PLASTICS? What a headache! I need some help from everyone here after todays trip to a local plastics wholesaler. I went with the intention of buying the ABS sidewalls, tip spacers & topsheet materials I need. I left without having purchased any materials and with more questions than when I went in. Maybe you all can help me.
First, the easy stuff, -ABS for sidwalls:
Judging from other people's posts, and the sidewalls available at Snowboardmaterials.com the ABS sheet I buy should be 1/4" thick. Is this the standard haircell on one side, smooth on the other, extruded ABS that I was looking at today? Just need some affirmation here because I am really clueless about plastics.
Little harder.... What to use for a tip spacer?
I've read that some people use ABS for the tip spacers. Anyone using UHMWPE? Either way, what is a good thickness? Looks like KK&K's cores plane out at about 3mm (1/8") I suppose that the tip spacer would be the same.
Impossibly hard. What to use for a topsheet?
I notice that the KK&K are using p-tex as their topsheets now. Is this Durasurf? or a UHMWPE for a industrial plastics supplier. The supplier I visisted with today can supply rolls of UHMWPE at 0.020" (0.51mm)thickness. This seems like it would be a good top sheet. I have not compared it's price to the thinner p-tex available from Crown Plastics (Durasurf).
---or----
Would a product like Isosport be better? I called Linsey at Snowboardmaterials.com and tried (with as much tact as I could muster) to ask him what the common name for Isosport is. I believe he said it was PBT. The closest the plastics supplier could think of was called PETG. It is a little like Lexan as best I could understand. It is only $15 for a 4x8 sheet, so I asked them to bring one in. Lastly, I was intrigued by polycarbonate, it seems like an ideal material, but I see that KK&K suffered a delamination problem with it, and the supplier warned that I would likely have a negative reaction the the epoxy. Specific chemicals are recomended for gluing it. I took some sample pieces of the polycarbonate just to do some of my own testing.
HOSE-MAN's JOURNAL - chronicling my ski build
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
i definitely feel your frustration about getting the plastics. i've simply given up driving around to my plastics stores only to encounter sales people that just don't have a clue as to what they're selling. plus i'm tired of my hands looking like swiss cheese after rumaging through all their stock.
i buy all of my sidewall and topsheet material from Durasurf from now on. it's just easier. i don't have an exact measurement for the topsheet material but i think it was half as thick as the base (approximately 0.5mm). as for the sidewall material it comes it 1/2" thick sheets. I think the thicker you can find the sidewall material the better. It'll give more room for error when laying up your core.
a note about the isosport topsheets. all three of us have had major problems with them. you have to keep in mind that these are designed for snowboard use and do not withstand the abuse that skis tend to have on each other. every single pair of skis i've made with the isosport topsheets have chipped significantly on their first day out and end up looking like junk real quickly. i'd recommend getting something stronger like that UHMWPE stuff your supplier has.
tipspacer isn't too much of a big deal in my opinion. i've ran out of my ABS stuff so instead of ordering more material i'm just going to use leftover base material. i'll have to double up the layers to get the right thickness but i'm sure it'll work fine.
you can also use fiberglass as your tipspacers. we did that with the Kananas and for the most part they turned out pretty well. it's just a little tricky getting the fiberglass pieces to stay exactly where you want them.
i think kelvin can tell you more about the polycarbonate stuff. we've only used them on the kung paoders, which are a part of kelvin's quiver.
i buy all of my sidewall and topsheet material from Durasurf from now on. it's just easier. i don't have an exact measurement for the topsheet material but i think it was half as thick as the base (approximately 0.5mm). as for the sidewall material it comes it 1/2" thick sheets. I think the thicker you can find the sidewall material the better. It'll give more room for error when laying up your core.
a note about the isosport topsheets. all three of us have had major problems with them. you have to keep in mind that these are designed for snowboard use and do not withstand the abuse that skis tend to have on each other. every single pair of skis i've made with the isosport topsheets have chipped significantly on their first day out and end up looking like junk real quickly. i'd recommend getting something stronger like that UHMWPE stuff your supplier has.
tipspacer isn't too much of a big deal in my opinion. i've ran out of my ABS stuff so instead of ordering more material i'm just going to use leftover base material. i'll have to double up the layers to get the right thickness but i'm sure it'll work fine.
you can also use fiberglass as your tipspacers. we did that with the Kananas and for the most part they turned out pretty well. it's just a little tricky getting the fiberglass pieces to stay exactly where you want them.
i think kelvin can tell you more about the polycarbonate stuff. we've only used them on the kung paoders, which are a part of kelvin's quiver.
