Knas wrote:The current design wouldn't work with plasma cutting unless one of the cogs would be cut as two different parts and sandwiched together
I don't understand why plasma cutting would not work - but I guess I might once I look at the drawings. Will figure out a way I suppose.
Knas wrote:[...] you just need to unscrew one thing and lift both the feeder and reel out and replace it with whatever
I get it. Still, I would like to just keep the reel with the feeder. If they are reasonably cheap to make, I'd rather keep a bunch of feeders than a bunch of reels in my stocks.
But I agree, it is more a matter of convenience and not super pressing issue.
Knas wrote:Any ideas on how to make a good tensions roller very welcome, this is driving me nuts!
I am with Juha on this one, I also think it there needs to be one roller per feeder. Maybe for a quick fix attach a fishing weight to the end of the cover tape and let gravity do the work.
In the long run, I think there are two possible approaches:
1) A spool that rolls up the cover tape; has to emptied every now and then
2) A set of rubber wheels or metal gears with "shallow teeth" (sorry, as English is not my native language I am having trouble to translate this; hope you get what I mean) similar to your butchered laminator but per feeder; spent cover tape is just routed outside the feeder so it is more or less endless drive
For 2 I am thinking "lego wheels" or more professional metal gears with a spring mechanism to push them onto the cover tape. For 1 anything is possible; either 3D printing or milling spools, or finding some ready made spool which just fits.
Both mechanisms need to be driven somehow. Again, two options:
a) Mechanically
b) Electrically with a motor
For a) I think the spool or wheels should use a spring loaded mechanism. Thinking of a clock spring attached to the rotary axis, which keeps tension on the cover tape, even when nothing is moving. By adding some additional gears to your existing mechanism, the spring could be tensioned again allowing endless operation.
When going for b) you either need control electronics to only advance tape in the right moment and by the right amount (dificult) or go for a clutch that allows to keep a preset torque. One idea I had was to use mechanical clutches, basically two discs with some rare earth magnets fittet into them (easy to 3D print or mill). While mated, they nicely transport the rotation. And depending on the magnetic force, they slip - with virtually no wear and tear.
Knas wrote:On another note, once i've verified that these work properly i will probably develop a electrified version that feeds automatically.
If you plan to do this, consider the approach that Brian took - he added a special head to actuate his mechanical feeders. The head only needs to move linearly along one axis (parallel to feeders). He also first tried solenoids (too weak), then a stepper + lead screw (too slow) and then ended up with a pneumatic cylinder and an extra solenoid. Compressed air was available on his machine anyways.
See it in action here:
https://www.youtube.com/watch?v=QdCzUlh ... Q&index=45
And find the writeup here:
http://www.briandorey.com/post/DIY-Pick ... ete.aspx#5
By the way, have you seen the discussion with William regarding feeders on OpenPNP group?
https://groups.google.com/forum/#!topic ... QUzQ3I7aRc
Do you feel like chiming in?
