[time-nuts] pick and place problems/design (was: OT stuffing boards)

[Bob Camp]

Hi


> On Jun 25, 2016, at 12:56 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
> 
> At home I have a parts bin and I find I need to stock about two dozen
> resister values.

Ok, chip resistors run about ten for a penny. Buy 1,000 of each for a buck a value. 
So far you have spent $24 and maybe tossed 10 resistors on each batch to come 
up with a good leader. Put the 10 pieces in a tray and use them for rework.

>  I can buy a pack of 1,200 resistors for about $12 and
> there are all 24 values in the package.

With the chips you now have 20X as many resistors for 2X the cost.

>  If I had to spend $20 per value
> I'd have to spend $480 and some how find space to store 24 reels.

If you spend $20 per value, you have 20,000 resistors per value.

>    Yes,
> one project is not going to need all 24 values but over time they all get
> used.

The same might be true of 20,000 but it might not be in a couple of lifetimes :)

> 
> The problem is worse with ICs.   I'm likely to only need one of a certain
> part ever.

Run them from a tray unless they are a common part

>  Yes there are some common parts like an op amp but mostly each
> project is unique.   So it seem silly to program a machine to pick on one
> single part and place it on one PCB.

Unless the machine already knows where the tray is and you simply tell it “tray 3 or Reel 6”.

>  I can do that quicker with tweezers.

Try a vacuum pickup … lots easier.

> For the machine to be use any use to me it needs to be "zero setup time”.

Well, your manual place process is not zero setup time so it is not clear that this is a 
reasonable goal. 

> 
> I think the ideal hobby sized machine is one that does not need parts on
> tape or reels.

Again, not a reasonable goal since there is no practical way to do that. 

Bob

>  It would be much slower per PCB stuffed but much faster to
> get the first PCB finished.  That is pretty much why I do hand work.
> 
> 
> 
> On Fri, Jun 24, 2016 at 11:27 PM, Hal Murray <hmurray at megapathdsl.net>
> wrote:
> 
>>> Also how many hobbyists are going to have reels of parts?
>> 
>> Reels of small resistors or caps are ballpark of $20.  I'd be happy to buy
>> one for any part that is likely to get use multiple times on a board and
>> again on the next board.
>> 
>> 
>> 
>> --
>> These are my opinions.  I hate spam.
>> 
>> 
>> 
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> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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