Anodizing Titanium with Detent Ball


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Okay, my fellow liner lock makers, I have a question for you regarding anodizing. I use 6al-4v titanium on all of my liners for many reasons; chief among them is its ability to be anodized. I love the way you can play with the anodized colors to contrast or compliment with scale material.

I anodize my liners as one of the last steps before the final assembly of my knives. At this point, I have the detent ball already pressed into the liner. So the problem happens during the anodizing process. As the liner is being anodized, the stainless detent ball is being etched at the same time, which takes the smooth surface of the ball noticeably rough as it rides across the blade tang, which is completely annoying. I have tried coating the detent ball with nail polish (don’t tell my wife ;)) before anodizing, but that didn’t solve the problem. I have resorted to masking off the lock bar after anodizing, cutting off the tape to expose the detent ball, and buffing the detent ball to return the high, smooth polish.

Does anyone have a better process that they use which works for this situation? I am basically a self-taught maker, so I would love to know how others tackle this procedure.


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Brandant, I set my detent ball after anodizing, on the one side I place a Teflon washer the thickness of the washers your going to use and a small hammer with a polished head to tap it in from the other side, with masking tape on the bottom side of the liner except along the locking bar, it works for me and I've never had any damage to the anodizing.


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Thank you for your response, Steve. I thought I might be putting the cart before the horse. I wonder if I can ask you for a little clarification of your process of detent assembly. I’ve made about a dozen liner locks now and am constantly working to refine my techniques and getting closer tolerances. My process goes something like this.

I set my detent ball in the lock bar, and then use the ball to locate and drill the detent hole in the tang of the blade before heat treating. After heat treating and finishing the blade, I grind the lock bar face back (I leave the lock bar a little long for fitting) until I get the proper lockup. After everything is fitted and tweaked, that’s when I anodize, and that’s when I run into the problem.

Would you be so kind as to describe your process a little more in depth? I would appreciate understanding your technique a little better if you are willing to share.

Does anyone else have a different approach on handling locking mechanism?


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Brandant, there's a few different ways to set the detent ball. I have read and heard that the ball should be placed just past the track mark on the blade so it actually gets pulled into the hole. this is tricky, at least to me. when you get it right it works perfect, if you don't...well the pain of making folders just intensified. I would also like to hear from other liner lock builders to hear how they do it, but this is how I set my ball.....
first, my knife is complete, blade heat treated finished and ready to be put together for good other than the lock fit up AND anodizing the liners.
next, I locate where I'll put the ball in the liner and drill a #60 hole using a carbide bit, here you have to be careful because later I go back and drill that larger with a#52 bit for the 1/16" ball so I want to make sure the #52 bit will have room on the lock.

Next, I assemble the knife except for the scales, I then close the blade tight and drill thru the existing #60 hole with the #60 carbide bit into the blade for the ball to fall into when closed.
next I disassemble the knife and then enlarge the #60 hole in the liner lock with a #52 and THEN prep and anodize the liners after that I and set the ball like I wrote earlier.

here is where I think I do something a little differently...
the #60 hole in the blade will have a tiny burr around it, I drill into that hole with a 1/16" carbide bit that will remove the burr and enlarge the hole just a little. and when I say drill, I mean I just touch into it a little, opening up a tiny bit. remember, the full width of the ball isn't going to go in it so if you go to far it will be sloppy. I enlarge the hole just so the wall of the hole will pull the ball in. and that's it.

this works perfect for me and seem's to rid some of the stress of getting the ball right. after this I set the lock to the blade.
the folders I build going this way close perfect, the ball pulls in and holds the blade closed nice and firmly.
I hope this works for you if you try it. Steve.

Note: this is assuming your using 1/16" detent balls, I also usually do a test run with the particular #52 bit I'm going to use on some scrap TI. to make sure the fit is right for the ball.


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Steve, thank you so much for your insight. I have always used the sharpie marker on the blade tang method where you color in the tang, work the blade open and closed a few times to see the detent track. It’s always been a royal pain to get the hole drilled in the tang in just the right place (slightly passed the stopping point of the ball) to get a good, tight lockup. I’m going to have to give your method a try with my next knife. I really appreciate you taking the time to explain your technique. Do you happen to have a source for a #60 carbide bit? I’ve never been able to find a carbide bit smaller than 1/16”.
Are you using ferric chloride for etching or some other acid? I can't say I've ever seen this ball detent problem and I have it installed before colouring. Frank


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Did you mask the ball with nail polish on both sides of the detent hole? The trick is actually letting the nail polish dry and putting it on thick.
Thanks for weighing in. I did try that a few times, but I never got it to work very well. It never seemed to protect the steel ball very well for me. Recently I started using ceramic detent balls. Problem solved! Simple solution, plus the action with the ceramic detent is noticeably smoother. It's a win win solution.