Close
0%
0%

Thrifty Pick and Place

Building a Pick and Place machine on the cheap, in a repeatable way.

Public Chat
Similar projects worth following
My SMD boards for my Tindie store are so simple and low volume that tweezering components for a day can stock the store for months. However I only did that in the first place to learn the process, so why not build a PNP machine anyway? As I can't justify it for itself (yet), it needs to be low cost. That doesn't mean crappy. High volume low-cost products repurposed are probably a better option that random one-off hacks.

Here's my initial thoughts.

Start with a low cost gantry type X-Y system - specifically the EleksMaker® EleksLaser-A3 Pro These are often on sale at Banggood, and are a complete laser engraver system, so it justifies itself for that, and can switch between engraver and PNP.

Features/wants:

1) OpenPNP compatible
2) X,Y,Z and C axes
2) Single head, with autochange nozzles
3) top and bottom cameras
4) 0603 placement (low bar)

I'll break out specific component details into build instructions and project logs. This sections will cover the current status and overall design.

For now, as I haven't built anything yet, it's a ramble.

I've learned not to over-think things when ordering hardware from China so my initial purchases did not have a lot of prior research.

The base system is the EleksMaker® EleksLaser-A3 Pro 2500mW Laser Engraving Machine currently on sale at banggood.com for $190. There is a version without the laser for $40 less, and the laser itself is $120. Seeing this bargain price triggered me to finally actually do this. Getting it with the laser means that if I don't get the PNP working (or useful) I still have a laser engraver to play with.

As this only comes with a 2-axis controller I also ordered the Geekcreit® CNC Shield UNO R3 Board 4xA4988 Driver Kit for $12. This is an Arduino R3 clone (probably not with the Atmega64u serial) and what appears to be a clone of the Protoneer 3.00 shield. This electronics is probably a stop gap.

  • Elekslaser A3 Pro Arrives

    Alastair Youngan hour ago 0 comments

    The framework for the project finally turned up in the mail, trade war notwithstanding. I'm not going to do a full unboxing/review on this as there are dozens already on the web. However I will make some comments based on my unit and how it differs or confirms some of the commonly listed issues.

    • Overall component quality and packaging quality is high.
    • No component list or instructions included. Most reviewers at least received a parts list, I did not.
    • The parts list on the banggood web appears to be for an older unit.
    • corner brackets appear sturdier than earlier models. Simple thick acrylic - lots of surface area. Overall rigidity is pretty good.
    • While all screws are long enough, some are only just enough. Especially the motor screws. I think they should be 12 mm and are only 9mm - only about 2 threads into the motor.
    • Screw heads on the M3 are really too small for the bigger than M3 holes in the acrylic. Rick of crackage there if over-tightened.
    • The holes in the motor mounts are oversize for the locating circle on the motor face, so location is set by the 3mm screws with their tiny heads, loose fitting holes and minimal threads. This will come loose, I'm sure.
    • No problems with the laser mount thumb screws - long enough.
    • Instructions on the wiki match my unit (apart from fictitious M3 screw lengths)
    • Includes cable management for the Y cables - feeds them through the slots.
    • Extra screws and spacers included. I really hate it when kit makers include the exact amount and then I drop one under a skirting board. (You know who you are IKEA!)
    • Plugged it in and it fired right up, responding to basic G code commands. The laser zaps. I only ran it for a second and it made stinky right away. Hood and air extraction will be needed for laser mode. Need that for the SMD toaster anyway....
    • Claims to be running grbl 0.9i
    • The belt tensioning setup is just as badly designed as expected.

    Too dark to take pictures.

  • Cameras Arrive

    Alastair Young09/15/2018 at 06:42 0 comments

    The cameras arrived today - the only parts that are not coming from China. They are, however, made in China. These 5mm "endoscopes" come with a fairly short USB micro A connector and an adapter to convert to standard USB A. This allows them to plug to many phones as well as PCs.

    On the windows laptop they both seemed to work but did not have good focus under 40mm (as advertised) with one of them being a bit less good than the other. At 40mm 0603 components are really small - and resolution is only 640x480.

    I had read that disposable cameras have usable lenses for this kind of stuff and a quick rummage turned up an unused Fuki Quiksnap with an expiry date of 2009. The battery had leaked inside it but it rendered 3 lenses, to of which - the main lens and the rear viewfinder lens - improved the eyesight of the cameras no-end.

    They are now mounted with Sugru moldable glue which will take a day to cure.

    They focus great at 28mm at which size 0603 are clearly defined and the biggest component I use - the SOIC-24 PCF8575 - fills the screen in landscape mode. 

