MEMBER ITEMS FOR SALE
Custom Knives | Other Knives | General Items
-------------------------------------------
New Posts | New PhotosAll Photos



Go Back   The Knife Network Forums : Knife Making Discussions > Custom Knife Discussion Boards > Knife Making Discussions > The Newbies Arena

The Newbies Arena Are you new to knife making? Here is all the help you will need.

Reply
 
Thread Tools Display Modes
  #1  
Old 10-03-2006, 09:05 AM
skipknives's Avatar
skipknives skipknives is offline
Skilled
 
Join Date: Jul 2006
Location: Hattisburg Ms
Posts: 599
Glue groove

Hi Guys
Last week I read a post about adhesives and although it was 17 pages long, I read every word and want to say thankyou to our science team.
It lightly touched on glue grooves in the tang and from what I read some glues work better if they are a few MMs thick.
The gentlman that tought me about knives always cuts a glue channel in the tang and so do I.
But he felt that drilling hole through the tang for weight reduction was a waist of time.
But after reading about steel prep and the glue, it seems that a few holes through the tang in addition to the glue groove would allow the epoxy to grab onto the handle matiral of the one side and form a continus bond through the holes to the other slab (of a full tang knife)
The reason I thought about this is in the tests the guys made it seemed the glues held to the handle wood better the steel.
My point is to ask the more experienced guys how they construct and prep under the slabs of a knife and is there more thing that can be done to make a better knife in that zone. Skip
Reply With Quote
  #2  
Old 10-03-2006, 09:57 AM
SVanderkolff's Avatar
SVanderkolff SVanderkolff is offline
Moderator
 
Join Date: Jun 2002
Location: Mildmay, Ontario, Canada
Posts: 2,472
Skip
I always put at least a couple of holes through the tang for epoxy hold and weight reduction. I also usually make some grooves in the tang side of the slabs also for epoxy grab. I figure the more places that the epoxy can hold to all the piecs involved the better.
Steve


__________________
Stephen Vanderkolff
Please come on over and check out my website. http://www.vanderkolffknives.com/
Thanks
Reply With Quote
  #3  
Old 10-03-2006, 11:02 AM
B.Finnigan's Avatar
B.Finnigan B.Finnigan is offline
Living Legend
 
Join Date: Jun 2005
Location: Near Rainier WA
Posts: 1,986
I do 1/8" holes and use a triangle file to cut "bird beaks" into the tang. The holes and bird beaks should be in proportion to the size of the tang, no too big or too small. I also grind 36 grit grooves on the sides. The more surface area the better but also not reducing the mass of the tang any more then needed which would weaken it.
Reply With Quote
  #4  
Old 10-03-2006, 12:29 PM
JediOkie's Avatar
JediOkie JediOkie is offline
Skilled
 
Join Date: Sep 2006
Location: Oklahoma
Posts: 684
Good question! I've been curious about that as well because I had a catastrophic faliure of epoxy. Partly I think because I sanded the tang and wood smooth and also I didn't let it cure long enough. So also on this thread should we allow longer cure time when using channels or holes in the tang to allow the thicker mass of epoxy to totally set?


__________________
Jayson H Bucy

"Live so that your friends can defend you but never have to" - Arnold H. Glascow
Reply With Quote
  #5  
Old 10-03-2006, 01:10 PM
skipknives's Avatar
skipknives skipknives is offline
Skilled
 
Join Date: Jul 2006
Location: Hattisburg Ms
Posts: 599
the glue is usuely set enough after 24 hours to shape.
but after reading a post about a gent doing gold inlays,, he gouged "teeth"into the bed where the gold would be plied.
So i bought a 3/4" diameter drimal disc saw blade ($15.) and started gouging grooves in the under side of my handle slabe on algles hoping the glue would set in them.

also wanted to know how the K&G in house glue did in the final results of the tests, (it wasn't on the graph.
Reply With Quote
  #6  
Old 10-03-2006, 01:17 PM
skipknives's Avatar
skipknives skipknives is offline
Skilled
 
Join Date: Jul 2006
Location: Hattisburg Ms
Posts: 599
B. Finnigan said somthing about "bird beaks"
Sir, is that refurring too a type of spur / hook on the tang for the glue?
or are they extra cuts in the holes thenselves?
Skip
Reply With Quote
  #7  
Old 10-03-2006, 01:49 PM
B.Finnigan's Avatar
B.Finnigan B.Finnigan is offline
Living Legend
 
Join Date: Jun 2005
Location: Near Rainier WA
Posts: 1,986
It looks like this VVVVVVVVV along the tang but not quite so close together. I do it on both sides of the tang. They do not have to be more then 1/16" deep to grab enough glue.

