Concrete molds ?

[a.badner]

has any thought of making contrete molds and just copy another ski design?

http://www.diyskate.com/concrete_mold_02.html

insted of a uncut board, just staple some thin plywood to a ski template?

Pros

- mdf lasts way longer than mdf
- less work with a router for every new mold
- cheaper ( a sheet of mdf costs about 50 dollars in canada and a bag of concrete is about 15 and steel mesh/chicken wire is $5/meter)
- you can run resistance wires/water pipes through the concrete for heat
- more accurate

Cons

- heavy
- hard to adjust if there is any faults
- can crack in thin spots
- a bit more complicated process to building it
- can not be adjustable.

your thoughts?

oh and little status update for the ones who care about me, ( not many i know)

I will sooner or later try this give you guys a full lab report, but i have suffered a severe concussion and am currently deemed to sit on a couch. I am restricted to the couch for the next month.

My ski season is over and build season soon begins WOOO!

[twizzstyle]

Hmmm interesting idea. I'd worry about the heat and any residual moisture in the concrete causing cracks. Maybe the chicken wire would be enough to prevent that. You'd have to figure out a good way of keeping the mold surface perfectly flat while the concrete cures.

[Richuk]

Concrete deletes the reset option. You're already producing great results, so you're only going to get better and re-design at a later date. Then you have to dump the concrete : (

What about a large re-useable mdf template - just a thought. CNC the template, use it. When it comes to redesign, cut a new template into the old one, adding 12 or 20mm sheet underneath to compensate. With your press, you might be able to do this three or four times?

And if you are adding sheets below the mold, you can use this flat area for dye sublimation, using your press to apply the pressure from above : )

This is still a work in progress ... working on calibration.

https://picasaweb.google.com/r.barnes01 ... 8766738210

An idea!

[Brazen]

That looks like it's going to work well. Awesome idea! Need another video though...

[a.badner]

but the concrete mold is SO much cheaper than an mdf.

and even if i do have to make a mold recall/adjusments, a new bag of concrete is still much less than mdf.

BTW people are extremely stingy with their CNCs in Canada, i got my ski template CNCed for 180 dollars.

[DutchDesigns]

Im not sure where you got yours cnc work done but I got 3 sets of templates and mold cut for 100 bucks! as long as your files are good they can just load them onto there system and mine were all cut in about 30 min, spent more time explaining to the guy about building skis

[DutchDesigns]

As far as MDF i managed to find 6 5ft by 9 ft 1/2 inch thick sheets for 5 bucks each!! all were damage at the lumber yard! So it pays to keep checking lumber yards for messed up material!

[chrismp]

if you have a university that teaches architecture or some engineering stuff near your place, just go there and see if they have a cnc router...usually they let people use it for small projects.

[a.badner]

PEOPLE STOP CHANGING THE SUBJECT! haha

I NEED MORE PROS AND CONS FOR CONCRETE MOLDS!

[MontuckyMadman]

way to heavy, you will die under the weight of your mold.

[twizzstyle]

PEOPLE STOP CHANGING THE SUBJECT! haha

I NEED MORE PROS AND CONS FOR CONCRETE MOLDS!

Pro: Doesn't need CNC.

Con: Doesn't utilize CNC.

CNC prices are nuts, more incentive for me to ditch my tiny CNC mill and build a larger one this year, I'd charge pennies for ski builders.


Back to the topic... how would you ensure the mold was flat? I see that as the biggest challenge.

[a.badner]

way to heavy, you will die under the weight of your mold.

Elaborate please! its not gonna be MUCH heavier than the mdf mold im using. ribs and two panels to fill in space. Apropos, you never really take out the mold these days. Even in the situation that im changing the shape of the ski i will always have someone to help me with moving the mold.

AND I ALREADY LISTED IT!

how would you ensure the mold was flat? I see that as the biggest challenge.

flat in which way?

on the base of the concrete? its going to be just as flat as the wood box/wood i use to cure it in.

or

flat on the mold side? its not supposed to be flat! duh.

well anyways add it to the list

[Alex13]

Concrete is strong in compression, but very weak in shear and tension. Unless you have perfect compression in your press (i.e. very flat surface, very flat base of mould and even pressure distribution) you will most likely crack the concrete pretty quick.

It's also heavy, so moving it would be difficult. An MDF mould is heavy enough as it is.

[twizzstyle]

flat on the mold side? its not supposed to be flat! duh.

Fail Adam!

Obviously the ski is not flat longitudinally, I mean laterally. We all know one of the biggest challenges in homemade skis is keeping the base flat. If you just have a bent board, when you pour in the concrete its going to want to bulge that board out. You could probably get by with using some angle iron bars as a frame to support the profile board while the concrete cures (but at this point with all the work going into just the frame to make the concrete mold, you could have two MDF molds made )

[a.badner]

[quote]when you pour in the concrete its going to want to bulge that board out[/quote]

ahhhh, yes good point. gravity, thou art a heartless bitch hha