Looking for an economical XY (well and Z) solution that is not for the normal use

[SparkyLabs]

Thanks Doddy

So the USB controller is indeed complex and a bit specialized. That is why I originally saw the cheap 300x180 ones as they have the simple controller that you describe that I could then put my own electronics on that could be connected to a computer. I'm not really set up to build good XY tables and all of the other mechanical stuff. I work for a mechanical engineering company so have access to people that can do some milling and turning of parts for me which I can draw up in 3D CAD.

My original thought was two sheets one on top of each other with sliders and to drive them with stepper motors or linear actuators with encoders. But the motors are about £100 each before I have done anything else. So I wondered if there were any existing things out there that would have a lot of what I need.

I will still need to design a picker that yes will need to rotate. I'm thinking something along the lines of a shaft with O-rings that can swivel in a body so that the air can come in between the two seals and go down the centre, then it can be turned from above.

PnP machines typically are complicated with camera's and all which is why I don't want to go there and make this a helping hand. So I have been through a few ways of doing it.

1) manually drive it around with direction buttons like the controller on that simple engraver thing, but that will take forever and longer than by hand
2) Have a keypad and punch in the coordinates of the part to pick up and the location
3) have a program drive the machine, this does away with the interface and HMI are a project in themselves. So I learn to do some VB that will provide an interface and commands to electronics that I need to make.

I think the third option is as much as I can do before it becomes easier to buy an off the shelf system. So camera's and software to inspect the part picked up is not an option, this is where the entry level fully automated systems fall down. Part feeders are also out at these are complex, bulky and are projects in themselves. So I have done away for the need for a camera with MK1 eyeball putting me in the loop. I will design holders for the standard tapes that the passive parts come on and the IC's. The tapes will be slid into these holders on the table with the film removed. Passives are always on a 4mm pitch so once I have learnt the location of the first part the locations of the rest are known and it is for me to confirm that the picker is in the correct location above the part to be picked up. If it is not I can make corrections that my program can remember so that if say after 10 parts it has drifted when I correct for the 11th the next ten are most likely to be fine. The parts are then taken to the location of the part is to be placed in and lowered just above the board where I again confirm correct location.

Now I won't be bothering with parts taller than 3-4mm, basically just small IC's and the small passives up to 1206/1812, no large capacitors or larger chips like TO stuff that can be hand placed it's just worth making a machine capable, this is about speed not full automation, the automation is to take out time I waste not be clever. My expectation of the accuracy is that the passives are in fairly tight pockets in the tapes so their initial pickup is likely to be accurate enough and these are the parts that there are most of so the least error is on the parts I have most of. The chips tend to be more loosely packed so their pick is not guaranteed and I may have to correct the placement of each one, that is fine as it is the chips that I find don't always self align on reflow and they need to be placed more accurately than I can by hand. So I don't mind these taking a bit more time but the idea is that as I can more them with a machine more accurately than I can by hand it saves the time of trying to get the solder bridge out later or a ruined board.

The picker will have a camera so this will save the strain on my eyes. So really what I m trying to do here is add the magnification that on my eyes is tiring but as a picture on a screen would not be. I avoid bending over a bench and getting back ache and I can place parts more accurately when required than I can by hand. Obviously doing such a system does mean that I have to be careful to not misjudge how good a human is at doing certain things that it is harder to get a machine to do. It will take some time to position parts that need manual adjustments but if I can feed the machine the coordinates and it broadly gets the parts there that is faster that me looking them up by hand.

this is by no means meant to be a pick and place machine but a helping hand. I am just trying to divy the work up between me and the machine. I will do what I do best which is visually check all is well and give the OK and the machine will do what i waste time doing which is trying to get parts out of tapes and find where an the board they go.

[Clive S]

I don't know if this helps but https://www.youtube.com/channel/UC5j...yZGhhokC5j49tg

[Doddy]

this is by no means meant to be a pick and place machine but a helping hand. I am just trying to divy the work up between me and the machine. I will do what I do best which is visually check all is well and give the OK and the machine will do what i waste time doing which is trying to get parts out of tapes and find where an the board they go.

