What if Allen screw is stripped?

A stripped Allen screw can be a frustrating problem for any do-it-yourselfer or technician. An Allen screw, also known as a hex screw or Allen bolt, is a fastener with a hexagonal socket in the head that requires an Allen wrench to tighten or loosen. If too much torque is applied or the improper Allen wrench is used, the facets inside the socket can become rounded off or stripped, making the fastener impossible to remove with a wrench. When an Allen screw becomes stripped, it may seem hopelessly stuck, but with the right tools and techniques, the screw can usually be removed or repaired.

What causes an Allen screw to become stripped?

There are a few common causes of a stripped Allen screw:

• Using an Allen wrench that is too small – If the wrench is undersized, it can slip and round off the facets in the screw head.
• Over torquing – Applying too much tightening force can cause the metal inside the socket to deform.
• Poor quality or damaged screw – Lower quality screws made of soft metals can strip more easily. Pre-existing burrs or damage inside the socket can also lead to stripping.
• Corrosion – Rust, oxidation, or built-up gunk inside the socket interferes with the wrench fitting properly.

The best way to avoid stripping an Allen screw is to use the properly sized hex wrench and avoid over tightening. High quality alloy steel screws and keeping sockets clean will also minimize stripping.

Can you remove a stripped Allen screw?

In most cases, yes, a stripped Allen screw can be removed, but it requires some patience and the right techniques. Here are some methods for removing stubborn, rounded-out Allen screw heads:

Use an extraction bit

Special screw extractor bits are made to grip and unscrew damaged fasteners. These bits dig into the soft metal of the stripped screw head to gain enough grip to turn the screw. Apply firm downward pressure while slowly turning the bit counterclockwise to back the screw out.

Use a larger Allen wrench

Sometimes a slightly oversized Allen wrench hammered into the stripped socket can bite into the facets enough to turn the screw. Gently tap an Allen wrench one or two sizes larger into the screw with a hammer, then try turning it out.

Drill it out

As a last resort, use a drill to bore out the stripped screw. Use a drill bit slightly larger than the screw shaft and carefully drill down the center of the screw to sever it. The remaining shaft can then be removed with pliers. Be extra cautious not to drill into anything behind the screw.

Use an EZ-out screw extractor

EZ-out extractors have a threaded flute that reverses the thread direction to back screws out counterclockwise. Hammer the EZ-out into the screw head and turn it gently with a wrench to remove the screw. Apply lubricant to make extraction easier.

How can you avoid stripping Allen screws?

Here are some tips to prevent stripping Allen screw heads in the first place:

• Use the correct size Allen wrench – Never use a wrench that is ill-fitting or undersized.
• Lubricate screws – Penetrating oil or threadlocker makes turning easier.
• Pre-drill holes – Drilling a pilot hole prevents screws binding up.
• Tighten gradually – Tighten screws in increments, not all at once.
• Use a torque wrench – Torque wrenches apply optimal tightening force.
• Choose quality hardware – High grade alloy steel screws resist stripping.
• Keep wrench perpendicular – Don’t use wrenches at an angle, which can cause slippage.

Following these best practices when working with Allen screws will help prevent screw heads from becoming damaged and seized.

Is there a way to repair a stripped Allen screw?

If an Allen screw head becomes slightly rounded out but there is still some socket left, it may be possible to repair it instead of fully replacing the screw:

File the socket facets

Use a small flat file to sharpen the blurred facets back to distinct edges. Remove any burrs or protuberances. Be careful not to remove too much material. Test fit an Allen wrench to ensure it seats properly in the filed socket.

Chase the threads

Run a tap through the screw’s internal threads to clean out any debris. Chasing will realign and smooth out the threads so they mesh properly with the female threads in the hole. This allows you to reuse the screw.

Use threadlocker

Applying a threadlocking adhesive will help secure a screw with damaged threads so it holds properly when reinstalled. Let the threadlocker cure fully before tightening the screw.

Use a screw insert

For badly damaged threads, a threaded insert can be placed into the screw hole to repair the threads and allow a new screw to be installed. Drive the insert into the hole and reinstall the fastener into the insert.

Use a Helicoil

Helicoils are coiled wire thread inserts that repair holes and provide new threads. Install a Helicoil the same diameter as the screw, then cut off any excess tail. The screw can then be reinserted into the repaired hole.

What’s the best way to remove a stripped screw?

Here is a quick summary of the most effective techniques for removing a rounded, spinning, or stripped Allen screw:

• Try tapping in a slightly oversized Allen wrench to get grip on the facets.
• Use a screw extractor bit that bites into the screw head for removal.
• Drill out the screw with a bit slightly larger than the shank if necessary.
• Use a reverse-threaded EZ-out extractor screwed into the stripped head.
• As a last option, cut or grind off the screw head and remove the shaft.

