Sunday, November 6, 2011

Graphics and Press stage 2

There are many options for graphics and most of them are relatively simple to create.  In industry they typically print the design directly onto the plastic top sheet or on a separate layer.  I don't have the technology needed to print directly onto a topsheet, although, I have taken steps toward this method. I just need a larger printer which is not in the budget...


I took two approaches to the graphics this year. The first method was to paint onto paper and directly on to the wood of the ski.  Painting on these two mediums is easily done with acrylic paints.  The paint on the wood will be slightly obscured due to the fiberglass layer between the wood and the top sheet.  The fiberglass becomes mostly clear when soaked in the epoxy.  The paper when soaked in epoxy will become ~75% transparent. The second approach, which I have taken in the past, was to get a sheet of fabric, purple in this case, and paint directly on it.  The advantage to this is that the fabric will be very opaque and you can get a solid color, but it absorbs a lot of epoxy and will add weight to the ski.

Some past designs:

2010 Goliath

 2009 Goliath, this is still one of my favorite graphics.



The Arlia's I am making for Megan have a cardinal as the focal point and are relatively simple.  I wanted the wood to show as part of the graphic as well.  Emily helped me paint the skis; I owe most of the credit to her.




I always place a horizontal line across the ski to indicate the binding center.  Note that this is not necessarily the center of the ski and will often be slightly back of true center.  Without this line it would be difficult to mount the bindings properly.  I also always put my JH symbol on the skis.

The skis I made for Matt, the Panjshir, use a similar technique in painting on both the wood and paper.  The focal point of these skis is the wolf graphic.




The Arlia's I am making for Rachel take a different approach using purple fabric and gold paint.  The fabric, when soaked in epoxy will become several shades darker.  The JH on this ski is made from gold leaf.



Once the graphics are complete the skis are ready to be pressed for the second time.  The built in alignment features on the mold makes this process as easy as setting the ski on the mold applying epoxy, fiberglass, the graphics layer and the top sheet.


A small paint roller can be used to remove bubbles from underneath the top sheet.  It works best to start the roller at the center and work towards the tip and the tail pushing the wave of bubbles out of the ski.


Since this is a cap design, the top sheet must fold over the sides of the ski.  The air bladder will do this to a certain extent on its own, but I use 2" of foam to help press the top sheet to the edges of the ski.


As always I use rubber gloves and a foam brush to spread the epoxy.


This is a picture of Megan's Arlia when first removed from the press.


The following video shows the layup and stage two press at 16x speed (complete with music!).


The images below show the skis as pressed with the flashing still connected to the ski.  The only steps left are to trim the flashing, sand the edges, and remove the protective tape from the top and bottom of the ski.




5 comments:

  1. great work jon
    great art work emi

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  2. hey jon,
    just came across your blog and was wondering how you managed to print to the topsheet. was that done on a regular inkjet printer? i've tried it with my epson 2100 and the ink always runs.
    thanks!
    chris

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  3. Chris,

    I did use an inkjet printer to print on the topsheet. I'm not sure what type of plastic you are trying to print on, but the side of the plastic I printed on was abraded (roughed up / sanded). I am guessing this allowed the ink to stick (in the small grooves) and dry. Note that if you rubbed the topsheet a small amount of dry ink came off.

    Jon

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  4. Thanks for the quick reply! I did use abraded and flamed topsheet...maybe it's the pigmented ink that runs. what model of printer are you using?

    btw, in your press calculations, shouldn't you multiply the pressure by two since the hose exerts the pressure on both surfaces of your press platforms? (i'm not an engineer!...unfortunately)

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  5. I have an HP Deskjet F4240; like you said it might just be the brand of ink, not entirely sure though.

    About the calculation, good question, you definitely made me think twice. I am an engineer, but that doesn't mean I actually know what I am talking about. In this case, the easiest way to think about it is to theoretically cut the ski press in half (through the bladder parallel to the ground. The bladder exerts a force on the upper half of the press and the resultant force in the braces is equal to only the force in that half of the bladder. The problem is symmetric so you only need to solve for the top or bottom. So in other words, you don't need to double the force. The finite element analysis model I ran illustrates this concept.

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