Heating Edges for Bending

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falls
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Heating Edges for Bending

Post by falls » Wed Apr 27, 2016 8:40 pm

Hello everyone
From my experience with 3/4 wrap when the edge is being forced into a tighter tip/tail curve the tendency of the edge to spring back to flat leads to very minor delamination with use.
Iggyskier from ON3P recently posted about detempering the ends of the edges to get better pressing into the mold shape and better fit to the curves of the ski shape. The moment ski videos also show the layup guys being able to very easily bend the ends of the edged bases up to match the prebent casettes.
I have heated some edge material with a propane torch until red hot and it is indeed a lot easier to bend. It lead to some discolouration of the edge material and I am wondering what peoples' experience is with edge preparation and bonding after heating. Is just cleaning with MEK/acetone/alcohol after heating and bending all that is needed or are people sandblasting? Is there any science to heating the edges (I know there is a lot with heating and cooling metal, but I mean more for practical purposes)
Thanks
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Akiwi
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Post by Akiwi » Wed Apr 27, 2016 10:46 pm

Yes, that interests me too. I haven't tried it as I thought the edge material will be much softer, and of course easier to bend, but also easier to ding and wouldn't stay sharp as well. (Of course not important on the tips / tails).
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SHIF
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Post by SHIF » Thu Apr 28, 2016 3:46 pm

I anneal steel edges before trying to make tight bends for doing a full-wrap. After marking them with a Sharpie so I know exactly where to start the process, I lay them out on fire bricks and use MAPP gas to get them glowing bright orange. MAPP gas is significantly hotter than propane so the job goes much quicker. Then after air cooling I use a rotary wire brush in a drill motor to scrub off all the soot. I made a simple fixture to hold the edges straight and keep them from moving. Final step is a thorough cleaning, end to end, using denatured alcohol.

My most recent two builds (I will post images to my journal soon) are not full-wrap so annealing was not necessary. It’s easy enough to cold-bend them if you start with a long enough piece to grab onto. Make a simple fixture from a couple large bolts and a bench vice. Saw a slot in one bolt to clear the edge tabs. Lever against the other bolt as you bend away.

Cheers,
-S

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vinman
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Post by vinman » Thu Apr 28, 2016 4:05 pm

Anneal, wire brush, clean with solvent of choice that doesn't leave residue.
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skidesmond
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Post by skidesmond » Fri Apr 29, 2016 3:21 am

I do 3/4 wrap too. I don't heat the edge to bend it into place. I hand bend using modified pliers and will slightly over bend so when it springs back it fits the shape of the tip/tail. The edge should fit the shape of the base as close as possible tip to tail.

Once I tack on the edge I will pre-bend the tip and tail to give it a slight curve upward. The pre-bending should be slight, maybe 1/2 or 1/4 of the actual tip radius. My cassette also has a pre-bend in the tip area.

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falls
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Post by falls » Sat Apr 30, 2016 2:53 am

thanks for all the tips.
My slight delams are downwards not outwards. Its fine in a rocker tip/tail as the curve is large radius, but is more pronounced in a normal tip/tail where the radius is tight.
I have done a heated bend around the tip of my next pair to try a full wrap.
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vinman
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Post by vinman » Sat Apr 30, 2016 3:05 am

I also try to leave a full edge tang at the end of the piece in the tips nd make sure to ti the edge far enough beyond the area where I thin it would get stress from bending while in use.
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OAC
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Post by OAC » Sat Apr 30, 2016 9:14 am

Anneal then using the "Edge brush 3000". No solvent on my material before layup! My de-lams (there has been a few I have to admit..) has never been on the edge/base side.

When using vacuum, anneal and pre bending is a good rule of thumb. I think sammer agree. :-)


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amidnightproject
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Post by amidnightproject » Sat Apr 30, 2016 5:03 pm

I use a sandblasting cabinet.

Picked it up on craigslist for $100. Blast media included. I drilled a couple holes on either side so that I could pass the edges into the cabinet and bam. Super clean edges after the anealing process.

pmg
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Post by pmg » Sun May 01, 2016 9:54 am

I also thought about annealing the edges and tried it one time. After that, I worked a bit on my nipple plier skills, and found that pre-bending both horizontally and vertically ain't that hard after all, just takes patience. So now I pre-bend the edges to the final ski shape, also makes layup easier.

Cheers
Philipp

kit
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Post by kit » Mon May 02, 2016 12:00 pm

"Anneal, wire brush, clean with solvent of choice that doesn't leave residue." - x2.

I bend them to the bases, laid up flat with superglue every third tang, then use a tip bender rig to shape tip and tail to profile before press. No delams.

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gav wa
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Post by gav wa » Tue May 03, 2016 5:31 am

Heating over about 300°c will permanently effect the hardness of the edge, your hard edge is now tempered, heat it to about 730°c and let it cool at room temp and you have normalized your edges and they have lost all their heat treatment and are now plain carbon steel.
I don't heat mine, I do full wrap even on swallowtail boards, but if you do feel the need try to keep the heat away from the contact points.

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