Poster: A snowHead
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tomb wrote: |
Idris, can you point out in the cross section i made above where your heating blankets are placed? Do you heat from top and bottom with 2 individual blankets?
TIA |
heat blankets are below your bottom ali sheet and above your upper ali sheet.
I run mine at 25C to keep things consistent and to let me make skis when it's -15C when I arrive for work.
I don't run higher temps because my resin doesn't need it and I don't want to get into the nightmare that is high heeat, high speed resins - allready been there wile working for someone else - 50%+ had camber different from planned.
I use underfloor heating, carbon on a plastic film - cheap (about 40 quid each) and you can't kill em by squashing. Controlled by a digital controller, that can be killed by short circuits.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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tomb wrote: |
Thanks loads for the info Idris!!
With regard to the cat track and the I beam... my I beam is 6" wide, to press 2 skis i'm guessing i need a working area of around 400mm? Is this where the cat track comes in? Does it allow even pressure to be applied across the 400mm working area even though my beam is only 148mm wide?
Sorry to ask so many questions but i cant seem to find any good info on the use of cat track?
Also...
I have 3 I beams, all of which i can carry by hand, lengths are (2380mm, 3372mm, 2400mm). They are currently resting on a trolley of mine in the work shop which only has 4 castors.... I'm a carpenter by trade so the mobile base is no worry, i can add extra strength to the frame where and when it is required.
Again thanks for the info! |
My pressing cavity is 36cm wide, Ptex comes in a maximum of 32cm wide I have more working area than is absolutely necessary. I can fit in a pair of fat pow skis with wiggle room.
A cat track spreads the load over it's width, if it's stiff enough, mine is 3 layer 22mm plywood or bits of hardwood about 25mm thick, does the job nicely.
Your lower mold will need t be strong enough to also take the forces.
I think 6" is quite narrow, how deep/tall are they? you might want to turn them on their side, that how richUK's press is built.
Cat track is fully explained on skibuilders, on both the ski builders how to (from the front page) and multiple forum threads
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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Idris, Thanks a million, ive just been looking at the high heat stuff, and as you said i came across reports of varying cambers not consistent with the mould used. They also cost a bomb for a decent sized silicone heat blanket!
Just out of curiosity , what is your cure time when heated to 25°c?
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RattytheSnowRat wrote: |
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i think i understand the cat track now.... its to apply an even distribution of pressure on the aluminium sheet in the press
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Don't see why the pressure should be any more or less evenly spread with or without the intermediate cat track. The only reason I can see where it would help is if the bladder/hose was not wide enough. It would also have to be pretty flexible. I suppose you could mock one up really easily by drilling and joining bits of box section on a wire then you could control the flex.
The other more interesting way of doing it would be to create a cat track out of smallish section rubber hose looped on itself and fixed together to create an inflatable 'cat track' of the required width. That way you could do both jobs in one and lose the separate bladder. You might have to guard/guide the looping with supports but I am guessing the pressure will stop any kinking or dead spots. You could retrofit a normal central heating cylinder with an electric heater installed on a thermostat, fill it with water and then pump air through the inner coil. The air would heat up and pass to the hose cat track supplying the pressure in your press. By re-circulating the air I am guessing you could control the temp very accurately.
No more need for thumping great bits of hose. |
Without a cat track you don't get flat skis/snowboards at anything above moderate (10psi) the hose forces the ski topsheet to be concave or convex, depending on where and how it makes contact - an ali sheet in between, even quite a tick one won't really service - had this problem will working for another ski maker.
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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crossed post there.... my beams are 10" x 6" or 250mm x 143mm, they are I shaped beams so i dont know how they could be turned to utilise the 250mm side?
Also i must be missing something cause i really cant see where on the skibuilders website they have the section on cat tracks... not that it matters now as im confident i understand them. Its interesting that you say you use 22mm ply, i have an abundance of that in my workshop, i think i may use that instead of forking out for aluminium
Again thanks for the info, it is greatly appreciated!
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Quote: |
Also I must be missing something cause i really cant see where on the skibuilders website they have the section on cat tracks...
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I'm with tomb, there's nothing in the lay up section that says anything about a 'cat track' and apparently we are not the only ones with an issue over this. The following is from the skibuilders forum:
"I have followed the directions almost exactly that are on the ski builders website. Of course, we have had 1 or 2 small additions to it along the way, but that's not the point. We are about 1 or 2 weeks away from layup on our first pair of skis, and I have started to read all of the forums a lot more. As I look into it, a lot of people talk about using a cat track. I understand the concept of it, I am just wondering if it is necessary. For a first time builder, do you think we could skip getting a cat track for our first few pairs, or should we go ahead and try to make/buy one? One more question concerning a cat track: in the press, does it go below or above the ski itself?" The answer was 'it's not really necessary if you get adequate cover for the bladder'.
