Picture a conveyor line at 3 a.m. A clevis pin slides out of a pivot arm. The stainless steel cotter pin that should have held it was plain steel, and months of washdown spray had eaten it through. One pin that cost cents now costs hours of downtime.

This happens more often than buyers expect. People treat pins as commodity parts and pick them last. Then the wrong pin, grade, or fit shows up on the line.

This guide fixes that. You will learn what each pin does, how stainless steel cotter pins differ from clevis and dowel pins, which grade suits your environment, and what to check before you order.

Quick answer: which pin do you need?

Use stainless steel cotter pins to lock another pin or bolt in place. Use a stainless steel clevis pin to build a pivot joint. Use stainless dowel pins to align two parts precisely. Choose 304 (18-8) for general use and 316 for salt, chemicals, or washdown. Confirm the standard and size before you buy.

What each pin actually does

These three pins look alike. They do very different jobs. Mixing them up is the most common buying mistake.

Pin	Main job	Load role	Reusable?	Needs a partner part?
Cotter pin	Locks a pin, bolt or nut in place	Retainer, carries almost no load	Usually single use	Yes. It needs a cross hole
Clevis pin	Forms a pivot or hinge	Carries shear load	Yes, if undamaged	Yes. It needs a cotter pin, clip or washer
Dowel pin	Aligns two parts	Locating, light shear	Yes, press fit	No, but it needs reamed holes

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Here is the simple version. The clevis pin holds the joint. The cotter pin holds the clevis pin. The dowel pin holds two parts in the same position every time.

Stainless steel cotter pins: the basics

A cotter pin is a folded piece of half-round wire. It forms a loop at one end and two legs at the other. You push it through a hole, then bend the legs apart. That stops the pin or nut from backing out.

Stainless steel cotter pins make sense wherever rust would weaken the retainer. Outdoor equipment, food plants, boats, chemical lines, and washdown areas are the usual homes. A plain steel retainer in those places fails first, and it fails quietly.

Two points matter here. First, stainless steel cotter pins are a secondary lock. They do not carry the working load. Second, they are meant to be fitted once. Bending the legs hardens the wire. Bend them back and forth, and they can crack.

Cotter pin types

Most buyers meet three styles when they compare cotter pin types.

Standard split pin. Both legs are the same length. It is the default for bolts, axles and clevis pins.
Extended prong. One leg is longer. It is easier to grab and pull out during service.
Alternative retainers. Hairpin clips, R-clips, and spring clips replace a cotter pin where you need fast, tool-free removal.

The head also varies. Most stainless steel cotter pins use a round eye. That shape sits low and will not snag a hand or a hose.

Cotter pin sizes

Cotter pin sizes refer to the hole diameter they're designed to fit, rather than the actual thickness of the wire. The wire is slightly thinner so the pin can slide into the hole easily. Measure the cross hole diameter and choose the corresponding nominal size.

The pin should be long enough for both legs to pass through the hole and bend back. A shorter pin won't lock properly, and one that's too long might catch on other parts.

Wootz.work makes cotter pins from 1 mm to 12 mm (1/32" to 1/2"). These sizes are used in small assemblies as well as heavy equipment

How to fit a stainless steel cotter pin

Check that the hole is clean and free of burrs.
Push the pin through until the eye sits flat against the part.
Bend the legs apart, one each way, around the pin or nut.
Do not reuse a bent stainless steel cotter pin. Use a new one.

Stainless steel clevis pins and how they pair with cotter pins

A clevis is a U shaped fitting. A clevis pin passes through its two arms and through whatever sits between them. The result is a joint that can rotate. Think of linkages, actuators, tie rods and hinges.

What is a clevis pin?

If you are asking "what is a clevis pin," here is the clevis pin definition in plain words. It is a headed, smooth cylinder with a cross hole drilled near the tip. The head stops it sliding through. The cross hole takes a cotter pin or clip that stops it sliding back out.

The smooth body is on purpose. The joint needs to turn or pivot, and the pin carries the shear load across it. That is why a stainless steel clevis pin needs a tighter tolerance on its diameter than a cotter pin does.

Clevis pin types

The common clevis pin types are:

Headed clevis pin. The classic style. The head sits on one side and a cotter pin sits on the other.
Headless clevis pin. No head. It has a groove or cross holes at both ends for clips or cotter pins.
Clevis pin with spring clip. The clip replaces the cotter pin for quick release.
Threaded or special pins. Used where a nut must clamp the joint.

Cotter and clevis pin pairing

The cotter and clevis pin pair works as a team. The clevis pin does the work. The cotter pin keeps it from walking out under vibration.

