Titanium Casting Defects

joe90

joe90

Joined
Aug 17, 2001
Messages
346
Hello all,

This is my first time post into this group, but have been cruising around here for a while, picking up information. I've never used a Balisong before, but thought it was time to give it a go.

I therefore went out and ordered a BM42 the other day. When I got it I found that it had some, what I considered to be bad casting, imperfections on the surface of the machined handles near to the pivot area (I have a backgroundin Mech Eng). They are bad enough to see black indentations in the titanium - one is about 3/4 mm long.

I've already posted a question regarding this to Chuck Kollnick, who tells me that minor imperfections are normal. I'm sure this is not "minor" - at least no to me. Qulaity production io

I was wondering whether any of you had seen or come across similar "defects" in the BM42 handles. I'm not at all pleased about this - not what I consider to be quality manufacturing practice.
 
I have one small "airpocket" next to the pressed in pivot pin on the safehandle of my BM42A, which worries me a bit.
 
Welcome to the forum. Would it be possible for you to post a picture for us to see?
 
Unfortunately I don't possess a digital camera. :( I thought about it at the time, and realised that this would obviously be have been the best option to take - then everyone could "see" what I meant.

A friend of mine does have one, but I was so displeased, that I promptly shipped the knife back to the shop, via courier, where I ordered it.

I even went so far as to speak to a Materials Engineering Professor at the local University about the quality of items produced by titanium casting. He told me that modern production techniques are extremely good and should virtually rule out all of these types of problems - which were more commonly found in earlier sand casting production ... where porosity was a big problem with the resulting cast.

If I get a chance on another - I hope not! - I'll take a picture and post it.
 
I hear ya dude, I have a deformed latch on my model 42, I emailed Travis @ benchmade and he said to send it back and he'll make it perfect. I'm waiting for my model 43 to arrive then I'll send the 42 back. Hate to be without one.
 
My BM42a came from the factory with perfect handles. A loose tang pin, but that was fixed. I have yet to see one of these defects. If someone has pics of deformations, I'd be interested to see them.
 
Usually the casting imperfections are seen when you cut into the Ti, like if you were to make a 42 latchless you might see some little "holes" in the handle, that is one of the huge problems that BM is facing for putting out production latchless (LL) Bali-Songs.
 
My 42 has 4 of these casting imperfections in the handles and 1 in the latch, that I could find. Unfortunately, I don't have a digital camera, either. :(
 
Here's the scans of my Ti imperfections...

It's so close to the latch pin, that I'm a little worried, too.

You can also see how I've rounded the bottoms of the handles for less palm bite, and rounded out the latch..

View
View
 
I have these imperfections on the handles of my 42 as well. There is one in each handle right under the pivot. I didnt really think anything about it until I read this thread. What Ti alloy does BM use for these handles?
 
I've got one or two of those, a big black scratch on the side of the latch, and a dent in the inside edge of the handle that is rounded like a bit of filework... except that it's not filework. It was rounded off, not rough, so it's clear that it was noticed, too.

I think I made a note of this before around here, too... I find it hard to swallow not really because of the brice of the knife (though it should be near perfect for $180 retail) but because of Benchmade's talk about .0005" tolerances. If their machining is so good, why is the handle so... unfinished looking?
 
Hello Dragon2.

It sounds as if you have the same defect as mine. If you look at the handle (knife is locked open) around the area where the tang pin sits(when the knife is closed). Just below this "tang pin location" area and to the left slightly I have an "L" shaped recession (defect). It is apparent on both handles in exactly the same position. One side is much more noticable than the other.

Small "pitting" marks which have already been commented upon in this thread seem to be random. The biggest problem I have is that like yourself these marks in exactly the same place - they are'nt random and they aren't small (ie 0.5mm say), though any good book an fracture mechanics will tell you that you don't need a big defect to incur a fracture when you take into account fatigue stressing.

I don't know what the Ti Alloy is, but I'm gonna find out.

The scans supplied by Blade_420 are very similar (if a little smaller) to the ones that I had.

