need help with the 500mm square test

[artbot]

i did the 500mm test a few weeks ago because i was getting wild swings/different distances printed from my jv3. i messed around with this test but could not get it to actually do anything.

the odd sizes are gone now. my printer just prints the same wrong distance over and over.

can someone look at these instructions (cut from the service manual)? maybe they will make more sense to someone else. the steps don't seem clear to me. is the box going to correct itself in the next test? my 500mm box keeps printing too large exactly the same way each time. the best i can figure is i am missing something.

thanks in advance!

aa

 

[ruckusman]

OK so you've done your 500mm square print, at step #3 you use the up and down arrows to enter what the machine actually printed in the X and Y directions - which from the instructions in image No1 are in 0.1mm increments.

The instructions aren't too obtuse but they're not exactly clear either as step #3 should have explicit instructions for entering the results, which are actually mentioned on the previous page - engineers HUH!!

 

[SightLine]

I remember doing that one a couple years ago and yeah - the instructions were somewhat lacking as usual. I think ruck has it right though but I think you need to left arrow first to clear any existing adjustment, then print the square, then enter the actual measured value. Been a long time though so I might be wrong and I do seem to recall something hokey about this particular calibration.

 

[artbot]

i think erasing a an entry before doing the test is a good way to start. i'd love to just do the test wrong once. then i could extrapolate what i did wrong rather than nothing happening.

BIG QUESTION:

i'm doing the test on paper. but then loading .030, and .040 aluminum. that means i really should be doing the test on those thicker sheets right? isn't this like calibrating an odometer and then putting on too tall of tires afterward? i figure i would just spray/adhere some thin paper to some .030 and that should hit the measurement in the middle.

 

[SightLine]

Hrm - I dont think the thickness would affect the feed rate - the weight of the material might I guess. A thicker road does not change the speed - larger or smaller wheels/tires would though.

Probably a good idea to set the calibration with the paper adhered to the aluminum either way though since thats what you run all the time.

Before this though - I'd first zero the user media comp values then set the media comp2 value in the service mode which is essentially the media comp basis value. That way you know for sure none of the media comps are affecting the measured x distances.

That being said - changing the media comps WILL alter the actual print sizes. One thing I'm not too sure of though is if the media comp2 or user media comps affect the 500mm square.

 

[artbot]

thanks sightline! i think i can figure this out. and you're right about the thick road thing. i keep trying to imagine what is the geometry of thickness to distance and it never makes sense that the top of the metal would suddenly be further than the bottom. ...good illustration.

 

[artbot]

kind losin' kinda catching on(?)

i'm still not printing and the files are stacking up.

to confirm (whoever can get back with me is a saint in my book).

after clearing the value i print the test.

1. the first print is proved to be 500mm on the nose going in the y direction.

2. the x direction is 502mm.

3. i adjust the x value to 502mm.

4. print again.

5. the x direction never moves away from 502mm! but it seems that the y is not moving around shorter and longer?

is this what the manual is trying to explain in the illustration with the dashed line?

(also, i've noticed there are two different test patterns. the draw pattern is missing a section on the left, the "enter" pattern is a complete 500mm box. what is implied by these two patterns. is the enter pattern the final? because it never changes either.

i guess i can create a 12"x12" tif to track my results too, because this test is not making sense. wouldn't the x after having a new value adjust then print to 500m with dialed in? no matter if i go up or down drastically, it stays at 502mm as if nothing has happened.

update: i have printed a 12x12 tif and got the x distance to move up and down. but i can't seem to figure out how to exit the test the same way twice and it store the number predictably. it's like parallel parking a boat hooked to a 4x8 trailer!

i would figure the value that i am adjusting to is not being saved.

grrrr!

 

[ruckusman]

OK so you've got movement in your X printed dimension - from page 2 hit enter to store these values...(don't touch either < or > as it will clear the values or re-print the square)

Then hit end

BTW I've never done this test, however that may actually be helping keep my perspective different....play with any computer hardware long enough and you get used to the counterintuitive menus that crop up from time to time

peace out

 

[SightLine]

I reckon it is also possible that while it takes and remembers the newly stored compensation values that the actual 500mm square pattern itself does not ever use those values. I've not had this issue on my JV33 but I do remember having to adjust this on the JV3 I had and it was specifically for x (feed direction) starting to get longer than what it was supposed to be. My guess for the root cause is either the feed motor or it's gears are starting to wear out.



If all else fails the next thing to suggest would be to use a compensation in your RIP if it has one. I know FlexiSign does - in Flexi you can even tell it how large you want the sample to be, it prints it, then you enter the actual printed size and it will automatically adjust all future prints based on that compensation value. Granted - this is what the printer is supposed to be doing with the 500mm square adjustment....