Match the materials where you can. A stainless steel clevis pin paired with a plain steel cotter pin gives you a stainless joint with a rusting weak point. Pair a stainless clevis pin with stainless steel cotter pins instead. Both parts then age at the same rate.

One honest warning. Common stainless grades are softer than heat treated alloy steel. If the joint carries a high shear load, check the numbers before you swap steel for stainless. A larger diameter or a stronger grade may be needed.

Cotter pin vs clevis pin

People often search for cotter pin vs clevis pin as if they compete. They do not. A clevis pin is the part being held. The cotter pin is the part holding it. You normally need both in the same joint.

Stainless dowel pins: precision alignment

Take a gearbox apart and put it back together, and the two halves need to line up just as they did before. That's where dowel pins come in. The same goes for fixtures, jigs, molds and die sets.

What are dowel pins?

If you ask "what are dowel pins" in a machining context, the answer is solid, ground cylinders. Their diameter is held to tight tolerances. You press them into reamed holes. The press fit is what locates the parts.

Do not mix this up with wood dowels. Metal stainless dowel pins are precision parts. They sit inside holes that are often reamed to a few thousandths of an inch.

Types of dowel pins

The main types of dowel pins are:

Straight ground pins. The standard locating pin.
Hardened ground pins. Better wear resistance for parts that are taken apart often.
Pull dowel pins. An internal thread lets you extract the pin from a blind hole.
Spring pins and grooved pins. Related parts that grip through elasticity or grooves instead of a precision fit.

Dowel pins stainless steel grade choices

Grade choice is where buyers get caught. Dowel pins stainless steel come in two families.

300 series (such as 304 and 316). These resist corrosion well. They are softer, so they wear faster on parts that cycle often. A 304 stainless steel dowel pins order suits food equipment, medical fixtures and outdoor frames.
Hardened martensitic grades (such as 416 and 420). These are harder and wear better. They give up some corrosion resistance. Choose them for tooling that sees heavy cycling in a dry shop.

Ask what the part sees, not just what it touches. Wear and corrosion pull in opposite directions here.

Custom dowel pins

Standard sizes cover most jobs. Some do not fit. If you need a nonstandard length, a special end chamfer or a tighter tolerance, you are looking at custom dowel pins. Send the drawing early. A small change in diameter tolerance changes the price more than most buyers expect.

18-8, 304 or 316: choosing the stainless grade

Most stainless steel pins are made from one of two grades. Both are austenitic stainless steel.

Grade	What it is	Best for	Watch out for
18-8 / 304	The general purpose grade. 18-8 is a name for the same family.	Indoor, outdoor, food contact, light washdown	Pitting near salt and strong chlorides
316	Adds molybdenum for chloride resistance	Marine, coastal, chemical, pharma	Costs more. It is not stronger than 304
416 / 420 (hardened)	Martensitic, heat treated	Dowel pins and wear parts in dry environments	Lower corrosion resistance

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Two points save money and trouble.

316 is a corrosion upgrade, not a strength upgrade. Do not buy it expecting a stronger pin.
316 stainless steel cotter pins make sense near salt water, de-icing salt or chlorinated cleaners. Away from those, 304 is usually enough.

Also think about the metal next to the pin. Stainless against aluminum can set up galvanic corrosion in wet conditions. Plan for isolation washers or a coating on the other part.

Wootz.work can work with material grades across stainless and other metals. See the material expertise page for what is covered.

Which pin should you use? A decision table

Your job	Use this	Why
Stop a clevis pin or bolt backing out	Stainless steel cotter pins	Cheap, simple, visible lock
Build a hinge or linkage	Stainless clevis pin plus cotter pin	Pivot with a retained pin
Align two machined parts	Stainless dowel pins	Press fit locates parts exactly
Fast tool free removal	Clevis pin with spring clip	No bending, no tools
Marine or salt exposure	316 stainless steel cotter pins and clevis pins	Resists chlorides
High cycle tooling, dry shop	Hardened dowel pins	Better wear life
Food or washdown line	304 or 316 stainless pins	Cleanable and corrosion resistant

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If you are still unsure, ask one question. Does the pin carry load, retain a part, or locate a part? The answer points you to the right row.

Standards: what to specify on the drawing

A good purchase order names a standard. It cuts down guesswork and makes inspection easier.

ASME B18.8.1 covers clevis pins and cotter pins in inch sizes. A standards summary lists the scope.
ASME B18.8.2 is the usual reference for dowel pins in inch sizes.
ISO and DIN standards are common for metric parts. Buyers often name ISO 1234 for split pins, ISO 2341 for clevis pins, and ISO 2338 or ISO 8734 for dowel pins.

