[gecko]

Hey guys
I want to have a thin bit of acrylic sandwiched inbetween two bits of multiplex but im not sure what the best way of sticking them together is.
Id like to avoid pinning them as i want a nice rounded handle to the catapult. Maybe i could put dowls through the acrylic and stick it that way?
Or if i score the acrylic so the surface is rough, will titebond stick the wood to the plastic anyway?

Take it easy, gecko.

 

[Hrawk]

Use a slow set 2 part epoxy. No need to score the surface. Pinning is always advised as it greatly increases shearing strength.

What is this multiplex you speak of? You mean plywood don't you?

 

[gecko]

Yes! I wanted to seem all technical to be honest as i hear that word thrown around so often! Yeah its plywood that i got from school, it was an off-cut. Do you think this poxy would be long lasting then?

Take it easy, gecko.

 

[Hrawk]

Yeah man, it works ok. The slower setting the epoxy, the stronger it is. Try and stay away from the 5 minute stuff. It will last for years if done properly.

The biggest issue is when you have flex and the layers de laminate. A few small pins stop this from happening. Brass braising rod, bicycle spokes, iron nails all make good pins.

As far as 'multiplex' goes, that is a German term. The English speaking world calls it plywood. This is why so many people have a hard time finding it. You call all the stores asking for multiplex and they have no idea what you mean. As soon as you say plywood, problem solved. Try Googleing both terms and you will see what I mean.

It's also important to know the grade of ply you are using. Most makers use a hardwood ply, usually birch. Be wary of using C/D grade ply as it is often full of voids creating weak spots.

Further Reading

 

[Danny0663]

Yes, use good quality epoxy. It's worth the extra money spending on a high quality two-part epoxy system.
Good luck.

 

[gecko]

Cheers Hrawk and danny for you help, i now know the difference between plywood and multiplex and i can finally give up typing multiplex into search engines! I probably will glue them with a two part poxy like you said, shape the catapult and then put some pins in it.

Cheers for all the help, take it easy, gecko

 

[Dayhiker]

Good thread. Can I jump in here and ask a question? (I'm just learning about glues now myself.) Why use 2-part epoxy? Would CA glue not do the job if you used the thick kind that will take a little flex?

 

[Hrawk]

CA is hard and very brittle. It has very low shearing strength and does not bond well to smooth surfaces. Most importantly in this situation the timber will 'wick' the glue away from the acrylic.

http://en.wikipedia.org/wiki/Cyanoacrylate

http://en.wikipedia.org/wiki/Epoxy

 

[Ethan]

Quickly going back to the plywood multiplex thing, how would you find dymalux or spectra ply in google is that simply coloured plywood?

 

[Hrawk]

Search for 'Dymondwood'

http://www.rutply.co...dymondwood.html

 

[Hrawk]

Dymalux and Spectra Ply can be purchased though Cousineau Wood Products

http://www.cousineauwoodproducts.com/

I would shoot them an email and check if they have any UK distributors.

 

[flippinout]

You can also get single blanks of the material from a forum vendor who's name I cannot provide due to forum rules regarding selling. Ask around and I am sure someone will point you to the vendor.

 

[Hrawk]

I recently purchased a few blanks from Flippinout Slingshots.

Shoot Nathan a PM, I'm sure he can help you out.

 

[Rockape66]

I used to make knives and with a little couterboring knifemakers rivets look very nice. The brass can be formed, filed, and polished to make a great presentation along with a secure hold.

 

[ZDP-189]

I would score the surface and 2-ton use epoxy.

 

[gecko]

I think the two- part epoxy is a great idea. Also, what would you say is the best way of polishing acrylic and wood. Beeswax?