Previously, I described a number of methods for desoldering PCB holes. My favorite technique is to use a desoldering bulb to suck out the excess solder. Unfortunately, the stock bulb tip is fairly wide, making it difficult to access holes near electronic components. The solution was to make a narrower tip out of Teflon (PTFE) on a lathe.
Comparison of desolder tip diameters. Left: Custom. Right: Stock.
The first step was to roughly size the Teflon block using the existing desoldering bulb tip. The block of Teflon came from eBay, but is also available at places like McMaster-Carr. Teflon is chosen because solder doesn’t stick to it and Teflon has a melting point (621 °F) that is much higher than most plastics.
Desoldering tip on Teflon block for rough cut
After rough cutting the block with a hacksaw, it was mounted in a four-jaw lathe chuck on a lathe. Unlike a three-jaw chuck, the four jaw variety is designed to hold rectangular objects as well as circular objects. The outer diameter of the block was then rounded using a cutting tool while the block was spinning.
Making a rod from a block of Teflon on a lathe
Next, the end of the block is reduced to the final diameter to fit into the bulb. In this case, it is 9 mm in diameter, but yours may differ based on the manufacturer and model of the desoldering tool. Notice below that the diameter then steps up to a larger size to prevent the entire piece from being accidently pushed completely inside the bulb.
Diameter reduced and large end hole drilled
A 3.5 mm to 4 mm diameter hole (I used a 9/64 inch) is drilled in the end, but not all the way through. The hole itself is even larger than the eventual outer diameter of the front of the tip. This hole provides both a reservoir and a larger exit than entrance to ensure the solder chunks don’t get stuck in the tip.
The bulb is test-fit onto the workpiece while it is still attached to the lathe.
Trying fit of desoldering bulb while still on lathe chuck
Finally (but not shown in photo), the end of the workpiece is faced and chamfered to make it easier to insert into the bulb. This is an important step, because the tip is going to be removed and reinserted quite often to clean out the solder residue.
The workpiece is then taken out of the lathe and the finished end is inserted into the chuck. At this point, I was too lazy to center it manually in the four-jaw chuck, so I switched to an auto-centering three-jaw chuck. The problem with taking a workpiece out of the chuck is that it will not be centered exactly the same when reinserted. That’s not a problem for the desoldering tip because it is not a precision piece.
Flipped in chuck to machine tip
A series of smaller diameters are cut into the block in steps. To achieve a nice taper, I could have unlocked the cross slide, but again, I was feeling lazy.
Rough machining of tip
Wearing a dust mask to avoid lung exposure to Teflon particles, the tip was then smoothed by sanding with fine sandpaper (400 grit working up to 1200 grit).
Drilling tip after sanding
The entrance hole was drilled with a #51 (1.7 mm) drill until it reached the larger exit hole. Even though my custom tip is much narrower than the stock tip, the sizes of the entrance and exit holes are identical. So, the capacity should be equal.
Profile of homemade narrower tip versus standard tip
I’m satisfied with the results. Alternatively, instead of machining the entire body, I could have mounted the stock soldering bulb tip into the lathe and simply narrowed the end.