Acrylic....little help??

[Cujo#31]

Is there ANYONE that actually knows how to do acrylic? I have taken the advice of many "experts lately with the same disappointing results. No matter how I prep my edges I'm getting crazing in my welds. Cutting the project apart for the second time tomorrow. It's thick acrylic, 1" sides and 1 1/4"front and back.

[Myka]

I haven't had that issue, not sure what you're doing wrong. Which solvent are you using?

[dino]

I used to work with it on occasion making helicopter windscreens. I believe crazing is normally caused by stress or overheating. maybe its something to do with the solvent? I know its really important to have flat surfaces. doubt that helps lol

[Cujo#31]

Using weld on 40 so not exactly sure. I might try weld on 4 and see if I get different results. Gotta say...acrylic has a STEEP learning curve.

[The Codfather]

Do you have some details?
I worked with acrylic for a couple years, made a lot of sumps and overflows.
I used weld on #4 for just about everything.
Let me know what you are building and Ill try to help.
The only time I used #40 was to bond acrylic to pvc.

[Delphinus]

Weldon 40 is nice to work with because it's thick and not runny but it's not easy to make clean welds with it.

Something runnier like #4 is probably your better bet for super clean joins, but it's much harder to work with (at least I think so). I think you get your pieces placed together first and applied with pressure, then you take a needle bottle thing and follow it along and the weldon wicks into the join area.

[WarDog]

Stick to glass. Hope that helps. Lol.

[sphelps]

For cast acrylic use #4, for extruded use #3. Given the thickness I would assume its cast. 40 is almost totally useless IMO, only good for filling gaps which in reality you should never have. I doubt any tank manufacturer uses 40 or something of the like. Also I'd argue using #4 is significantly easier than 40 provided your edges are prepared properly.

You need to use a router or jointer (edge planer) to finish the edges and make them flat prior to gluing/welding and use a syringe with metal tip to apply the solvent. I remember seeing a good post somewhere with someone using a good technique for bubble free seems with thick acrylic. Basically used pins as spacers then flooded the joint with solvent and removed the pins. Personally I've always just balanced the acrylic panel in place and used the syringe with good success but I rarely worked with anything thicker than 3/8".