Another Ski Press is Born

For discussions related to designing and making ski/snowboard-building equipment, such as presses, core profilers, edge benders, etc.

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skidesmond
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Another Ski Press is Born

Post by skidesmond »

Here’s my ski press in progress. It’s almost done. A couple more nights/weekends worth of work and it should be complete. I’ll post more pics when it’s completed.

What I’ve learned is to research and plan as much as possible, which I did and this forum was a tremendous help. Thanks to everyone who has posted their experiences. I realized everything takes longer than expected. If I thought it was going to take a month it took 2 months. I think I started in May. I thought by the end of July I’d have a set of skis made. Well here it is in September and I’m still working on the ski press. But eventually I had to start, and make adjustments as I went along.

What would I do differently? A lot of things. I would have preferred to make the ski press from tubular steel or I-beams. But I didn’t have the resources ($$$) nor do I know how to weld. I went with wood and I would have preferred to use glue-lam or LVL beams. It would have been a big time saver.

Since I work with wood (mostly furniture) as a hobby I went with what I know. I’ve seen other presses made using wood and they looked robust enough, at least most them did. ;)

I decided not to use dimensional (2x8x96) lumber since most of the lumber at the big box store is crap. I sifted through a stack of lumber to find ½ dozen useable ones. I would have had to run the lumber through the planer and joiner in order to make them flat. Too time consuming.

The Wood beams:
Instead I opted to rip OSB plywood in 8 inches strips. I use 3x4 - 4x8 sheets of OSB. This turned out to be time consuming since I had to rip 7 sheets. Not to mention OSB is heavy. I made a jig in order to drill the holes evenly in every strip. I used ½ inch threaded rod to bolt the plywood to make the beams. Did some sanding and it was done.

Steel Re-enforcements:
Now that the wood beams were made (and heavy), I realized that making a wood frame to hold the beams probably wasn’t going to work. After reading about the stresses and forces when using a pneumatic style press, steel was my only option. Actually my press was originally going to use 2 - 6 tons bottle jacks instead of pneumatic style. Since it seemed most presses are pneumatic, I made the switch.

Lucky for me a friend of mine had a stash of 4inch steel U channel. We discussed dimensions and he welded up the 2 steel supports you see in the pics. Thanks Chet! They weigh about 85 pounds each.

Ski Press Assembly:
When working with so much weight you have to work carefully. I had both wood beams lying on their sides on a platform. I slipped the steel over each end of the wood beams and attached beams to steel. I used a 12 inch drill bit to make the holes in the wood beams so I could attach it to the steel plates on the U channel frame. I used 12 bolts for the top and 12 bolts for the bottom. That was the easy part. Now I had to stand it upright on the base platform. I estimate at this point the press is weighing about 650 – 700 lbs. Well there was no way I could stand it up on the base platform. Luckily I had the 2 6-ton jacks and they came in handy. I jacked up the beam high enough where I was able to cautiously tilt it upright. Whew! I was done for the night.

Wood beams laying on base platform with steel framing.
(ignore the 2007 date on the pics. I hadn’t reset the date/time)

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Tools I used to upright the press, 2 - 6ton jacks, wood blocking. I was going to take pics as I went but once I started I didn’t want to stop.
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The opening between the beams may be too large (16 inches). I may have to unbolt the bottom beam from the steel frame and pad it with wood blocking to close the opening.

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Bottom Adjustable Form:
I wanted an adjustable form so I could make skis from 150cm – 185cm. There was a post already on how to make a simple one. So I used that one as a model. The camber is about 1 inch. Sounds like a lot but from reading other posts the ski tends to relax after it is pressed, so hopefully it will. I used snoCAD-X to get the basic design of the bottom form.
I used MDF and it machines nicely but what a mess it makes. Luckily my router has a dust pickup attachment so the flying dust was minimal. Where a mask! I made a jig to drill out the holes evenly. The MDF is 3x4 thick so I used my ½ inch plunge router to drill the holes. They came out perfect and assembling the bottom form was easy. I used 1/2inch threaded rod and bolted it together. Yet another heavy piece of equipment.
Still need to attach the end blocks so they slide.