- Kam S Leang (aka Little Kam)
-
Enduro_Skiin
- Posts: 17
- Joined: Mon Sep 12, 2005 3:17 pm
- Location: Maine
Ski manufacturer dimensioning
Through my travels if have found that ski companies can be slightly misleading with their given dimensions of skis. You already pointed out that width dimensions are only truely given for one length ski.
Here is something else to chew on. Under closer investigation of a pair of 190 Volkl Explosivs (2004), the cord length of the ski is only 186 cm, Tip-waist-tail seemed good though. I got shorted over an 1.5" of ski that I paid for. This indicates to me that there may be some inaccurate published measurements of high production skis, maybe a marketing scheme.
This also makes me wonder how they are giving the radius of sidecut for the ski as well. I had figured an equation that took some liberties to calculate given Rsc from supplied dimensions of skis to back out Rsc for shorter versions. It works pretty well when verified against volkl and atomic, Mid-fat and fat skis. I will be back to post it when I find it.
Here is something else to chew on. Under closer investigation of a pair of 190 Volkl Explosivs (2004), the cord length of the ski is only 186 cm, Tip-waist-tail seemed good though. I got shorted over an 1.5" of ski that I paid for. This indicates to me that there may be some inaccurate published measurements of high production skis, maybe a marketing scheme.
This also makes me wonder how they are giving the radius of sidecut for the ski as well. I had figured an equation that took some liberties to calculate given Rsc from supplied dimensions of skis to back out Rsc for shorter versions. It works pretty well when verified against volkl and atomic, Mid-fat and fat skis. I will be back to post it when I find it.
I've been going to Tap plastics and they are pretty helpful.
For the sidewalls we are using 3/8" abs. 1/2"would be better but Tap does not stock 1/2". For the tip spacers, we use 1/8" abs. As Kam mentioned, it's easier just to get it from the same place, and the next time I order base material, I'll probably get all the other stuff as well.
The UHMW that you can buy off the shelf is a little different from the ptex from Durasurf. 1.) Durasurf stuff is sintered (which doesn't matter for the top), 2.) it is abraded and ready for bonding. For some reason, doing it at home with a sander doesn't do nearly as good of a job as the durasurf.
Isosport makes a bunch of different topsheet materials. I think the stuff from snowboard materials is ISOCAP, which is designed for cap skis. This is probably why it chips so easily is a sandwich construction. They do make ISOTOP which is meant for sandwich construction. You can contact http://snowboardmfg.com/index.htm for ISOsport material. I talked to them a long time ago and can't remember the exact pricing, but I think it is expensive.
Polycarb looks great out of the press, because it is really clear and shiny. It did not bond well and delaminated pretty quickly. It's hard to abrade things at home with a hand sander. Maybe if you had a sandblaster, that would work better.
-kelvin
For the sidewalls we are using 3/8" abs. 1/2"would be better but Tap does not stock 1/2". For the tip spacers, we use 1/8" abs. As Kam mentioned, it's easier just to get it from the same place, and the next time I order base material, I'll probably get all the other stuff as well.
The UHMW that you can buy off the shelf is a little different from the ptex from Durasurf. 1.) Durasurf stuff is sintered (which doesn't matter for the top), 2.) it is abraded and ready for bonding. For some reason, doing it at home with a sander doesn't do nearly as good of a job as the durasurf.