I think my looped hose solution above would remove the concave/convex issue as the pressure would be pushing out equally from a hundred or so balanced points. As long as you raise the pressure very gradually the matrix should all exert pressure evenly across the entire length and width of the ski. I shall try it and report back
If we want to buy and ship a 'super' ski press, some dude on the skibuilders site is selling one in Madison, WI.
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tomb wrote: |
crossed post there.... my beams are 10" x 6" or 250mm x 143mm, they are I shaped beams so i dont know how they could be turned to utilise the 250mm side?
Also i must be missing something cause i really cant see where on the skibuilders website they have the section on cat tracks... not that it matters now as im confident i understand them. Its interesting that you say you use 22mm ply, i have an abundance of that in my workshop, i think i may use that instead of forking out for aluminium
Again thanks for the info, it is greatly appreciated! |
Will find some pics of beams used in a press this way (or I'll draw to explain). Will post a pic of my press to explain the cat track.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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Idris, Thanks again, ive been thinking about it and the only way i could envisage it being done is to notch the timber/mdf moulds around the I beam, is that how it's done?
RattytheSnowRat, nice link... have you have any luck sourcing a uk based ptex supplier? I'm having difficulty but did find some UHMW (http://www.bayplastics.co.uk/polyethylene.htm) is this the same stuff you think?
Also does anyone know if you can used printed vinyl as a graphics layer?
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tomb, I just realised there is a cat track positoned in the google diagram you posted on page 2 .......
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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RattytheSnowRat, yeah there is also one shown in my illustration in page 7.
I'm struggling to find a 4th rsj to allow me to build a double ski press :/
But I do think I've sourced some ptex... I was going to ask idris to confirm that ptex is the same stuff as UHMW polyethylene sheet??
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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P-tex is a sort of brand name, you could also look for IsoSpeed or Durasurf. Ultra-High-Molecular-Weight Polyethylene is the generic description for the material (can be described as high-modulus polyethylene, high-performance polyethylene also) you want the sintered version if possible. To be honest, I was going to get in touch with one of the other ski makers in the UK and see if I could piggy back on their ordering so we both could save some money. I did look at suppliers and there are some in France but you have to watch the quantity levels ordered.
Otherwise you can ship from the States for small amounts to start with: http://snowboardmaterials.com/pages/base.htm
feef seemed to know of a possible UYK source ... feefy? .... feefster?
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You know it makes sense.
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I got a supplier, our plastics supplier in work. The 2mm sheets (2m x 1m) were £14 each for both black and clear
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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Scrub that last comment, the polyethylene is a lower grade than required!
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Poster: A snowHead
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feef, did you manage to find a uk stockist, I'm at a dead end :/
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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tomb, Not yet, but I'm going to meet up with my mate who works for Rossignol at the weekend and see if he has any leads.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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I have ordered engineering plastic from here in the past.
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feef, nice one, fingers crossed he does!
rjs, thanks but I've tried every major plastic stockist I can think of (include the ones in your link), no one had polyethylene with the PE value required
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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tomb wrote: |
feef, nice one, fingers crossed he does!
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He's the chap that trained me as a ski-tech. Thinking back, we had entire ski-lengths of base there which we were stamping patches out of so it must be easy enough to get ahold of.
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feef wrote: |
tomb wrote: |
feef, nice one, fingers crossed he does!
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He's the chap that trained me as a ski-tech. Thinking back, we had entire ski-lengths of base there which we were stamping patches out of so it must be easy enough to get ahold of. |
Was that as rossignol? Cause it would be a small expense for a company like that to ship from the USA.
I've found people who will ship it over from the USA but I was hoping to find someone who had it on the shelf where I could order a small amount at a time instead of a full roll.
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tomb wrote: |
feef wrote: |
tomb wrote: |
feef, nice one, fingers crossed he does!
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He's the chap that trained me as a ski-tech. Thinking back, we had entire ski-lengths of base there which we were stamping patches out of so it must be easy enough to get ahold of. |
Was that as rossignol? Cause it would be a small expense for a company like that to ship from the USA.
I've found people who will ship it over from the USA but I was hoping to find someone who had it on the shelf where I could order a small amount at a time instead of a full roll. |
no, this was before he started with Rossi. He is a very experienced ski-tech and, as he would say, I was his 'bitch' when we worked in the ski shop. We were buying the stock from somewhere, but I didn't know, nor need to know where from. I'd just tell the boss what we needed.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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I had a chat with Shug yesterday at the ski show and asked about base material. He suggested that we could try AnythingTechnical : http://www.skiequipmentuk.co.uk/ as they would likely supply smaller quantities.
