Description

Description

27pc Internal & External Lathe Threading Bar Kits [16-25mm]

Available in 16-20-25mm Shank Kits

Each kit includes the following 24 Inserts:

10 x 16ER ACME Inserts [2 of each] 8, 10, 12, 14, 16 Pitch for your External Holder

10 x 16NR ACME Inserts [2 of each] 8, 10, 12, 14, 16 Pitch for your Internal Holder

2 x ER AG60 Inserts for your External Holder

2 x NR AG60 Inserts for your Internal Holder

1 x Holder for External thread cutting

1 x Bar for Internal thread cutting

1 x Torx Key

Here is a chart showing the standard ACME thread dimensions for sizes ranging from 1/4" to 1". ACME threads are often used for power transmission systems, and the chart includes the major diameter, pitch, and thread angle for these sizes.

Standard ACME Thread Dimensions (1/4" to 1") with Recommended ACME Inserts

Size (inches)	Major Diameter (inches)	Pitch (inches)	Thread Angle (°)	Recommended ACME Insert
1/4"	0.2500	0.2500	29	1/4"-16 ACME
5/16"	0.3125	0.3125	29	5/16"-14 ACME
3/8"	0.3750	0.3750	29	3/8"-12 ACME
7/16"	0.4375	0.4375	29	7/16"-12 ACME
1/2"	0.5000	0.5000	29	1/2"-10 ACME
9/16"	0.5625	0.5625	29	9/16"-10 ACME
5/8"	0.6250	0.6250	29	5/8"-8 ACME
3/4"	0.7500	0.7500	29	3/4"-6 ACME
7/8"	0.8750	0.8750	29	7/8"-6 ACME
1"	1.0000	1.0000	29	1"-5 ACME

Major Diameter: This is the outermost diameter of the ACME thread.
Pitch: The distance between adjacent threads. ACME threads generally have a larger pitch compared to standard V-threads.
Thread Angle: Standard ACME threads have an included angle of 29°.
Recommended ACME Insert: This is the recommended insert size, which corresponds to the thread and pitch specified. The number after the dash (e.g., 20, 18) refers to the number of threads per inch (TPI).

ACME Inserts are often used in lead screw applications, where high strength and durability are required.
The thread pitch directly impacts the efficiency and load-bearing capacity of the ACME system, with finer threads (larger pitch) generally offering smoother operation but potentially lower load capacity.

1. Overview of ACME Threads

Profile: ACME threads have a trapezoidal shape, with a 29° angle at the flanks.
Purpose: Primarily used for power transmission, as they can handle both radial and axial loads.
Applications: Lead screws, machine tools, actuators, jacks, and other mechanical applications.

2. Threading Bars and Inserts

Threading Bars: These are long, bar-like tools that hold cutting inserts for creating threads. They are available in both internal and external configurations:
- Internal Threading Bars: Designed for creating threads inside a bore or tube.
- External Threading Bars: Designed for creating threads on the outside surface of a workpiece.
Carbide Inserts: Carbide inserts are used with threading bars for cutting threads. For ACME threads, special inserts with the correct geometry for the trapezoidal shape are used.
- Carbide: The most common material for inserts, carbide is preferred due to its hardness and heat resistance.
- Geometry: Inserts for ACME threads must match the 29° thread angle, which is different from standard V-threads.

Thread Cutting Process

Set the Tool: Insert the threading bar into the machine’s turret, ensuring that the insert is aligned with the centerline of the bore.
Initial Pass: Make an initial light cut to ensure proper alignment and check the hole’s diameter.
Threading: Perform incremental passes to gradually cut the internal threads to the desired depth. It’s crucial to maintain the 29° flank angle to ensure proper thread geometry.
Final Cut: Make the final pass at full depth, ensuring the ACME thread profile is accurately formed.

Considerations

Lead and Pitch: Ensure that the lead (distance the nut moves per revolution) and pitch (distance between threads) are correct for the ACME thread design.
Insert Wear: Carbide inserts will wear over time, so check the cutting edges periodically to maintain threading accuracy.

Thread Cutting Process

Set the Tool: Mount the external threading bar on the machine and set it up so that the insert is aligned with the workpiece's centerline. Ensure that the cutting edge aligns with the surface to be threaded.
Initial Pass: As with internal threading, make an initial light cut to check for alignment and thread accuracy.
Thread Cutting: Proceed with incremental passes to gradually cut the external ACME threads. Each pass should remove a small amount of material to maintain control over the thread shape.
Final Pass: Complete the final cut to the full depth, ensuring the 29° flank angle and thread pitch are maintained.

Considerations

Tool Path: Keep in mind the tool’s path and ensure that the insert remains tangent to the workpiece surface during each cut. This is particularly important for external threading.
Cutting Speed: High cutting speeds are typically used for external threading, but ensure that the cutting speed is appropriate for the material being threaded.