UHMW sidewall treatment after profiling?

[switzch]

Just wondering what you guys do to the top and bottom of the sidewall material after planing a core with UHMW sidewalls. My thinking is that the top and bottom of the sidewall may have some bonding/delam issues since they haven't been treated due to the planing process. Is a flame treatment required and if so how does this impact the core & original sidewall bond?

[knightsofnii]

yes, sand and flame the crap out of it... others can give you better pointers but it shouldn't hurt your core and sw/core bond

[twizzstyle]

I still don't get how people are profiling with p-tex sidewalls. Every time we try, once it gets thin the planer rips the sidewall off and munches it up really good We've ruined quite a few nice cores doing that.

[Brazen]

I'm using the CNC for profiling and, as yet, haven't had a problem with the ptex. Yet. As to the flame treating before layup...ALWAYS )

[Richuk]

I'm just thinking out loud, but what about this for an idea. When putting a core through the planner we all allow for snipe, lets say 10 cm each end. Well, if the problem is partially caused how thin it is planned and increased vibration that follows, then instead of allowing the snipe material to be planned down to the thickness of the tip. Re-shape the mold so that this waste material remains at 5 mm, then reduce to 3 mm as it reaches the tip. I am thinking that pressure of the rollers front and back would keep the tips, at it thinnest point, compressed as it was cut.

I would bevel the edges in advance to reduce the amount of material being dealt with.

Might need to increase the snipe allowance to 15 cm - depending on the width of the rollers?

[MontuckyMadman]

Good idea rich. We have seen this in the router bridge setup. How bout profile the uhmw separte as a slab and rip and attache to the core after it is profiled seems closer to industry method. Thicknessing sander is the way to go if attached to the core for profile. We see this from never summer and swell panic.

[Richuk]

How bout profile the uhmw separte as a slab and rip and attache to the core after it is profiled seems closer to industry method

Yep, I've read this too, but I'm sceptical about sending a sheet through a planner, which really means I don't won't to replace my planner if it goes wrong. Is this what you are doing?

[Brazen]

I usually profile an entire plank of uhmw on the cnc then rip it for sidewalls, this works fine unless the shop is so cold the plastic won't lay flat on the table

[ben_mtl]

Isn't it a pain then to bond the profiled sidewall to the profiled core ? it's very thin at the tips.. might be tough to clamp !

[Brazen]

So far, so good with this method Ben. I run a contour pattern on the backside of the sidewall material to allow for a .060 channel for the edge tangs, profile the whole plank then rip it. Just tack them to the core with superglue

[MontuckyMadman]

I don't use plastic sidewalls.
There are lots of ways to attached things instead of clamping with glue.
Think temporary and sticky. Hot glue or super glue works also.

[ben_mtl]

And then epoxy fills the "gap" between the core and sidewall during layup?

That's the tricky part I don't get : with the "temporary" holding of the sidewall, how do you make sure you have a strong bond sidewall/core in the final product?

[falls]

Remember that there is also the top and bottom of the sidewall that anchors with epoxy too. These surfaces are subjected to the 50psi of the press and teh bottom side is pushed against the bottom glass layer (with or without VDS over it) and the top side has the top glass layer forced down on it also. For a sidewall to tear away from the core the top and bottom bonds must fail also.
If your sidewalls are retained by blocks or a long retainer such as in a cassette then as the layup heats and expands this will also provide pressure between the core and sidewall as the epoxy oozes in there.