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How hot to heat a polyurethane ski boot shell for home molding/punching?

post #1 of 6
Thread Starter 

I am planning to try to do some home stretching on a pair of Dynafit ZZero 4 U MF boots:

 

 

TRARD.jpg

 

Why do this myself?  Well I've been to two good bootfitters, who have declined to try to modify the boot in the way I would need, which would involve stretching it in at ankle height on the inside about 3/5ths of the way back and around sole height on the outside at about 2/3rds of the way back.  The boot fitters I've talked to say that it's hard to punch out a boot in that area and basically seem not to want to risk destroying it.  I've had them about a year, and I don't think I could take them back.  I could try to sell them used, but I thought I would rather try to see if I could make them work rather then get rid of them and start looking again.  The short version of what is wrong is that with a heel lift & a non-custom footbed I've been able to ski them all day without pain, but then when I take them off my feet start to hurt, to the point where for the rest of the evening I can't put any weight on the foot.  I can feel that what's happening is that the part of my foot around the instep and a little back is being compressed (I have wide feet and the widthe goes all the way back to the instep area, plus wide ankle and a prominent muscular area below the inner ankle).

 

I have some ideas about how I can stretch them and I though I would try - I'll supply a "trip report" if it works out :)

 

So my question is how and how hot to heat them.  I've heated boots shells over a pot of steam in the method recommended on the zipfit site.  I'm at sea level, so this will be fully 212° but I feel like I might need to get them a little hotter for the stretching I need.  Can I do this in the oven (with a thermometer of course)?  Any other comments or recommendations?  I'll throw in a foot picture just in case it helps:

 

IMG_0832.jpg

 

post #2 of 6

Hi cometjo,

 

 

     Learning to heat and stretch plastic shell boots is a process which usually destroys a few (boots) along the way, best to practice on a pair of junk boots first, that way nothing is lost.  The secret is 212 degrees will not get it and putting them in the oven is not a good idea---your wife might have to get a new oven if you melt down (messy).  You will need to get the shells up to 300 degrees to erase the plastics memory and make the stretch hold. If you heat the entire boot how will you hold it (300 degrees) without leaving finger prints all over it and deforming the whole thing?  We spot heat.

 

     A boot fitter would know how to remove material from the inside of the tongue for more instep room, plus there are tools made for stretching the shell instep upward at the second buckle (see tool here http://southern-ski-tools.southernski.com/tjs3.html). Width stretches are done every day at our shop and are a common issue with getting the boot to fit wide feet.

 

     Read the WIKI "Which boot will work for me" at the beginning of this section, specifically about shell fitting your boot first, to see if it is worth doing all this work if the first place.

 

mike

 

 


Edited by miketsc - 2/8/12 at 8:07am
post #3 of 6

seriously 2 fitters won't stretch your boot as they are scared they will wreck it!!!! brilliant, but please find a real fitter

 

you may get a bit of plastic disfigurement when working on certain areas  of a boot like this but nothing scary and to be scared to work on a boot is not going to do their business any good

 

as Mike says the forefoot width stretch is a simple one, the instep/ankle one may be a bit more tricky but with the right tools and a bit of patience should be perfectly doable, but the key is the correct tools and a bit of knowledge, self stretching a boot can work but tends to end up with more molten boot parts than is generally desirable 

 

where are you based, i may have to set up a shop in the area if that is the competition i can expect

 

 

post #4 of 6

Hey CEM i wanna open a sshop in that area...come on they wont stretch it... Have you tried a footbed...that can off load the ankle alot?

jeff

post #5 of 6
Thread Starter 
Quote:
Originally Posted by miketsc View Post

Hi cometjo,

 

 

     Learning to heat and stretch plastic shell boots is a process which usually destroys a few (boots) along the way, best to practice on a pair of junk boots first, that way nothing is lost.  The secret is 212 degrees will not get it and putting them in the oven is not a good idea---your wife might have to get a new oven if you melt down (messy).  You will need to get the shells up to 300 degrees to erase the plastics memory and make the stretch hold. If you heat the entire boot how will you hold it (300 degrees) without leaving finger prints all over it and deforming the whole thing?  We spot heat.

 

     A boot fitter would know how to remove material from the inside of the tongue for more instep room, plus there are tools made for stretching the shell instep upward at the second buckle (see tool here http://southern-ski-tools.southernski.com/tjs3.html). Width stretches are done every day at our shop and are a common issue with getting the boot to fit wide feet.

 

     Read the WIKI "Which boot will work for me" at the beginning of this section, specifically about shell fitting your boot first, to see if it is worth doing all this work if the first place.

 

mike

 

 


Hi miketsc, thanks.  OK maybe I can't do this...I think the boot is good: 2cm shell fit, on the large side I know, but I figured that would be OK for hiking & that a footbed should hold my heel in place.  I think the problem is that the stretching needs to be behind the second buckle.  But it sounds like maybe I can find a bootfitter willing to try?

 



Quote:
Originally Posted by CEM View Post

seriously 2 fitters won't stretch your boot as they are scared they will wreck it!!!! brilliant, but please find a real fitter

 

you may get a bit of plastic disfigurement when working on certain areas  of a boot like this but nothing scary and to be scared to work on a boot is not going to do their business any good

 

as Mike says the forefoot width stretch is a simple one, the instep/ankle one may be a bit more tricky but with the right tools and a bit of patience should be perfectly doable, but the key is the correct tools and a bit of knowledge, self stretching a boot can work but tends to end up with more molten boot parts than is generally desirable 

 

where are you based, i may have to set up a shop in the area if that is the competition i can expect

 

 



I'm in Ottowa Canada, but I was doing the bootfitting in northernVT - the places I tried were well recommended shops at Stowe and Sugarbush.



Quote:
Originally Posted by drbalance View Post

Hey CEM i wanna open a sshop in that area...come on they wont stretch it... Have you tried a footbed...that can off load the ankle alot?

jeff

 

I've have a footbed in there - it helps, but there is an overall circumference of the boot at that point issue in addition to the fact that I'm pronating and pressing against the inside wall - hence the internal pain I described, not a hotspot.

 

 

Anyway, if any one has suggestions of where to go, I'm very open to having someone else do this.  I'll be in whistler in a week, so any suggestions there, eastern Ontario or Northern VT would work.  I also get to NYC at times, and this is seeming like a longterm project....
 

 

post #6 of 6

fanatico in whistler..

 

heat the boots in a pot of hot water.   80'C or so...

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