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Top Adjustable Form:
This was more difficult to design. I couldn’t really find a design that would fit what I had so far. I was able to look at a few in the forum and work out a design that fit my press. I didn’t want to use MDF this time as it is heavy and thought I’d have a hard time attaching that much weight to the top wood beam. I chose 2x6 lumber instead. It worked out ok.
I still need to do some minor shaping on the form and attach it to the top wood beam. I’ll post more pics so you can see how it will slide to different lengths.

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Here’s a pic of the top form in front of the press looking at the top of it that will mount to the top beam. It’s not fully completed. The center bolt is ½ threaded rod. It holds the finger boards in place that are in between the finger joints of the form. This design will allow the form to expand and contract as needed.

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I still need to slot the outside frame (the 2x4) and run threaded rod through the form and the 2x4 frame, then attach to the top beam. I'll post more detailed pics once it's competed showing how I built and assembled it.

Ski designs:
While I was thinking about how to work out details on the ski press I designed some skis. I designed the skis using snoCAD-x. I have 3 different designs 177cm 12/66/96, 174cm 116/70/102 and 168cm 118/65/104. Primarily the designs are for skiing east coast conditions. The cores vary from solid maple (no glue up but a solid piece of wood), solid ash, and poplar/maple and polar/ash.

I lucked out again with the wood. My friend Chet had a stash of maple and ash at his at his parents’ house. The wood came from his land he cleared when he built his house, about 15 years ago. The wood had been sitting in the basement since then. At one point his father was going to use it for furniture and other projects but never got around to it. Unfortunately he died last year. They had no use for it and they knew I made furniture and cutting boards (and now skis) as a hobby. So they offered it to me. Thanks again Chet!

Ski Cores:
At first I tried making a core using the router/bridge method. I spent a lot of time carefully making the jig and bridge. In the long run it was just too difficult and time consuming. I have a planer so I used a planer crib and could make decent core in about 10 minutes. I need to tweak the crib design but it’s much faster. Of course a CNC machine would be great! :D

Other stuff:
I did some experimenting by mixing acetone and Plexiglas as a sealant and glue. Acetone melts Plexiglas. It didn’t work as a glue. I glued 2 small pieces of ¼ inch plywood. After a day of drying I was able to pry the boards apart with out too much trouble. Wood glue would never fail like that. Seals wood nicely though. However I’m not sure if it will crack in cold weather under stress. I’ll try more tests… paint a thin strip of wood with the mixture, let it dry then put it in the freezer for a day or so and see how it flexes. I’ll post the results.
I also tried using it on cotton cloth. I did not glue or epoxy the cloth to wood but just painted it on the cloth. It dried hard as expected but the cloth did not dry flat. Kind of curled up and shunk. I don’t think it would make a good sealant in place of top sheet material as the acetone would probably weaken the epoxy on the ski.
I did graphic lettering on vellum paper. It’s a semi-transparent paper. The supply store (Staples) didn’t have rice paper. I put the acetone/Plexiglas mixture on a piece of wood then the vellum paper and sealed it with acetone/Plexiglas mixture. It dried ok and the paper was almost transparent but the paper wrinkled. I don’t know if vellum paper will work with epoxy.
So unless the top sheet is a wood, acetone/Plexiglas probably won’t work.

So this is it so far. I need to do some finish work on the press, purchase the pneumatic hose and hook it up, buy expoxy. Already have base material, fiberglass and edges from WWW.SKIBUILDERS.COM.

More pics to come after the weekend.
plywood
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Post by plywood »

nice concept! good to see some new ideas ;)
plywood freeride industries - go ply, ride wood!
jvangelder
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Post by jvangelder »

Wow i really like the mold design, very modular.
skidesmond
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Post by skidesmond »

Since the hardest part I had was figuring out how to make an adjustable top form I thought I'd post on how I made mine. I got the basic idea from the design of how dining room tables expand. With that as the basic idea here's how I made the top adjustable form.

( btw - here's a website I use to convert inches to cm,
http://mg-jewelry.com/mmtoinches.html )

First I determined the size of skis I wanted to make. I wanted to be able to make skis from about 155cm to 190cm max. Then I determined the shape of the top form. The total length of the top form is 60in. Then I cut the form in equal halves.

