Crazy thought-Bearings instead of pivot pins.

May 15, 2001
I can tell by the look on your face that you think I'm completely nuts, but the idea has been flying around in my head like a moth near a candle. I know it's very hard to make a durable bearing small enough to fit in the handles of a balisong, but I'm just saying "What If?".

What if a bearing that small could be fitted in the handle of a balisong and used in conjunction with a small pin on the blade? Wait a minute, this idea does seem kinda screwy, doesn't it? :confused:

Oh, well, I thought I heard something about it on the 'net, or somewhere else for that matter. Anyway, the thought just occured to me, and i had to get it out of my head. :D
I've suggested this before, I think somebody suggests it every few months. Too expensive, but a cool idea. Someday...
That idea was tossed around a little under a year ago - late August - early October -ish.

There are a number of reliability & safety issues that come up with this kind of idea. I'm going to assume that by the word "bearing" you're referring to sealed bearings much like one would find in skateboard/rollerblade wheels, only much, much smaller, rather than a "bushing" or an unsealed bearing.

1) To insert bearings into handles would require the removal of more hard material, and likely compromise the handles' strength & durability. Inserting bearings into the tang, same problem.
2) Such bearings are not designed for the abuse that balisong pivots endure. Yes, they do handle lateral stresses in (for example) skateboards and rollerblades, but a balisong pivot endures through much more lateral force (taking into account frequency of lateral stresses and size of the joint) in just a few minutes than the average skateboard or pair of 'blades will in several hours. Considering the extremely small size of bearing to handle Problem #1, there just wouldn't be enough load-bearing material left in this type of bearing to handle it.

Someone (I disremember whom) had the idea of trying very small thrust bearings (thrust bearings are surface-mounted dohickeys that allow two flat surfaces to rotate beside one another, rather than between an axle & wheel type set-up) between forks & tang, which might have helped solve these problems, but I don't remember if any actual experimenting was done to see if it would work.
The reasons that were just given, lateral stress, etc, are the reasons I knew it wouldn't work, but I mainly wanted to see if anyone was thinking along those same lines. BTW, I worked with AC electric motors, and I've seen sealed bearings with individual ball bearings the size of golf balls in them. The average sized bearing I worked with was bigger than a .50 cent piece. :D

Well, I guess the whole press-fitted-pin thing is going to be with us for a long time, or at least until I get my own BM-42, which will probably be sometime next year. :mad:

Anyway, have fun with your own knives, and watch those aerials! :D
When I brought it up, I was told that a few custom makers have bade bearing balis, but that the BM42 was faster than any of them. I still wouldn't mind seeing a bali with some micro "skate" bearings. In sealed sets around the pivot pins.
I once worked for a bearing manufacturer that has since gone out of business.

I can definitely tell you that there are bearings being made that will work in a Balisong. I'm not talking about loose balls in a track here, but rather self contained units that just need to be slipped in.

I actually researched this quite extensively awhile ago. Heres a few examples of thrust bearings that I think could serve the purpose:

If you want to learn more about different types of bearings, check this out:
Originally posted by willOthewisp
Such bearings are not designed for the abuse that balisong pivots endure.

Most bearings are not designed for that sort of stress, that is very true. There are, however, bearings that will work. One of the reasons that BG42 is such an expensive steel is because it is used in critical bearing applications. Like in Jet Engines for Aircraft. It has excellent qualities for a blade steel and in other applications as well. This is one of them.

It would not hurt my feelings one bit if all commerical steels were canned and BG42 became the standard that ATS-34/154CM is now. It is an excellent steel and it is an excellent steel for bearings as well.

It would all be in the design of the knife and the particular type of bearing used. But if it were designed right, BG42 could most certainly take the stress.

Like Clay said, yes, there is stress involved in a Balisong's pivot area, but we're not talking skateboards here, nor are we talking about ball-bearing swivel nunchaku either.
"Latrobe BG-42 is a good steel, even a great steel. The heat treating is not exotic and any commercial heat treater can heat to specs required including the -120 treatment which is the standard cryo figure.

Unfortunately, Latrobe Steel provides <font color=red>BG-42 for bearing applications</font> and not specifically for knifemaking applications. This is handled by their specialty steels division. They produce the steel in bar stock and in small runs of such. Bar stock will not work for major manufacturing processes. Most companies use lasers like ours that require sheet stock material.

Yes, Latrobe will do a run for a certain quantity and dollar amount. It is not always the price but the ongoing availability of raw material that is the determining factor in choices made by manufacturers.

Our factory is set up on a just in time model and long lead times and guarantees of only small quantities, prohibit the use of this steel.

The Latrobe company does not look at the knife industry as a large enough customer to release mill time to address to address cutlery in the tonnage needed to supply major manufacturers at this time.

Perhaps this will change in the near or distant future. <font color=red>Remember, they make this steel for turbine bearings and almost all of their production goes to that application."</font>

~Ernest Emerson
Actually, 154CM/ATS34 is also a turbine bearing steel. Very few steels are designed for knives. Sandvik 12C27 is the only one that pops to the top of my mind, at the moment.

Okay, we've found that maybe using ball bearings isn't such a bad idea, nor is it the next best thing in balisong design, either. Before things get too nasty, I recommend we take a long recess and re-convene here next weekend. :D
Originally posted by e_utopia
Actually, 154CM/ATS34 is also a turbine bearing steel.

Learn something new everyday, that's why this place is great.

In light of that, and the fact that Hitachi [ATS34] and Crucible [154CM] will produce it in sheet form, but Latrobe will not. Do you think that is because Hitachi and Crucible have embraced the Cutlery Industry and Latrobe has not?

As per Mr. Emerson's comments, apparently BG42 is not available in sheet form and only in bars. I wonder what the other major application of ATS34/154CM is besides cutlery and bearings. I also wonder which is preferred by various industries for bearing applications, BG42 or ATS34/154CM.

I have advertisements from Bali-Song USA from the late 70s and early 80s advertising the Custom Bali-Songs as having 154CM. Just an interesting tidbit~side-issue.
Come to think of it, I'm 99% certain that several other 'knife steels' are really bearing steels. Knives take much the same stresses as bearings, so it makes sense.

I think if Latrobe got enough requests for sheet BG42, they would produce it. But, for that to happen, enough large manufacturers have to ask them about it to make them see that there is a market. So, if you want BG42 to become more common, I guess the best bet is to talk to every large manufacturer you can find, so they will call up Latrobe and make inquiries.

None of them really 'embrace the cutlery industry', but they are more than happy to embrace the cutlery industry's money, if they think there is a large enough, market.