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how shock resistant is acraglas


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Hello All,

I am finishing the handle on my bauernwehr for the kith 2012. I did not like the horn scales I had on because I needed to buff them better and they had a defect that I found when polishing. Since I had not pinned them yet, but only epoxied with long-set stuff. It took two raps with a hammer to create a shear force to knock each scale loose (a small ball pein at that).

This is sad performance, although I wanted it to fail in this case.

 

Many of you have converted to acraglas due to your experience with firearms. So, please tell me specifically, how shock resistant is the stuff (I suspect it is due to recoil, but I wanna know).

 

Any tips on its use would also be appreciated, since it seems I need to find something besides epoxy if I can.

 

thanks,

 

Kevin

Edited by Kevin (The Professor)
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As with all adhesives, surface prep is everything. I like Acraglas a lot. Never tried to knock it loose, but it is doing some things that I would not have believed adhesive alone would do, in my shop, on tool handles and some paintball kit (pvc tubes to make the marker look like a PIAT on the outside, with secure mounts made of micarta for the marker inside, fastened only with acraglas to the tube). These things get beat to death on the field at D-Day, and survived just fine. I use it for everything that requires epoxy if I have it (and that is the usual situation).

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Kevin,

 

This isnt surprising to me, and isn't really reason to stop using epoxy IMHO. On full tang construction, epoxy isn't enough. But if you add a couple of straight pins it makes it pretty bulletproof. The pins prevent shear weakness and epoxy is extremely tough in linear adhesion.

 

If I have to rely on adhesive alone, I use JB Weld. It very strong and has better shear resistance than epoxy.

 

Dave

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I know they use for bedding the actions of big bore rifles. My own experience is that the handle will shatter before the Acra lets loose, but I do mostly stick tangs. The archery guys often use one of the Tightbond products, but that is wood on wood. I've been using G/Flex by West System for the last year or so. I'm really happy with it It's cheaper than Acra, it's a 1:1 mix, but it's yellow when hard, though takes dyes well. Alpha requires a Resellers Permit on file, that way they don't have to mess with sales taxes and stuff.

 

Geoff

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Ditto on what Dave said. I use JB Weld most of the time when gluing up a knife. I have use "culter's cement" but I think my mix was nothing like what they used to use way back when. I have tried to be more traditional of late but I am afraid some modern products just seem to drag me back into the now. Some recent post on the qualities of Acraglas have me intriqued though. I may have to give it a whirl.

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Thanks for the info.

Howard - good to know. Also, I used to help the local paintball store on weekends with their forest battles and forts. That D-Day camp is crazy.

 

Dave - you are right, of course. I think what bothers me is the possibility that the shock could snap the epoxy and leave only the pins holding. Sure, especially on horn, I will be able to peen the pins down into countersinks to hold the scales. It is likely overkill to worry. But, I do. No real rational answer other than that. I just do.

 

Geoff - thanks for the info on other products.

 

Troy - I am thinking of acraglas and the old, very old, fashioned recipes. I think the older stuff was a lot more shock resistant, IF you had the mix right for the environment you lived in. Things from CT would probably melt off due to heat in Texas or the Sahara, and vice versa.

 

thanks again. I will have to make some cutler's resin and buy some acraglas and have fun. In some ways, if I had faith in myself, the idea of mixing a batch of home brew adhesive that workes on a traditional style of blade is quite appealing. Same thing that has a lot of us smelting. Get to REALLY understand the materials and construction.

kc

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I think what bothers me is the possibility that the shock could snap the epoxy and leave only the pins holding. Sure, especially on horn, I will be able to peen the pins down into countersinks to hold the scales.

 

Kevin,

 

In my experience this isn't an issue. The pins don't allow any shear, so the epoxy doesn't lose it's grip. I don't even peen my pins, they are just straight and held by a drop of epoxy. I learned this method from the classic David Boye book, and have used it since I started making knives. I have a hunting knife I made in 1989 that is epoxied with regular old, five minute epoxy and straight 1/8" round brass pins that has been dropped and abused for years and the scales are still just fine. It's even been dropped so hard that a chip of the cocobolo handle slab broke off on the butt end, but the rest of the scale is fine.

 

Anyway, it's obviously your call, I just thought I'd let you know that epoxy and pins seems to be a very, very reliable method of handle construction in my experience.

 

Cheers!

 

Dave

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I used it to bed rifles sometimes, or to repair poor bedding jobs - never had a problem.

 

It's pretty tough - I once repaired a stock which had cracked because of misaligned and poorly machined pillars that had been acraglassed in place. The stock actually broke before the acraglass let go.

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I had tried a few different products a couple of years ago and the one I settle on had a 30 minute set time. It is no longer available though. I've read through testing results here and on several other web sites; some knife related, some not. I use a few different products now.

 

Wood on wood I'm using gorilla glue.

 

At the ricasso/guard I'm using JB Weld.

 

Tang to handle material:

If I wan't a quicker set up I use Loctite 328. Fairly fluid material and requires an activator.

 

Most of the time I use Loctite, Hysol 120 HP. It comes in a dual tube set up. You have to use an applicator gun(think caulk gun). You can also get mixing tubes that attach and dispense the product mixed ready to use. It has a 120 minute set up time.

 

The loctite products are both structural, commercial type adhesives.

 

I've got some of the West Systems epoxy and some of the Acraglass though I've not used either yet.

 

I really should do a trial of all and see what results I come up with. I just haven't taken the time. I've changed jobs recently and get little enough time in the shop as it is. I'm relying on testing, results, and procedures proved by others. To date with fantastic results.

 

One note about adhesion. I'll try and find the posts that provided the following tips; they have proved true for me.

 

THE CONDTION OF THE MATERIALS BONDED AND THE PROCEDURE/APPLICATION APPEARS MORE IMPORTANT THAN THE ADHESIVE. Many of the adhesive today are great products and will perform excellently. The conditions I've found to work the best are as follows.

 

Metal to be bonded should be sand blasted (where possible) as opposed to scratched (say with a 60 grit belt). I've been able to do this with a cheap gravity feed gun from harbor freight.

 

On wood, don't sand too fine, 120 or less is adequate. This has the added benefit of on mortise tangs of hiding the seam. Using an 80 grit on the bonding surfaces allows the wood to mesh at the joint and blend better.

 

Don't press the joint too tightly.

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thanks for all of the info Jarret and Sid.

I have been epoxying/gluing wood at between a 40 and 80 grit, and other things like horn with the finish the get right off of the mill. Clean with alcohol and epoxy. The milled finish may be a little too smooth. Metal with around a 36-80 grit finish. I once had scales just fall off when I epoxied a tropical hardwood that was naturally very oily/waxy and did not prep with scratching and then cleaning with alcohol or acetone. I use alcohol more than acetone simply because I use alcohol to get the epoxy off of me and parts of the knife where I don't want it right after glue-up. So, I have a big bottle ready as part of my standard prep kit.

 

take care,

Kevin

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