LitePlacer.com forums

Erm I now have much to think about.

PCB height, Needle height, are all known. never change for me all that can be worked out using the top sensor.

Problem is I guess component height. I dont change jobs much so I could measure everything manually till all the feeders work.

But anyways. Did you see anyone successfully use a pressure sensor to detect if a component is picked.

Negative pressure (vacuum) sensor for pickup detection: Reza built something by soldering extra pins to TinyG, connecting an analogue sensor and hacking firmware + software.

See here:
http://liteplacer.com/phpBB/viewtopic.p ... ssure#p492

I am thinking about adding some similar sensor to my machine as well, but will probably go with another USB / Serial line and small microcontroller instead of changing TinyG.

Would also require software changes in LitePlacer, of course.

I could bodge a sensor like Reza used into a opamp comparator and replace the switch. probably will be less hassle than sending digital values to the PC.

The only issue I think though is that. this will not release in the same way as the normal liteplacer. Because it will always be active when carrying the component. Maybe in non homing routine this switch is used for collision detection and stops the machine as in MACH3 milling machines. I am sorry please know I have not got TinyG yet so I dont really understand all of the software.

I like the look of this ebay pressure switch product. Although maybe I will look for a better more trusted brand.

http://www.ebay.co.uk/itm/Air-Negative- ... 0866399193

Reza did not replace the switch. He used one of the ADCs on the ATMel MC built onto TinyG to get a linear pressure reading from the sensor.

His use case was to detect when parts were not picked up correctly or got lost while travelling - not to detect that a part was hit.

P&P procedure is as follows (just looking at vacuum):

1) turn on pump
2) lower needle onto part
3) operate solenoid to pickup part (needle vacuum is only enabled now)
4) check pressure to make sure part was picked up
5) keep checking while head is moving
6) place part
7) release vacuum

I think I will implement the belt and 2 heads. mainly to counter balance the motor and not feel like so much of a bodge, Check the link I am showing (You need to zoom in close to see the counterbalanced heads). I think you can wire steppers in Parallel also and with Nema 8 lower current motors Tiny G will be fine, so both component rotations could be on the same driver and then controlled by the same Z motor who drives both on the belt. I wont implement 2 heads to make it faster, but more so I can install a Nozzle for 0805 and another for SOIC for when the software is able.

This will mean my heads only have around 25mm maximum clearance with my E3 2" (ruffly 50mm) rails, I think that could be OK because the taller capacitors are around 10.5mm max.

http://www.aliexpress.com/item/TM300A-D ... 96249.html

I reed the Vacuum as a switch will be slow, maybe to slow for calibration of height. I think for me I will just measure each component height and write them all down in my logbook and enter manually. Any crashing should be light, I will put the Juki Nozzles and also the up spring to control the pickers up weight if required.

Also I will put a roller on top of the GT2 Gear, this should mean the belt can never jump out the groove.

I will update drawing soon and upload.