Base and strip holder

[gasmeter]

Hi

Looking forward to starting the build of my kit soon , its due for delivery today.

I am looking at having a 8 - 10mm thick aluminium base .
I assume that this would solve any rigidity issues.
Can you anticipate any issues with the vision system because of the shiny base ?

For others info I anticipate it to cost <200 euros with a laser cut camera hole.

I am also considering making some two part lasered bases for holding tape strips of components.
This would consist of a long rectangular plate either with a lasered top piece to hold/ align the tapes and supply any free component slots to accurately place free components.
This would then drop into a couple of tapped holes in the pick and place base.
The same thing could be achieved from a block with a milling machine but laser cutting is so inexpensive it hardly seems worth the effort.

I assume though there may be an issue with black / white tapes vs the colour of the metal ?

The idea is I could make up one (lets call it a component pod) per board.
I will share the drawings / pics / prices with the forum if it works out.

Peter

[JuKu]

> Can you anticipate any issues with the vision system because of the shiny base ?
> I assume though there may be an issue with black / white tapes vs the colour of the metal ?

Yes, I can see potential issues with the shine and colour, but nothing that a strip of tape or paint could solve.

The vision system is looking at the tape holes, and needs reasonable contrast. I would imagine that light gray paint/tape would work. (The color of the esd mat you can see in my pictures is too dark for black tape.) if you can live with a limitation that some slots are for black tapes and some for white, this becomes trivial.

Fyi, I'm re-arranging my table setup. I took away the mats and redesigned some rulers, so that there is white or black stripe that goes under the holes area. It's just neater that way. I'l make a post about that one of these days. It does restrict some slots for only black tapes and some for only white, but I can live with that.

[mrandt]

Hi Peter,

I chose a 22mm MDF (wood-based substrate) panel for my table - the material is commonly used to make furniture and should be available cut to size from many hardware stores at very resonable prices.

To achieve the necessary rigidity, I have built a very solid base from 45x45mm alu extrusion profiles.

Top frame has an additional extrusion in the middle for support.

liteplacer_table_01.jpg (17.09 KiB) Viewed 6757 times

All connections were made with through hole with rigid M10 self tapping extrusion screws.

liteplacer_table_02.jpg (18.5 KiB) Viewed 6757 times

This is actually the under construction for a different table - smaller and does not have the middle beam in the top frame. But idea is the same.

liteplacer_table_03 .jpg (14.49 KiB) Viewed 6757 times

With 22mm MDF plate mounted.

liteplacer_table_04.jpg (12.71 KiB) Viewed 6757 times

Machine to date :-)

liteplacer_mrandt.jpg (29.74 KiB) Viewed 6757 times

IMHO wood or wood like material is much easier to handle, especially as I tend to change around and improve my machine and table setup. Also, it can be replaced for cheap if necessary. Let's say, you wanted to move your camera and the threaded holes to fix your strip feeders or add automatic feeders and had to add additional cutouts - easily done with MDF and a jig saw and power drill. But 8mm metal? Not so easy.

Just my two cents

I am also looking into building strip holders. I like the design by Felix of LowPowerLabs:
http://lowpowerlab.com/blog/2014/07/23/ ... ick-place/

Sicne I do not have a laser cutter myself, I will probably try 3D printed trays first and see how that turns out. I will let you (and others) know and would appreciate if you could share your experience regarding the strip holders.

Best regards
Malte

[gasmeter]

Thanks guys

Thats really useful advice.
I do have some of the construction frame so I think as the example shown looks so neat I will change to that and MDF.

As for the feeder strips , that looks great I will get some made.

FYI I have found several places in the uk that will laser cut for less than I can normally buy the material so don't be put off.

They will laser cut almost any material and one off's, usually the postage is the biggest cost.

I am sure its the same in the rest of europe.

Thanks for all the great advice links and pics.
My kit arrived, well packed

Looking at starting assembly tomorrow.

Peter

[RinusDamen]

I realy do like this lasercut strip idea, but before i power up my lasercutter: Its not completely clear to me how these lasercut feeder strip will handle:
1. Removing te protection tape? Before or after sliding the component strip into the holder? If the tape needs to be removed before sliding into the holder your components will for sure flip out of the tape.
2. How are different component hights handeled?
3. Can the liteplacer downlooking camera look through the clear acrylic to measure the tape holes?

Are the lasercut files somewhere (free) to download? Are all material specifications clear?

[mrandt]

Hi Rinus,

I have neither built nor used this strip "feeder", should probably call it "strip tray" or "component pod" as Peter suggested - I just found it on Felix's site a while ago and liked the idea.

I think your remarks are spot on - here are my thoughts:

> 1. Removing te protection tape? Before or after sliding the component strip into the holder? If the tape needs to be removed before sliding into the holder your components will for sure flip out of the tape.

On most SMD component strips I have in stock, the cover tape's width is smaller than the strip itself (e.g. 8mm strip has ~5mm tape). The guide holes cannot be covered anyways and usually there is also a small gap on the opposite side. If the cutouts in the top plate are wide enough, you could probably peel off the tape after you have inserted the strips.

> 2. How are different component hights handeled?

Felix mentioned on his website that he made the slots high enough to fit the tallest components he uses and - if needed - he would just put some cardboard / plastic / used strips underneath the strips if they are too lose. While I think this is not perfect, it probably works fine.

I guess the alternative is to make different strip trays for different heights. As you will also need different widths, we could come up with some sort of modular design where many smaller trays are combined for one assembly. If you want to use computer vision to detect the holes, you might also need different colors for the base material...

> 3. Can the liteplacer downlooking camera look through the clear acrylic to measure the tape holes?

Without having tried, I would guess not. There will likely be reflections on the clear acrylic which will disturb circle detection. Again, one could make the cutouts in the top large enough to not obstruct the camera's view to the holes.

On the other hand, I believe we might not even need computer vision when using such a component tray. We could use a simple pin to fix the strip in the slot. Then, assuming the tray (or combinations of trays) is somehow mounted to the table in a known position and orientation, we would just teach the machine the location of the first component and the relative distance to the next. Most commercial machines work this way, so it is probably accurate enough. Not having to use camera and image processing per component would greatly speed up things, too.

Another option could be to put fiducial marks on both ends of the component tray and enhance the software to calculate position and orientation of the component strips - this way we could automatically compensate for misalignment along both axis.

Thinking further, we could even attach a QR code to the individual component trays so the machine could automatically figure out which component is where...

Sorry, my mind is running wild now

What do you think?

[mrandt]

I modeled and 3D-printed the following tray tonight. It fits standard 8mm strips with height 1mm - so most passives such as resistors, capacitors, etc.

I have cut out the hole locations from the top plate so that the downlooking camera can see the holes, thus I can use the LitePlacer software without modification.

Tape can be peeled off after inserting the strip.

So far it works nicely

CAD drawing of Malte's test component tray

mrandt_8mm_component_tray_drw.jpg (37.47 KiB) Viewed 6715 times

Photo of 3D printed component tray

mrandt_8mm_component_tray.jpg (58.37 KiB) Viewed 6715 times