Higher Bond Strengths if Cured at Elevated Temperatures?

[greybeard]

I use Techni-glue CA in my bow lay-ups, air cured and I am happy with the results.

I want to try Smooth On in my bow making workshops because its extended pot life will enable clients to glue up a bow in one operation.

Any extra information re heat curing would be welcome as the following statements are a little confusing.

I have heard that some epoxy glues attain higher bond strengths if cured at elevated temperatures.

The following is from the manufacturer;

EA-40® Transparent Laminating Epoxy Adhesive

EA-40 Clear Epoxy is an unfilled low-viscosity epoxy adhesive that can be spread easily in thin films that are almost transparent after curing. Mix ratio is 1:1 by volume. When mixed 2A:1B by volume, EA-40 will achieve greater heat resistance and improved physical properties.

EA-40 is versatile and can be used for many different assembly and repair applications ranging from electrical potting to jewellery assembly to repairing plumbing fixtures. Bow makers have come to know EA-40 as a tremendous laminating resin. EA-40 provides highly moisture resistant bonds meeting the performance requirements for Federal Specification MMM-A-188, Type III.

EA-40® Epoxy Adhesive - 24 hour cure time.

This statement is from Bingham’s;

Smooth-On Epoxy Glue
Specifically engineered for bow construction, with the longevity, flexibility and memory required to construct a fine bow. Smooth-On, a 1 part resin to 1 part hardener epoxy, requires 4 hours curing time in a heated environment of 150-180 degrees.

I believe they are referring to the same product.

Daryl.

[Gringa Bows]

G'day Daryl,i use smoothe-on and i put my bows in the hot box for 4hrs at 60deg c. then next morning mark them out and cut to the lines with a table saw without any probs,i was told they do have higher bond strength with 4hrs heat,i think Jeff gives his 6hrs from memory.............i think it meant 24hrs cureing time was without heat.

[Stickbow Hunter]

Daryl,

I have been using Smooth-On for approx twenty years and will not use any other epoxy for gluing my bows as it has more than proven itself.

I have a couple of Technical Bulletins from Smooth-On relating to the EA-40 epoxy. From my reading of these bulletins the mixing of Parts A and B at the ratio of 2A:1B is mainly for improved heat resistance eg: 80C+. At lower temps the normal mix ratio seems to give better strength results. I use the normal mix ratios but mix by weight and not volume.

I like to cure at 60 degrees C for 8 hours and have corresponded with Smooth-On directly and they stated this proceedure should give me excellent results; which it has over the years.

I cure at this high temperature as opposed to room remperature because it clearly states in the Tech Bulletins that you will get increased physical properties and performance when cured at the higher temperature. It also states that if you cure at room temperature you should then cure at 65 degrees C for 4 - 8 hours for the afore mentioned reasons.

Another reason I cure at elevated temperatures is that I can glue up one afternoon and work on the bow the next morning.

I think that a pot life of two hours is reasonably accurate but I like to glue up in less time then that.

Jeff

[greybeard]

Hi Jeff and Rod,

Thank you for the information.

Thinking of going to the heat strip system offered by Bingham. It appears to be more expensive than setting up a hot box with all the ancilliary gear but as a plus it requires very little space.

Has anyone had negative feed back on this system? The Bingham catalogue states that the heat strip system will cure the glue in 1/4th. of the oven time.

Daryl.

[Gringa Bows]

Daryl, i've never tried the heat strip,yet but ive read on a yank site that a few of them are going from the hotbox set up to the strip,i'de be interested to see how it goes for you,if you decide to go that way

[Stickbow Hunter]

No experience with the heat strips either but I know they are used a lot in the USA. I think you can cure the Smooth-On in about two hours using the strips.

If you go down that path Daryl just check if you would need a transformer to use them out here as we run 240 volt and the USA runs a lot lower voltage I believe.

Jeff

[greybeard]

Hi Rod and Jeff,

Thanks for the feedback.

Ordered all the gear from Bingham’s for the heat strip setup including a voltage converter.

I have an air compressor that has been sitting in my garage for near on two years and has only seen about two hours of work so I ordered all the air hose gear so I can do away with the current clamp system.

When all the gear is set up I may be able to rent out the workshop on an hourly basis.

Daryl.

[Gringa Bows]

Looking forward to hearing what you think of the heat strip,its one of those things i've been gunner try but havent yet.

[rodlonq]

Gidday Daryl,

The heat strip idea is great, not real cheap but when you consider the price of shed space a very good idea.

