ETLB Squawk Forums — Archive

G'day,

New member here with my first post. I'm currently acquiring supplies to start an 1100R build.

So I will just say that I understand that in the grand scheme of a build the epoxy cost should be negligible and so one should propbably pick an epoxy based on characteristics rather than cost. But as you know T-88 costs an arm and a leg down under (about $190AUD per 1L or about $140USD per quart) so I'm looking at alternatives. Thats just not really viable if I have to get 3 or more litres.

I came across Bote-Cote Epox-E-Glue at about $65AUD for 1kg (which I assume is going to be just under a litre): http://mail.boatcraftnsw.com.au/epox-e-glue/info.html

https://boatcraft.com.au/Shop/index.php?main_page=index&cPath=49
https://www.woodworkmachinery.com.au/product-page/epox-e-glue
https://mmvic.com.au/product/epox-e-glue-kit-coloured/
https://marinetimbers.com.au/product/epox-e-glue/
Etc...

I'm just not sure about the whole paste consistency aspect. Though I do like the strong gap filling properties and that there wouldn't be sag. Seems like it would be fairly forgiving, if not slightly harder to apply?

Below are some specs I could compare from their data sheets (which I've also attached):

Epox-E-Glue:
Viscosity: 450,000cps
Compression Yield: 13,053psi
Tensile Strength: 6,962psi
Tensile Elongation: 6-8%
Tensile Modulus: 377,098psi
Flexural Modulas: ?
Flexural Strength: 11,023psi
Heat Deflection Temp: 122-131°F

T-88:
Viscosity: 20,000cps (once mixed)
Compression Yield: 12,500psi
Tensile Strength: 7,000psi
Tensile Elongation: 7.5%
Tensile Modulus: ?
Flexural Modulas: 375,000psi
Flexural Strength: 11,500psi
Heat Deflection Temp: 119°F

Based on those stats the Epox-E-Glue seems actually quite similar to the T-88, besides the viscosity of course. Seems like it might be a winner. But...

It does mention in the instruction sheet that when using Epox-E-Glue with timber that the timber should be sealed first with a thinner epoxy to prevent excessive soaking in and starved joints (it doesnt specify end grain).

But I would have thought a more viscous liquid (a paste in this instance) wouldn't soak in nearly as much?

I even downloaded an information and data sheet for T-88 from Aircraft Spruce and it says it can be thickened for use on end grains to prevent excessive absorption. So...thickening T-88 prevents absorption but is only needed for end grains, yet the much thicker Epox-E-Glue needs all surfaces sealed prior as a matter of course? What am I missing here?

I'm sure there's just something I don't understand. Like perhaps the fillers used to thicken the T-88 also helps prevent absorbtion somehow, but the standard stuff used to make the Epox-E-Glue doesn't? Something like that? Surely its not just marketing...them trying to get you to buy more of their product. "Oh yeah, you definitely also have to use the Bote-Cote Thin Epoxy in order for the Bote-Cote Epox-E-Glue to work 😉".

If I have to buy thinner epoxy to seal the timber first then there goes the cost savings, and it would take more time having to mix twice every time...so that would be an easy "NO" for Epox-E-Glue.

Maybe I could just include a standard wait time after I've applied the epoxy but before I join pieces to allow for some soaking in?

Of course I could use other epoxy systems  that would just require me to add things like thickeners and thinners, cabosil, microspheres, this, that, and the other. But I honestly just want a simply epoxy system like T-88...just mix 1 to 1 and go.

Thoughts?

