Any way to flatten a 12x12 3/16 phenolic sheet?

[Joe Williams]

Hi all,

I bought some phenolic for the first time recently to make both a router plane base and a powered router base. The 1/8" sheets I bought are dead flat but the 3/16 sheets are warped a little. That's about the last thing I want, is there a way to finesse them with heat or compression back into shape or is it just that I should send them back? I was thinking about letting them sit under some weight for a while but not sure if that would make one drop of difference.

Thank you.

[Pat Barry]

Typically phenolic sheets are laminated up in a high temperature press. In order to do what you want, you would need high enough temperature and that depends on the exact phenolic resin used. Glass transition temperature might be anywhere from 140C on up to close to 200C. So, temperature wise, you could do it in an oven (not saying how much stink there would be). Then you would need to have it under pressure with a couple of heavy, very flat plattens. I think that's where the difficulty lies. If it were me , I would try to get it replaced rather than to 'flatten' it in this manner.

[Joe Williams]

Thank you will do

[george wilson]

Will the /16" piece flatten when you screw it to the router base? Since phenolic is a plastic hardened by heat in the first place,there's no way to flatten it. Heat it a lot and you will get a terrible toxic stink as it tries to break down into the components it was made from.

[Dave Anderson NH]

George is correct. True phenolic resin based plastics are thermoset material. That means that once they are cured they will not change shape when heated again. If heated to high they will outgas and even higher will cause them to burn. The thermoplastics like acrylic, polycarbonate, polyethylene, etc all will respond to heat treatment.

[andy bessette]

Replace it with thicker epoxy-glass.

[Joe Williams]

Thanks everyone, I think the sheet that goes on the router base will probably be ok.. it's going to be wider though than the router, kind of oblong. I love the extended base that they make for the Festool OF-1400 and I am going to make that for my smaller dewalt.

The router plane is an LN 71 open throat (god why did I buy the open!) so I am hoping I can find a flat enough piece to make it in the two 12x12 inches I have. I also have some cool t-nuts from switzerland that I ordered like 3 years ago for this purpose and am finally getting around to it. They are really cool fasteners I will have to show them when it's done.

Thanks again all, learn so much every day from everyone!

[Ted Phillips]

I agree with everyone - once phenolic is cured, it is permanently set. I have experienced some movement in knife scales I've carved out the material - but the main problem was using cheap canvas-based stuff from China. It tended to warp in humid environments. The domestic linen and paper-based phenolic is much higher quality and doesn't absorb much from the atmosphere. In the real world, the only way to flatten phenolic is to machine it.

[Joe Williams]

I actually messaged the ebay seller because I like doing that before reviewing poorly if at all possible and let them have a chance to fix it so the review is good. The guy is sending a complete new order.

Always nice to deal with businesses that are so decent.