Isosport makes a bunch of different topsheet materials. I think the stuff from snowboard materials is ISOCAP, which is designed for cap skis. This is probably why it chips so easily is a sandwich construction. They do make ISOTOP which is meant for sandwich construction. You can contact http://snowboardmfg.com/index.htm for ISOsport material. I talked to them a long time ago and can't remember the exact pricing, but I think it is expensive.
Polycarb looks great out of the press, because it is really clear and shiny. It did not bond well and delaminated pretty quickly. It's hard to abrade things at home with a hand sander. Maybe if you had a sandblaster, that would work better.
-kelvin
I'm not sure that I agree. I think that the filler in the tip might have some impact on how the ski busts through crud. If the filler material is supple, it will to readily flex but may create a marmonic & lead to chattering or dampening issues. A tip that is to stiff may lift the body of the ski and fail to initiate solid edge contact. I don't know this for a fact, I am just guessing.littleKam wrote:tipspacer isn't too much of a big deal in my opinion. i've ran out of my ABS stuff so instead of ordering more material i'm just going to use leftover base material. i'll have to double up the layers to get the right thickness but i'm sure it'll work fine.
you can also use fiberglass as your tipspacers. we did that with the Kananas and for the most part they turned out pretty well. it's just a little tricky getting the fiberglass pieces to stay exactly where you want them. .
More plastics questions.....
What dimension is the 1/2' thick ABS that durasurf is sending you? Surely you are not shipping 4x8 sheets.
Is the ABS you are using for your tip spacers just the standard smooth on one side, hair cell on the other ABS sheet?
Sounds like the p-tex top sheet is the way to go. I was just hoping for something more transparent.
it's true that tipspacer can have an affect upon performance issues such as crudbusting, lift, etc. but i try to address these issues into my core rather than into the tipspacer material itself.
from durasurf, the tipspacers are made from UHMWPE and come in a white color. the minimum sheet size you have to order is about 6" x 72" and you're supposed to rip the strips yourself.
for my old ABS material it was smooth on both sides.
from durasurf, the tipspacers are made from UHMWPE and come in a white color. the minimum sheet size you have to order is about 6" x 72" and you're supposed to rip the strips yourself.
for my old ABS material it was smooth on both sides.
- Kam S Leang (aka Little Kam)
I posted this in the general "heated press" thread when I guess I should have put it here. Best of luck and all. To quote myself...
You said you were taking the heating element out of an old heater for your press, which seems like a good idea to me. How are you mounting it? I had a kinda crazy idea about making your own silicone blanket. You could lay out the wire in some regular pattern and than cast silicone around it. Doing a little googleing it seems that ordinary silicone caulk is rated to 400 deg F and you should be able to thin it with xylene [nasty stuff, but at any hardware store]. I was thinking: lay out the wire in a shallow mold; cast a layer of silicone as thin as possible and let cure; flip it and lay a very thin layer on what was the bottom. Holding a vibrating back massager to the bottom of the mold should make it level out pretty well. It seems silicone doesn't like to bond to silicone that's allready cured so that might be a problem if you're not gentle with it.
You said you were taking the heating element out of an old heater for your press, which seems like a good idea to me. How are you mounting it? I had a kinda crazy idea about making your own silicone blanket. You could lay out the wire in some regular pattern and than cast silicone around it. Doing a little googleing it seems that ordinary silicone caulk is rated to 400 deg F and you should be able to thin it with xylene [nasty stuff, but at any hardware store]. I was thinking: lay out the wire in a shallow mold; cast a layer of silicone as thin as possible and let cure; flip it and lay a very thin layer on what was the bottom. Holding a vibrating back massager to the bottom of the mold should make it level out pretty well. It seems silicone doesn't like to bond to silicone that's allready cured so that might be a problem if you're not gentle with it.
Things have been slow going lately for lack of free time to spend on the ski project. Yesterday I did get to do some shopping. I purchased the wood for the wood cores. About 12 board feet of maple and 8 board feet of poplar. I also scored a sample walnut veneer that is large enough for one pair of skis for free.