Cheers

I'm a big fan of West Systems Epoxy. I don't know how expensive it would be where you are? I bought a Mini Max built with T88, and I've done several repairs on my Max with West. The repairs  involved working around the original T88, and in some cases de-bonding it. I was not impressed with the T88. I know it has been an excepted standard for years, but it is 40+ year old technology. There are probably even better epoxies then West (and probably more expensive too) but West is well respected, and has been used by many builders. A friend of mine built a Bowers Fly Baby exclusively with West 105/206. There are pictures of it a number of places on the net, but here are links to 2 sites where you can see pictures of an immaculate homebuilt. Bowersflybaby.com
klasskote.com    

Cheers. Yeah I did briefly look at West Systems. From what I saw some people used G-Flex which I wasn't impressed with from the data. Everything was about half the strength of the T-88 and Epox-E-Glue listed above. Though from what I saw, most people using West Systems werent using GFlex but just the more standard stuff and were adding things to make it more viscous, add strength, etc, and I'm just not that keen on doing that. It just complicates something that should be simple. If I only had to do it once then yeah but I'll have to mix up hundreds of batches so I just want to make it simpler and streamline it, remove margins for error/differences between batches etc etc.

Hi Mat

I built my Eros, initially with the T66 supplied. When that ran out, I used WEST. The WEST was far better in my view. You can thicken it or not as you wish - it's not very difficult!

In the past I have built dinghies and an aircraft wing test piece using WEST, all with excellent results.

I'm not talking G-flex here, just the hot or cold originals.

Whereabouts in Oz are you? I'm in country Victoria, and there are at least 2 other current builders on this site, both in Vic.

Good luck with your build

Bruce

Ha ha okay okay. Two replies and two people saying "use basic west systems and adjust as necessary". I guess I'll have to check it out. Leave it with me. But is there genuinely no simpler system I can use here is Oz?

I will just say that when I'm saying "simpler", its not that I think it's difficult to mix in additives or anything. I get it. It'll take 10 seconds extra per mix. Not that big of a deal. I've used laminating epoxy in the past as I've made a few surfboards and added I've stuff like microspheres. Yeah its easy enough.

I do find it interesting that I've got two replies and two people poo pooing T-88. I thought perhaps hundreds of MiniMax's had been built using the stuff. I thought it was fine.

Anyways I definitely did want something with decent gap filling ability. Reason being that I've been watching Dennis Tyson's build on youtube and he is very meticulous about applying his epoxy yet when he routed some bits it revealed cavities/dry spots. If he got them then other will too, and I definitely will. I couldn't help but look at all the other joints that weren't routed wonder about them too. Doesn't exactly inspire confidence or peace of mind. I feel like something thicker that didn't sag would help eliminate those spots. Though, in the same way I said "hundreds have beem built" with T-88, it applies here too I suppose.

Oh and I'm in Victoria also...outer eastern suburbs of Melb.

Whats with the Victorians and MiniMax's ey? Haha

Another recommendation for WEST System(tm) epoxy.  I know it is readily available in Australia.  With the technical guides you get from them it is very hard to go wrong and you can exactly create the mix you need for the particular use.  If you take advantage of all their information you can definitely build a stronger aircraft.  I would get not only their technical manual but their book Gougeon Brothers on Boat Construction.  The section on hardware bonding is especially useful.  Of course much of the boatbuilding info isn't applicable but a surprising amount is.  For instance it is absolutely amazing what a very tiny fillet of filled resin will do for strength where pieces are joined at an angle.  You can read reviews of their publications in the publishing section of my website http://www.macnaughtongroup.com

Tom

Since boat building has now been mentioned, the friend that I referenced in my earlier post also built two wood boats with West, that are ocean capable, before he built his Fly Baby. Strength wise cabosil is better then microspheres. There are other materials which can be used to thicken, and strengthen your mix such as ground glass, chopped glass, chopped carbon fiber, and cotton flock, but that's over kill for 99% of the joints on a wood airplane. Many glue joints on wood airplanes are clamped, nailed, or in some way squeezed together. so depending on how good your joints are you might not need to thicken your glue. T88 is a 50/50 mix which is easier then West which is a 5 to 1 ratio, but they have measured pumps that dispense the correct amounts by simply pumping one stroke from each container. I myself use a scales for measuring, so that I don't have to deal with dripping pumps. That's a personal choice because most of my West projects revolve around model airplane building, and fiberglass parts where I often measure in grams.

