Angler's Thread Set BSF 3/8 x 20: Which thread is used in fishing accessories?
The fishing thread is in most cases a BSF 3/8 x 20 thread. It is a British fine thread, also known as a Whitworth fine thread. Typical features include a diameter of 3/8 inch, 20 threads per inch and a flank angle of 55°. This exact thread makes it possible for many accessories in fishing to be combined, attached and removed again.
What thread is the fishing thread?
Anyone who goes fishing has probably used the so-called fishing thread many times without even consciously noticing it. It is found in many accessories that are regularly screwed together, loosened or replaced. For example, in bite alarms, banksticks, rod rests, rod pods, landing net heads, landing net handles, adapters or quick connectors.
The major advantage: many of these parts can be combined with each other. A bite alarm fits onto the bankstick, a rod rest onto the holder or an adapter between two existing components. For this to work reliably, the thread must fit precisely.
In most cases, the fishing thread refers to BSF 3/8 x 20. The designation is easy to explain:
BSF stands for British Standard Fine, meaning a British fine thread.
3/8 inch describes the nominal diameter.
20 means that there are 20 threads over a length of one inch.
Converted, 3/8 inch has a diameter of approximately 9.525 mm. 20 threads per inch result in a pitch of 1.27 mm. This means: with one complete turn, the accessory moves 1.27 mm further into the mating thread.
The flank angle is also important. BSF 3/8 x 20 belongs to the Whitworth thread form and has a flank angle of 55°. This exact point is crucial when the fishing thread is confused with metric threads.
Is the fishing thread a metric thread?
No. The typical fishing thread BSF 3/8 x 20 is not a metric ISO thread. It is an inch thread and belongs to the Whitworth thread form.
The difference is not only in the unit of measurement. It is not simply a matter of inches instead of millimetres. The thread profile is also different.
A metric ISO thread has a flank angle of 60°. The BSF thread, or Whitworth fine thread, has a flank angle of 55°. This difference may sound small, but in practice it is decisive. The thread flanks do not sit cleanly on top of each other when a metric thread is combined with a BSF thread.
For this reason, a metric thread may look similar at first glance and may even be possible to start for a short distance. However, it does not really fit. The connection can become stiff, run crooked or damage the existing accessory.
| Characteristic | Fishing thread BSF 3/8 x 20 | Metric ISO thread |
|---|---|---|
| Measurement system | Inch | Millimetres |
| Thread type | British Standard Fine / Whitworth fine thread | Metric ISO thread |
| Flank angle | 55° | 60° |
| Pitch specification | Threads per inch | Millimetres per revolution |
| Typical risk | Confusion with a similar metric thread | does not fit cleanly with BSF 3/8 x 20 |
This is exactly why it is not enough to look only approximately at the diameter. The complete thread designation is always decisive: BSF 3/8 x 20.
Why is the exact designation BSF 3/8 x 20 so important?
At first glance, a fishing thread can look similar to a metric thread. This is exactly where mistakes can quickly occur in practice. Similar, however, does not mean suitable.
If the wrong tool is used or an unsuitable counterpart is screwed in, the connection can become stiff, jam or be damaged. In the worst case, the thread turns are deformed. The accessory can then no longer be screwed together cleanly later, even with the correct counterpart.
This does not only apply to newly cut threads. Problems can also occur with existing accessories if parts are combined that look similar but do not have the same thread standard.
That is why, when buying, repairing or making your own parts, you should always check carefully whether BSF 3/8 x 20 is really present. Especially with adapters, older components or inexpensive accessories, it is worth taking a close look at the thread designation.
Where is the fishing thread used?
The fishing thread is used wherever accessories need to be securely fastened and still quickly released. Typical examples include:
- Bite alarms
- Banksticks
- Rod pods
- Rod rests
- Landing net heads
- Landing net handles
- Adapters
- Quick connectors
- Holders
This is especially practical for equipment that is frequently modified, transported or adjusted. If you change your setup, you do not have to use a completely new system every time. Often, a suitable connecting part with the correct thread is enough.
A typical example is the landing net. The thread is often located at the connection between the landing net head and the landing net handle. This allows the landing net to be dismantled for transport or combined with another head if required. However, this only works reliably if both sides really have the same thread.
The fishing thread is also important for bite alarms and rod rests. The bite alarm must sit securely on the bankstick so that movements are reliably transmitted. A rod rest should be quick to mount, but must not wobble or sit at an angle during use.
Why should you take a closer look at fishing accessories?
BSF 3/8 x 20 is widely used in fishing. Nevertheless, you should not blindly assume that every accessory is automatically compatible. Deviations can occur especially with adapters, older parts, special solutions or imported goods.
The problem is simple: if two parts only fit approximately, you often only notice the mistake when screwing them together. The thread then does not run smoothly, sits crooked or blocks after only a few turns. If you then continue turning with force, the internal or external thread can quickly be damaged.
A simple check is better:
- Is the thread designation specified?
- Does it really say BSF 3/8 x 20?
