[time-nuts] OT stuffing boards: was GPS interface/prototyping board
kb8tq at n1k.org
Fri Jun 24 16:33:38 EDT 2016
A “low cost” auto pick and place does have some things in common with a 3D printer:
Drive is by stepper motors
Micro stepping stepper motor drivers are used
Belt drive is pretty common
Tube support and circular ball bearings are generally used
You have X, Y and Z drive
Very custom software to drive them that may or may not be open source
A setup and calibration process that may not be a lot of fun
A requirement to do some trial runs before you do anything important
There are generally a few things different between my 3D printer and a simple pick and place:
The drive is on both sides of the X / Y region
The X/Y is *much* larger than the Z
There is a Z rotation (4th axis) on the pick and place.
My 3D printer has one head, two heads is about as low as they go on pick and place
The parts feeders are a big part of the pick and place machine and there are a lot of them (even on a simple one).
The base plate is a lot heavier duty (more rigid)
Vacuum to do the parts pickup
Pressure to blow off a stuck nozzle
Some means to detect that a part has been picked up
Interchangeable pick heads (the head size needs to match the part size to some degree)
A “small” (“desktop”) pick and place is a meter square. Most 3D printers are much smaller.
— As you move up, the pick and place *might* have —
A camera to check parts on the placement head to properly align them (“up camera”)
A camera to check the board and align to it (“down camera”)
Four or more placement heads.
Enough variety in feeder widths to match the size of the reels you have :)
No matter what you do for a pick and place, you will need:
Some way to mount the board on the machine
Mounting holes (or whatever) on the board to match up with the machine
A design allowance that keeps parts out of the area contacted by the mounting setup
Fiducial marks to line things up that are of a type the machine can work with
There are lots of details….The 3D printer takes cad files and generates motion information.
The pick and place take the output of a PCB layout program and generates motion information.
It goes on and on ...
> On Jun 24, 2016, at 2:59 PM, Graham / KE9H <ke9h.graham at gmail.com> wrote:
> Don Latham said
> to Discussion
> I do not see why a small pick and place assist system could not be built on
> a 3-d printer.
> Lots of problems to be solved...
> How do you take loose parts or cut tape or tape reels and get the right
> part out, and into the chuck, oriented in the right direction?
> How many different kinds of parts, sizes, shapes, pin counts, IC
> footprints, can you handle at once?
> How do you know it is the correct part?
> How do you know where the "+" end, or "pin 1" is?
> How do you know that there actually is a part in the chuck?
> How do you know the part in the chuck is oriented the way you expected it?
> How do you know where the footprint on the circuit board is located? (to a
> few thousandths.)
> How do you know the part left the chuck and ended up where you intended it
> to be?
> Commercial systems have answers to all of these questions. In many cases
> involving intelligent vision systems.
> Once they are all answered, then you have a PCB unique set-up / programming
> effort to instruct the placement machine all about today's specific board
> and parts list to be assembled.
> I can usually build one or two boards by hand about as fast as an engineer
> can do the placement machine specific PCB programming and verification.
> --- Graham
> On Fri, Jun 24, 2016 at 11:52 AM, Don Latham <djl at montana.com> wrote:
>> I do not see why a small pick and place assist system could not be built
>> on a 3-d printer.
>>> On Jun 24, 2016, at 8:32 AM, Attila Kinali <attila at kinali.ch> wrote:
>>> On Thu, 23 Jun 2016 20:16:34 -0500
>>> Oz-in-DFW <lists at ozindfw.net> wrote:
>>>> 1. Pick and place machines use a lot of floor space (even for the
>>>> "small" ones are more than 1/2 a bench.)
>>>> 2. Even the best ones require pretty continuous tuning. If you aren't
>>>> using them continuously each new run is a new and different
>>>> experience. Often unpleasant for the first few scrapped boards.
>>> The trick is to use semi-manual pick&place machines for low volumes.
>>> Ie machines that you do not program, but guide by hand. This allows
>>> faster and more accurate placing of components than would be possible
>>> with a pure manual process, but does not have any of the complexity
>>> of the fully automated solutions. The components do not need to be
>>> 100% exactly centered, as the surface tension of the molten solder will
>>> pull the parts into place (which is also the reason why the copper inside
>>> the solder resist mask should be symmetric).
>>> These machines are still all pretty expensive (IMHO, the cheapest
>>> start from around 2kusd IIRC), but with the continuous growth of the
>>> market, and that market becomming more and more professional/proficient,
>>> the production volumes of these machines will for sure rise and thus
>>> cheaper. I am pretty sure that we will see hobbyist marketed pick&place
>>> build upon open source based control systems in the next couple of years.
>>> There are already a couple of DIY systems out there, that look quite
>>>> Solder stencils make **all** the difference.
>>> Oh, yes! Please, do not try syringe dispensers! These fail more often
>>> they work. Also pay the additional couple of bucks to get a steel stencil
>>> instead of a kapton one. Especially if you make more than one or two
>>> or those with fine pitch.
>>> Attila Kinali
>>> It is upon moral qualities that a society is ultimately founded. All
>>> the prosperity and technological sophistication in the world is of no
>>> use without that foundation.
>>> -- Miss Matheson, The Diamond Age, Neil Stephenson
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>> Felix qui potuit rerum cognoscere causas.
>> Lucky is he who has been able to understand the causes of things.
>> "Noli sinere nothos te opprimere"
>> Dr. Don Latham, AJ7LL
>> Six Mile Systems LLC, 17850 Six Mile Road
>> Huson, MT, 59846
>> mailing address: POBox 404
>> Frenchtown MT 59834-0404
>> VOX 406-626-4304
>> CEL 406-241-5093
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