On the right side of the from I removed wood measuring 3/4in deep and 9 linches long. I did this with my table saw and dado blade. See pic below:

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Then I did the other half of the form:
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Where the material was remove I used a filler board and made a 1/2in hole in the center. It's hard to see in the pic but it's there. You'll see why in later pics:
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My top form is 12 inches wide, so it requires 8 - 2x6x60 boards. So I repeated the above process for each of the 8 boards.

Once I had all 8 boards and filler boards cut and holes drilled I used 1/2 in threaded rod in each end of the forms to hold the end pieces together. The center hole and threaded rod is for fastening the mounting rail (2x4) to the top wood beam. You see that pic later.
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The next job was to cut the mounting rail. This rail will be mounted to the top wood beam when the form is complete. Also had to cut slots on the rail so the form can slide. The center hole keeps the rail and form together. To cut the slots in the rail I used a mortiser to cut the 1/2 in slots. The rail is on top of the form in the pic below:
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Here's how the rail is mounted to the form:
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Next was to drill 1/2in holes in the form that align with the slots. To drill the holes you could use a very long drill bit if you're confident enough that you can drill a straight and level hole or use a big drill press. I decided to make some marks where I wanted the hole and then take the form apart and drill the holes individually, measuring for each hole on the forms. It was time consuming but the holes lined up nicely. Then I re-assembled and bolted everthing back together.
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Now I just need to mount the form to the underside of the top beam.
The outside rails get permanently attached the beam. To adjust the forms length I loosen the nuts/bolts in the slotted holes and the center nut/bolt, slide to correct length and tighten them back up.

I'll post more pics when I get that done. I'm done for the night.
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MontuckyMadman
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Post by MontuckyMadman »

wow nice.
Did you do some load analysis in determining dimensions for your wood press?

its HUGE!
skidesmond
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Post by skidesmond »

Not really. I'm not an engineer and don't pretend to be one. I looked at a lot of other presses in the forum. Also talked to some builder friends of mine and one who is a mechanical engineer. I told them the amount of pressure I'd be using (around 40 psi). They are the ones who said I'd need a steel frame in order to keep the beams from blowing apart. Actually I was going to use Wood I beams and they said it would probably break. Good thing I talked to them and took their advice. They thought I was nuts at first for even attempting this project. But the more I talked to them they got intrested in it as well.
I did see in the forum where somebody used wood I beams and they flexed a lot!! So that was out. Even if I get a slight flex I can live with it. My friend Chet has more steel should I need it.
So it "should" work.
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KevyWevy
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Post by KevyWevy »

if the friend is around and still has steel, i'd say maybe make a brace for the middle. especially since you have such a trick mold set up, you could slide it all in from the ends. but, im no engineer as well. it just seems like you'll have a lot of deflection in the middle with your braces so far out to the sides.
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KevyWevy
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Post by KevyWevy »

but obviously, that wouldn't work if you were dead set of attaching your top mold to the top beam.
skidesmond
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Post by skidesmond »

KevyWevy wrote:if the friend is around and still has steel, i'd say maybe make a brace for the middle. especially since you have such a trick mold set up, you could slide it all in from the ends. but, im no engineer as well. it just seems like you'll have a lot of deflection in the middle with your braces so far out to the sides.
He does have more steel. We talked about doing the same thing if I noticed any deflection. We even talked about getting real fancy and making the front fold up and down with a latching mechanism so I'd be able to load the skis in front with out having to unbolt and rebolt the steel framing. Similar to the way Kingswood made his press. But his is all steel.

btw -I tried to do a stress test of sorts. I don't know if it's represenative of the real thing, when I get the pneumatic hose but.... For kicks I placed a 4 foot level on the top of the press, then I took my 2 6-ton jacks and placed them between the 2 beams with some wood blocking to protect the beams. I started jacking to see how much force I could put on the beams and to see if the level would move. I didn't detect any movement in the level and succeeded in putting a nice hole in the wood blocking from the jacks.
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KevyWevy
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Post by KevyWevy »

yeah, thats what we did. i cut the middle supports a little longer so that when they hinge down, it turns into a little shelf, so thats where we lay up the ski.

