Screw attached scales?

R

Remyrw

Joined
Jun 17, 2010
Messages
1,054
I was thinking about doing some countersunk screws to attach scales to a full tang blade but ran into the minor issue of the blade only being so thick. I can't see getting screws in from both sides and having a solid hold.

I see two possible solutions and maybe there's others out there folks can suggest.

1. Offset the screws so there's one set of holes for each side, threaded to match the direction needed. For example, a setup with two screws per side plus a thong hole would mean drilling five holes and tapping two from each side for the screws. It seems this would be an EASY solution, and work just fine, but it means things aren't symmetrical. Depending on the design that might or might not be ok, also depending on the screw size and design. A small and subtle screw where the offset is around 1/4" is less distracting than if I use larger ones where I might need as much as 3/4".

2. Drill a larger hole for a threaded sleeve that is threaded for screws from both sides. I'd drill the scales almost like a reverse corby situation so the sleeve could fit into the scales enough to give room on each side for the screws to firmly anchor. The only downside I see to that option other than the slightly more complex setup, is that it doesn't work so well on thinner scales, like a 1/8" or 3/16" textured material like G10, which is where the original idea started. The sleeve would either be a snug fit into the hole or somehow made permanent via solder or epoxy.

Ideas, suggestions, other methods?
The goal is a easily removed or swapped handle design on an edc type knife. I might scale it up for larger designs, but then the threaded sleeve is less of an issue on width, and most likely there'd be some epoxy involved too.
 
Well dang, that's pretty handy, I won't have to scour hardware stores at least. How solid does it lock up, well cut threading? I don't think I'd risk it with 1/8" thick scales, but anything thicker should be good enough. Maybe if I really wanted the 1/8 I could just not countersink.
 
Not sure what you mean. Some production knives (RAT/ESEE)that use this dab a bit of thread lock on the crew tip to lock them down. Mine seem to snug down nicely; I wouldn't wory about them loosening.
 
Well, if the threading is sloppy, that short a depth isn't always so secure. It sounds like these are well done so no worries there.

Thanks guys.
 
#2. If you have a lathe then make em yourself. I purchase some 304 SS round stock slightly larger than the diameter (relative term there, depends on the application what "larger" really is) of the screw, true it up a hair, drill, tap, cut to length. I make sure that I cut the diameter as close to the true diameter of your holes in the tang as possible, and the holes in the handle are as close to the major thread diameter as possible, helps with getting stuff to line up when dry fitting and shaping the handles. This also applies to the clearance hole in the handle for the sleeve if the scales are removable.

As long as you are not making the scales removable, the function of the glue is to hold the scales on, the screws are there to stop shearing forces. So, you do not necessarily need the screws torqued down to 400 ft# of torque with 7 threads engaging per screw. Thread locker will hold em in. But if you are not using glue, make the sleeve longer.

My only problem is I have to make a couple at a time cause I drop the little suckers and lose em in the pile of crap on my shop floor!:grumpy:
 
Last edited:
How thick is your tang? If it's 1/8", that's plenty of thread for 4-40 or 2.5mm from both sides. Way too thin for 8-32. The item mentioned earlier is 1/4" long. If your tang isn't this thick, it really won't work. If it's 1/4" thick, why not just thread the tang itself for 8-32.

I really like the 2.5mm screws because they have a nice 3/16" head and much finer threads that the almost same sized 4-40. Although, you can get a 4-40 tap just about anywhere, but you have to order a 2.5mm tap.
 
I was leaning toward the 3/16 ones, and if i go with thinner steel I could counterbore the scales a bit. I am skeptical about how well the 4-40 would hold, since on the smaller ones it IS going to be no glue, at least that's what I'd like. I will just have to test it, not the end of the world, if it doesn't seem secure enough I just continue from there to the larger diameter hole, put the sleeve in and finish up.

Part of why the sleeve is attractive is not having to be so careful about only threading half way. It's easier to drill the proper size hole and secure the sleeve than carefully tap every one half way from each side, at least for me.

No lathe here, I still don't even have a drill press or bandsaw. I'm planning on picking up either a cheapo at HF for short term use while I hunt around for a used good one or if I get lucky on craigslist or a local swap group I'll pick up an older delta or something. I know I won't be able to drill larger diameter holes in steel with the cheapo, but as long as I respect its limits I should be ok for my needs. If I really need larger I have access to a big industrial unit, it just isn't quick access. The bandsaw is being delayed for now, an angle grinder will suffice for the moment. I've seen cheap bandsaws fail, I'd rather just wait and buy at least a mid level unit.

