Robin's smt Pick and Place build

[Robin Hewitt]

Hi, I'm in the middle of a similar project. So far I am good for 0805 parts, 3216 LEDs, SOT23 parts.

Must have missed the e-mail notification.

What a splendid looking machine, is that a multi-nozzle head?

[flippersplace]

Yes its morphed into a bit of a monstronsity. Although I've still a few hundred PCB's to finish running through this machine I've already started collecting bits ready for making a new one based on the experience so far. This one has 24" X & Y screws and I will stay with that size for the new one. The primary factor for speed I'm finding is lower mass, so I'm thinking an overhead gantry type machine, with 1-2 heads on each side. Heads to be pneumatic preferably for both weight, speed and built in 'give' via compression.

For rotation, I think it's actually just easier to automatically rotate the PCB's base rather than each head, particularly as my Excel GCode generator groups sets of pick place operations per each rotation already. Automatic component feeding is always in the back of mind but thus far is not necessary.

But, what I'm really interested in is fast / light mechanisms for centering components, mounted on each head...

[hixo]

hello.. just wondering, how do you compute for the correct nozzle type for a specific product? is there a standard computation for the nozzle inner hole?
hope someone could answer..

[Robin Hewitt]

Tricky... :naughty:

I don't think you can do it simply as area * vacuum differential > mass of the component.

If you look at the tip it is cut to leak air. Bernoulli tells us that when you force air through an orifice it will try to close that orifice. Perhaps leaky is extra sticky.

[hixo]

so how do you generally select the type of picker that must be use?

[Jonathan]

so how do you generally select the type of picker that must be use?

Pick one :whistling:

[Robin Hewitt]

Aim for the largest that you can reliably pick the part with, allow for the worst case resolution on your tape feeder as well as the nozzle placement.

If physically aligning the part on the nozzle you may need to snatch it back when the tapper opens so a good flow rate helps.

OTOH, if you don't have an autochanger you may decide to compromise on a single tool that picks your entire selection of discretes.

Suck it and see

[matt-b2]

Hi Robin,

I too am working on a DIY SMT pick and place machine and I've found your work very inspiring.

Can I ask, where did you source the small linear slide for the Z-axis, the leadscrews and anti-backlash nuts from? Also, what shape Z-axis cam are you using?

Thanks,
Matt.

[Jonathan]

Have you made any progress with this?

[Robin Hewitt]

Have you made any progress with this?

Some. I got the tape feeder down to 4 moving parts per tape which is OTT. I want one moving part per tape with all the complicated levers mounted on the head so I only have to make them once.