Of nozzle adapter and force

[wormball]

Hello!

I measured that the liteplacer exerts 100 to 500 grams of force on the placed part. I think this is too much, especially for 0402. On the other hand, juki nozzles have spring in each nozzle, and i suspect that their force is significantly lower. Since juki nozzles are quite expensive (and brittle?) and there is too much to redesign to use (and automatically change) them, i want to decrease the placing force with the existing (or maybe new) samsung adapter. So my questions are:

- Are there adapters with weaker spring on e. g. aliexpress?

- How to disassemble/reassemble the samsung adapter?

- What is the diameter/length of the spring?

- What force is exerted with juki nozzles?

- Are there any official recommendations for maximum force during placement?

Thanks in advance.

[JuKu]

The nozzle spring should not activate during normal placing. Instead, the tube should be mounted so, that it moves freely up and down a couple of mm's. When you push up from nozzle tip, the tube should move up, then the switch triggers, then the bottom shaft collar hits the bearing. Only after this should the nozzle adapter spring start to compress. When letting go, the tube should go fully down, in all rotation settings, releasing the switch. When you set up the Z height, you measure the amount of movement there is between the nozzle tip "just touching" the target and the switch triggering. You also set the "placement depth" somewhere in between.

You can fine tune the downward force by the springs on top of the tube. I found the weight of the tube to be just right for me, I don't use the springs.

[wormball]

The nozzle spring should not activate during normal placing.

I know. And i also do not use springs. I even had not measured what is the force when the nozzle spring is squeezed.

100 g is the static force when the tube is displaced by about 0.5 mm, but i suspect that dynamic force is significantly more, but i do not know how to measure it. Now i have 8000 jerk and 9000 speed on the Z axis, but maybe i will rebuild the liteplacer (somewhat like openpnp/chinese machines) so i will get the Z speed about 50 000. And in this case i am afraid that the pnp head will occasionally smash the parts instead of placing them.

Maybe it can be overcome by holding boards only by edges (like in industrial machines), but i think it is harder to do than replace the nozzle spring, and i am not sure that the nozzle won't hit the board in such way that placed parts will be thrown off, and also it does not solve this problem for tapes.

When i place parts manually, i apply about 20 - 50 grams of force.

[JuKu]

TinyG has jerk management, so when it approaches travel end, it slows down. In other words, it will not smash parts, no matter what the speed is. You can control this by the acceleration setting (which actually controls jerk).

I don’t know how to change the spring in the nozzle, nor if there is lighter loaded adapters available.

[wormball]

TinyG has jerk management

I had read about this and find it disappointing that it can not be reverted to good old acceleration setting. As far as i get, it effectively drops maximum acceleration by about two times. And for short moves the speed impact will be more severe, at least if they tell all the truth in their article.

it will not smash parts, no matter what the speed is

If we had infinitesimal placing depth, it of course would have zero speed and zero acceleration during touchdown. But the placing depth is finite, so speed is also finite, and i hear definite knocking sound every time it picks or places (unlike manual placing). Maybe i should try decreasing the placing depth, but when i tried this last time, not all the parts were placed, maybe due to uneven height of makerslides screwed at the corners. I hope that with the weak spring i won't need precise height measurement at all, like with juki nozzles.