock last time...... I am STUMPED.... but not knowing near enough about it...... I have no clue.....

This is the same IGES file I was getting all the help with except I got it much cleaner before I exported the Iges.

Anyway- I cant wait to hear what ya guys think./....... I looked for hours in the simulator and cant figure it out. I do know one thing though - Visual Mill is giving me fits...... scaling, zooming, part stock, you name it - it acts crazy.......... maybe its a source of the problem ?

Tom

[hardmill]

Heres a screen shot of your nc file backplotted in
Meta-cut.

PEACE

[hardmill]

#2

PEACE

[balsaman]

I backplotted the file too. There is nothing wrong with the nc file. I still suspect your z axis is stalling. Slow down the z axis and try once more, or do a dry run.

Eric

[ninewgt]

How does an axis 'Stall' ??????? Is my stepper getting to warm or something ? I was running it slow anyway - like 30-40 inches a minute, I slowed it down with my feed rate override......

wow, I am stumped and now worried about my machine......

[HuFlungDung]

Ninewgt, unless you have encoder feedback to your controller, on your various axis, you are largely running on "faith" that the tool position is correct. This is why I like servo motors, with encoder feedback, because the motor will have to make the move, or trip the overload on the drive amp feeding it. The controller software should also monitor the position error and halt the program execution if the motor is too far out of commanded position.

Having said all that, could you email your nc file to me as well? Thanks.

mcewan.machining@sasktel.net

[keithorr]

Originally posted by ninewgt
How does an axis 'Stall' ??????? Is my stepper getting to warm or something ? I was running it slow anyway - like 30-40 inches a minute, I slowed it down with my feed rate override......

wow, I am stumped and now worried about my machine......

If he got the same gouge in another location, it's his z axis.

Depending on the accel/decel rate, and the duration of pause between steps, it is possible to have the z axis fail to change direction, i.e. down to up.
I've seen my z axis go down as the g code commands, and then go down even further when it was supposed to change direction.

I have a different driver, but as an example, I need to set my accel, max stepper speed, circular interpolation timer rate, Idle line off delay, idle line on delay, DIRECTION TO STEP DELAY, Bus delay, and jog delay.
The delay settings allow the motor to do it's thing and get a chance to sit idle before the next pulse is sent. The intervals are set in millionths of a second, so it's not like the machine is jerking around.
If I set the values too low, I get the same results you describe.

On a good day, with the right temperature, humidity, moon phase and such, I can get the machine to run at 100 ipm and everything looks very impressive.

If I am contour milling, I go much slower. 40 ipm max, and even then, I need to consider if the toolpath has any sudden direction changes or risk loosing steps.

[cadcam]

I have to ask Are you running this on a home made CNC router or a industrul router or CNC milling machine..

The only time I see a Z move to were was not suppose to has been do to a bad grounding job on a few cnc Haas ,Fadal few other,s

Or the other case were you have a bad axis board.
the starving for data look ahead useally creates and studdering being a lack of look ahead in the buffer to encoder..

Most of the time for problems that he has stated is due to bad Gcode out put or operater interface. We all know this one.

Thanks jay

JM2C

[balsaman]

The axis stalls when the power to move it excedes the power available from the stepper motor. Steppers produce more torque at slower speeds. The combination of lifting the z axis and the spindle and the cutting force may be too much at the speed you are running. Slow feed rate down to 20" per minute and try again, or chage the roughing pass so that the finish pass is cutting less material.

Eric

[keithorr]

"We all know this one."

Do we?

It's a stepper router.

His original post: http://www.cnczone.com/showthread.php?threadid=845&s=
"Sanyo-Denki steppers with 48 volt power supply"

He also writes of rapid speeds of 300ipm and dry running a file at 250 ipm. Then another post where he cuts a 2-1/2D sign at 125 ipm and a gear at 80 ipm, then the boat model at 30-40 ipm.

This is the same thing I went through when I got my router. Balsaman may or may not have experienced the same thing. As he says "Don't ask me how I know"

Many of us with stepper machines start out running a fast ipm, then learn the limitations of the machine and what it can really do. Given the small moves involved in 3d contour cutting, the machine rarely gets up to the speed expected. Over tuning the accel rate or decreasing the delay times to make up the difference can cause the motors to stall or run in the wrong direction.

There is documentation on the gecko website about delay settings.

[anoel]

Yeah but in the sign and gear NC files the Z is pretty well static at most points in the file. Note that in the one sign cut that his Z rapid gouged the sign. I'd be curious if that wasn't due to the Z loosing a few steps. His router is huge.... His rails are handling all of the weight on the x and Y axis and the rack and leadscrews are not hadling a load. His Z axis is pretty darned heavy for a stepper that has to bear the entire weight of the Z Axis. In the Boat hull the Z is moving constantly on the finish pass. So there's a lot of chance for loosing steps.

[balsaman]

How does an axis 'Stall' ??????? Is my stepper getting to warm or something ? I was running it slow anyway - like 30-40 inches a minute, I slowed it down with my feed rate override......

Don't worry about your machine. It is very nice, and will work great, once you get to know it. I suggest you may want to find a spring or gas cylinder to counterbalance the z axis weight. This will take some stress off the stepper. My stepper machine had this feature on the z axis and it works very well.

Eric