Robin's smt Pick and Place build

[matt-b2]

Good luck with your machine.

Thanks. Interesting idea re. the tape feeders. I've not put a great deal of thought into feeders yet as I'll probably add them after the rest of the machine is built. So far my very embryonic plan is to actuate each feeder individually with its own low cost DC motor and worm gear drive winding the cover tape over a roller to separate it from the main tape and onto a spool. I'll use some sort of hairpin switch to index the tape via its sprocket holes. I am, of course, hoping that most tapes will cope with being pulled forward via their cover tapes rather than their sprocket holes even though this is not how things are intended to be done.

Matt.

[Jonathan]

Have you made any progress with this?

[Robin Hewitt]

Have you made any progress with this?

Some. I got the tape feeder down to 4 moving parts per tape which is OTT. I want one moving part per tape with all the complicated levers mounted on the head so I only have to make them once.

[Robin Hewitt]

I've got a bit stuck working out the tape feeders, here's a whacky idea...

Remember that famous drill that cuts a square hole? I think I can use that idea to convert rotary to rectilinear motion. A conversion that can get complicated PDQ when you try to draw the mechanism.

The problem is advancing taped components. I want to drop a pin vertically into an index hole, move it forwards exactly 4mm then lift it vertically clear.

With one pin for all tapes, I can have lots of tapes because they can be closer together. The pin feeder mechanism moving with the gantry.

So, using the square drill idea, the plate holding the pin has 2 square holes in it. The holes fit over two oddly shaped shafts turning 2mm off centre. One rotation advances the tape 4mm.
Picture shows 18 degrees in 30 degree steps

[Robin Hewitt]

... shafts turning 2mm off centre...

Okay so I didn't quite understand the mysteries of the Reuleaux triangle but I do now.

My rounded out Reuleaux. without the pointy bits. looks okay but the centre doesn't move in any approximation of a circle

The centre of a true Reuleaux, constrained in a square, follows a sort of circle defined by the ends of 4 elipses. Mine looks like a finger painted flower

I can get true vertical/ horizontal motion if I fix the square and float everything else.

I have ordered gear wheels and lumps of brass, so I have until that arrives to simplify it.

[Colin Barron]

Hi,
are you still working on the project?
regards
Colin

[GEOFFREY]

My CAD drawings are there to make sure everything fits together and can be assembled. The perspective is reminiscent of ancient Egypt, I keep most of it in my head if I'm doing the machining :naughty:

My CNC package works exclusively with AutoCAD DXF files so I extract shapes as and when I want to cut them. There is no 3D pic of the whole thing.

Suppose I should show that there really is some kind of plan though...

That looks pretty impressive for "some kind of plan. G.

[Robin Hewitt]

are you still working on the project?

I have 2 problems.

I have to switch PCB supplier and I cannot decide who.

I bought a 3D printer and I have a notion that it will make the component feeders simple if only I can figure it out.

[Stupoty]

I have 2 problems.

I have to switch PCB supplier and I cannot decide who.

I bought a 3D printer and I have a notion that it will make the component feeders simple if only I can figure it out.

If your still working away on this as a back burner thing this may give some inspiration :)
http://www.eevblog.com/2014/11/19/ee...-factory-tour/

Stuart