Epoxy is temperature dependant on curing. I made some micarta out of denim and after gluing all the layers I pressed it in my vise. The average temp at the time was in the low 40's and it took just under three days to cure. I usually do my gluing in the house so it cures faster but the vise is in the shop. For a while I thought I may not have mixed it right but I decided to wait it out since each day is got much harder.
Reply With Quote
  #8  
Old 10-03-2006, 09:58 PM
tmickley's Avatar
tmickley tmickley is offline
Registered
 
Join Date: Jun 2002
Location: North Mankato, MN
Posts: 0
Interesting questions. I have learned that the better the surface is prepared, the better the adhesive works. I have seen epoxy 'rivets' snap easily from shear forces applied to the scale. I trust surface prep far more than 'rivets' of epoxy from my testing (not all of it was documented in that thread despite it's length)
Mechanical locks of epoxy with no place for the epoxy to 'get out of the way' like a hidden tang knife, effectively locking in the tang are clearly worth the effort and I do that on every hidden tang knife I make.

I do not make locks of epoxy on full tang knives with scale handles as I think the surface area lost to the rivet hole is better used for adhesive grip vs. 'rivet lock'. This is purely opinion since I never tested for this and I think it would require some fairly sophisticated tests to come to a definate conclusion. If some one would use rivets of epoxy, you would want to use big thick ones, 1/4" at least. Shearing off 1/8" rivets of epoxy is fairly easy.

I'd sure like to hear othe opinions on this one.
Reply With Quote
  #9  
Old 10-04-2006, 08:26 AM
DaveRuhlig's Avatar
DaveRuhlig DaveRuhlig is offline
Master
 
Join Date: Sep 2006
Location: Tampa, FL
Posts: 840
Great topic! I've always subscribed to the school of thought that the more surface area for the epoxy to adhear to the better. With this in mind I think adding holes, bird beaks, divets, etc. could only be helpful. I agree with Tracey though, I think the guys up at MIT may have to come up with a test for this to get any real conclusions.
Reply With Quote
  #10  
Old 10-04-2006, 08:44 AM
AcridSaint AcridSaint is offline
Guru
 
Join Date: Jan 2004
Location: North Carolina
Posts: 1,144
I could be totally wrong here, but I don't believe that putting holes in the tang will help glue bonding on a full-tang knife. I'd rather have a very very thin epoxy line than a glob that goes all the way through the knife because the more expoxy you've got the more area that you have succeptible to shearing. If you have enough force to shear the slabs from the tang then you've already destroyed the knife or the handle, imho. If the two, four or six expoxy "pins" are the only part still bonded in your handle then you've got problems aside from shearing anyways, like trapping water/moisture between the slabs and the tang. For a full-tang knife I say just glue and screw/pin it, not that I'm an expert or anything, just another guy with another opinion.


__________________
Cap Hayes

See my knives @ knives.caphayes.com

This quote pains me:
-- "Strategically placed blood grooves control blood spray in covert deanimation activities." --
Reply With Quote
  #11  
Old 10-04-2006, 08:28 PM
skipknives's Avatar
skipknives skipknives is offline
Skilled
 
Join Date: Jul 2006
Location: Hattisburg Ms
Posts: 599
Hay Cap
I respect your different view so lets you and I play a game of Point/ counter point.
and although you think I'm over thinking this, I'll reason out my point and then you interject your counter point. then someday we'll go drink a beer together.
Ok here we go:
The holes in the tang are ports or duct works to allow the epoxy layer on the left to join the epoxy layer on the right and sence the bond between epoxy and wood/bone is better with steel , we now have one mass of epoxy instead of two thin buttered spots.
and sence the epoxy fills the voids then the arguement of trapped water is minimal.