Oh, oddly enough, I have a bunch of 2-56 screws and the tap so I could certainly use those, but they're a bit smaller than I had in mind. If I go that route though I might do a pattern like you would with a 4 or more pin handle design. Again, with no glue on a thin tang I'd be worried about it, but if I just treat it as a pin replacement method and glue things it'd be fine. That would be ideal in a situation where I wanted to put 1/8" textured G10 scales (or titanium) onto a knife.
 
Last edited:
okay, so I am drunk so bear with me. First things first, you will not have enough threads tapping the bare blank to hold scales without glue. I mean they will hold for a static view but if you have any shear load the threads will pull. MAybe not first time around but it will pull. There is not enough for both bolts on either side.

You would be surprised how 2-56 button heads look on an average sized knife. Right now I am working on a steak knife with .300 long sleeves and 2-56 button heads.

HEY, if I am wrong somebody lemme know!! I appreciate the correction.
 
Ok, in order.
I'd have to tap from each side because a screw is *break, full stop, collapse to floor laughing at myself* ok, now I feel really freakin stupid. For some reason my brain was picturing it with the threading being opposite from each side, not sure why I was, but once I got that idea in there it just didn't get examined again.

For Gixxer, you're very right if the knife without glue was anything particularly large or meant for rough use. The initial concept was for a small and relatively delicate knife, thin was the goal but also removable handles so they could be changed at will. After all the suggestions and questions here I'm starting to think that if that's the desire I'd be better off with offset holes just because going that thin isn't going to allow room for the screws, but if I start with a thick enough tang and just grind down the blade a bit I'd be ok.
Past that, I also like the screwed on idea for larger stuff, but in those cases it would be glued at the end. The screw attach method would be a way to put them on, shape and then remove to do a coating on the blade and tang. I spend a lot of time in and around salt water, even stainless has issues, but if I completely duracoat the knife it'll survive a bit better. Still need to oil the edge but I also plan to work on a sheath design that helps that. After coating and the finish is cured the handles would be epoxied in place in addition to the scews.

It's all very conceptual still, I haven't even fully tested the durability of the coating on a blade. It works fine on other stuff, and in theory the one I'm using is flexible enough to not crack or chip on a knife, but we'll just have to see.
 
I have used screws and threaded inserts on knives that were going to be parkerized, wherein the scales have to be pretty much finished before the final mounting because the blade is already coated. I used the 3/16" threaded pivots (1/2" long) and the 6-32 button head screws from the folding knife parts page on Tracy's site. The screw heads are a little over 1/4" and the pivot barrel (threaded insert) is 3/16", so the tang and scales have a 3/16 hole bored through and the scales have a counter-bore of a little over 1/4" on the outsides to let the screw heads sit flush or a little below.
The 1/2" insert goes into the scale on either side of the tang and takes the sheer forces, the screws essentially act only as a rivet head.
 
Remyrw: I know, it messes with the mind some times. Don't try to figure it out, just have faith that you can put a bolt into a nut from either direction. I agree with Gixxer that there's not enough thread to hold with bigger sized. However, you wanted removable scales that you could change. I don't think even 2-56 or 2.5mmx.45 would have enough thread to not strip out after a few changes. However, if you're set on removable scales that could be changed, I have an interesting idea. First, you need a couple pins for alignment through the tang into the scales. Then use a small neodymium magnet in the tang and steel decoration in the scales(maybe just steel wires glued inside the scales). Magenetic scales!!!!!!


Gixxer, you know what you're doing a lot more than I, but is there an adverb missing in this sentence? They look, big, small, green, something? Or just how they look?

gixxer said:
You would be surprised how 2-56 button heads look on an average sized knife.
Click to expand...
 
Last edited:
I said that with the meaning that even though it is a button head screw it is small enough to not become the first thing that stands out and overpowers the flow of the knife. You know, like a nice slim knife with big honkin corbys or flat head screws? Just my opinion there on that one. Corbys are not that bad but depending on the knife super wide flathead screw heads detract from the flow of a knife.
 
Last edited:
You must log in or register to reply here.
Back
Top