Review West System G-Flex VS Bob Smith MID Cure - Testing

J. Keeton

J. Keeton

Joined
Nov 15, 2005
Messages
1,201
So, I started a thread (here) last month to talk about West System's G-flex epoxy verses Bob Smith Industries (BSI) Mid Cure two part epoxies.

It sounded like some testing was in order!

Setup:
  • Two square pieces of linen micarta affixed to two square pieces of 1095
  • Surface prepped on granite with 120 grit paper
  • Drilled holes in all 4 pieces for pull part testing
  • Scribe'd lines in the pieces for proper over lap alignment
  • Cleaned the surfaces with alcohol before glue-up
  • Mixed both glues for 25 seconds before application
  • Used 2 spring clamps of the same manufacture on each sample
  • Cured both samples @ room temp for 24 hours
Testing:
  • Froze the samples for 12 hours
  • Baked the samples at 180 for 2 hours
  • Performed static load testing @ 135 and 225 lbs
  • Attempted to perform dynamic load testing with 135 lbs for ~ a 12'' drop
    • Micarta busted before the samples parted!
  • Ran the samples though the dish washer twice
  • Did a "smash test".... #trademark
  • Finally... did a vise/lever/break test
Results:
  • The samples were indistinguishable in performance all the way up to the lever-break test.
  • The vise/lever/break test appeared to show that the G-flex sample took more force to break off and "flexed" more during the break test.
Video of Testing:



Edit: I know this testing wasn't perfect... Just doing the best with what I had!

Cheers,
James
 
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Thanks J. Keeton J. Keeton !

I’ve been thinking about trying G/Flex my self. Time to order some.
 
Can't go wrong with West Epoxy (G/Flex)...Iv'e used it for 30+ years, mostly in structural marine (boat building), and some wood working furniture, applications and it has never let me down....whether a serious structural component on a boat able to withstand thousands of pounds of force, or a knife handle, I am a believer. As a knife maker, I could use a less expensive brand, but why would I want to sell a knife with anything less than what I feel is the best product available. I do prefer the G/Flex over the West 105/205 resin/hardener for knife building applications, the additional flex capabilities are a bonus over the traditional epoxy.
 
I've been wondering about the newer "Blade Bond" epoxy and what makes it special or different, as I haven't really read much about it but it is apparently meant for knife makers, hence its name.

Thanks for sharing :thumbsup:

~Paul
My Youtube Channel
... (Just some older videos of some knives I've made in the past)
 
coldsteelburns said:
I've been wondering about the newer "Blade Bond" epoxy and what makes it special or different, as I haven't really read much about it but it is apparently meant for knife makers, hence its name.

Thanks for sharing :thumbsup:

~Paul
My Youtube Channel
... (Just some older videos of some knives I've made in the past)
Click to expand...
I have used it on many knives.

It is a great product and wish it where easier to get because when i need it, it seems to always be sold out.
 
Carterwhopkins said:
Can't go wrong with West Epoxy (G/Flex)...Iv'e used it for 30+ years, mostly in structural marine (boat building), and some wood working furniture, applications and it has never let me down....whether a serious structural component on a boat able to withstand thousands of pounds of force, or a knife handle, I am a believer. As a knife maker, I could use a less expensive brand, but why would I want to sell a knife with anything less than what I feel is the best product available. I do prefer the G/Flex over the West 105/205 resin/hardener for knife building applications, the additional flex capabilities are a bonus over the traditional epoxy.
Click to expand...

Carterwhopkins Carterwhopkins I totally agree... That's one of the reasons I tested these two. I wanted to confirm if one of them was superior. Piece of mind has value. That value is the reason I put corby or loveless on all my knives. For me personally "overbuilt" is a goal.
 
I have had very bad runout with Gflex 650. To the point where the epoxy seeps totally out of an area. If doing a full tang knife, I will use GFlex 655-8, or add Colloidal Silica Filler in my GFlex 650.
 
bmilleker said:
I have had very bad runout with Gflex 650. To the point where the epoxy seeps totally out of an area. If doing a full tang knife, I will use GFlex 655-8, or add Colloidal Silica Filler in my GFlex 650.
Click to expand...

I often use 403 Microfibers for a little bulk and fill, I also use 423 Graphite for color.
 
Glad to see the Bob Smith do so well. I used that exact one for 5 or 6 years before being given a couple containers of Blade Bond. When the BB ran out, I am working on a batch of G-Flex. Have no complaints about any of the three.

For those who question "what difference does it make"... Since none of the glues in question seem remarkably superior, and all function fairly well the same, for me the cure time is a factor.

I work on blades on Saturday and Sunday. The faster the cure time, the more I can finish in a weekend. Switching from 15 min Blade Bond that is full hard in an hour to G-flex that is full hard in 2 hours in front of a heater or 3.5 hours in ambient has made me have to switch around my production processes. That extra time for the glue to cure is an annoyance when you only get to work on weekends.
 
bmilleker said:
I have had very bad runout with Gflex 650. To the point where the epoxy seeps totally out of an area. If doing a full tang knife, I will use GFlex 655-8, or add Colloidal Silica Filler in my GFlex 650.
Click to expand...

How 'sticky' is the 655-8? I love using Hysol E-120HP or E-20HP. The consistency is right and it's not to sticky. One other brand I used had a nice consistency, but it was like honey and hard to work with.

Also, I'm wondering about using G/Flex in a hidden tang. I like Acraglas because it's dimensionally stable - designed for filling voids in gunstocks. That's a little different priority than just adhering stuff.
 
Sando said:
Also, I'm wondering about using G/Flex in a hidden tang. I like Acraglas because it's dimensionally stable - designed for filling voids in gunstocks. That's a little different priority than just adhering stuff.
Click to expand...

G/Flex works well in hidden tang....it's the only epoxy I use for that.
 
The 655-8 easily flows into voids. It’s thicker, but not that much. I use it for sticking dovetailed starboard to fiberglass, etc
 
WC53 said:
The 655-8 easily flows into voids. It’s thicker, but not that much. I use it for sticking dovetailed starboard to fiberglass, etc
Click to expand...

"Flow" is not how I would describe 655-8. Can it be put into voids and stay there, yes. But, I wouldn't say it flows anywhere on its own. That's why I switched to it. 650 was flowing OUT of areas for me.

I wonder how much a difference in location makes. Maybe your location allows 655-8 to flow more than where I live. I am in Saskatchewan, Canada.
 
As a side note in relation to the conversation above; I found that the BSI MID cure and G-Flex 650-8 “flowed” at around the same consistency for my location (Midland, Texas). Ambient temp was around 60 degrees Fahrenheit at the time.
 
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