Patience and care is needed when dealing with a stripped Allen screw to avoid damage. Don’t force tools or over-torque. If one removal method doesn’t work, try an alternative. With persistence, most seized screws can be successfully freed.

What tools do you need to remove a stripped screw?

Having the right tools on hand will ensure you can remove a stripped screw successfully. Here are the most essential implements:

• Screw extractor set – Includes reverse-thread extractors and left-hand drill bits.
• Oversized Allen wrenches – Larger than the original screw’s wrench size.
• Cutting oil or penetrant – Helps extractors bite in and loosens threads.
• Hammer – To tap in extractors or Allen wrenches firmly.
• Electric drill and bits – For drilling out screws as needed.
• Plier set – To remove screw shafts after drilling.
• Helicoil kit – For thread repairs if reusing holes.
• Tap and die set – To clean and realign threaded holes.
• Dremel or grinder – For cutting off seized screw heads.
• Hex screwdrivers – Alternatives to Allen wrenches for difficult angles.

Having this essential toolkit on hand for screw extraction and repair will save lots of headaches. Always use quality tools, work patiently, and take care not to damage hardware.

Can you fix a stripped screw hole?

Yes, there are ways to repair a hole after removing a stripped screw so it can accept a new fastener. Options include:

• Use a Helicoil insert – These coiled wire inserts renew damaged threads.
• Re-tap holes – Running a tap through realigns threads.
• Use threadlocker – This helps secure screws in distorted holes.
• Drill holes out oversized – Enlarging the hole allows using a bigger screw.
• Use wall anchors – Plastic anchors fill holes and provide new threads.
• Use an oversized screw – Pair with a threadlocker for grip.
• Fill hole with epoxy – Steel-filled epoxy hardens into new threads.

Assessing the extent of thread damage and choosing the right repair technique will get holes back in working order. Take steps to prevent future stripping like pre-drilling, lubricating screws, and using impact drivers carefully.

What sizes of Allen wrenches are there?

Allen screw head socket sizes are typically measured in millimeters (metric) or inches (SAE). Here are some of the common Allen wrench sizes:

Metric Allen Wrenches

0.5mm	0.7mm	1mm	1.5mm	2mm
2.5mm	3mm	4mm	5mm	6mm
8mm	10mm	12mm

SAE Allen Wrenches

1/16 inch	5/64 inch	3/32 inch	7/64 inch	1/8 inch
9/64 inch	5/32 inch	3/16 inch	7/32 inch	1/4 inch
5/16 inch	3/8 inch	7/16 inch	1/2 inch

It is critical to always use precisely fitting Allen wrenches so the flats make full contact in the screw socket to avoid stripping. A set with both metric and SAE wrenches in fractional sizes covers most needs.

Should you pre-drill for Allen screws?

Pre-drilling appropriately sized pilot holes is highly recommended when driving Allen screws into materials like wood, plastic, or metal. Here’s why:

• Prevents screws splitting wood fibers apart when tightening.
• Allows screws to insert more easily without binding up.
• Reduces the force needed to drive the screw.
• Decreases the risk of screw heads stripping out.
• Helps keep precision alignments intact during assembly.
• Provides space for shards to clear when self-tapping screws cut threads.

For wood, use a bit around 75% of the screw shank width. For metal, choose a bit nearly equal to the shank. Take screw length into account so you don’t drill too deeply. Adding a countersink also improves seating. Taking the time to pilot holes is worth it to boost results and avoid problems.

How much torque should be applied to an Allen screw?

The recommended tightening torque varies depending on factors like screw size, materials joined, thread type, and applications:

• Plastic to plastic: 2-4 in-lbs (0.2-0.5 Nm)
• Self-tapping screws into metal: Approx. 15 in-lbs (1.5-2 Nm)
• Machine screws into tapped metal: Up to 25 in-lbs (3 Nm)
• Wood screws into wood: Up to 45 in-lbs (5 Nm)
• High loads: Up to 125 in-lbs (14 Nm)

It’s important not to overtortque and strip screws. Use the low end of guidelines and increase torque gradually until an Allen wrench starts to flex or cam out of the socket. Employing a calibrated torque wrench is best to precisely control torque. Only tighten screws as much as needed to achieve adequate clamping without excessive force.

Conclusion

Stripped Allen screw heads can certainly be frustrating, but are usually repairable with some perseverance and the right tools. Avoiding overtorquing hardware and using proper Allen wrenches are the best ways to prevent rounding off the precision socket facets. If a screw does become seized, specialized extractors and reverse drill bits can typically remove it. Re-tapping stripped holes and using inserts will have your parts reassembled in no time. With care and patience, you can keep Allen screw assemblies secure without damaging expensive components.