Handle Strength Testing - Corby Bolts & Epoxy Only
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- Опубликовано: 4 июл 2024
- I've been looking at new ways to attach the handle scales on my knives, in the past I've been using peened pins but I've been having issues with the peening process discolouring the G10.
I found a new fastener that I wanted to try out (Miniature Corby Bolts) so this video details the testing process.
I've had a few people ask me why I don't just use Epoxy by itself, I've tried this in the past but it didn't stand up to my testing very well... I test this again in this video, but with some surprising results!
When you started REALLY cranking on the handle, I couldn't help but squint and turn slightly away as if you were actually doing the test right in front of me!
Chris Moore Yeah it's definitely a little scary! Safety gear definitely recommended!
Nice to know I wasn’t the only one
I was amazed at how far the knife bent and returned to straight before finally snapping. Good test video Aaron. It is also proof of your quality product.
Thanks very much mate!
Awesome work on another fine video with a more technical aspect than most, always appreciated!
Very interesting to see the stress' affect in a prying scenario. I'm amazed at how much force it took to break the blades. As an amateur knife maker, I really appreciate you sharing your experience. Thank you!
thanks again for a useful tip! i'm used to 'scratch' the tang and micarta scales with a dremel before applying epoxy [and writing some enchantments on it for good measure] but i'll certainly try this. cheers
I found this after watching your knife steel test. Such a good video. I just did my first knife which turned out really well CPM3V. I had made some cutouts in the tang. When I was making the scales I oiled the blade and clamped one scale at a time to the knife and poured epoxy in the voids. This created a vaulted scale which fit structurally into the knife.
I did this for two reasons. I had problems with a Esee LS's scale moving when I would batton. I also did this so I would not have to glue the handles on the knife as it is a survival knife that I wanted the handles to be changeable.
Second I used Titanium flipper pivot bolt assemblies (you could use stainless or whatever). These bolts had a large head which really clamped the scales down.
SO I have a vaulted mechanical structure holding the handles from side impacted. This also gave the handle incredible strength from the scale flexing independly from the tang.
I also have extremely secure fastening from the scales moving in the same manner from the Hardware I used.
I highly recommend this type of assembly for certain must be tough blades. I have had the blade flexed to 50+ degrees with absolutely no handle separation. I also believe this construction replaces any strength loss by my machining of the tang. I pounded the knife in a tree and stood on it infront of my friend and bounced. I weight 190lbs.
You are a true craftsman who test their work.
Thanks mate! Sounds like you have your handle setup well sorted!
Idea for Cranking the handle next time use a pipe. when the blade breaks it will break inside the pipe keeping most of the shrapnel from flying in your direction. Also it will keep your finger safe from the blade when it finally gives way. Though I do understand the importance of us being able to see the blade bending and see how far you have to go to exceed its limits.
Dang it hurt to watch u do that to such a beautiful knife.Dude your skill level and knives are awesome. HUGE FAN.
That green micarta/g10 handle is gorgeous! Almost didn't wanna see it destroyed.
I actually used the micarta accidentally, and am not personally a fan... This is what it was supposed to look like: imgur.com/a/05AJZ
Yes i agree they did perform very well . I don't think anyone would put a good knife through that but you never know great video i am a fan of your work.
I would generally expect that my customers never do anything like what you saw in the video... A knife is not a pry-bar for sure. For me it happens to be a convenient method of stress-testing my knives, and also if someone got in a jam and had to abuse their knife in an emergency I'd like to know that it will be up to the task!
Thank you so much for your informative videos! I am about to take on making my first knife and I really like your methods. You are a good trainer! keep up the great work....and videos! I might be back with questions when I get going!
Thanks mate! Glad you liked the videos!
I'm not sure if someone's already suggested this, but in order to allow the epoxy to hold to its max. potential, I've seen guys drill several small holes through the tang and little craters in the handle to form "epoxy rivets"
Hello again Aaron,
My apologies for asking a question that I could very easily, and did Google. I found the Corby bolts along with the step drill bit however I would like to thank you again for your very concise and informative videos. You are a great teacher!
Ken :-)
+ken barker Hey Ken! As you found I do drill a stepped hole. I used to do it with the step drill like you saw, with the CNC now I do it with two separate tools, but that's not really a process you can do by hand....
Gough Custom Ahhhh yes....I'll bet that cnc machine sends your accuracy through the roof. Thanks for getting back to me man.
Have a great day Ken :-)
+ken barker It sure does! Been very useful so far!
Thanks for the information. Your videos are very helpful.