- Can the part be started straight and without force?
- Does the thread run evenly?
- Are there any visible signs of damage or dirt?
This check is particularly useful when fishing. The equipment is used outdoors and quickly comes into contact with water, mud, sand or soil. Salt water, poor weather conditions and mechanical stress can also cause thread turns to become dirty, worn or covered with deposits.
The connection may then run less smoothly even though the correct thread is basically present. In this case, you should not immediately assume the wrong thread size, but first check for dirt and damage.
How do you use a fishing thread correctly?
When ready-made fishing accessories are screwed together, the thread should run smoothly. It should be possible to start it straight and screw it in without much effort.
If it catches or jams, it is worth taking a quick look at the cause:
- Is there dirt, sand or soil in the thread?
- Are individual thread turns damaged?
- Is the part being started straight?
- Is BSF 3/8 x 20 really present?
- Has it possibly been confused with a metric thread?
- Are there deposits caused by water, salt water or long storage?
Important: a thread should not be forced to fit. If a part does not run cleanly, either the thread designation is not correct, the thread is damaged or it is dirty. Force does not solve the problem; in most cases, it makes it worse.
For regularly used accessories, it can help to keep the threads clean and briefly check them after use. Especially after contact with sand, mud or salt water, the connection should not simply be screwed together and packed away.
How can you cut or rework a fishing thread?
If a fishing thread is to be newly produced or reworked, the right tool is required. Here, too, the rule applies: do not improvise and do not simply use a similar metric tool.
A tap is used for an internal thread. This allows, for example, an adapter, a mount or a component to be provided with a suitable internal thread.
A die is used for an external thread. This allows, for example, a bolt, a connecting part or a self-made adapter to be provided with a suitable external thread.
The BSF 3/8 x 20 version is always important. Only this creates a thread that fits common fishing accessories and can be screwed together reliably.
This is particularly interesting for anglers who want to repair, adapt or build accessories themselves. Anyone making their own holders, adapters or connecting parts does not need just any similar thread, but exactly the right fishing thread.
Cutting fishing threads cleanly with VÖLKEL
For VÖLKEL, the fishing thread is a good example of how even small applications require precise tools. It is not about cutting just any thread. It is about creating exactly the connection that will later fit cleanly with existing accessories.
For this purpose, VÖLKEL offers a fishing thread set BSF 3/8 x 20. The set consists of a tap and a die. This allows internal and external threads to be cut or reworked to match the common application in fishing.
This is particularly useful for:
- damaged threads
- self-made adapters
- custom holders
- repairs in the workshop or hobby sector
- special solutions for existing fishing accessories
- reworking worn or dirty threads
The advantage lies in reliability: anyone who works with the right tool avoids incorrect threads, protects existing accessories and ensures that the connection runs cleanly later.
Especially with accessories that are regularly assembled, dismantled and transported, this pays off. A cleanly cut thread is easy to screw together, sits straight and ensures that the connection holds reliably.
Conclusion: With the fishing thread, the exact designation matters
The fishing thread is a small detail with a big effect. It ensures that many accessories in fishing can be connected to each other. In most cases, it is BSF 3/8 x 20, meaning a British Whitworth fine thread.
The difference compared to metric threads is important. BSF 3/8 x 20 has a flank angle of 55°, while metric ISO threads have 60°. That is why a similar diameter is not enough. If the thread profile, pitch and measurement system do not match, the connection will not fit cleanly.
Anyone mounting accessories should pay attention to a clean and smooth-running thread. Anyone who wants to cut or repair a thread themselves should not improvise, but use the correct tool for the job.
With the VÖLKEL fishing thread set BSF 3/8 x 20, internal and external threads can be produced or reworked to match the common application in fishing. This keeps the connection reliable, clean and compatible with existing accessories.
FAQ about the fishing thread
Is the fishing thread metric?
No. The typical fishing thread is not a metric thread. In most cases, it is BSF 3/8 x 20, meaning a British fine thread based on the Whitworth thread form.
What flank angle does the fishing thread have?
The fishing thread BSF 3/8 x 20 has a flank angle of 55°. This distinguishes it from metric ISO threads, which have a flank angle of 60°.
Why does a metric thread not fit cleanly with the fishing thread?
A metric thread differs from the fishing thread not only in the measurement system, but also in the thread profile. Metric ISO threads have a flank angle of 60°, whereas BSF 3/8 x 20 has 55°. As a result, the thread flanks do not sit cleanly on top of each other.
What pitch does BSF 3/8 x 20 have?
BSF 3/8 x 20 has 20 threads per inch. This corresponds to a pitch of approximately 1.27 mm.
Where is the fishing thread used?
The fishing thread is commonly used on bite alarms, banksticks, rod pods, rod rests, landing net heads, landing net handles, adapters, quick connectors and holders.
Which tool do I need for a fishing thread?
For an internal thread, you need a BSF 3/8 x 20 tap. For an external thread, you need a BSF 3/8 x 20 die. With the VÖLKEL fishing thread set, both suitable tools are available.