Do not assume that inch and metric standards give the same dimensions. They do not always line up. Pick one system and state it on the order.

A note on wording. Pins are made to these standards. A manufacturer does not "hold" an ASME certification for them. Ask for the standard on the drawing and the inspection report on delivery.

How to buy stainless pins without surprises

Cheap pins cost a lot when they fail. Use this list before you place an order.

Name the grade. Write 304, 316 or the hardened grade. Do not write "stainless" alone.
Name the standard. Add ASME B18.8.1, B18.8.2 or the ISO number.
Give size and length. State inch or metric. Add tolerances for dowel pins.
Ask for documentation. Material certificates and inspection records help with audits.
Plan the finish. Passivation improves corrosion resistance on stainless parts.
Check lead time and minimums. Small runs of custom dowel pins can cost more per piece.
Ask about duties. US buyers should know the landed cost, not just the unit price.

Tariffs change how a fair price looks. A low unit price from one country can lose to a higher price with clear duty paperwork. Wootz.work supplies tariff inclusive pricing documentation for US buyers. See the global delivery page for how shipping works.

Common mistakes with stainless pins

Reusing a bent stainless steel cotter pin.
Fitting a cotter pin that is too long or too short for the hole.
Using a plain steel retainer in a stainless joint.
Ordering "stainless" without a grade.
Buying 316 for strength when 304 would do.
Pressing a dowel pin into a hole that was drilled, not reamed.
Mixing inch pins into a metric design.

Dowel pin manufacturer or clevis pin manufacturer: what to look for

When you pick a dowel pins manufacturer or a clevis pin manufacturer, the unit price is only part of the story. Look for four things.

Range. Can they make your size, in your grade, as a standard or custom part?
Documentation. Will they supply material certificates and inspection reports?
Consistency. Will batch two match batch one?
Communication. Will someone answer engineering questions fast?

Quality management matters here. Wootz.work holds ISO 9001:2015, ISO 14001:2015 and ISO 45001:2018 certifications. Read how inspection works on the quality assurance page.

Where Wootz.work fits when you need pins made

Many buyers do not want to chase five suppliers for one small part. Wootz.work is a manufacturing partner that sources and manages production for you.

Here is what that looks like for pins.

Wide size range. Cotter pins from 1 to 12 mm, clevis pins from 4 to 25 mm, and dowel pins from 2 to 20 mm. Spring pins are available from 1.5 to 16 mm.
Standards. Parts can be made to ASME, ASTM, DIN, ISO, JIS and SAE specifications. State which one you need.
One point of contact. A single team handles quoting, production, inspection and shipping.
Engineering support. An India based engineering team reviews your drawing before production starts.
Fast quotes. Expect a response in 24 to 48 hours.
Low risk trial. The sample box lets you test parts before a bigger order.

See the full range on the industrial fasteners page. If you already have a drawing, send it for a quote.

Buyer checklist: before you order stainless pins

Is the pin a retainer, a pivot or a locator?
Which grade fits the environment: 304, 316 or hardened?
Does the cotter pin size match the cross hole?
Is the standard named on the drawing?
Are hole tolerances right for press fit dowel pins?
Is the metal next to the pin compatible?
Do you have material certificates and inspection records?
Have you checked landed cost for US delivery?

FAQs

What is a cotter pin used for?

A cotter pin locks another part in place. You slide it through a hole in a bolt, shaft or clevis pin. Then you bend the legs apart. That keeps nuts and pins from backing out under vibration. It acts as a safety lock and does not carry the working load.

Can I reuse stainless steel cotter pins?

Treat stainless steel cotter pins as single use. Bending the legs hardens the wire, and a second bend can crack it. A new pin costs very little. In critical joints, replace the pin every time you open the assembly.

What is the difference between a split pin and a cotter pin?

There is no real difference in most shops. Split pin is the common name in the UK and in ISO documents. Cotter pin is the common name in the US. Both describe the same folded wire pin with two legs.

Is 316 better than 304 for cotter pins?

316 resists chlorides better, so it suits marine, coastal and chemical use. It is not stronger than 304. For indoor or general outdoor use, 304 usually does the job at a lower price.

Do I need a cotter pin on every clevis pin?

Not always. A clevis pin needs some kind of retainer. That can be a cotter pin, a spring clip or a washer and nut. Choose a cotter pin when you want a simple, low cost lock that is easy to inspect.

Can Wootz.work make custom dowel pins?

Yes. Send your drawing with the grade, diameter, length, tolerance and quantity. The team reviews it and replies with a quote. Dowel pins from 2 to 20 mm (1/16" to 3/4") are within the standard range.

Stainless Steel Cotter, Clevis, and Dowel Pins: Which to Use