/ Boot oven temperature?

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Smelly Fox - on 07 Mar 2019

Can any ski techs / boot fitters out there what temperature you set your oven for softening plastic boots for modification.

My knowledge is nearly 10 years out of date, and I need to do some DIY...

Cheers,

Trist

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Doug on 07 Mar 2019
In reply to Smelly Fox:

boots or thermofit inners ?

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Smelly Fox - on 07 Mar 2019
In reply to Doug:

Sorry I wasn’t very clear was I... the boots themselves. I’d consider a heat gun normally, but looking for a more general and less aggressive solution.

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Guy - on 07 Mar 2019
In reply to Smelly Fox:

I'd be very wary about putting the whole boot in an oven as there are typically a bunch of glues used which might not take well to being heated to the temperature needed to manipulate the shell.

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Smelly Fox - on 08 Mar 2019
In reply to Guy:

Yeah, your probably right. Although I’m pretty sure there is no glue on my boot shells... plastic welds maybe, but not glue.

I seem to rememer having some success back in the day with boiling water. I’ll maybe try that.

Thanks anyway...

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Kean - on 08 Mar 2019
In reply to Smelly Fox:

Don't know about using an oven...sounds dodgy, though.

(Disclaimer...certainly no expert!) I've had a lot of success using a heat gun and digital laser thermometer off Amazon for 30-odd pounds...the critical temperature I use is 160°C. I heated the plastic slowly inside (if possible) and out...this is important (a production manager in a skiboot factory told me). Inside and outside makes sense, otherwise you're setting up some sort of distortion in the plastic I guess. Why it's better to do it slowly I don't know...same sort of reason I guess. I heated to 170°C once and the plastic starts to bubble, but certainly in my experience that's just proved to be cosmetic and hasn't led to anything catastrophic happening. I fashioned a "punch" by using bits of 1" x 1" wooden cubes, drilled to take a length of threaded bar in the middle that I can adjust with a nut. (If you manage to come up with a better solution do please share!) If you want, I could stick a photo on my album, I guess.

I play around with the "punch" until I get the right length, then heat the plastic.  As soon as it hits 160° I stick on a glove and ram in the punch, then hold it in place and wait for the temperature to drop below around 50°C (again, slowly).

Also, my boots are Pebax/Grilamid, which apparently has more "memory" than standard PU, meaning it tends to want to return to its original shape. (Plus I think the same thing happens to the liners) This I can confirm because it does seem that every year I have to redo them, but now I've got my routine down, it's literally a 30 minute job.

I combine this with thermoforming my liners by putting them in an enclosed space (I used a box) and heating them thoroughly inside and out with a bog standard hairdryer. Before doing this I prepare my feet by sticking a foam patch onto the pressure point I'm trying to sort out. I've been lucky because my problem has been my ankle bones and a bit of width around my little toes, which with my boots I can access easily to get a good "punch" from the inside.

Before doing this my boots were basically unusable. Now I can ski tour all day with nary a twinge.

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kevin stephens - on 08 Mar 2019
In reply to Smelly Fox:

I’d pay a boot fitter to do it

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Smelly Fox - on 08 Mar 2019
In reply to kevin stephens:

I am one (or was one) just couldn’t remember the temp of the oven I had in the workshop.

Thanks for the insite anyway though!

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Smelly Fox - on 08 Mar 2019
In reply to Kean:

Good post, cheers!

The boiling water method has worked for me, although time will tell on the hill... if it’s not enough though I’ll give you method a go. (I do wish I had my old workshop tools though...)

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kevin stephens - on 08 Mar 2019
In reply to Smelly Fox:

I did read somewhere that heating up a linen bag of un cooked rice in an oven then stuffing it into a boot shell works?

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kevin stephens - on 10 Mar 2019
In reply to kevin stephens:

Correction, this method seems to be more for pre-heating thermofit liners rather than shells

http://www.skiall6.com/forum/8-equipment-talk/2953-instructions-for-heat-molding-liners-with-rice

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