PLASTICS (agian)
I found a clear plastic that I will be trying out as a topsheet material. It is called PETG. The thickness is .020" and was only $15 for the 4x8 sheet. It is crystal clear but a little bit softer than I expected it to be. Even if it bonds well it may still be damaged easily by edge contact from the other ski.
As far as the ABS for sidewall & tip spacer goes, I have decided to order them from Durasurf(Crown Plastics) Along with some black ptex for bases and clear for topsheet if the PETG doesn't workout.
EDGES: I found a pipe bender that with a few small modifications will function handily as an edge bender. Pics will follow soon.
PLASTICS (agian)
I found a clear plastic that I will be trying out as a topsheet material. It is called PETG. The thickness is .020" and was only $15 for the 4x8 sheet. It is crystal clear but a little bit softer than I expected it to be. Even if it bonds well it may still be damaged easily by edge contact from the other ski.
As far as the ABS for sidewall & tip spacer goes, I have decided to order them from Durasurf(Crown Plastics) Along with some black ptex for bases and clear for topsheet if the PETG doesn't workout.
EDGES: I found a pipe bender that with a few small modifications will function handily as an edge bender. Pics will follow soon.
Describing this will be difficult, so I will go capture some images of the heaters & their intended destination. Basically I am going to remove the heating elements from the radiant heater & mount them underneath my press. They will have to heat the steel which will distribute the heat & in turn heat the press area. Quite a bit of electricity will likely be consumed to accomplish this, but the initial investment is $0.00 so it's worth a try. I have not sourced it yet, but I intend to use the temperature regulator system from a conventional kitchen oven to keep the heat right. A probe will have to be embedded into the imediately above the ski to sense the temperature.collin wrote: You said you were taking the heating element out of an old heater for your press, which seems like a good idea to me. How are you mounting it?
just got done with the order from Durasurf. The top sheet material is 0.030" I ordered the minimum order of 10m. I ordered DuraJet base in black this time, also 10m. Side wall material is sold 13" wide, 3/8", 7/16" and 1/2" thick and as long as you want it. I ordered a 6' length. I elected to not order tip spacer material because it had the 10m minimum order & I would never use that up. I will get some ABS from the local plastics distributor.
edit for spelling
edit for spelling
hose-man, your article is up! http://www.skibuilders.com/articles/skidimensions.shtml
- Kam S Leang (aka Little Kam)
-
Enduro_Skiin
- Posts: 17
- Joined: Mon Sep 12, 2005 3:17 pm
- Location: Maine
Great reference Hose-man
I love the table of dimensions, glad you put in all the man hours on it. All die-hard number lovers will love the publication by John Howe, "The new skiing mechanics."
John currently builds his own salomon/freeride skis out of Jay, Maine. He formally worked for Head skis as an engineer. If you want to see how his brain works with ski design I recommend purchasing his book.
All though his designs are not as contemporary as ours, in a sense they are with radical sidecuts and tapers. Just a suggestion.
John currently builds his own salomon/freeride skis out of Jay, Maine. He formally worked for Head skis as an engineer. If you want to see how his brain works with ski design I recommend purchasing his book.
All though his designs are not as contemporary as ours, in a sense they are with radical sidecuts and tapers. Just a suggestion.
Re: Great reference Hose-man
Is that near you? and, Have you visited? or, is that you?Enduro_Skiin wrote:John currently builds his own salomon/freeride skis out of Jay, Maine.
I took a look at a web site a while back that had a bunch of info about the book. It may have even been John's website. It was interesting, but didn't hook me well enough to buy it.
How much did the side wall material cost?hose-man wrote:just got done with the order from Durasurf. The top sheet material is 0.030" I ordered the minimum order of 10m. I ordered DuraJet base in black this time, also 10m. Side wall material is sold 13" wide, 3/8", 7/16" and 1/2" thick and as long as you want it. I ordered a 6' length. I elected to not order tip spacer material because it had the 10m minimum order & I would never use that up. I will get some ABS from the local plastics distributor.
edit for spelling