Understanding Pivot Screws on Scissors and Shears

There are three basic types of screws on shears plus variations on a theme of these three types. There are regular screws, thumb-nut adjustable screws and UFO or tamper-proof screws. 

However, I will begin with a story about a shear with a regular screw.

At a hair show in Chicago, a lady brings her Hikari shears to the Hikari booth for sharpening. (Hikari shears start at $299.00 for their budget shears and go up to over $1700.00) At this particular show, Hikari was not sharpening, but recommended another sharpener at the show. She brought the shears to the other sharpener who explained Hikari’s warranty would be void if they were not sharpened by Hikari, but she insisted anyway because she wanted the shears sharpened that day.

Two weeks later she “discovered” that her shears in her words were “ruined” because they were folding hair and demanded a replacement overnighted to her salon. After copious conversations between her and the sharpener, her complaint sounded like a loosened screw. Since Hikari shears have regular split screws, this is a common occurrence with these types of shears. Although the sharpener explained how to tighten her screw she angrily asserted, “I know how to tighten a screw and these shears are ruined. I want a new pair to replace these.”

Another suggestion to send out a local Chicago sharpener who is a certified master sharpener with the NBTSG was to no avail. Finally, the sharpener agreed to replace the shears and that is where I became involved since I have contacts with the Hikari Corporation.  I spoke to the stylist and told her replacement means just that, she must send in the shears to be replaced.

A week later I received her Hikari shears. I video taped me taking them out of the box. They were so loose the screw barely kept the shears together. There is no way the sharpener returned them that loose. She must have loosened them. As they were, they would not cut. Once I tightened the screw, they cut very well with only a slight push. This push could have been caused by her trying to cut with loose shears. Certainly they were not ruined.

However, the sharpener had already agreed to replace them. After contacting Hikari, they had a reconditioned pair I was able to purchase for the sharpener and send directly to the stylist in Chicago. I assume she is happy because she has not called to complain. The so-called “ruined” pair will be sold as used for more than the price of the replacement. So everyone is happy now.

The lessons learned from this are:

1. Stylists very often have loose screws.
2. It is the job of the sharpener to teach the stylist how to adjust their screws. Be sure the have the proper knowledge and tools to do this.
3. Double check the screw adjustment and triple check before handing a shear back.
4. Never agree to replace a shear until you have had a chance to look at it and inspect it. The customer is not always right.
5. A shear that folds hair usually has a loose screw.
6. Stylists sometimes loosen screws for whatever reason that goes into their head.
7. Good can and very often can come from bad.

Regular Screws

Regular screws usually have a slotted rounded head style but can on occasions have a variety of head styles. These screws are not normally available at a hardware store and are sometimes specific to a particular shear model. Most often, the shaft of the screw is split. This means that the length of the screw where the threads are has a split. The purpose in theory is the screw opens wider and holds the adjustment more securely. The truth in reality is that the split often closes up and the screw will not hold the adjustment.

To adjust regular type screws, never over tighten then loosen to the correct adjustment. If you do this you have created the thing you were trying to avoid. You have pushed the sides of the split closer together and the screw will not hold. This is why the sharpener needs to use a screw driver, scissor pliers or other device to tighten the screw somewhat and check the adjustment.

How to adjust a regular screw:

1) Tighten a little more and check the adjustment. Tighten again and stop once the tension is set to your preferences. Do not over tighten.

2) Wiggle the handles to seat the washer in place. Check the adjustment again and retighten if necessary.

3) Open and close the shears a few times to be sure the screw is holding.

4) Put a drop of oil on the head of the screw and on the ride.

5) Repeat steps 2 & 3

If the screw is not holding, you have several choices:

1)      Use medium (blue) loctite to hold the screw

2)      Slightly damage or rough up the threads to create a slight but on the screw and adjust

3)      Add something into the hole like dental floss, broom straw, rubber band or some other creative object to make the hole smaller to hold the screw in place.

4)      Use plumbers or Teflon tape over the threads.

5)      Insert the screw and adjust appropriately. Turn the shear over and ping the thread side of the screw with a hammer and a nail punch to create a bur on the outside of the shear to hold in place.

6)      Replace the screw.

7)      Sell them a new shear.

8)      Open the split in the screw.

This last step can be risky. I have broken the screw on more than one occasion. One time I did this sharpening in the salon on a cruise ship and did not have another screw to replace the broken screw. I have seen many different ideas on how to do this successfully. My favorite method of opening a split screw is to keep the screw in the single side of the shear and use a knife, spatula, razor blade or some other skinny object (depending on the screw) to open up the slot. This will hold the screw steady and in place. You don’t have to purchase extra equipment for this purpose. It also supports the screw shaft.

Thumb Screws

Thumb nut adjustable screws are the favorite among most sharpeners because of their ease in taking the shears apart without extra tools or gizmos. However, stylists usually complain about this type of screw with complaints that it “gets in their way,” “makes the shears too heavy,” “shears fall apart when they turn the screw.” While these are the downside, the ease of use has made this one of the most popular screw types.

The adjustable thumb nut screw is by in large just a decorative nut with a choice of “clicker plates,” “springs,” or “metal washers” (depending on your terminology) that keep the thumb nut screw from loosing and backing out. These types of washers were briefly discussed in the article on washers, but I will elaborate on each now.

