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Using Metal-Grip, P-Tex and a soldering iron to repair a core shot

Doug Briggs

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I got a pretty nasty core shot yesterday while skiing Upper Dunes at Breck. I felt it when it happened and later while I was continuing the run, the ripped base material significantly affected how the ski would track. I used the other ski's edge to scrape off the material which I saved (no littering). You can see the material I removed and the trimmed core shot below. I used a knife to trim the gouge as it had some jaggies. Be conservative with a knife. Original material is better than repair material unless you are doing an actual patch with base material. I may show that process later.


I like to use Metal Grip, a commercially available product designed specifically to provide a bond between a core/metal and P-Tex. I apply it with a soldering iron that has a flat or chisel tip. Here you can see the pieces of metal grip that I have placed on the ski. I used the soldering iron as a hot knife to cut the Metal Grip into small pieces. When you apply the Metal Grip you aren't trying to fill the hole, but to create a layer of material that will bond to the core/metal leaving space to add P-Tex on top. Metal Grip can not be applied by burning as P-Tex can. This is the primary reason I use a soldering iron now for most of my repairs. I got it for the Metal Grip and use it, instead of fire, for P-Tex.

Working the Metal Grip in with the soldering iron. Note that I let one side of the iron's tip go into the gouge. This insures that there is space left to add P-Tex. I'll let the iron's tip go into the gouge on the other side as well.

Once the Metal Grip has cooled, I remove the excess with a Panzer file.

I'm applying the P-Tex now. Since I'm filling the space now, I just melt P-Tex straight from the coil of P-Tex; P-Tex in a coil or on a spool is designed for use in a P-Tex repair gun. It is smaller in diameter than a stick and easier to work with the iron. You can do the same with a P-Tex stick, however. The tape is there to hold the P-Tex so I can take a photo. Normally I hold the P-Tex in one hand, the iron in the other; no camera involved.

Spreading the P-Tex around.

The first clearing of the excess P-Tex with the Panzer file reveals dips where I didn't use enough. This is fine. You don't need to completely fill the hole in one fell swoop. You can go back again with more P-Tex as below.

The second layer of P-Tex.

Filed with the Panzer, then scraped with a metal cabinet scraper that has a sharp, square edge.

I could take this to the shop and apply structure to the repair. If this wasn't a ski that I expect to damage some more, I'd do that. A race ski, for sure, would get the repair structured if it were of this magnitude.

It is always important to fix damage like this quickly as water can penetrate the damage and begin delaminating the ski. Additionally, any dirt or wax that finds its way into the damage can reduce the effectiveness of the repair. If you haven't been able to repair the ski promptly, you could apply some Metal Grip or P-Tex, then pull it out. This is an effective way to remove any loose material and foreign matter. Wax remover could also be used, but you run the risk of leaving some solvent behind.

Another thing to note is that original P-Tex has a higher temperature than P-Tex repair sticks. You can heat the base up with the soldering iron and it shouldn't melt where the Metal Grip and P-Tex stick will.
 
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Drahtguy Kevin

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Hell, that ain't nothin'. Wait until I drop off my Patrons after their Jones Pass adventure. Better have Chuck order supplies...
 

Monique

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I don't expect to do repairs like this myself, but I really appreciate the insight into how it's done!
 
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Doug Briggs

Doug Briggs

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It isn't going to accept wax all that well. Sintered bases accept wax not because the plastic absorbs wax, but the microscopic spaces in the sintered (as opposed to extruded) plastic can hold the wax. Melted P-Tex is not sintered P-Tex. It is monolithic (generally speaking) and doesn't have the voids to hold wax that a sintered base does.

Note that the melting point of P-Tex for repairs is different than that of P-Tex in your skis originally. The repair illustrated works because the Metal Grip, then the P-Tex adhere to the materials of the ski. If the original base melted at near the same temperature as the repair materials, this type of repair would be much more difficult.

If it's a PE/wax emulsion and not just PE, sure.

Please elaborate on this.
 
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Doug Briggs

Doug Briggs

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Hell, that ain't nothin'. Wait until I drop off my Patrons after their Jones Pass adventure. Better have Chuck order supplies...

I look forward to reviving your Patrons.
 

cantunamunch

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Please elaborate on this.

Oh. Sure. You know how people are always moaning that ptex candles have 'wax' in them and therefore the bond isn't altogether as strong as it could be? Well, that part's true, depending on the blend and specific grade of PE.

But the part that isn't obvious is that the unburned 'wax' that gets into the repair also creates voids in the PE melt. Voids that are not on the scale of voids in sintered powder, certainly not connected like those are, but some voids nonetheless.
 
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Doug Briggs

Doug Briggs

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Gotcha. I've not evaluated the P-Tex I'm using. All of it is designed for use in a gun of one sort or another. We have the large P-Tex sticks for stick guns as well as the P-Tex wire (illustrated above) but we don't have the wire-shooting gun. Until I arrived with a soldering iron, we'd burn the wire if we didn't use the gun. The big sticks in the gun are great in black, but in clear, the P-Tex doesn't melt as easily which I presume is part of the chemical make up of the stick relating to clear vs black. While I use the clear P-Tex stick in the gun, I prefer to use the clear P-Tex wire with the soldering iron. The soldering iron isn't nearly as quick for large repairs as using the gun, though, so if there is a LOT of work to be done, the gun comes out.

