Wood & PR

[jttheclockman]

For those that cast materials like wood with PR or metals with PR do you have any issues that should be watched for when doing this such as particular woods or metals not adhering with the PR??? Do you get any seperation between the two materials due to expansion and contraction??? Do any of these issues come up after the blank is spun to size and finished??? Thanks for the replys.

 

[B727phixer]

Cocobolo is not fond of PR, I have heard you can wipe it down with alcohol, but I never tried it. I also seem to have a problem with shrinkage when I do WW cast, so make sure your mould is deep enough. I'm sure there are others but can't think of any now. Others will fill in the blanks...:biggrin:

 

[jskeen]

be sure that you clean off the bark/punky stuff/whatever down to good solid wood before you try to cast! It might seem like a good idea to leave that stuff on there for the PR to "stabilize" but it don't usually work in my direct experience, and from what I've heard from lots of other casters. Some use a dremel tool, others chisels and scrapers or files and rifflers. I use all the above some time, but mostly a wire brush on one of my bench grinders. the resin bonds best to clean, solid wood, anything else tends to make the joint separate.

Also, don't leave cans of pr in an unairconditioned shop in Houston in the summer. Turns out you don't necessarily NEED catalyst to get the stuff to set up, just plain old hot will do the trick pretty quickly.

You don't NEED vacuum or pressure to cast with pr, but it sure increases the success rate. Gotta balance cost of materials against equipment cost in relation to the volume of casting you plan to do.

That's about all I can come up with right now, may come up with some more tomorrow morning after a few cups of coffee.

Oh, yeah, remember, Have Fun!

James

 

[workinforwood]

I would think that with metal..meaning like a sheet of metal, then PR would be best. With worthless wood, Alumilite always is superior. Alumilite will penetrate the wood better, it won't shrink away from the wood and it is not brittle so it can withstand the drill and chisel better. If you are casting something like Steel wool, it won't matter which product you use. To cast a sheet of metal, or a hard substance like Corian, then Alumilite is going to be a problem and PR a big success, or at least with Corian it sure works great, not sure about a sheet of metal. The issue with hard things like Corian is that it will push on the chisel when you turn it at a different rate than the Alumilite. The constant fight the corian gives you will cause the bond between the alumilite and the corian to fail. Similar situations happen with Alumlite over snake skins and labels where alumilite will want to stretch to accomidate a press fit pen part and PR will not..so PR will either crack or it won't during final assembly and the alumilite will just let go and stretch every time. They are both great products that definitely out perform one another depending on the situation.

 

[JohnU]

I didnt see it mentioned but make sure your wood is dry. Heat it up in the oven before casting. I also had a problem with pr sticking to osage. Im guessing dense woods are the problem child.

 

[rdunn12]

PR doesnt like cedar either,been there done that.

 

[Mr Fixit]

How will PR do with Oak? anybody tried that?

Mr Fixit

 

[robutacion]

Hi had a few initial problems with the Majestic Olive wood, mainly if with dense heartwood or not as dry as it could be. I could see some "separation", particularly in blanks with only 50 or 60% wood on them, the outer skin where the PR (only thing available to me...!) was to stick to. This as to do with the natural oils of the olive, the more heartwood or flaws the more the oil is found in high concentrations, is this same oil that forms the colours and protects (self repair) the fractures or found within the wood, very much like the antibodies we create around a cut or bruise, trying to heal.

I quickly fix the problem by using thin CA to coat all the surfaces where the PR needed to stick properly. I should mention that I also use a wire brush to clean and rough up the sticking surfaces, followed by a good blow with the air gun.

So far, I haven't found any more separations on those olive wood casted blanks nor on any of the other woods that I used so far for casting. I have 30+ other woods to use for casting so, I will not be surprised if I get another one that requires the same treatment will see...!

Good luck with yours...!

Cheers
George