The Lounge

The latest Goodwill Find...You Never Know What Might Be Ther

In this forum you can chat about anything you like.

The latest Goodwill Find...You Never Know What Might Be Ther

Postby Jon Chandler » Thu Aug 08, 2013 8:42 pm

image.jpg
image.jpg (711.18 KiB) Viewed 295 times


For those that don't recognize this, it's a pneumatic solder paste dispenser. It automagically presses the plunger to eject a dot of solder paste, then it pulls back the plunger to prevent drips. This one, which is a name brand current model, was on the shelf at Goodwill for $12.99. You bet I snapped it up!

The list price is $350, and I've been wanting one... :)
Jon

Check out the TAP-28 PIC Application board at http://www.clever4hire.com/throwawaypic/
User avatar
Jon Chandler
Moderator
Moderator
 
Posts: 3172
Joined: October 2009
Location: Seattle WA, USA
Has thanked: 144 times
Have thanks: 325 times

Re: The latest Goodwill Find...You Never Know What Might Be

Postby Jon Chandler » Sat Aug 17, 2013 2:59 am

I ordered an accessory set from eBay (China) which arrived yesterday. Tonight I hooked up a foot pedal switch and after some head scratching, determined it was normally closed instead of normally open. Fortunately, the internal switch was SPDT, so I moved a wire and I was in business. The only remaining complication was a non-standard air-inlet fitting. Some 3/8" ID tubing slipped over the end of the fitting, secured with a screw clamp.

I thought that the "business end" was a piston, but it's much simpler than that. A plastic cap is pushed into the syringe, forming an airtight seal above the solder paste. The air adapter locks on the top of the syringe with an o-ring seal. Air injected into the cavity at the top of the syringe forces the paste out.

The dispenser automatically times the air pulse when the foot pedal is pressed. This time, the air pressure and the needle diameter work together to control the size of the dot. I found about 60 PSI air pressure, a dispense time of 0.17 seconds and a brown needle (unknown gauge, came with the solder paste) seemed to give me decent results.

The paste didn't want to stick to the board. After some trial and error, I found that holding the syringe almost vertical (almost perpendicular to the board) and actually pressing down a bit gave me decent dots of solder. Other solder paste may work differently.

Once I had the technique down, it took only a few seconds to apply solder for a MAX7219 on one of my display boards. After that, I positioned the IC in place and used my hot air station to solder the chip down – man, this was so much easier than using an iron! It took only a few seconds to heat up the solder.

The results from my first trial weren't perfect, as you can see from this picture. Two small solder bridges can be seen on the IC; these could be easily fixed with a soldering iron

A solder paste dispenser and a hot air station are highly recommended if you're using SMT parts. Bargains like my Goodwill find here don't come around often but the low cost (about $100 each) will provide serviceable tools.

image.jpg
image.jpg (498.27 KiB) Viewed 253 times
Jon

Check out the TAP-28 PIC Application board at http://www.clever4hire.com/throwawaypic/
User avatar
Jon Chandler
Moderator
Moderator
 
Posts: 3172
Joined: October 2009
Location: Seattle WA, USA
Has thanked: 144 times
Have thanks: 325 times

Re: The latest Goodwill Find...You Never Know What Might Be

Postby Baldor » Sat Aug 17, 2013 4:30 am

Seems the hot air station could be a litle cheaper. I'm looking to get one to start working with SMD parts:

Hot air only:

http://www.ebay.com/itm/ATTEN-AT858D-SM ... 3a82f2edcd

Hot air + iron:

http://www.ebay.com/itm/FST-2-in-1-SMD- ... 565913e782

Of course, quality unknow.

The solder paste dispensers start at about 100$ in ebay.
Aprendiz de mucho, maestro de casi nada.
Random avatar
Baldor
Valued Member
Valued Member
 
Posts: 356
Joined: August 2012
Location: Asturias (Spain)
Has thanked: 71 times
Have thanks: 53 times

Re: The latest Goodwill Find...You Never Know What Might Be

Postby Jon Chandler » Sat Aug 17, 2013 6:35 am

This is the one I have. It seems most of the similar ones now include an iron too.

The ones above include the blower in the hand piece. The type shown here has the blower in the base. I guess the trade off is more bulk and weight in the hand piece vs a shorter, stiffer connection because the hand piece is connected with a tube. I haven't heard any complaints about either design.

The temperature and airflow can be adjusted separately. At the lowest temperature of 100 degrees C, the tool is perfect for shrinking heat-shrink tubing.

Most of these tools have an automatic cool down to prolong the life of the heating element. When the handle is returned to the holder, the heat is shut off, but the blower continues to run until the temperature drops to 100 degrees C.


image.jpg
image.jpg (168.85 KiB) Viewed 243 times
Jon

Check out the TAP-28 PIC Application board at http://www.clever4hire.com/throwawaypic/

For this message the author Jon Chandler has received thanks:
Baldor
User avatar
Jon Chandler
Moderator
Moderator
 
Posts: 3172
Joined: October 2009
Location: Seattle WA, USA
Has thanked: 144 times
Have thanks: 325 times


Return to The Lounge