If you still disagree come back with your reasons cuz I might be spending too much work under my handle slabs,,but i don't think i'm waisting my time.
How say you?
Reply With Quote
  #12  
Old 10-04-2006, 10:11 PM
AcridSaint AcridSaint is offline
Guru
 
Join Date: Jan 2004
Location: North Carolina
Posts: 1,144
Skip, I'll take you up on the beer next time one of us is close enough to the other, if you come my way I'll even buy! Here is a little clarification on my thoughts from earlier:

The bond between the tang and one scale is the paramount issue, in my opinion, not the bond between two scales. When I mentioned water being trapped I didn't mean to imply that it would be trapped in the hole/groove in the tang, but actually between the tang and scale, just under the surface. What I'm saying here, is that if the bond between the flat of the tang and the flat of the scale breaks then you will have a place for moisture to penetrate, regardless of any additional bond between the two scales.

Now, as for the bond itself, I don't believe that this is stronger in any way, especially when compared to pinning or screwing. My reasoning behind this is that the material is not stronger than the metals we use to pin/screw, nor is it capable of providing the same sort of opposing force. Pinning or screwing will both draw the scales closer together and remove any gap between the tang and the scales, as well as evening out your glue line, something that glue rivets can't do well.

This is part of the reason why I say that glue channels and rivets don't help full-tang knives. If you are pinning or screwing then the forces that have acted to break those bonds as well as any glue bond on the tang are surely going to be enough to break the glue channels loose or shear them. If you're not pinning or screwing I still don't see an advantage because, by my reasoning, by the time you're relying on that bond it's already too late.

I'll go on to say that, in certain circumstances, I believe the glue rivets can weaken the knife handle. The reasoning behind this assertion is in the strength of the glue. Neither shear strength nor tensile strength have a linear relationship with the glue's mass and eventually the thickness (in my opinion just a few thousandths) reaches the point of diminishing returns. In most knives the glue is definitely going to be the weakest material for tensile strength and in many cases it will also have one of the lowest shear strengths, so in my opinion, it would serve us well to minimize the weakest material.

Furthermore, I believe that lateral forces applied to thicker pools, channels or glue pins will result in a bond failure much faster than if lateral force is applied to a thin, contiguous glue line across the entire tang, although I don't have any good research to back that up.

So, in my opinion, any gluing beyond relatively low thickness per square inch of surface is at best making a marginal difference to the positive and at worst adding another point of possible failure.

That's just my reasoning, I guess we'd have to call the glue manufacturers in for some good clarification. I'd definitely like to hear from you, or anyone else who thinks I'm wrong, because I want to make the best stuff I can, just like everyone else here.

Regards,


__________________
Cap Hayes

See my knives @ knives.caphayes.com

This quote pains me:
-- "Strategically placed blood grooves control blood spray in covert deanimation activities." --

Last edited by AcridSaint; 10-04-2006 at 10:14 PM. Reason: removed an extra "shear" in a bad place
Reply With Quote
  #13  
Old 10-04-2006, 11:47 PM
B.Finnigan's Avatar
B.Finnigan B.Finnigan is offline
Living Legend
 
Join Date: Jun 2005
Location: Near Rainier WA
Posts: 1,986
I regard glue as the insurance policy and never the one and only bonder. I have found the "v's" when done on a tapered tang act as a rivet if the the tang hole is slightly undersized. I work the tang hole so it slides up to 3/8 to 1/2". Then after applying JB weld I gentley hammer swage it on up to the guard. I have done everything I could to try to slide it back off even when the JB weld is still very wet and it won't budge. The jb weld is almost just a space filler to keep moisture out.

It is worth it to try many different techniques and your gut will tell you which one is the one for you. The advantage of forums over a book or video is you get many different techniques vs just one to try. This used to frustrate me but now I have grown to appreciate it. My definition of a boring thread is one that everyone agrees on the topic (a rarity) and the thread usually dies a quick death. I want to see a complete disection of the the thread topic with guts and bones laying all over the place.
Reply With Quote
  #14  
Old 10-05-2006, 12:11 AM
skipknives's Avatar
skipknives skipknives is offline
Skilled
 
