Autofocus on the green laser

There’s only like ten people using the green laser and yet every time I come in the auto focus is doing something different.

FIRST… where’s the setting to offset how far the table drops down after the switch detects height?

SECOND… why is the lens height always different?

THIRD… I’m thinking about just ditching autofocus altogether on that one and eyeballing it every time. I ran some slope tests and left them on the table. If I don’t trust autofocus I won’t use it, and if people crash the head all the time from doing autofocus wrong maybe we shouldn’t use it. How important is this feature?

For what it’s worth, many makerspaces and other laser users fabricate a spacer that they use to manually set the workpiece-to-lens distance, and with some laser manufacturers, that’s the only way to set it in the first place.

I think making a simple little jig for the laser head to sit in on top of the material would make manual focus a lot easier, and the plastic would probably be better on the head than the metal puck when it goes too far.

I think I’d make a few out of scraps of the pink foam left over from the fire truck build. If it gets smooshed, just throw it away and know that it probably didn’t damage the head.

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The two ways I can think the tub length is changing is that people are crashing the head into objects on the table. I don’t know why someone would need to take the lens off unless they had to clean it.

I will shoot you an email where the setting is to change the offset, and you will need a password to change it. It is changed in rdworks and written back to the controller.

Do you think the probe distance is not repeatedly consistent?

I was planning to make a spacer tube to fit over the tube. I need to get the OD on the exposed tube. Then if someone has to remove the lens they would just push it to the top until it stops then tighten it like the rabbit.

Kim, do you have the measurement to make a manual focus gauge block? There might be one in the tool box from the mfg. I think it might be red plastic. It is something we would need to do for calibration purposes.

Hey Tom - I caught up with Zac who showed me how to change the setting in the controller. It was set to 6mm… we don’t know who did that, but that’s a bad setting. The head of the laser needs to be about 6-7mm above the surface of the material. I made an angle wedge test and left it by the computer, it helps visualize it. The hockey puck is about 5mm high and the sensor seems to trip around 1mm so I can’t remember if we set the backoff at 0 or 2, but it was all good again.

Since we don’t know who set it to 6 I was going to say we all need to be better at telling each other when we change a setting like that… but I didn’t tell you that zac and I changed it Friday, so I’m not setting a great example there huh!

I do kinda like the idea of a 7mm foam block in place of always chasing down autofocus.

The focus depends on the distance between the lens and the focus sensor. Since this is not currently fixed (the lens tube can be moved up and down independent of the sensor) there isn’t much point in adjusting software offsets. Either the sensor needs to be attached to the lens tube, or we need a way to make it easy to set the tube in the same place consistently.

Two weeks ago, I was there with Steve T. It was out of focus and the tube distance must have moved. Due to not having a precise way to set the tube distance I changed the distance to 6.2mm. That was focused off of the current position of the tube. We tested it, and it was correct for the tube potion at that point. I was thinking of the next person to just need to focus and go, not change the tube length.

I agree with Christian about mounting or repeatable calibration. Until the sensor is mounted on the nozzle/tube in a fixed way this will be a challenge.

If we can’t repeatedly set the tube distance each time we have to take it off then we will need to change the offset to produce the focus. That procedure needs to be documented, and we (I) need to follow it. it sounds like we are all fighting each other by following partial tribal knowledge, not clear procedures.

I will try to stop by after work to take the dimensions. I can try make a calibration tube for the laser this weekend.

I am sorry, for taking the a short cut and not taking the time, and following up with you guys/gal with what was done. It was just one of those things where someone caught me saying something was not working, and I was trying to leave.

I was not able to make a spacer, due to time spend performing maintenance on the lasers.

@ssaner Thanks Steve

I found the z sensor was very loose. I tightened and adjusted the nozzel to the 7 mm +/- 0.25mm ish. Steve T was running it and had no problems with focus.

I crashed it last night. Thanks, Kim, for getting it all back in order. If there was something that the proximity sensor could trigger off of that had a ledge, hard or maybe swing-away, that the tube could then be set to, that would make the whole thing pretty easy to duplicate. I’ll be back down there tonight to cut some stuff on the red laser. (I had some odd issues on the green one unrelated to this. I’ll look for another thread about it, or start a new one.) I might see if I can throw something together real quick based on how it’s currently set up, if somebody else wants to validate it.

Dave