I got very interested and had a good look around. In the Traditional Bowyers Encyclopedia (Bertalan, 2007) it seems both Pearson and Bear (and probably numerous others) use similar techniques for production bows. I thought you might like to see the buildalong at the link below. This fellow has documented the procedure very well and also highlighted a couple of traps for those new to heat strips.

http://www.piratesofarchery.net/bb/view ... 792972d444

I hope this is as helpful for you as it was for me.

Cheers........Rod

[greybeard]

Hi Rod,

Thank you for the link. It answered several points that had been going over in my mind.

If you factor in the outlay over twenty plus bows in a bow workshop situation it is cost effective and should give consistant results.

Daryl.

[rodlonq]

Gidday Daryl,

After a lot of thought (even though my knowledge is purely theory from lots of reading, haven't made a bow yet ) I reckon you still might need an oven to properly dry out and perhaps preheat components before gluing up. What do you think?

That said, it would still be easier for a person on their own to lay up a bow with heat strips and leave the form on the bench, rather than having to lift it off the bench and into the oven. Also the quick turn around would be useful for those making a lot of bows.

Cheers.... Rod

[Gringa Bows]

Speaking of heat strips,have you tried them yet Daryl......

[greybeard]

Hi Rod & Rod,

I am still waiting on the USPS to deliver.

Bingham’s confirmed the goods had left their warehouse on October 8, 2010.

Tracking results show that the goods left from ISC San Francisco at 12.40 am on October 15, 2010.

I visited the local post office yesterday and from their checking the parcel should be here Wednesday.

Usually goods from Bingham’s arrive within seven to eight day.

All the bow components are finished just waiting on the heat strips etc to arrive.

If in doubt I pre warm the components before the glueup.

Daryl.

[Gringa Bows]

Daryl,i'm glad its not just me,i ordered stuff on the 4th binghams sent it on the 8th.tracking said it left san fran cisco on the 14th at 410am ,i got onto Auspost and their records show nothing,i was beginning to think i'd lost my order,so hopefully i get mine same day as you....this is the longest its ever taken..

[rodlonq]

Daryl and Rod,

I too sent an order on the 10 Oct and it shows up on the online order status as received but doesn't appear to be shipped yet

Rod

[Gringa Bows]

Bugger Rod,they're usually pretty good,must be the postal mob.

[rodlonq]

Got an email this morning saying they reckon my order will be dispatched in a day or two.

[Gringa Bows]

Yep i tracked mine and it arrived in Aus.315pm yesterday yeehah

[Stickbow Hunter]

That is just terrible service!!!

It would seem that it is at the postal service end and not Binghams. The whole postal system seems to have gone downhill in the past few years as things seem to take longer to get anywhere and a lot more stuff seems to go missing.

Jeff

[Gringa Bows]

Yeah mate its the postal mob,Elmont from Binghams could'nt be more helpful he tracked it from his end and let me know what was going on top bloke.

[greybeard]

Hi Rod,

"Yeah mate its the postal mob,Elmont from Binghams could'nt be more helpful he tracked it from his end and let me know what was going on top bloke. "

When your order is confirmed by Bingham's you should recieve a follow up email a day or two later similar to the following.

Dear .....
Your order id 4027 from 05th October 2010 06:20 has been updated from Order Received to Order Shipped on 08th October 2010 17:05.
Your tracking number is CJ 008 376 509 US

Copy and paste the tracking number into the following link for updates on the location of the shipped goods.

http://usps.ems-tracking.net/

Daryl.

[Gringa Bows]

Yeah Daryl i knew where it was by the tracking number till it left Sanfrancisco two weeks ago then nothing,so i got onto auspost yesterday morning and there was no record of it in aus.so they told me to get Elmont to look in top it and they would investigate it with USPS and a few hours later it arrived in Australia and took 9 minutes to go through customs,going by the times in the email.

[GrahameA]

Morning All.

I can only speak from the feedback I get from Daryl and the occasional order I piggyback back on his orders. Usually the order arrives very quickly, 7 days at the most, this time it seems to be going somewhat slower. It is not Bingham's issue but rather the Postal Service which seems to be a bit poor in it its service.

[rodlonq]

Hello All,

I got a message this morning my order has been shipped (20 days?)! Lucky I am flat out with work at the moment otherwise I may be a bit disturbed about the delay . By the time the postal service gets it here will be well over a month from order to delivery.

I'd say if your planning a project for over Xmas get your gear ordered real soon

Cheers,
Rod