odd problem with 600x400 xy lines jittery

[neorazz]

every thing seems fine on horizontal motion
when the gantry is moving in the vertical direction straight lines end up wavy
i though something was loose but if you rerun the job the wobble is the exact same pattern
any ideas ?

[Tech_Marco]

You need to provide more information before one can make some suggestion.
We don't know the speed you have and we don't know what kind of machine you're running.
Plus, what happen if you just cut a square box or a circle.
I think you may want to do some basic test and post the result before one can provide some though.

If you just said: "It is not working ,why?" sorry we really can't help without enough info

Marco

[neorazz]

its a home built unit from buildlog 2.0 designs

i modified the frame and built in the 600 x 400 gantry from your shop (order #192817)

its controlled by a awc608 dsp running two tb6600 stepper motor drivers @ 1/16 step

i cant run it any faster than about 10mms or the y axis is wobbly as shown i have to turn down the laser to 3% to keep from incinerating everything at that speed

turning on ppi helps some but just masks the problem

my x-y stage came fully assembled other than belt tension i haven't tried any adjustments

it almost seems as if the y gantry motion was bouncing like a car on a dirt road the bumps are repeatable not just random wobble also from the picture you can see the x axis seems to be just fine
curves are horrible unless you slow down to 10mmsor less

the advertised speeds of the gantry are X:500mm/s, Y:350mm/s

should i expect to be able to laser at those speeds ?
or is that a theoretical top speed ?
i cleaned and lubed the rails

any help appreciated

[scrappyjedi]

Just wondering if there has been any update on this issue? Today I was running a job on the laser and this exact issue started showing up. The odd thing is that it showed up in the *middle* of a file that I'd loaded earlier that morning and had already run successfully several times during the day. Nothing was changed in the file or in the controller config- I changed media sheets in the cutter, hit start, and when I came back to collect the pieces about 15 minutes later, the top row or two were fine, but the ones further down the sheet had jagged edges. When I ran the file again, *all* of the pieces had jagged edges (ours are repeatable, too), and we've been troubleshooting ever since. So far we've:

Changed out the bearings
Checked the belts
Changed both the X and Y stepper drivers out with spares that we had on the shelf
Changed out the power supply for a spare we had on the shelf (thank goodness we keep spares on the shelf!)
Hooked an oscilloscope up to both the controller output and the stepper motor output to verify the signal

So far none of these have worked. I've also tried cutting at slower speeds, and the jagged peaks are simply closer together, not smoothed out, so speed is not the issue.

I'm at my wits' end and in a bind as I just had 4 days of downtime last week due to a bricked DSP 608. I ordered a new DSP and just got it installed on Monday and was hoping to have the full weekend to cut. For once I would like to just have things run smoothly!