Monday, January 28, 2013

SMD Manual Part Picker

I’ve been working on designing a PCB using all 0603 SMD parts.  Prior to this, the smallest SMD parts I’ve attempted were 0804.  I ordered the PCBs and I’ve been trying to alleviate my concerns about not being able to actually work with these tiny parts once they arrive.  They are almost too small to deal with using tweezers, so I’ve been shopping around for an inexpensive vacuum part picker.  However, I’ve discovered that there are really expensive ones and there are really cheap ones with not much in between.  I can’t justify a really expensive one ($1000+) and the cheap ones have terrible reviews. 

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So, I’ve been thinking like any maker would…why not make my own?  I started by studying this version based on reversing an aquarium air pump to create suction.  It has most of what I wanted except that when I went to order the tips I quickly became overwhelmed and it seemed that this would-be cheap project was quickly going to get very expensive.  Well, as luck would have it a day after I’d about given up on the project Hack-A-Day featured this one that caught my eye because of one very small feature.  He used a soccer ball inflator needle for the tip.  I thought that would solve my expensive tip dilemma problem perfectly.

There was one thing I didn’t like about any of these other builds.  They all used various ink pens or syringes for the handle and the assembly seemed overly complicated and frankly not very pretty.  I had a better idea that anyone with access to a drill press for a few minutes could build and end up with a really nice end-product.  Of course, in perfect Software & Sawdust fashion, it had to be made out of wood!

I had most of what was needed in the shop except the aquarium pump & hose.  So, off to the pet store I went and picked up a Tetra Whisper 10 and some black silicone hose because it’s much more flexible and less likely to kink than the vinyl hose.  You can get all the parts off amazon.com for about $10.  The other tutorials had recommended using a pump with two diaphragms but I suspected this was overkill for the parts I was interested in working with and I was correct.  So, I spent less than half what the larger pumps would cost and it also occupies less space on my already over cluttered desk.  Win, win!

imageWhen I was at the pet store picking out a pump, there were a couple very similar options but I ended up breaking the tie with the Whisper 10 because it had a nicer appearance and I thought it would look a little more interesting sitting on my desk.  It actually turned out that this was an excellent choice.  Because of the way the diaphragm is designed in the Whisper models, it only took me about five minutes to make the modification necessary to convert it from an air blower to an air sucker.

Now that I had the pump converted it was time to build my “pen”.  I started by cutting a length of 1/2” wooden dowel about 4” or so long.  I determined the length by holding the dowel in my hand and cut it the length that was minimum but would fit well in my hand.  I then used a center finder to mark the center on both ends of the dowel.

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My plan was to drill a hole all the way though the dowel and attach the inflator needle at one end and an air hose union at the other end.  These two parts are different sizes.  So, I was going to need to drill different size holes in each end. 

To simplify the drilling process and make it much easier to drill straight through the dowel without coming out a side, I decided to make a jig to hold the dowel perfectly perpendicular.  I did this by chucking up a 1/2” drill bit in to my drill press and placing a block of wood underneath it and drilling into it a couple inches.  Now I had a way to hold my dowel securely and perfectly parallel to the drill bit.

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Using the jig to hold the dowel, I then drilled a small starter hole in each end of the dowel using a small 1/8” drill bit. Drill as deep as your bit will go.

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Next, using a 9/32” drill bit I then drilled a hole in one end for the inflator needle.  In order to make sure that I end up with a hole all the way through the dowel when I was finished, I drilled as deep as my bit would go.  Then I stopped the drill and pushed the dowel up onto the bit and placed another piece of wood underneath my jig so that I could acquire the full reach of the drill bit.  Be sure that you do not go all the way though to the other end of the dowel!

 

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Test screwing in the inflator valve!

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Next, we’ll flip the dowel over and do the same thing to the other end using a 3/16” bit. 

Note, if you are building your own using my instructions you should always test fit your holes by drilling into a piece of scrap wood first and testing that your inflator valve or hose union fits perfectly.  Adjust your drill bit size accordingly if it’s not a perfect fit.  There is no guarantee that the sizes that worked for me will also be correct for you.

