Zack726,
Threated rods M12 class 8.8: € 55,-
Steel members: € 40,-
Wood for press: € 35,- (but got it for free)
Fasteners for press and molds: € 25,-
Wood for molds: € 36,-
Bladder: 6-pack of beer
Coupling / connector for bladder: € 8,-
-------------------------------------
So total around 200 euro.
Buuk
Buuk's ski building journal!
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
Finally some progress :)
My progress last weeks:
- Ripped ash wood into strips and planed
- Vertically laminated cores
- Builded an alternative edgebender and tested succesfully
- Shaped the core
- Treated UHMWPE sidewall using UV-ozon (not often used method) and glued the sidewalls to the core
- Planed the cores
- Did make a groove in the sidewalls for the edges
- Started building a core profiler
Hope to press my first skis this weekend!
Will post pics soon!...
Buuk
- Ripped ash wood into strips and planed
- Vertically laminated cores
- Builded an alternative edgebender and tested succesfully
- Shaped the core
- Treated UHMWPE sidewall using UV-ozon (not often used method) and glued the sidewalls to the core
- Planed the cores
- Did make a groove in the sidewalls for the edges
- Started building a core profiler
Hope to press my first skis this weekend!
Will post pics soon!...
Buuk
Make things as simple as possible, but not too simple
Hey !
I think you probably found the cheapest but still efficient way to build a press ! Very impressive, and it gives me a lot of inspiration ! I was not really plannning on building a steel frame (can't weld), neither on using vaccuum !
I have one question about the image 8 (I can't post urL yet).
I can't understant how the top piece of wood is hanging ? Is it screwed in the metal frames ?
Are you able to easily slide your molds into this frame ?
nb: sorry for my poor english
I think you probably found the cheapest but still efficient way to build a press ! Very impressive, and it gives me a lot of inspiration ! I was not really plannning on building a steel frame (can't weld), neither on using vaccuum !
I have one question about the image 8 (I can't post urL yet).
I can't understant how the top piece of wood is hanging ? Is it screwed in the metal frames ?
Are you able to easily slide your molds into this frame ?
nb: sorry for my poor english
Under pressure
The first ski is being pressed right now!
Can't wait till tomorrow morning!
Can't wait till tomorrow morning!
Make things as simple as possible, but not too simple
Finished my skis just before Christmas, so time to upload some pics.
I will add comments later! COMMENT IS FINALLY ADDED!
Buuk
The skis core is made out of ash, I did choose for this type of wood because it was not that expansive and it has good properties. On the image you can see the wood being ripped into strips. The strips are arranged in such a way that there is symmetry (as far as this is possible) around the length axis.
I glued the wood together using Titebond III ultimate wood glue and this gave a rocksolid bond. I used way too much glue as you can see on the image and it buckled a bit because I clamped a relative thin surface with quite some clamping force. A lot of improvement can be made at this point.
To cut out the contour for the ski I cutted out a template using a water jet cutting machine at university. This worked nice, but had the disadvantage that I had to make the template out of two pieces.
Above you can see both the metal contour templates mounted on a piece of MDF to copy it to the wood core.
Here I routed out the core and I am fine tuning the wood core using a chisel.
And this is the result after creating the two wood cores.
Afterwards I glued the sidewall to cores using epoxy. I treated the sidewalls using a UV-ozon method which uses some special type of striplight to get oxygen in the surface to be able to bond it. I also used the flame treatment method which also seemed to work good enough. I hope to perform some test with both methods later on.
After gluing the sidewalls to the core I first planed the cores and then routed a groove for the edges.
Then I builded a profiling table and profiled the core, this was quite easy. I hope I have the possibility to make a profile using the water jet cutting machine next time to get a smooth slope in the profile.
Close-up of the profiling process.
Then, a few weeks later I cutted out the tip and tail spacers and glued them to the core using Loctite superglue (cyano-acrylate glue). I didn't really have time to reduce the thickness of the tip/tail spacers to the core thickness, because I wanted to finish them before my wintersports.
Then I started preparing the mold for pressing. I used a aluminium plate at the bottom and top of the layup to obtain a smooth layup surface.
Then I started the layup process. I first putted 200gr/m^2 UD fibreglass on the base...
Then 420 gr/m^2 biaxial fibreglass...
And wetted this...
This is what the result looked like.
Now I added a the white topsheet.
Then I placed a aluminium plate on top, placed the firehose and the top mold and packed it in painters plastic.
Then everything went into the press at about 4.5 bar pressure and the next morning after about 16 hours and a sleepless night, the first ski came out.
My first completed ski next to the materials for the second ski. As you see in this picture, I also used damping rubber above the edges and in the tip and tail.
This is during the flashing process. It took me quite some time to find the correct setting for my jigsaw.
And this is the final result!
And this is me showing the ski! (location is Nendaz, 4 Vallées, France)
I will add comments later! COMMENT IS FINALLY ADDED!
Buuk
The skis core is made out of ash, I did choose for this type of wood because it was not that expansive and it has good properties. On the image you can see the wood being ripped into strips. The strips are arranged in such a way that there is symmetry (as far as this is possible) around the length axis.
I glued the wood together using Titebond III ultimate wood glue and this gave a rocksolid bond. I used way too much glue as you can see on the image and it buckled a bit because I clamped a relative thin surface with quite some clamping force. A lot of improvement can be made at this point.
To cut out the contour for the ski I cutted out a template using a water jet cutting machine at university. This worked nice, but had the disadvantage that I had to make the template out of two pieces.
Above you can see both the metal contour templates mounted on a piece of MDF to copy it to the wood core.
