Running 75 dpi test

[Allan Rabanales]

Hello folks.

I have a 40 watt Zing and would like to run the 75 dpi test to see where along my tube is. I came across this while searching and have searched to try to get more specific info.

I have made a 100% black square and I am ready to raster it on a piece of black anodized aluminum. Now here is where the noob comes out. When I made the template in Corel, I made the rendering resolution to 75 dpi. Was it here that I put the 75 dpi or do I leave it at 300 and change the dpi in the epilog dashboard? If it is to change it in the dashboard how do I change it to 75 dpi? The lowest I can go is 100 dpi.

I am sure that I am missing the obvious.

Thank you all for your help.

Allan

[Allan Rabanales]

I tried with 100 dpi which is the lowest I know how to achieve.

Here are the pictures of the square.

Can anyone interpret the image?

Thanks

Allan
DSC02972-2.jpgDSC02972.jpgDSC02972-3.jpg

[Michael Hunter]

Nice round dots, so no big worries about the tube.

For the wobbles and unevenly spaced lines -

1 Check that the lens assembly is fastened securely to the carriage *.
2 Check the belt tensions - in both the X and Y directions.
3 Check no dirt trapped in the splined drive pulleys.
4 Lubricate X rail / lens carriage bearings

* easy to leave it a bit loose if you remove it for cleaning : been there, done that!

[Allan Rabanales]

Michael.

Thank you. I feel better about the tube now. I will now look into the belts and pulleys.

How much tension is there supposed to be on the belts?
I bought this machine used and do not have something to compare it with.

Thanks Allan

[Kev Williams]

Good old wobbly lines-- My LS900 does that, has done since brand new, and it's one of the main reasons for banding. As the lines per inch get closer together, the wobbly lines overlap in places, and the difference in where they do and don't overlap shows up as banding.

But- it only does it in raster mode, and speed isn't much of a factor, other than the wobble reduces somewhat at slower speeds. Setting up a series of horizontal lines at 75 lines per inch (make a line and make mulitple copies at .013" apart) and running them at 75dpi results in dead-straight lines. Doing this is a good test to verify something in the drive train isn't loose. Try it- if your vector lines are nice & straight, all is well. Mine has always passed this test...

[Michael Hunter]

Not familiar with the Zing, but it might be similar to my setup :
There is a spring-loaded adjuster for the X belt (opposite end to the motor) - loosen the screw, run the carriage backwards and forwards by hand a few times and then re-tighten the screw.

The Y belts are a bit of a mystery - I never got a straight answer to how tight they should be.
I run mine so that the middle of the top part of the belt can be pressed down onto the bottom using medium-gentle force when the beam is in the "home" position.
Make sure that the beam is still square to the bed after adjusting.
Hopefully someone will come up with something a bit more scientific!

[Kev Williams]

Figured it wouldn't take long to do this---

Raster on top, wobbly-- vector on bottom, not wobbly...

NO ONE has ever been able to explain this to me...

DSC03359.jpg

[Tony Lenkic]

Kev,

Are you reducing the speed when vectoring? That may be one of reasons.

[Dan Hintz]

Figured it wouldn't take long to do this---

Raster on top, wobbly-- vector on bottom, not wobbly...

NO ONE has ever been able to explain this to me...

DSC03359.jpg

Is the carriage traveling at the same physical speed (I don't care about settings, just physical speed) between both tests?

[Kev Williams]

In the first test, no- I was rastering quite a bit faster than vectoring-

So I did another test. The raster is done at 7 speed and 10 power, the vector is done at 100 speed and 40 power. 75 lines per inch, 200 dots per inch. The engraved areas are 3" long...

My machine vectors pretty slow, even at 7 speed it was rastering slightly faster than vectoring, but not much, roughly 6" per second raster to 5" per second vector.

The test did the raster first, then vector outlined the raster, then the straight vector lines.

Interestingly enough, the wobble is much worse this time. Seems that accel and/or decel may be part of the reason, as the middle is fairly straight, and it seems that one end of each line wobbles badly while the other end is fairly straight. But even though the middle is FAIRLY straight, it's still wobbly, while the vectored lines don't wobble a bit.

DSC03363.jpg

.

[Doug Griffith]

Assuming you are rastering in both directions, it looks like it's happening on decel only. My thought is that it's less of a wobble and more of a shudder. The waves are so close together that it appears to be at the carriage and caused by slowing down the mass of it. Possibly loose bearings.

[Dan Hintz]

Assuming you are rastering in both directions, it looks like it's happening on decel only. My thought is that it's less of a wobble and more of a shudder. The waves are so close together that it appears to be at the carriage and caused by slowing down the mass of it. Possibly loose bearings.

Agreed... but my guess would be during accel, not decel.

[Doug Griffith]

Agreed... but my guess would be during accel, not decel.

I'm basing my guess on the image. The top line is straight on the left and shudders on the right.