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Tomb,
Idris has visited my workshop on a number of occasions, so you're putting him in a difficult position when you ask him to say what he has seen.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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richuk, I do apologies, I don't mean to tread on anyone's feet! I take it you build skis as a living?
feef, thanks for the lead... I've emailed them enquiring about the base material.
I've also sourced some free 2"x2" steel box section, roughly 100m of the stuff, so it looks like me press will actually get built
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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Quote: |
I hope you're all putting this useful info into the wiki too
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m8 - totally forgot, sorry. I'll try to make some space in my day to redeem myself. The ski materials section of that site http://www.skiequipmentuk.co.uk/ is worringly empty at the moment - do you think they heard we were coming and hid everything?
richuk, I thought that's why we have PM on this site - just kidding. If my cunning plan(s) work(s), I promise I'll share. It's taking shape and I've just realised there are two additonal benefits to the proposed structure. Now, if only that blasted scrap dealer could work out how to use the phone and return my call ....
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Honestly, we'd encourage you to go for it ... but just note a press built using RSJ's has the capacity to do a lot of damage to you - personally. You'll get a sense of it when you inflate it for the first time. I-beam's are not designed to resist a load in the direction you are considering and I can't see from the photo if the seams are welded or cast ... you wouldn't be the first to split an old seam.
Spend a bit of time getting this phase of the build right ... do the research until you are happy you have it, as short cutting this part of the process will not pay dividends. We're not bothered if anyone ends up with our solution, you can't ski a press.
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You know it makes sense.
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I've been doing some more digging into the UHMW. There's either way more grades than I first thought or some of the suppliers in this country over charge more than the Devil on a soul trade. It's also possible that both those prior statements are true.
I asume the answer is 'yes' but has anyone tried a teflon based ski? If so why did it not catch on (I assume it might be becasue of a 'ding' repair problem)?
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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RattytheSnowRat, I've searched high and low for UHMW, and I couldn't find anything with a PE value of over 1000 and I think most bases are 4000 or grater??
I've tried emailing crown plastics in the USA to see if they have an up to date uk stockist list...
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Poster: A snowHead
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There are a few people still holding very small amounts, but not enough to make skis with. Assume you can get ski materials (base, edges and VDS). I'm sure Idris would help you with ski materials, as will I.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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this is such a happy and helpful thread
where's the abuse and trolling?
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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You need to Login to know who's really who.
You need to Login to know who's really who.
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not used one. I think it would work if you were careful. My concern would be that it might damage the flat tongues that go under the base if you're not careful
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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richuk, thanks m8. You and Idris are real people. If either of you are in London, get hold of me and I'll buy you a beverage or two in one of the sleezy dives I frequent.
ed123, we are Troll hunters
tomb, I've got a couple of those in specialist sizes. They are really just for pipe and work best in tandem with a snake. I can bend normal edging by hand but the DIY bender on the skibuilders site is easy enough to knock up and I was planning on doing it for the thicker edging strip I was hoping to source. I wouldn't get that bit of kit just for doing edges but if you plan to bend some pipe in that diameter as well it might be a buy. The real problem is that you will need three-ish hands to bend edge using that tool. Using the skibuilders set up lets you get more leverage on the strip which means more precise bends. I thnk feef might be right about the base flanges but looking at my bender I think you might be able to avoid that by bending the edging strip upside down (as it were) so the flanges are on the top. It would still be fiddly but not impossible.
Make up the skibuilders set up on 22mm ply with a vise plate on the bottom then you can just pop it in and out of a vise when needed and store it out of the way the rest of the time. Certainly easier, might even be cheaper.
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a keep-it-on-the-first-page *BUMP*
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Yeah my progress is again lagging, the box section I got is too thin a gauge. I also have a pile of uni work to complete and work is also very busy :/
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Quote: |
a keep-it-on-the-first-page *BUMP*
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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Hey Guys,
I've been awol again with work, but it has given me a chance to do some research.
I noticed that people were looking to use I-beams to build the frame for the ski press, but is there any reason against using a lightweight material like aluminium? We have been using an aluminium frame to mount a small winch to pull-in power cables on a wind farm and it has worked well. It has been designed to withstand significant forces (c.4 to 6Te)...not that anywhere near this would be required to press a ski!
A fairly simple question, but also has the aim of keeping the thread on the front page.
David
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dalamb84, The problem with aluminium is it's such a pain to work with, especially weld. It oxidises is a few minutes so you have to work fast. Using regular MIG equipment is a PITA unless you're used to working with Al (in which case you're probably using TIG). Using regular steel grinders and files etc get clogged very quickly.
If you're used to working with it, then great - If you're used to working with steel, best stick with steel.
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