After drilling the other side, test fit the hose union.  This one needs to be snug as I don’t plan on using any glue to hold it in.

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Notice the sharp square edges at the ends of the dowel?  That’s not very comfortable to hold and doesn’t look very good.  Let’s fix that by turning our drill press into a drill lathe!  Start by chucking up the dowel into the drill press.  Do not tighten much more than hand tight or you will mar or crush the dowel.  Just tighten enough that it will not fly off.  The only tools we’ll be using to shape our dowel is sandpaper.  So, there’s no need to worry about much pressure being applied to the wood.

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Start up the drill and let’s start shaping the dowel.  I started with 80 grit sandpaper to get the general shape I wanted and then used 120 grit and finally 400 grit sandpapers to make it perfectly smooth.  Be sure to keep an eye on your wall thickness.  You do not want it to get less than about 1/8” thick outside your hole or you won’t have enough wood to attach your other parts to safely.

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Do one end then unchuck the dowel and flip it over and chuck it back up and do the other side.  Make it look however you want.  The idea is to make it fit your hand comfortably.  This is what I ended up with after about 5-10 minutes.

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We need to drill one more hole in the side of the handle.  This will allow us to turn the vacuum on or off using the pressure of our finger to release the vacuum.  Hold the handle in your hand so that the inflator needle end is at the end nearest your finger tips and pretend you are using it to pick up parts.  Figure out where the best place for the “button” needs to be to give you the most comfortable use.  Drill a 1/16” hole there.

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I then applied some paste wax to the threads of the inflator valve before screwing it into the dowel.  This serves two purposes.  It will lubricate the threads and allow them to screw into the wood easier and it will also help seal the connection.  This isn’t a permanent connection.  So, if we need to change to a different tip method later we can probably do so without having to build another handle. 

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Screw the needle into the correct end of the handle.  You will probably need to use pliers to hold the needle while turning the handle with your hand.  If it feels like the hole is slightly too tight, use some 400 grit sandpaper wrapped around a tiny dowel rod to sand the inside of the hole to slowly make it slightly larger.

Before we connect the hose barb to the other end, we need to put a finish on the wood.  This will make the wood look better but more importantly it will seal the wood and prevent our vacuum from being lost.  Most wood is very porous especially when drilled to be this thin.  I would normally finish this walnut wood using a coat of Danish Oil and then a coat of paste wax.  However, I didn’t feel patient enough to wait 24 hrs for the Danish Oil to dry.  So, I just applied a coat of paste wax.  The end product doesn’t look nearly as nice as it would with the Danish Oil but this is good enough for me.  The wood will naturally darken over time with use as it absorbs the oils from my fingers.

Here’s the finished product!

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Time to test it out!

All was working great with various sizes of small parts which was my main concern and reason for building it.  The fact that it doesn’t pick up the larger parts doesn’t bother me at all.  I can pick them up with my fingers or tweezers.  If I ever change my mind about this then I can always upgrade my pump.

However, I did have one big fail.  When I pulled out the 0603 parts I intended to use the picker on I quickly realized that the inflator tip was too large and it sucked the part up into the handle.  So, I’m going to have to work on the tip.  I found a syringe needle (left below) I own for applying glue to very tight places and it looks like it’ll do the job nicely.  So, an adapter to allow the smaller needle to fit snuggly within the larger needle may be the solution. (Note the tiny 0603 LED part between the two needles below)WP_20130127_019One other thing I plan to improve upon will be to add an on/off switch to the pump that is easily accessed without having to unplug the pump when not in use.  The power strips in my office aren’t easy to access.  So, a switch on the pump itself will be a nice addition.  I’m going to have to do a little shopping around for one that will be right for the space available inside the pump enclosure, though.

This project (minus the documentation) really only took about an hour to complete and could be done for a cost of about $10 by ordering the parts online ahead of time.  Overall, I think this is going to be a very handy tool to have at my disposal as I find myself moving more & more into smaller SMD designs.

How would you improve this project?  Leave your comments below.

1 comments:

Ian Lee, Sr. said...

nice job .. congratulations

http://asseenontvhose.blogspot.com/

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