Greetings from Utah. Wow, looks like you've got the heat treat part figured out pretty good :-)
Thanks! I tempered those blades a little higher than usual (475ºF) so they'd pose more of a challenge for the handles :D
Another great informative video. The strength of your knife is amazing! I hope you will offer a stainless version soon. The market is ripe for an all environment all around brushcraft knife. Shalom!
+aHigher Power Thanks mate!
Good test lol. Scary to watch but hay it works.
keep being awesome!
Cheers mate!
I bought a enzo that I how to assemble the handle myself. It came with the corby bolts as well. I used epoxy in the threads as well then I sanded the screw head with a file so it looks like a pin now & is super flush with the scales. It is holding up very well thus far.
Sounds like it will last practically forever!
Yeah its the same as you're doing now. Just wanted to let you know it's working well for me so far. Then again I dont stick'em in a vice lol
John Kenneally Haha, yeah not trying to deliberately break your knives definitely makes them last longer :D
Lol yeah well @least we have you for that. Helps me understand what a steel capabilities are alot better
John Kenneally Always glad to be of help!
Man, the knives that you broke make me cry. You're super great at knifemaking!
Thanks! They perished for a good cause :)
true enough, for the better.
I think it would be interesting to try a threaded pin.
Pins + epoxy means you have adhesion in all 3 dimensions. Its my personal opinion that whilst epoxy did well in the short term, without pins it only has adhesion, and not compression (from pins glued in through the tang). The second you get a little entrance point and things start to corrode, or a little stress crack in the epoxy from heavy use..... the knife has started on the road to failure. The glued pins add strength in all three planes, and minimize how much a small failure can progress to a serious one.
Personally I would rather have 2 hex bolts than just epoxy. Its just glue after all.
Yep, overall I agree with you. Your arguments are the reason I've never used epoxy by itself on a knife that went out to a customer.
Glad it made some sense, Im not from an engineering background so wasn't sure it was intelligible.
Hey, I remember you talking about this on bladeforums.
Yep, the thread on BladeForums was what prompted me to do the video!
Aaron I know this is an old video, and maybe some other person has already addressed this, but when you wet sanded before the epoxy test you got what's called mechanical adhesion, the epoxy had something to really bite into, now imagine the grip if it were 80G on both the steel and handle material!
In my opinion knife makers finish their tangs too fine, they finish them to the same standard the rest of the knife is finished to. It's a matter of pride I know. I on the other hand rough grind my tangs and handle material so the epoxy has good bite 'mechanical adhesion' , when you add Loveless or Corby Bolts to that, they are not coming off unless run over by a tank!
Hey mate! yes I hear you completely! These days when I'm gluing something like this I usually sandblast the glue surfaces as that gives the best mechanical bond!
Aaron, I have retired out of the nuclear power industry and the epoxy we used was some really tough stuff. It is called Barco Bond. I used the last of my Barco Bond on a knife handle of plastic and it has held up fine for bushcrafting. I have not abused it like you did breaking your knives. Astro Chemical makes the Barco Bond.
+K5KE Cool mate! I will check it out!
Great video, thanks for the upload. What type of epoxy do you use? Also, did you rough up the scales and tang before applying the epoxy?
I love your videos and I am going to start making my own knives soon because of your videos. I live how you use no machines or anything else. I am so inspired. Would you please show a video of how to make a forge like yours or where I can buy something similar. I have looked online and have only seen fancy ones for several hundred dollars. I would like to send you my first knife
Hey Dan!
If you Google '2 brick forge' you should find instructions for making something small and cheap.
Very kind offer to send me a knife, but really not necessary. Give it to someone you love and have fun making more!
-A
Top notch
try soldering tungsten onto the edge of the knife it makes it lot stronger and keeps the durability to. Mine cut through glass!! This process is before you grind of corse
Hi Aron have you ever tried cutlers rivets. There is a flat head and a male and female end which go together and are a extremely tight fit. You have to hit it with a hammer to put them together. I love using them. Only bit I fin hard as I don't have the right tools is getting the countersink step right. You won't have the same problem as the peened rod because they are flat not like a cone.
Hey Scott! I have not used cutlers rivets in a long time... I would like to try out a modernized version of them at some point though!
Thank you a lot for the detailed insights in your testing. "Wet sanding the epoxy into the tang and scales" - Could you please explain this to me? What I know is: Roughing the surfaces of the tang/scales with 60grit sandpaper (crosswise or diagonal patterns) will give the epoxy more "bite". Some people use a wire brush after they apply the epoxy in order to "work" the glue into the material... Is that basically what you meant or do you use sandpaper to do this?
