Machine doesn't go to right position

[w52918]

Hi,
I have two issues here:
1) every time I home the machine, then make it go to "start position" of Nozzle #1, it can move to right position. When I move the machine to other positions, like #6, then if I click "start position" of Nozzle #1 again, the machine moves back, but miss the #1 nozzle a little bit. It shifts to left (about 1.5 mm).
2) I tried to place the example project "Hello World". But the machine cannot go to right position to pick up components. It misses the components a little bit, like 4 mm. I have set the camera position several times, but it's still not working.

Can anyone help? Thank you very much.

[JuKu]

Hi,
This sounds like a mechanical issue. Please check that everything is tight. Especially, the symptoms fit to a loose pulley (tight enough to work, but loose enough to slip on the flat portion of the motor shaft).

Sorry for the late response, I was travelling earlier this week (and airlines make their best effort to get the energy out of me).

[w52918]

Hi,
This sounds like a mechanical issue. Please check that everything is tight. Especially, the symptoms fit to a loose pulley (tight enough to work, but loose enough to slip on the flat portion of the motor shaft).

Sorry for the late response, I was travelling earlier this week (and airlines make their best effort to get the energy out of me).

Thank you for your responding. The problem is still there. But after manually setting the distance between camera and nozzle, it works much better now.

And I have another question: sometimes the machine check the holes when I picking up componets, but sometimes it doesn't. Is there an option that I can set the machine to check the holes every time?

[JuKu]

The "place fast" method checks only the first and last holes, the older place looks for each hole. The fast method is more accurate, as it finds the tape angle too.

[w52918]

The "place fast" method checks only the first and last holes, the older place looks for each hole. The fast method is more accurate, as it finds the tape angle too.

Thank you. My machine can pick up the components very well. But it miss the position when placing. All the components are placed 2 mm to the right. Can I set the machine to check the fiducials every time when it try to place a component?

[JuKu]

> I set the machine to check the fiducials every time when it try to place a component?

You can't, but there is something off in your machine. let's find out what. If you want, we can do this off-line or here. To start:

- Select a component in the CAD data table and click "Measured location". do you get the camera centered on the component?
- Do you use slack correction?
- What is your squareness correction value? Also, does your machine use comma or dot as a decimal separator?

[w52918]

>
- Select a component in the CAD data table and click "Measured location". do you get the camera centered on the component?
- Do you use slack correction?
- What is your squareness correction value? Also, does your machine use comma or dot as a decimal separator?

I didn't use slack correction before, but now I use it. And I change the squareness from "0.0015" to "-0.0055". It works much better. And I use dot as decimal separator.

But I also have two problems here:
1, I still need to manually set the distance between nozzle and down camera. If I let the calibration do it, the machine can't catch component as well as place them into right places.

2, When I try to place loose parts, the first one works fine. But it gives an error when the machine try to pick up the second one. It triggers the down limit switch of Z axis. My nozzle height is about 26 mm, but the machine automatically set the place/pick height to be around 30 mm when after it places the first part. When it's placing the second one, the machine directly goes 30mm down, then trigger the limit switch. Do you know how can I fix the problem?

[JuKu]

1: You should let the calibration handle the values. First, you should have a mark on the large pulley and keep the mark at the same position (like pointing towards front) for zero. If the mark is not at zero before switching the machine on, manually turn it so. This is because there is no homing on rotation axis, but the calibration needs consistency.
The way it is supposed to work is that you set the distance between nozzle and down camera once, at zero rotation. Then, you also set the up camera location without turning the nozzle. This gives us nominal values. The nozzle calibration then measures the difference of the nozzle tip from the nominal value, for each nozzle at several rotation values. This way, the software knows the true position of the nozzle tip, regardless of rotation or the nozzle.
To diagnose, you can click probe down. This takes the nozzle down to the spot shown on the camera, using full correction. Probe down (n.c.) does the same, but ignore the nozzle correction values.

2: Your placement depth and backoff values don't match. First, please make sure that the tube can move freely up and down, and falls fully down under its own weight on all rotation values. Then, set switch so that there is more room. The height calibration measures two z values. One is fully down, where the switch triggers. The other is "just touching". Ideally, you have a mm or two difference between these. The difference is the backoff value. The placement depth is how far the tip goes down from the "just touching". You want the placement depth to be less than the backoff, so that the switch is not triggered, but still putting some force to the part so that it sticks to the paste.

[w52918]

1: You should let the calibration handle the values. First, you should have a mark on the large pulley and keep the mark at the same position (like pointing towards front) for zero. If the mark is not at zero before switching the machine on, manually turn it so. This is because there is no homing on rotation axis, but the calibration needs consistency.
The way it is supposed to work is that you set the distance between nozzle and down camera once, at zero rotation. Then, you also set the up camera location without turning the nozzle. This gives us nominal values. The nozzle calibration then measures the difference of the nozzle tip from the nominal value, for each nozzle at several rotation values. This way, the software knows the true position of the nozzle tip, regardless of rotation or the nozzle.
To diagnose, you can click probe down. This takes the nozzle down to the spot shown on the camera, using full correction. Probe down (n.c.) does the same, but ignore the nozzle correction values.

JuKu, thanks for you reply. With your instructions, the nozzle can pick-up and place parts without triggering the switch. But the machine still miss the parts about 1mm in both x and y axis. Here are the steps I did for the machine:
1, set the distance between nozzle and down camera, at zero rotation.
2, click "Calibrate curr." button at Nozzle Setup page.
3, test the machine with both "Probe down (n.c.)" and " probe down". The "Probe down (n.c.)" does pretty well(first figure), but "probe down" misses the point about 1mm(second figure).

Can I set the machine just use nominal distance between nozzle and down camera, in other words, can I disable the nozzle correction?
And can you tell me the focal length of the camera? I may need to adjust the down camera position. Because the image processing for the tapes is unstable no matter how I set the algorithms' parameters.
Please help me to solve the problems. They drive me crazy. Thank you so much!

[JuKu]

JuKu, thanks for you reply. With your instructions, the nozzle can pick-up and place parts without triggering the switch. But the machine still miss the parts about 1mm in both x and y axis. Here are the steps I did for the machine:
1, set the distance between nozzle and down camera, at zero rotation.
2, click "Calibrate curr." button at Nozzle Setup page.
3, test the machine with both "Probe down (n.c.)" and " probe down". The "Probe down (n.c.)" does pretty well(first figure), but "probe down" misses the point about 1mm(second figure).

It looks like your up camera location is off. In step 1, perhaps you omitted to set the up camera location? When you set the distance between nozzle and down camera, you should take the nozzle over the up looking camera, and set that position too. Please see https://www.liteplacer.com/setting-camera-locations/, the bottom section.

The idea is to store the locations for one nozzle at zero rotation, and measure the difference on other nozzles and rotations to know exactly where the tip is. And because of this, it is also necessary to mark the zero rotation position, and before powering the machine, check that the rotation is at zero.

Can I set the machine just use nominal distance between nozzle and down camera, in other words, can I disable the nozzle correction?

Yes: On the Run job page, "Don't use Nozzle correction" checkbox.

And can you tell me the focal length of the camera? I may need to adjust the down camera position. Because the image processing for the tapes is unstable no matter how I set the algorithms' parameters.

It should be from a few centimeters to few ten cms. If your camera is not good, you might need a replacement, please see viewtopic.php?f=3&t=6015. My apologies for not catching this issue beforehand!