In truth, I'd rather use black all the time as I think it results in a better repair, despite the color, but when a ski comes in that isn't a black base, I use clear for the customer's aesthetic sake. Now if it is a combo of black and clear, I use black in almost every case. I'm typically not going to change colors in a single repair. I've had problems with clear sticking in some cases as well. I'd call a customer to see if they'd accept black for a better repair.

FWIW, I take the time to use clear on my Bent Chetllers (the only skis I have with clear bases) because the graphics are important to me.

 

Jacques

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Okay. Seems a good place to add my base repair video. Enjoy!
 

Scrundy

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Where would one get a hold of this metal grip in coil form? And would JB weld work the same to prime?
 

Atomicman

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I got a pretty nasty core shot yesterday while skiing Upper Dunes at Breck. I felt it when it happened and later while I was continuing the run, the ripped base material significantly affected how the ski would track. I used the other ski's edge to scrape off the material which I saved (no littering). You can see the material I removed and the trimmed core shot below. I used a knife to trim the gouge as it had some jaggies. Be conservative with a knife. Original material is better than repair material unless you are doing an actual patch with base material. I may show that process later.


I like to use Metal Grip, a commercially available product designed specifically to provide a bond between a core/metal and P-Tex. I apply it with a soldering iron that has a flat or chisel tip. Here you can see the pieces of metal grip that I have placed on the ski. I used the soldering iron as a hot knife to cut the Metal Grip into small pieces. When you apply the Metal Grip you aren't trying to fill the hole, but to create a layer of material that will bond to the core/metal leaving space to add P-Tex on top. Metal Grip can not be applied by burning as P-Tex can. This is the primary reason I use a soldering iron now for most of my repairs. I got it for the Metal Grip and use it, instead of fire, for P-Tex.

Working the Metal Grip in with the soldering iron. Note that I let one side of the iron's tip go into the gouge. This insures that there is space left to add P-Tex. I'll let the iron's tip go into the gouge on the other side as well.

Once the Metal Grip has cooled, I remove the excess with a Panzer file.

I'm applying the P-Tex now. Since I'm filling the space now, I just melt P-Tex straight from the coil of P-Tex; P-Tex in a coil or on a spool is designed for use in a P-Tex repair gun. It is smaller in diameter than a stick and easier to work with the iron. You can do the same with a P-Tex stick, however. The tape is there to hold the P-Tex so I can take a photo. Normally I hold the P-Tex in one hand, the iron in the other; no camera involved.

Spreading the P-Tex around.

The first clearing of the excess P-Tex with the Panzer file reveals dips where I didn't use enough. This is fine. You don't need to completely fill the hole in one fell swoop. You can go back again with more P-Tex as below.

The second layer of P-Tex.

Filed with the Panzer, then scraped with a metal cabinet scraper that has a sharp, square edge.

I could take this to the shop and apply structure to the repair. If this wasn't a ski that I expect to damage some more, I'd do that. A race ski, for sure, would get the repair structured if it were of this magnitude.

It is always important to fix damage like this quickly as water can penetrate the damage and begin delaminating the ski. Additionally, any dirt or wax that finds its way into the damage can reduce the effectiveness of the repair. If you haven't been able to repair the ski promptly, you could apply some Metal Grip or P-Tex, then pull it out. This is an effective way to remove any loose material and foreign matter. Wax remover could also be used, but you run the risk of leaving some solvent behind.

Another thing to note is that original P-Tex has a higher temperature than P-Tex repair sticks. You can heat the base up with the soldering iron and it shouldn't melt where the Metal Grip and P-Tex stick will.

Doug nice write up. Just how I do it too! This is one of my favorite tools. It makes smooth the repair with the panzer so much easier. http://www.fktools-us.com/Product-Details.asp?Part-Number=3370

3370.jpg
3370b.jpg
 

mdf

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Swiss Toni

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Metal Grip is an ethylene acrylic acid copolymer. P-tex repair material is simply LDPE its all made by an Italian company that mainly makes slalom poles and safety netting called Liski. As it’s not the same as the base material it doesn’t weld to the base, if you want a better bond flame oxidise the sides of the gouge with a fine blow torch. You could also use LDPE thermoplastic welding rod.

A much simpler solution would be to use a methyl methacrylate adhesive (MMA) such as Scotch-Weld DP8005, some MMAs bond well to steel and low energy plastics such as polyethylene. They are also about as hard as the base material. You just fill the gouge until its proud of the base wait for it to cure and file it flush. You can’t get any wax into it, but neither can you get any wax into the LDPE p-tex repair material.
 

John O

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I have the Kuu iron -- it has a mid-width tip that seems to work well for working in and smoothing repairs.

I've got the same iron, pretty sure I got it from slidewright once upon a time. I've been happy with it as well.
 

Scrundy

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I did a experiment with JB weld before fixing mine shot. I mixed a small amount put in 2 piles, I then put ptex right over before it cured. Came back in 20 to check adhesion and man that ptex stuck so I went ahead and did my ski. The second pile I was going to wait till JB cured and then ptex,but with results I got before cured I was very happy with I didn’t bother. 1B3DA94C-4BAF-441E-B92F-462E450713FA.jpeg BCE18E63-6846-4F96-AA0A-3E250C4E7639.jpeg 787571C2-337C-47BF-9A50-9227344D1245.jpeg
 

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