A typical thumb nut screw assembly consists of the following:

·         Thumb nut most often with grooves on the bottom side and a smooth or decorative top

·         Clicker plate of some sort with one to three knobs or nipples to catch the grooves on the thumb nut (or sometimes it is just a rubber donut type thick washer that holds the shear together by friction)

·         Washer

·         Bolt. The bolt will usually have a square shaft that leads to the round shaft with threads or a round shaft that leads to a square shaft with threads.

Normal assembly of thumb screws:

• The bolt with the washer go into the round hole of the back side of the shear. (Note sometimes the shaft is square, not round and, yes, sometimes the square peg goes in the round hole!)
• The bolt fits up into the top blade of the shear. Wiggle and work the shear and the bolt until it engages and the two blades are together with no gap.
• Insert the clicker plate.
• If it is an internal clicker plate (see illustration) press the metal washer clicker plate into correct flush positioning using tweezers, needle nose pliers or a probe.
• If it is an external round clicker plate (see illustration) be sure the pointy nipple aligns and goes down into the hole on the shear.
• If it is a leaf type clicker plate, be sure the nipple at the lower end of the plate fits into the hole and the top aligns to the contour of the shear.
• Fit the thumb nut screw over the bolt, turning slightly in the counter clockwise direction until you feel the nut engage in the threads, then tighten to the desired adjustment.

Trouble shooting.

Other than loosing or breaking the clicker plate or other parts, the largest problem with these screws occurs with the leaf style clicker plates. Often the plates which are designed to be somewhat spring-like in action become flatter and the screw will not hold an adjustment. There are two solutions to correcting this problem.

1. Increase the bend in the clicker plate. I often hold one part with my needle nose pliers and with the plate laying flat on the table increase the curve or bend in the metal. Usually this works good. On one or two occasions the leaf broke.
2. Put a metal washer under the leaf plate to increase the bend. (see metal washer illustration) Many shears now commonly come with a metal washer under the plate for this purpose.

It is a good idea to have additional parts if possible of the adjustable screws although I rarely have to replace a defective one. I usually need these because I dropped a part and can’t find it.

 UFO Screws

Many years ago an employee at Bonika Shears began calling the odd tamper proof pivot screws “UFO Screws.” I believe this is the first place this term was coined. Since then this has become the common use name for odd screws, especially those that have the two slots to be adjusted with a “spanner-type” screw driver bit. This is now a very common screw.

The UFO screw will be the final segment of the “Understanding Your Scissor Parts” series. This screw can be confusing since it needs special tools to adjust and the flat part of the two piece screw can be on the back of the shear or as a decorative piece on the front of the shear. We have UFO screws of both varieties among Bonika Shears. Even though the flat portion is frequently on the front of the shear, for the purposes of clarity, I will refer to the flat portion as the bottom of the screw set and the part that takes the adjustment tool as the head of the screw set.

Normally the UFO screw will have an internal clicker plate or a rubber donut under the head of the screw to prevent the shear from loosening up. The two slots, slits or holes on the head can have a variety of configurations in regards to spacing and width. It is important to have a number of UFO adjusters and some additional spanner bits for your screwdriver so that you are armed to deal with any shear that comes your way. In the factories they usually have a modified screwdriver; I assume modified using a Dremel to carve out the right configuration for their particular screw. As field sharpeners, we do not have the luxury of a customized screwdriver and must have on hand every bit and UFO adjusting coin available. Harry Megowan designed a handle for these coin shaped adjusters made from a dowel stick. These give a better torque for the standard UFO coin shape tools for these shears. By the way, Harry won the best idea award at the Jam in an earlier year with this simple tool. The simplest ideas are often the best.

While I feel certain of the origin or the name, I am not sure of the origin of the UFO screw design. I assume it was not designed to make it more difficult for sharpeners to work on these shears although it seems that way. We have found on our Bonika Shears that have the UFO screw, we have less complaints or warranty issues with the pivot mechanisms that we do with other design of screws. Often stylists and I assume groomers objected to the bulky knob systems that interfered in their cutting. However, the preferred regular flat screw had the issue of loosing after constant use. The UFO screw was most likely born to address both of these issues.

The first of the UFO screws I encountered in my career was the original Vortex Shear. It had a UFO style head and the back was a hex. It came with a complicated two part system that hooked onto the UFO head via a device that attached to the handle and a mechanism to adjust the back. Invariably the stylists would lose these tools and we were unable to adjust the shears. I would use needle nose pliers on one side and an allen wrench on the back side and found I was always one or two hands short of taking the shears apart. I am so glad those shears were changed.

Trouble shooting on this screw is straightforward. The first concern is to be conscious of which side of the shear screw head is attached. I have often seen these installed backwards. Next, be alert as to the number and placement of washers. Look carefully for internal clicker plates (see previous article) so as not to lose these. I have found that adding an additional washer sometimes helps in those cases where the screw will not tighten adequately.

There are a number of other unusual and odd screws which I may address in an article at a later date. For more help on pivot screws from regular screws to UFO’s and all in between,  I would suggest “Screwing Around with Josh” from the 2014 Sharpeners Jam DVD collection from Bonika Shears.