    The downer is on the interface side. The two  cameras need to be plugged into opposite sides of the laptop to get different usb host. According to https://github.com/openpnp/openpnp/wiki/USB-Camera-Troubleshooting-FAQ and  https://github.com/openpnp/openpnp/wiki/OpenPnpCaptureCamera if you use OpenPnpCaptureCamera and set the camera to use a compressed format like mpeg, you can put two cameras on one host. These cameras only do YUV uncompressed video. This is a minor bummer as I was planning to combine all the USB on a multiport 3.0/2.0 hub and have only one wire to worry about.

  • Proof of Concept Quick Change Nozzle Holder

    Alastair Young09/10/2018 at 04:21 0 comments

    Ran up a very rough proof of concept for the Juki quick change nozzle holder.

    Material is phosphor bronze (from scrap bin - valve guide stock), wee magnets from the fridge and a dummy juki nozzle roughly turned from steel.

    The magnets hold and grab the "nozzle" gently but firmly, but removal force is just a few grams. Most importantly with the magnets installed the right way round, the tip is not noticeably magnetized. 

    Positioning of the magnets is critical - looke like they should be a little above the bulge in the nozzle shank. There is a strong centering force right there, so we'd want to use that to pull up and make the nozzle face pull against the face of the part. 

    Presumably when a component is being held the vaccum will strengthen the bond, but we don't want the thing to re-center and drop when vacuum is released.

    So hole depth is critical, as is magnet placement, as is nozzle seat diameter. I see some jigs and a reamer in my future.

    Thinking black Delrin for the material for the real thing.

    Credit where credit is due, this idea came from "alex" https://groups.google.com/d/msg/openpnp/IG9cEUypjtM/bqkRM8PEHwAJ

    with the lightbulb moment at:

    https://groups.google.com/d/msg/openpnp/IG9cEUypjtM/1sfj1XyzKAAJ

View all 3 project logs

  • 1
    Controllers

    The controller that comes with the Elekslaser is the EleksMaker® ManaSE (version unclear) which seems to be a an arduino nano and supports two driver modules - seems to come with two A4988. As one of these has to drive two steppers I'm thinking that may not be optimal. It also comes with it's own firmware which, if I blow it way and install GRBL, may not happily return to laser use. So I'm thinking I leave it as is and maybe come up with a way to swap in a different controller when I want to go PNP.

    The 4 driver shield on order appears to be a clone of the Protoneer V3.00 which is GRBL compatible. The fourth driver can be jumpered to clone one of the other axes or run off D11 D12. I think the obvious thing is to clone the Y axis as it is a two-motor axis. GRBL only does 3 axes on the Atmega328p, and it's unclear to me if I could use the GRBL Z for OpenPNP C. 

    I had some thoughts of using the GRBL spindle speed option to drive a servo for one of the axes (Z), until I read up and decided I really want a stepper for Z.

    So that means if I am using GRBL (i.e. the low cost option) I need another controller for the C axis. OpenPnP docs talk about sub-drivers though I am not 100% sure that you can delegate the actual axes to these or just other peripherals. I would think if any axis could be delegated it would be C.

    I haven't read up on the RAMPS controller yet, and there is a 5 driver RAMPS board with Arduino Mega2560 for $21. That seems to be a 5 independent axis system with lots of pins for controlling other stuff. Hmmm. 

  • 2
    Z axis

    There are a number of Z-axis options already designed on Thingiverse and a $50 Eleksmaker option, though the latter is specifically for the lazer mount which is (I think) bigger than the Nema 8 C stepper.

    I think we have some old CD-ROM drives around and I thought about hacking something with that - but the objective here is to be repeatable. So a stepper is the way to go, as long as the cost can be kept down. The laser comes on a quick mount, so whatever I do the head assembly - including Z and C axes and camera - should mount into that.

    Update 9/8/18

    Looking at the various available kits - $50 up - they seem awfully bulky and overengineered. We're only supporting a Nema8 stepper stepper and a nozzle - 100g? The eleklaser one only has 40mm travel and is meant for laser focussing.

    So parts in the cart from Bangood

    9MN Miniature Guide Linear Support Rail Slide Bearing Steel Ball Holder/Retainer (175mm) . This as a flat rail with ball race up each side and a sled. The whole thing is only 8mm deep. 

    8mm lead screw and nut - 2mm lead.

    8mm to 4mm coupling to connect to the Nema8 z axis stepper from robotdigg. 

    Total spend there for Z axis - $31 including shipping. If it works I have something at half the price and much more compact - (more available bed).

    The z-axis stepper will be mounted on the Y carriage with aluminum angle. The carriage will also be aluminum angle. Aluminum angle unbraced may flex? Add bracing or use heavier gauge.  

  • 3
    C axis

    Looks like the common way to go with this is a hollow shaft Nema-8 stepper. They now are available with built in nipple for an extra $1. Cool.

    So that's a no-brainer.

    Update 9/8/18. Stepper ordered.

View all 8 instructions

Enjoy this project?

Share

Discussions

Similar Projects

Does this project spark your interest?

Become a member to follow this project and never miss any updates