Basically all I did was to clean the surfaces thoroughly with ethanol to get any oil off them, then I applied the epoxy. I then used a piece of 150 grit sandpaper to sand the epoxy into the surfaces...
If in understand the physics properly it's probably actually better to use finer sandpaper, the reason being that finer sandpaper creates many small scratches instead of fewer larger ones, and many small scratches will have a larger surface area than few big ones... Glue bond strength is really about surface area if all other things are done correctly. Sand-blasting is the best way to prepare the surfaces for gluing, but failing that wet-sanding the epoxy in seems to work very well!
I'd recommend you try gluing some small scraps of metal to scraps of your handle material using the different methods and see what works best! It's fun and it's a great way to get a sense of the differences...
Nice
Hello Aaron,
I believe that's what I heard you say your name is. Quick question please....do you drill a stepped hole for the corby bolts as they have two different diameters in the shaft?
Thanks Ken :-)
O1 tool steel holds up pretty damn well to that bend test. It's goes to like 60 degrees. Going to make some chief knives out of that stuff.
+Karl Rosner Hey Karl! Yes O1 makes good knives when heat-treated properly!
Hey just a question, how do you get that grey shading on the knife blade, you'll see what I mean if you look at part 4:40-5:-. Great knives by the way I like em
Dear Gough,
Epoxy has to do a lot with the surface of the Two things being glued together,
To create better bonds you could Drill Extra holes (Even if small) On the Blade,
and put partial small holes on the Inner side of the scales, so the Epoxy would have the knife to attach to, and it could work into all the crevices. I actually enjoy Paracord handles also, and I've seen Mike Snody, Soak his Paracord handles on an Epoxy, To make a Hard handle out of Paracord, I hope this helped,
Thanks for your time.
-F-Knives
Thanks for watching!
Adding holes to the scales or tang only increases the surface area a marginal amount unfortunately. The strongest glue bond that I've tried so far was achieved by sand-blasting both parts before glueing them together. The etching created by the sand-blasting creates a huge number of new surfaces and allows a very strong bond.
I didn't show the sand-blasting in the video because that's not equipment that most people have access to...
-Aaron
GreeenApplez I ended up buying a KMG grinder, I like it very much but it's definitely quite expensive... I hear the 'Esteem' grinders that are sold through BladeForums are also very nice!
Gough Custom Thanks, I Saw some Prices and I am Stuck on that huge Price, they seem Worth it though..
GreeenApplez The other thing to watch out for is that there's a BIG learning curve with using a grinder, even when using a good jig. It took me 12 blades to get a decent grind doing it by hand, and then when I switched to using a jig it still took me 2-3 blades before I nailed it... So that was about 15 blades in total that were not good enough to go out to customers. Luckily I have used them all for testing so they've served a purpose.
Well, many people have a Jig for an Angle, but not for Depth, So usually people go way far into their grinds and bevels, have a constant angle(that is just the tilt of the table), and a a piece that stops it from going to close to the belt, (another piece) Best of luck!
Love your scientific approach to testing. Do you have access to West Systems G-Flex? Some of my canoeing friends swear by G-Flex and West suggests it for dissimilar materials.
I wonder if sanding the resin into the blade and scale might leave some residue that could degrade the bond? Just brainstorming.
I haven't tried g-flex, but this is the 2nd or 3rd time I'm hearing about it within the course of a few days so it sounds like maybe I should have a look at it!
West Systems actually recommend wet-sanding the resin apparently, it didn't look like it left any residue to me, and that was a pretty strong glue joint!
New ideas are always good :)
Gough Custom Interesting.......But the Gougeon bros know their stuff. Good luck in your testing!
Would having a bolt of a thicker diameter and bolt shoulder in the position closest to the ricasso help at all? It could possibly support a greater load than the skinnier corby.
It would definitely help! I'm pretty happy with how that little Corby performed though, given what I did to it!
I'm likely going to move up to the next size of Corby fasteners which should be stronger again.
Another nice video!
Did u acid-etching this "test-blades" ?? its dont look like a satin finish ? :)
In this case they were actually sandblasted.
Do you leave the bolts sticking out of the handle and then file down the drive ends? Do you epoxy or loctite the threads of the bolt? Is it easy to figure out how deep to drill your shoulders.
BTW thanks for all your videos. Please consider my annoying questions a complement to the value of the knife making knowledge in your videos and that noggin of yours.