The question really is, if you can get these sort of defects in the material - visible to the naked eye - when the material has been machined, how many more could there be inside the material hidden from view?, and what effect may this have on the long term life of the knife? As far as I know the BM42 has only been retailing for about a year.

Using Ti casting is not the same are using Ti billets which are forged. Perhaps this is why Microtech (as far as I can determine) have gone for a full machined TI handle from a forged billet rather than a cast. However, it may also be due to their more "squar-ish" handle design ... similar to Ralph's Gemini.

I'm not too sure about most, but I personally expect a lot of quality from a $150 retail knife - especially when it comes from a reputable manufacturer.

Just as an aside (and I know it's not really applicable in a balisong forum, but thought I'd mention it anyway):
1. I've had no quality issues with the Korean manufacture of any of the CRKT knives ... and they're a 1/3 of the price.
2. I'm having a similar "quality" issue with the Leatherman Wave.
 
I'm with you, Joe, about the CRKT knives. I'm very impressed with the quality they can produce for the prices they charge.
There was even talk of them making a balisong, but I think that they ran into the same US Customs problems that lead to the discontinuation of importation of Taylor, Parker, Valor, Frost, Compass, Star, and a lot of other sweet balisongs from the eighties.

I have five CRKT knives, and I can't find flaws on any of them.
 
Hey Joe90, that pretty much identifies my problem. Like I said, I found them when I got the knife in the mail, but didnt think anything about them. I have some interesting bits of info on casting flaws I thought I would post. Generally, up to a certain size, they are allowed. Even in cast parts for cars, where failure could be catastrophic, there is a certain amount of porosity allowed, although its very low. I talked to a fellow in Boston about 2 years ago whos full time job was x-raying cast auto parts and looking for these flaws. Perfection is rare, and I am sure that the Society of Automotive Engineers, or whoever decides whats allowed, permits a small amount of casting defects. I have x-rayed some welds on stainless tanks, and a certain amount of imperfections are allowed, based on how thick the base metal is. The real point is that imperfections are allowed in parts or joints that are considered critical and that are under much higher stress than a balisong handle. It should not be surprising to find that there are casting flaws in a knife handle. The next time I have an x-ray job, I'll take my BM-42 along and see whats inside the handle. This may be a while, but as soon as I can, I'll let you all know whats in there for sure.
 
Dragon2,

What I find interesting is that the exact same defect is in the same place on both knives! ... a random defect?

You may be able to pick up internal defects with ultasound as well, though my knowledge with Non Destructive Testing methods is not high.
 
I'm a big fan of ultra sound. The equipment we have is not well suited to testing parts as small as we are talking about here. A co-worker used to do NDT for the Marines and they had some more verstile ultrasonic setups.
As for the same defect same location, I don't know how BM casts the handles. Maybe the ones you and I have were made on the same mold, if they use a permanent mold system. Once you get set up and start casting, a defect that occurs on a particular machine could occur over and over. Then again, they may be using a disposable mold of some kind.
I reread your post about where the flaws are, and I think mine may be on the other side, due to a misinterpretation of your description. Mine are at the bottom of the window that the hilt/guards pass through on the outside, visible when the knife is locked with the blade inside the handles. Let me know if the flaws are indeed in the same place.
 
Hi Dragon,

No, yours are on the other side. On mine, when the knife is locked with the blade in the exposed position, the defect is below and to the left (thogh quite close) to the area where the tang pin rests - when in the folded "safe" knife inside handle position. Not the same position. Wonder why BM didn't just machine them from stock?
 
I believe it was CRKT about which there was an article in Blade a while back (have to check). They were raked over the coals big time by U.S. Customs (in Oregon I believe), for a one handed opener because the pivots were too loose. The agents were even practicing opening the knives with a flick so they could call them a "switchblade" or whatever would be illegal. This might well sour any thoughts CRKT had about balis. While we all appreciate the job law enforcement officers, including customs officers, do in protecting us from things that can harm us, pocket knives including balisongs would not be on my list of items from which we need protection.
 
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