How to Use Reverse Tap to Pull-out Stripped Screw Properly

When removing screws and bolts that have been stripped off the cross slot or hex head, the first step is to utilize locking pliers or a tagline, but when those are not available, an extractor, a tool called a reverse tap, may be used. An extractor, which loosens bolts by screwing a tapered left-hand thread into it, may seem simple and convenient, but if used incorrectly, it can cause more damage than it is worth, so it is necessary to work carefully.

Dirt and excessive rust clogging the crisscrossing grooves is a danger signal.

I tried to poke a screwdriver in and turn it with the rust and dirt stuck in the cross-slot, and it slipped the groove. When dealing with rusty bolts and screws in the maintenance and restoration of old motorcycles, it's important to remove the dirt and keep the tools in place.

When loosening a Phillips screw, it's an ironclad rule of thumb for the job to focus on the force of pressing down rather than the force of turning the screwdriver. However, a surprising number of motorcyclists have crushed, or nearly crushed, the grooves with a come-out by applying a screwdriver to a dirty cross-groove when turning an old, dirty motorcycle bolt.

Speaking around the engine, screws around the drive sprocket area, where spattered chain oil often hardens into a clay-like substance, can be dangerous. The clay oil is soft and will fit in the crisscross grooves in its own way if you press a screwdriver against it, so you'll want to loosen it up as it is, but if the crisscross grooves are clogged with foreign matter, a pick tool or brush and parts cleaner is the first thing to do.

Care must also be taken when loosening a bolt that has rusted bright red. If you try to loosen the bolts with a poor grip on the tool due to rust, you may strip the hexagon head, and if you try to turn the bolts without spraying lubrication spray, the hexagon head may break off.

If the screw or bolt heads are still in place, but you can't use a screwdriver or wrench to loosen them from the outside, you can use locking pliers to loosen them from the outside. However, depending on where the screws or bolts are installed, there may not be enough room to handle the pliers or a metal tip. A cap bolt installed in a recessed position will also not allow the pliers to grab it.

A tool called an "extractor" or "reverse tap" is there for such situations. They vary from manufacturer to manufacturer and product to product, but what they all have in common is that they have a tapered tip with a left-hand thread cut into it.

A common screw is a right-hand thread, which tightens when turned clockwise and loosens when turned counterclockwise. On the other hand, left-handed screws are tighter when turned counterclockwise and looser when turned clockwise. To give you an idea of what we're talking about, the right-side rearview mirror on a Yamaha is a left-handed screw.

Since the extractor is a left-handed screw, the extractor is designed to bite into a tapered tip of a stripped screw or broken bolt and turn it counterclockwise so that it bites into the screw or bolt and then pulls it out tightly.

If the extractor snaps, it's more trouble than it's worth.

Yamashita Industrial Research Institute is the only manufacturer specializing in socket tools, and the reverse tap, named Bolt Twister, is designed to be turned by a T-handle, etc./It has a 3-inch square recess. The diameter of the tip where the left-hand thread is cut is the size of the tool, and size 2 corresponds to M5, size 3 to M6, and size 4 to M8. This product comes in a set of six sizes and can be purchased separately for each size.

Looking at the principle alone, it seems ideal, but it's not always that easy.

To use the extractor, pre-drilled holes must be drilled in screws and bolts, but if these holes are off-centered, or if the extractor is screwed in at an angle, the extractor itself will break more easily than expected. Extractors are supposed to be harder and stronger than steel bolts because they bite into steel bolts, but the low stickiness of the material causes them to break if unreasonable force is applied.

If the broken head is exposed, it may be possible to grab it with locking pliers and remove it, but if it breaks off in the screws or bolts, the extractor itself is too hard to stand up to the drill blade.

This is why even professional mechanics want to avoid extractors unless they have no other choice but to weld a loosening bolt to it if there are any screws or bolt heads left, or to fix the parts with the remaining bolts to a milling machine and use a tool called an end mill to dig and remove the bolts bit by bit. Many people say

You can easily buy them in tool shops or online, but know that the risk of failure is not small.

Still, if you use it, you'll have to be as careful as possible when drilling the preliminary hole.

When using the size 3 bolt twister, the diameter of the preparatory hole should be 3.2 to 3.5mm in diameter. I drilled a hole with a 2.5mm diameter drill at first and then enlarged it with a 3.5mm diameter hole so that it would not lean against the original screw.

If you try to turn it in a tilted position against a screw or bolt, the risk of breaking not only bolt twisters but extractors and reverse taps in general increases. It is hard enough to bite into the screw, but it is not so sticky to pry force. Therefore, it is important that the hole is straight.

If you understand the precautions to be taken with extractors and you still decide to use them, the most important thing to keep in mind is the drilling of the pre-hole. Conversely, if you don't screw up the pre-hole, the risk of the extractor breaking is small and you have a better chance of rescuing the screws and bolts.

I used the Bolt Twister from Yamashita Industrial Research Institute, a manufacturer specializing in socket tools, familiar to us from the ko-ken brand. Many extractors are turned by a tap handle, but this Bolt Twister is turned by a 3/8" ratchet handle or T-handle.

The thickness of the screw to be pulled out is the M6 used to fasten the crankcase and stripped the cross groove where the chain grease was stuck near the drive sprocket. As mentioned above, if I had used a shocked driver after removing the grease from the groove, I probably wouldn't have stripped it. This is a classic example of cutting corners and getting stripped.

Because it was a moped motorcycle, I took the engine down from the frame and cleaned the perimeter of the bolts, and drilled the pre-hole. Use the bolt twister according to the diameter of the bolt, but in the case of the M6 screw, the diameter of the hole is 3.2-3.5mm, and use the size 3 bolt twister.

Comparing the cross-slot of a Phillips screw to a bolt, it's certainly easier to follow the cross-slot of the screw and aim at the center of the pre-hole, but I'll start drilling the hole with a smaller-than-recommended size drill, hitting the center punch so that the drill blade is properly centered.

At this point, it is important to take care not to tilt the drill against the screw to be pulled out. It is also important to use a sharp cutting edge because if the cutting edge of the drill is not sharp enough, the preparation hole will tend to be oval or tilted.

When the preparation hole is ready, insert the bolt twister and turn it counterclockwise while pressing down. Once you feel the tapered tip bite into the screw, spray the screw liberally with lubrication spray and heat the area around the screw with a heat gun before turning the handle.

If the bolt twister does not bite when you turn the handle, there may be an insufficient force to push the bolt twister, or the tip of the bolt twister is too shallow for the screw to screw in. The smaller the screw diameter is, the narrower the tip of the Twister is, the deeper the preparation hole is needed.

Careful drilling of the preliminary hole allowed the size 3 bolt twister to bite into the screw and pull it out safely.

There are many situations where you will encounter screws and bolts that are difficult to loosen while tinkering with your old motorcycle. It's important to keep an extractor or reverse tap out of the way, and to apply dirt and rust remover and lubrication spray, but if you have no other option but an extractor, take the utmost care in working with it.

The more you turn the bolt twister counterclockwise, the more it bites into the lower hole, the more it can loosen screws and bolts that have been stripped by the tool. However, if the screw is tightly adhered to by corrosion, even the bolt twister may not loosen. In such a case, the diameter of the drill can be gradually enlarged and the screws and bolts can be removed. In this way, female screws are more likely to be damaged, so make a new female screw with recoil.