RocketCityGardener That's correct. Drive heads are left sticking out and then I grind them off. A bunch of epoxy gets into the threads during the assembly process, and I think that should be sufficient to prevent any accidental undoing. I've actually got a bolt back at the shop that I screwed together while it was full of epoxy and tonight I'll get to test how good it is at preventing the bolt from coming undone...
Drilling the shoulders the right depth isn't too hard. Basically I just worked out how deep the socket on the fastener was, then drilling the shoulder 0.020" deeper as insurance.
Atomedge here, this is good news as the knife I'm making with Weebus is based on Corby Bolts as well as Epoxy with a black micarta handle. This is great news as far as durability goes.
Hey mate!
I was using the tiniest Corby bolts for this testing too, any regular sized corby will be even stronger!
-A
Which West Systems Epoxy do you use? a 105 resin with a 207 harder? And do you use a filler? Thanks for the interesting video!
I'm using West Systems 105 with the 205 hardener. It's slightly amber colored, but in thin layers it's plenty clear enough for the tiny glue-line that you'll see on a knife. I'm not using any filler, as I understand it the fillers are generally only needed when the layer of epoxy is thick, to add mechanical strength. The glue layer between the handle and the scale is only 0.001" or less, so it shouldn't need a filler.
That said it might be interesting to try a filler and see how it goes! Although I think most of them have a strong white color, so you'd have to add a dye to the resin to hide the filler.
Fantastic! Finally a product for Knife making that they actually sell in the Netherlands! Thanks for your advice!
Alexander Bol Good to hear! I they sell g-flex you might want to have a look at that too.
I ordered some G-flex as well: I read about it on BB forum, and i will use it for my knife with Oakenwood handles. I'll keep you posted about my results!
Alexander Bol Sounds good, I haven't tried it yet, but it keeps coming up!
Are you planning on doing a build video using the new parts?
Yes, I'm still ironing out all the parts of my new process but once the dust has settled I'll be doing a start-to-finish video showing how I make my knives now. New heat-treatment methods, Cerakote application, grinder & jigs, and more! All fun stuff!
Awesome. Very interested to see how everything holds up. Definitely wondering how cerakote holds up. I thought you had to bake it on so I didn't know if it would mess with the temper.
Bill Purvis I'm very sure everything should hold up well. The Cerakote will wear over time (as all coatings do) but it should do so gracefully I think.
Cerakote is baked at 250ºF which is lower than the 400ºF temper, so it won't affect the hardness of the steel...
Good to know. Looking forward to the the new vids! Also thanks for the responses, most famous RUclips folks don't lol
Bill Purvis Well when I get famous I'll make sure I stop responding :D
the stress the top fastener is under must be intense!
held up very good
Yes, there must be a lot of stress there! I would love to work out how much, but I have idea where to start on that...
I'm pretty sure the first fastener actually breaks in half at 1:57, but the fasteners were all bent a little during installation because of the tapered tang on the scrap blade I used. I imagine when they were installed properly they would be even stronger!
Gough Custom I bet if you added a washer between the G10 and micarta layers that you would not be able to break it off. You would need to mill a slight recess into one of the layers to place the washer prior to sticking them together. That may not work for your process as I don't know exactly how you are making your scales. Anyway great videos, I've learned a lot watching your process. Thanks!
HardWayLearnt The fastener itself looked like it broke right in the middle, rather than the head pulling through, so I don't think a washer would be able to help unfortunately...
Wow. Good to know. You had mentioned the comparrison with pins and the head of the bolt pulling out so I thought you meant both had done so. It makes me wonder if a longer bolt that engages more of the threads might have held up even better.
HardWayLearnt I've read in multiple places that as long as 3-5 thread are engaged then the strength of the thread-to-thread joint will exceed the strength of the material itself, so I don't think a longer bolt will help. A wider one definitely would though, and I may end up changing to a slightly larger bolt... Mainly for availability reasons, but it would also have the side-effect of being stronger.!
Gough were those fasteners brass if so maybe stainless would be a little stronger if the fastener broke.
Hey Michael!
The fasteners were 303 stainless, I may move to the next size up for the fasteners but I'm pretty happy with how it performed as it was!
I found that epoxy and gorilla glue without pins easily comes off a handle when the knife is dropped from shoulder height or a minor impact from a hard surface (hammer). However, pinned I don't see this issue.
Can you maybe show some tests on different epoxies and other adhesives (like gorilla glue)? I would love to see the differences.
Sounds about right... I really don't trust un-pinned handles. Even more-so I don't trust pins without heads.
Which is why Croby bolts are pretty much perfect in my opinion! Acorn bolts would be even better if I could find some in the right size.