Join Date: Jul 2006
Location: Hattisburg Ms
Posts: 599
I can't find fault in your counter, I yeald to the point of screws being one of the best ways to assist the glue/epoxy over just pins.
But I have two pionts to counter on and bere with me on my powers of discription.
(pulling numbers out of the air) picture a rectangle 1" X 3" =3sq inches
now picture the same rectangle and add a third dimintion length wise (slightly cupped)
starting at zero at both edges of the rectangle and concaving to a depth of a 1/16" inch in the center evenly. (not being a math whiz) I can't tell you how much more area there is but I know it is greater.
on this primis,,more sq-inches to bond to = stronger bond.

second point: The bond will most likly brake from the steel first (smaller pores)
now let us remove the factor of handle pins for a moment and discuss sheer forces on the two rectangles.
Rectangle one mated with another flat surface : only needs to overcome the weight of one of the rectangles to slide.
the second rectangle (with depth) has a mirror oppisit of a glue mass in the hollow.
This will require a greater sheering force to slide the two from there resting position.

the only compairison that comes to mind is the pull start mec on a lawn mower:: in one rotation it spinns freely but the oppisit rotation introduces wedges between the two "sheering"discs locking them together (bad example)

so far i dont think i've bettered my position any.
As far as contacting the manufactures of the epoxys / glues,, I would supose that thier only responce will be to tell us that thier product is the best one on the market.
Reply With Quote
  #15  
Old 10-05-2006, 05:58 AM
AcridSaint AcridSaint is offline
Guru
 
Join Date: Jan 2004
Location: North Carolina
Posts: 1,144
Haha, I will agree with you about the glue manufacturers! Actually, I think loc-tite might have some good input on the subject, but I'm not the smartest guy to be asking them about it.

As far as your first point, I agree 100% that the bond to the wood or steel will be stronger, but I believe that the additional mass of the glue negates any benefit it might have. If the concave is too drastic then you run into problems of glue mass that I mentioned before, as well as the problem of trying to make sure your fit is tight enough to press the glue completely into the bond. Since we can't see what's going on under the scales, we run the risk of trapping air under the bond and actually making it contact less surface or making the glue structure itself weaker. If the concave is too shallow then I don't see a net benefit large enough to justify the steps involved.

As for the second example, I will also agree that the bond will most likely break from the steel first. This example is actually a good one for me as well. If we try to shear a block with a concave hollow of glue then we will likely find that it doesn't shear off of the surface of the block at all, but in the center were there is no rigid support or material to bond to. In my understainding of glue shearing, the surface bond is not what you have to worry about in most cases, but the bond of the resin itself. When compared to a thin bond with rigid materials on either side, I think that the leverage is greater in the concave a therefore an increased shearing risk exists.

Now, with that being said, I would also like to say that if I am totally wrong about the shear strength of the glue decreasing with increased mass, I still believe that the additional bond is not beneficial because of the big picture. Devcon lists a strength of 2000lbs / sq. inch of bond I believe (not that I use it, it's just conveniently listed), so, if surface prep is optimal and product perfromance is within manfucturers specs, even a small knife handle would require enough force to totally destroy the handle materials before breaking the bond. At this point I think that glue failure looses relevence.

Lastly, I do believe that glue channels are beneficial to hidden-tang knives, especially with a thick setting glue like JB Weld. The difference is in the construction, the surface area must be increased in this case to ensure a secure bond and the forces acting on a hidden tang are totally different than that of a full-tang blade. Also, thanks to the snug fit we have a much better chance of removing any air pockets.

So, unfortunately, I can't draw things out or wave my hands around to get my point across. This is acutally a pretty difficult subject to argue with because I'm struggling for worded examples even though the pictures are clear in my head. Hopefully I make some sort of sense to someone!

Any other thoughts?


__________________
Cap Hayes

See my knives @ knives.caphayes.com

This quote pains me:
-- "Strategically placed blood grooves control blood spray in covert deanimation activities." --

Last edited by AcridSaint; 10-05-2006 at 06:00 AM. Reason: Removed useless line, added line for clarity.
Reply With Quote
Reply

Tags
blade, fixed blade, knife, knives


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -5. The time now is 02:57 AM.




KNIFENETWORK.COM
Copyright © 2000
? CKK Industries, Inc. ? All Rights Reserved
Powered by ...

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
The Knife Network : All Rights Reserved