Here I routed out the core and I am fine tuning the wood core using a chisel.
And this is the result after creating the two wood cores.
Afterwards I glued the sidewall to cores using epoxy. I treated the sidewalls using a UV-ozon method which uses some special type of striplight to get oxygen in the surface to be able to bond it. I also used the flame treatment method which also seemed to work good enough. I hope to perform some test with both methods later on.
After gluing the sidewalls to the core I first planed the cores and then routed a groove for the edges.
Then I builded a profiling table and profiled the core, this was quite easy. I hope I have the possibility to make a profile using the water jet cutting machine next time to get a smooth slope in the profile.
Close-up of the profiling process.
Then, a few weeks later I cutted out the tip and tail spacers and glued them to the core using Loctite superglue (cyano-acrylate glue). I didn't really have time to reduce the thickness of the tip/tail spacers to the core thickness, because I wanted to finish them before my wintersports.
Then I started preparing the mold for pressing. I used a aluminium plate at the bottom and top of the layup to obtain a smooth layup surface.
Then I started the layup process. I first putted 200gr/m^2 UD fibreglass on the base...
Then 420 gr/m^2 biaxial fibreglass...
And wetted this...
This is what the result looked like.
Now I added a the white topsheet.
Then I placed a aluminium plate on top, placed the firehose and the top mold and packed it in painters plastic.
Then everything went into the press at about 4.5 bar pressure and the next morning after about 16 hours and a sleepless night, the first ski came out.
My first completed ski next to the materials for the second ski. As you see in this picture, I also used damping rubber above the edges and in the tip and tail.
This is during the flashing process. It took me quite some time to find the correct setting for my jigsaw.
And this is the final result!
And this is me showing the ski! (location is Nendaz, 4 Vallées, France)
Last edited by Buuk on Sun Apr 29, 2007 1:14 pm, edited 1 time in total.
Make things as simple as possible, but not too simple
Yeah, too busy with a lot of things... sorry!
They skied pretty good, but were a little too soft, but it was a fantastic experience to ski on my first pair of homebuild skis!
Last time I have been busy doing some calculation on the ski stiffness etc. as some of you know. Just finished some updates and additions to my Matlab program. Will also post more about this soon.
I will certainly write some text at the images soon.
About the firehose, it's just a 150 mm diameter hose, for more info about it check: http://www.mandals.com/index.php/mandal ... e/guardman
They skied pretty good, but were a little too soft, but it was a fantastic experience to ski on my first pair of homebuild skis!
Last time I have been busy doing some calculation on the ski stiffness etc. as some of you know. Just finished some updates and additions to my Matlab program. Will also post more about this soon.
I will certainly write some text at the images soon.
About the firehose, it's just a 150 mm diameter hose, for more info about it check: http://www.mandals.com/index.php/mandal ... e/guardman
Make things as simple as possible, but not too simple
Well, what did I do during the long time that I didn’t post anything at my own ski building journal?
Of course I tested my first pair of homebuild skis! They were a bit soft with 10 mm under the boot and a 600 gr/m^2 fibreglass layer on top and bottom, but the skied fantastic!
Furthermore when I saw Bambi’s deflection calculation spreadsheet I directly found out what I wanted. I started up technical computation software called MATLAB® and started to write a simple 1D finite element calculation. After finishing this program it seemed that it took around 60 seconds to calculate the deflection. So I started to speed up the code and now it takes around 0,4 seconds. In the program not only the deflection is calculated, also the slope is given and information about the binding position. Recently I added another method of calculating the ski stiffness, so the results are comparable to flex patterns measured by Endre and a weight approximation of the ski. One other calculation I want to add in the future is an optimization of ski weight at a predefined stiffness with the core thickness and glassfibres (and directions) as variables to be optimized. Also damping is something interesting, so maybe this is also something for the future. At the moment I started to work on my next pair of skis. I already adjusted the mould and am now working at the core profile which will probably get a nicely curved shape. I will keep you informed!
Of course I tested my first pair of homebuild skis! They were a bit soft with 10 mm under the boot and a 600 gr/m^2 fibreglass layer on top and bottom, but the skied fantastic!
Furthermore when I saw Bambi’s deflection calculation spreadsheet I directly found out what I wanted. I started up technical computation software called MATLAB® and started to write a simple 1D finite element calculation. After finishing this program it seemed that it took around 60 seconds to calculate the deflection. So I started to speed up the code and now it takes around 0,4 seconds. In the program not only the deflection is calculated, also the slope is given and information about the binding position. Recently I added another method of calculating the ski stiffness, so the results are comparable to flex patterns measured by Endre and a weight approximation of the ski. One other calculation I want to add in the future is an optimization of ski weight at a predefined stiffness with the core thickness and glassfibres (and directions) as variables to be optimized. Also damping is something interesting, so maybe this is also something for the future. At the moment I started to work on my next pair of skis. I already adjusted the mould and am now working at the core profile which will probably get a nicely curved shape. I will keep you informed!
Make things as simple as possible, but not too simple
Wow, well done. That looks brilliant. Looking forward to seeing how the skies turned out after pressing.
I've used a vacuum press in the kitchen, patching up holes to stop leaks in the bags that has been used once already. The major leak was spotted and gained good enough pressure. Although the skies didn't turn out totally flat with reasons understood, a pair to be treasured and enjoyed was born.
Good luck on your cool press.
I've used a vacuum press in the kitchen, patching up holes to stop leaks in the bags that has been used once already. The major leak was spotted and gained good enough pressure. Although the skies didn't turn out totally flat with reasons understood, a pair to be treasured and enjoyed was born.
Good luck on your cool press.