Okay, I have more questions (and more challenges) with what you say - but I think you know your own mind. An hour soldering under a stereo mic is enough for me and my back - so I appreciate your intent. Despite this, progressing this will be a project no matter what.

If I was looking to do this within the use/cost constraints you say, I'd pick up the most physically robust of the GRBL-based machines and look to adapt the firmware or integrate with the control software a joystick/joypad controller. The mechanical builds are... appropriate for your use-case (and it pains me to say that). You're not going to get fantastic placement speeds - imagine 5 seconds traverse speeds in the working area. but that gives you time to think. I've since read that the thread pitch on at least one of those machines is 5mm, so that's higher resolution (but lower speed) than I mentioned earlier.

It's a project no matter how you look at it. It's do-able, I wish you luck. Personally - mic, a pot of of tweezers, soldering pencil and frequent breaks. But I rarely go north of a 100 components on the occasional board.

[SparkyLabs]

Okay, I have more questions (and more challenges) with what you say - but I think you know your own mind. An hour soldering under a stereo mic is enough for me and my back - so I appreciate your intent. Despite this, progressing this will be a project no matter what.

If I was looking to do this within the use/cost constraints you say, I'd pick up the most physically robust of the GRBL-based machines and look to adapt the firmware or integrate with the control software a joystick/joypad controller. The mechanical builds are... appropriate for your use-case (and it pains me to say that). You're not going to get fantastic placement speeds - imagine 5 seconds traverse speeds in the working area. but that gives you time to think. I've since read that the thread pitch on at least one of those machines is 5mm, so that's higher resolution (but lower speed) than I mentioned earlier.

It's a project no matter how you look at it. It's do-able, I wish you luck. Personally - mic, a pot of of tweezers, soldering pencil and frequent breaks. But I rarely go north of a 100 components on the occasional board.

Yes this will be quite the project as it is which is why I am being careful about not trying to design anything I can already buy and to avoid features that are too complex for what the intent is and just keep reminding my self that this is to be a relatively simple aid not full automation.

At the moment it's taking over a minute per passive, some of that I can reduce with a hand held sucker tool if it works as a lot of time is spent trying to get parts up the right way having tipped them out of their tight tape pocket. So a 5s movement time is fine really. The few 300x180mm machines that state an accuracy say 80-100µm which is not bad and the controllers seem easy to work with. I spend several seconds as it is entering the part designator into the PCB software to locate where the part goes so in less than that time a machine can just go to the location and in less time than I spend carefully rotating the PCB around and "getting into position" the Z axis can lower and await my confirmation after any minor adjustment. At the moment to deal with rotation I rotate the entire board as I have to go in from the side that the location is closest to and be very careful about not knocking anything else. My last board was 175x90mm so most parts had to go in from two sides rather that all 4.

The PCB design software will output a part position file. I use KiCad so I can add my own fields to parts (and I am sure other programs do it too) as I create them which I am doing a lot of at the moment. So I can put into the bill of materials columns for things like the height of the part in the tape and on the PCB so that the Z axis knows how far to travel and stop at pickup before confirmation and on confirmation. I can put in the pitch of the tape. So if I load the BOM and position file into a program I will have all of the information it needs about the part to pick up and where to get more after the location of the first is known and where on the board to move to.

So yes if I use one of those off the shelf systems I can then concentrate on the picker head and software as the one thing I am not equipped to do is start making CNC beds. I can do a controller that over a serial to USB adapter will talk to a PC so that apart from the 3 axis's that the basic bed comes with I can also issue from the same USB port commands to control the rotation stepper motor, pump, pump solenoid and anything else I need. The only other USB port I will need is for the camera that I will have to look into and should be available off the shelf that sits on the picker mechanism to give me a nice big picture on screen of what my picker is doing. I think that is as simple and functional as I can make it without trying to do the impossible.

For example rather than relocate to an origin on each operation if I have to manually correct I can decide to tell it that it made a permanent positioning error and to use the corrected location as the new true location so all of the position offsets can be recalculated on the fly if it drifts.