What is a Tap Used For?
Taps serve the function of creating internal threads within a hole, establishing a threaded surface to accommodate the fastening of a bolt. Among the various taps available, spiral-pointed and spiral-fluted taps enjoy widespread use. Spiral pointed taps feature straight flutes that facilitate efficient coolant distribution, each flute possessing an angular design at the cutting chamfer to manage chips effectively. These taps push chips forward, aligning with the tapping direction. On the other hand, spiral-fluted taps exhibit flutes that spiral around the tap’s axis, effectively removing chips from the hole. To understand how to choose the appropriate tap for your application, refer to our video on spiral pointed vs. spiral fluted taps.
How to Thread a Hole?
The process of tapping a hole involves creating threads on the interior of a drilled hole to facilitate the insertion of a bolt or machine screw. Follow these steps when approaching a threading task:
1. Determine the correct size for drilling based on the bolt size:
Ensure that the hole is smaller than the bolt’s diameter, as the threaded area will increase the diameter. Utilize a tap & drill chart to match the tap or bolt sizes with their corresponding clearance drill bit size. Drill the hole using the clearance drill size specified on the tap and drill chart.
2. Identify the tap required for threading the drilled hole:
Consult the tap & drill chart again to align the tap size with the corresponding clearance drill bit size (used to drill the hole).
3. Tap the hole:
Initiate tapping by turning the tap clockwise until you sense resistance from the threads cutting into the workpiece material. For each full clockwise rotation, perform a half rotation counterclockwise to break off accumulated chips, clearing space for the tap’s cutting edges. This step may be less crucial with spiral flute taps, especially with spiral point taps.
4. Test the hole:
After tapping the hole and while the tools are readily available, conduct a test to ensure satisfaction with the result. Before inserting the screw or bolt, remove chips from the hole (use compressed air or chip retrievers). Once the hole is chip-free, insert and screw in the bolt. If any resistance arises or the bolt doesn’t cleanly thread into the threaded hole, rerun the tap through the hole if necessary, ensuring the threads start in the same place to prevent cross-threading. Smooth any rough edges on the hole’s exterior with a deburring tool for a polished finish.
What Function Does a Die Serve?
Dies are employed to create external threads on a rod, establishing a threaded surface for fastening a bolt. The die is applied to a specific rod diameter for the desired thread size and pitch. External threads are cut manually with a round die secured in a die stock. Round dies feature three or more cutting edges, with cavities between each to facilitate chip removal.
See also: How To Get Rust Off A Cast Iron Skillet With Vinegar
How to Generate an External Thread on a Rod?
1. Secure the round die in a die stock:
Insert the round die into the centre of the die stock, tightening the screws around the die with a flat-tip screwdriver. Ensure the screw connection holes are in the correct position.
2. Thread the rod:
Align the round die with the rod’s edge, turning the round die clockwise onto the rod with gentle pressure. Take your time to ensure a straight thread cut.
3. Remove the die from the rod:
Upon completing the external thread cut, unscrew the round die in the counterclockwise direction.
4. Test the thread:
After threading the rod and while the tools are readily available, test the thread to ensure satisfaction.
Tap & Die Sets
Consider investing in a tap-and-die set for frequent threading applications. These sets offer compatible taps and dies, usually accompanied by a tap handle and a die stock. Most sets include molded cases to securely store components, making them easily accessible for your needs.
Tech Team Pro Tips
1. Pay attention to any unusual resistance while tapping the hole. When uncertain, back the tap out a few threads to prevent chip binding within the hole. Lubricants like TapIt-All or Tap Magic can make tapping the hole easier.
2. Difficulty removing a screw? Applying heat using a torch for a few moments often loosens the thread locker, making it easier to back out the screw. See more tips on removing a broken screw here.
Originally posted on February 2, 2024 @ 9:50 am