Improvements of our DIY pick and place machine


Dear community,

As mentioned in the blogpost SMD Best├╝ckungsmaschine (in german only), we built a DIY pick and place machine with BAM&DICE.

Because it worked very reliable, we made an effort to enhance the positioning accuracy and the diversity of components.
The result is presentable:

pnp-machine-neu web

The rotation axis of the first version has been rebuilt completely. We replaced it with a NEMA8 motor with a hollow axis.
It is mounted on a new installed vertical axis which can be moved up and down with a second motor.

neue-spitzen-halterung web

This way it is no longer necessary to move the whole Z-axis, which vastly improves the over all speed.
The hollow shaft is equipped with a cut 1ml syringe with cannula. For increased grip we slipped a rubber tip over the cannula.
The silicon tube of the first version was not leak-proof enough.

neue-spitze web

As you can see on the picture the whole construction is not perfectly straight so that the tip varies its position when turning, but this can be easily compensated in the software.

The next step was the replacement of the trays with real dispensers, so called feeders.
With huge components the trays are quite usable, but small components tend to bounce when collecting them.
So it happens that while collecting one component the 3 next to it bounce out of the tray.
These usually do not sit next to the tray but somethere on it, so that when collecting the next component not only does nothing stick to the tip but also the tray is shifted, because the tip collided with it.
That the tip is also bent by this is nothing I have to mention separately...

All things considered: suboptimal

The first idea was to buy used, professional feeders and integrate them somewhere in the machine. The problem was that these professional feeders are huge:

professioneller-feeder web

As comparison I inserted a typical spool of SMD-components.
The feeder is quite a clever solution considering the mechanical transport ot the components, but the crank for it is very stiff.
The mechanical construction to move this crank would be just too big - we don't have that much space in our DIY machine.
On the other hand such a feeder costs several hundred euros - a bit exaggerated when the feeders are more expensive than the whole rest of the machine.   

So we looked for alternatives and found a very simple system:

new-feeder1 web

In this system the components are also presented separately.
The feeding works by pulling off the cover tape which is wrapped around the motor shaft.
An optical sensor in the middle of the feeder tracks the tape of components at the side of the holes and always releases only one component.
As one can see in the picture this feeder is by far smaller than the professional one and so can be integrated into the machine much easier.

This system has some small disadvantages:
The wrapped cover tape has to be changed every 1000-2000 components.
You need one stepper motor and one sensor for each feeder.
The component tapes have to be respooled because the optical sensor is on the wrong side of the tape.

new feeder2 web

The only difference of the feeders among themselves is the size of the component slot.
This slot shoud fit the size of the component tape very well.
To not 3D print the whole feeder for each test, we only 3D printed the front part and adjusted the slot size until it fitted.

feeder-test web

After the adjustment to the different component tape sizes the complete feeders have been 3d printed.

The controlling works still with BAM&DICE.
Since we use 4 of 5 stepper motor drivers for the axes, we had to connect a second BAM&DICE for controlling the 4 feeders.

The feeder controller monitors some digital inputs which are connected with outputs of the first BAM&DICE.
With these I/Os the movement of the feeders can be requested.
As soon as one of the I/Os turns high, the feeder controller turns the corresponding stepper motor until it gets a high-low state change of its optical sensor.

The software, openPNP could be adjusted to the new feeders with some small modifications.

After installing all 4 feeders we made a small video to show the outstanding performance of our DIY machine:

If you are interested in the feeders, the pick and place tip or the electronics or rather the interaction of all parts, you are invited to write an This email address is being protected from spambots. You need JavaScript enabled to view it. to us.
We share the 3D models and send a download link to our version of the openPNP software.

The next adjustment is the further improvement of the feeders:
The separation of the feeding part and the part in which the components are released.
On the one hand one has more space around the motor shaft so it will be no longer necessary to change the cover tape every 2000 components. On the other hand the whole part should be designed in a way that one can use the SMD spools without respooling them.

Greetings from the lake constance

The 2PrintBeta - Team

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