What do you mean by wet sanding ?
Basically just sanding the epoxy into the tang and the handle scales with a piece of sandpaper while the epoxy is still wet.
do you think epoxy and hammer peened handles are strong and durable enough? I've been making knifes with with epoxy and peened pins
Yes, absolutely. I think they're very strong. Only reason I stopped using them was because they're a pain in the ass. I use corby bolts now which are about the same strength, but much easier to fit.
Thanks alot!
which west systems epoxy are you using ? I am assuming g-flex, but the thickened or not thickened version ?
AOS AIRSOFT I'm using their 105/205 system. It's much harder and thinner than the g-flex which means that clean up is easier. I would like to do a test with the g-flex at some point though.
Gough Custom Thanks for the help!
what materials do you use for your handels
+arrow vs Deathstroke I use a composite material called G10, it's great stuff!
+Gough Custom18:21
"+arrow vs Deathstroke I use a composite material called G10, it's great stuff!"
Thanke you
How much does a knife with about a 4 inch blade cost? With a common wood handle.
I don't currently do any knives with wooden handles, as G10 is much more durable, perhaps in the future I'll look into using some woods, likely the very tough ones like desert ironwood and such.
The 4" Resolute is about $300.
Where can I get some of those fasteners you are switching to?
Only 2 places I know of: Jantz Supply (the call them 'mini corbys') or JephCo.
The larger corby sizes are available lots of places.
Ok thanks
When is next video?!
Not sure yet. I took some video last night of the process of carving a spoon with one of my knives, but I'm not sure that's really that good of a video... I plan to have some others in a month or so...
Has anyone ever tested JB Weld only scales?
There's probably a forum thread out there somewhere!
@@GoughCustom I have used JB Weld on several knives now and it holds great. In gluing metal like a bolster or pommel to wood I believe JB Weld is stronger than West Systems.
Mr gough custom, I have recently started to make knives. I'm using o1 tool steel and homemade micarta Scales. I want to sell my knives... It takes me about 12-14 hours per knife. And I am wanting to sell them for 80$ (usd). Could u give me some advice to get my selling started?
Hey mate,
Well first things first I'd say you need to put your prices up. If you've got $30 in materials in a knife, and you're charging $80 for something that took 14 hours to make then you're only making $3.57 per hour!
If you're not relying on the money obviously you can sell them at whatever price you like...
Best points to help sales: make them as high quality as possible, make them as beautiful & functional as possible, get a website that looks nice, get the word out.
Lots of different ways to do all that, but everyone has to decide on those aspects for themselves.
best of luck!
-Aaron
How can I order one of your knives ?
Unfortunately my order list is closed for the moment as I'm totally swamped. If you'd like to be notified when my order list is open again you can sign up for my mailing list: goughcustom.us7.list-manage.com/subscribe?u=e68bfaf38703e9e806947e6a6&id=cfba35d5a3
Thanks!
Myself I like removable handles so that if they ever fail I can replace them myself.
That's fair enough. To get one of my handles to fail you'd have to be doing something pretty terrible to them... And if you do get them to fail then I'll replace the knife! My main issue with removable handles is that the gap between the handle scales and the blade tang is not sealed which creates a place for water and other contaminants to stick and potentially create corrosion.
Yeah I can see that being a problem for sure when the owner isnt sure theres a problem and down the road,crack,snap from rust etc. Much respect man,love your attention to detail. I wasnt being an ass,I love your knives,I was just thinking out loud lol.
Philmor Bowls No worries man! I always like to hear what other people are thinking, I may not always agree, but it's good as it makes me re-think my assumptions!
Waht will cost a blade without handels
Sorry, I only sell complete knives.
Sorry if you've already answered this, are you able to live off of the profit from your knives alone, or do you have another job?
I only make knives like 2 days per week, then the rest of the time I work a regular job. I imagine it would be possible to go full-time with the knifemaking, but I think it might suck the fun out of it...
Nnnoooooo dont do it!!!! I wld rather test it for you. Without breaking it I wld just carry it around forever if it holds up forever then ull know its good! This video is gonna break my heart I dnt know if I shld resume play. Lol
Haha, well take solace in the fact that both those blades were pretty ugly up close. I'd had them kicking around the shop for a while because they weren't good enough to use in an actual knife... I prettied them up a little for the video, but they were still pretty rough!
Lol still wlda loved one lol but none the less your videos are always awesome.
John Kenneally Thanks mate, glad you enjoyed the video!
Cheers!
that is one hell of a blade