G'day Greg, yeah I'm aware the microspheres are not good for strength. They're good for making a lightweight and sandable filler which what I used it for on the surfboards...to fill in dings, smooth and seal the foam before laminating. I was just using it as an example to say that I've added things to epoxy before so I get that its easy in the grand scheme of things. I was just hoping for something easi-er...just mix 1 to 1 and go. Not mess around with crazy fine powders with which I'll feel the need to wear a mask when using. But I've given up hope for that so mixing fillers it is 👍 No worries.

And I also don't like the idea of pumps. I'd probably just use syringes. Thats what I've done in the past for small amounts doing surdboard ding repairs. Unless the pumps are really good and have fine control for small amounts? But yeah the dripping. I can relate with that...sort of. I've got 4 flavours of milkshake syrup with pumps in my kitchen that inevitably drip after use...cant be having that with epoxy haha.

Anyways, so...

Before today I was stupidly under the impression that laminating resin and glue/structural resin were different. But from what I've just read, laminating resin isn't really a thing, there's basically just epoxy resin and then fillers for changing its properties to be a structural glue or a sandable filler, etc.

And so speaking of my previous surfboard making, I've actually got about 2L left of that resin which I ignored until now as I assumed it was "laminating" resin and thus unsuitable. But I just looked at the website for it and says it can be used as a glue with fillers, and they sell fummed silica. So all this might have been in vain. Haha sigh.

Judging by the technical data its almost but not quite as good as west systems (it was cheaper, so...) so I might look at buying the smallest west systems resin/hardener I can get and do a bit of a comparison. But seems like it MIGHT be okay.

And yeah thanks Tom. Sounds like its worth a read so I'll get on to that this evening. Also, the fact you mention that the west systems has a lot of literature and guides sounds like a good thing and that might still make it my choice since the brand I've got doesnt have such extensive guides...or any that Im currently aware of. I might have to send the company an email and see what they say. I imagine the ratios have to be fairly precise to get the required outcome?

So thanks a lot everyone!

I'm chiming in late here but I'm building a Hi-Max in Melbourne using West system and I know of at least one Mini-max down under that was completed using West system and and another one that is currently under construction that is also using west system.

I have also used West Systems, never used any additives with it and find it "bomb proof".  But I will play Devils Advocate and also add you cant go wrong with the T88, except for the price you will have to pay for it. I like the T88 for the small jobs, which is most everything, but I like the West Systems for larger areas like the spar cap to spar web bond, lower viscosity makes spreading it out much easier.

Gday MathYou

My HiMax was built using FR100 as per attached spec sheet. I mixed it using the weight method. Was easy to work with. Was around $60 for 1lt.

Cheers, Mick

Hi MathYou,

I'm building a Mini-Max in Victoria (Ballarat).  I've been using West System and it seams very good to me.  The main difference from using T88 is that the best practice with West System is to first apply un-thickened to both surfaces of the joint, then apply again with thickener to at least one of the two sides.  I've been using 105 Resin with 205 (fast) or 206 (slow) Hardener, depending on the temperature at the time of the glue-up and the expected minimum overnight after the glue-up.  The two hardeners have different recommended temperature ranges.  I've been using the 403 thickener.  If you decide to use West System my suggestion is not to bother with the metering pumps.  Because you would be using small quantities most of the time you can go by weight, using a small precision scale, or you can go by volume using plastic syringes.
Send me a PM if you want to get in touch, I'm always keen to know other fellow Australian Mini-Max builders and there are many ways we can help each other.

Yeah I didn't like the idea of the pumps at all. I'm just using two bottles (similar to the squeezy sauce bottles but with finer control) and go by weight. Much easier portion control.

The epoxy I currently have is leftover from surfboard laminating, and thus I got the slow hardener to allow longer working time with that. It was great for laminating a surfboard during summer...not so much for gluing timbers in winter. Bloody hell it takes ages to cure! Haha sigh. But it was essentially free since it was leftovers from another project so I'm not really complaining.

Anyways thanks again everyone!