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skidesmond
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Post by skidesmond »

Progress on the ski press.

I got my hose from Hosecraft USA ( http://www.hosecraftusa.com/ ). I bought 6 in PD2 PVC HEAVY DUTY LAFLAT DISCHARGE HOSE. It can handle 150 psi. Skibuilders.com has been out of stock for awhile and according the their specs they buy from the same place. FYI - When you buy it direct you'll pay for 25 feet whether you need it or not. I ended up using 2 - 10 foot lengths for my press. Better to go a bit longer than too short

So here's how I connected the 2 hoses. I took advice from a previous post that used info from www.happymonkeysnowboards.com and it's good advice. I bought basically the same items they used for the air compressor hookup. It worked great. The air hose connectors are leak free and I didn't need any silicone or sealant around the hole. It's clean and neat. WICKED NICE!

I do have a slight leak on 1 end of each hose. Not a problem though. Some sealant (silicone or epoxy) should take care of it. Over all I'm pretty pleased.

This pic shows the parts I used. These can be found at most hardware stores. I got most of them from Tractor Supply Company (TSC), Aubuchons and ACE hardware. Believe or not the hardest part to find was a large rubber washer and large brass nut. The bolts are 1/2 inch hardened steel bolts 1 1/2 inch long with matching washers and nuts from TSC.

The large brass threaded bushing gets inserted into the hole you cut into the hose. Make the hole carefully so it's tight., and the large rubber washer and brass nuts secure it from the inside of the hose. The air connector threads into the brass bushing. Use Teflon tape on all connections.

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The 6 in. hose is almost 10 in. wide when laying flat and deflated, so take that into account when building your press and forms.

Take care in drilling the holes in the hose and the flat stock steel used to seal the ends of the hose. I drilled 1/2 holes in the hose. But because of the rubber and threads in the hose you don't get a clean hole. Don't over drill the hole or you'll risk a big air leak. I had to screw the bolts through the rubber hose, took awhile but that air pretty tight w/ a minor leak.

Here's a pic of the final hose assembly:

The blue hose is 1/4 in. ID (internal diameter) air hose. This can be found at most hardware stores and available by the foot. The blue hose is attached to the red hose and to another air connector. The air connectors are attached to a T connector. The T connector is attached to a small ball valve and on the end of the ball value is a male quick-disconnect, that's used to hook up to an air compressor. Teflon tape is used on all threaded connections.

I like the idea of the ball valve, so when I disconnect the air compressor I don't get blasted with air from the hose. And it doesn't cost that much. If you got this far with your ski press what's another $10.
':D'

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Time for a cold one!
skidesmond
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Post by skidesmond »

Update on the ski press:

Here's the problem.... I couldn't get the hose to bend into the tip and tail blocks on the lower form. I thought maybe the hose was to wide/fat when inflated (6 inch hose) and not able to bend into such a tight radius of the tip/tail blocks. After a few nights of trial/error I got it just about figured out.

No doubt, the space between the 2 beams is too large. Raising the lower form about 3 inches off the lower beam and cutting 1.5 inch as off the top of the tip/tail blocks gave me a better fit when inflating the hose. The hose is still not filling in the tip area 100% but it is much better. If I pad the tip area right between the hose and cat track w/ 1/2 inch strips of wood I get 100% fit.

So, next it to raise the bottom form 1/2 inch more OR make a new cat track that is bigger. Right now the cat track is strips of wood 3/4 x 3/4 x 12. I think if I make it a bit taller say 3/4 x 1.5 x 12 that will work too.

Let you know how it works out.

Epoxy is on it's way from QCM. Talked to Collin and he was very helpful. He recommends using heat but I told him I'd being pressing at room temp. He said it will work ok but heat is better. I told him a heat blanket is the next phase :D . I'd like to try to get at least 1 pair made and then see where I need to improve the layup process, trim/finish process.

Hopefully the epoxy will arrive this week and I'll have a pair made by the end of the week.

It's also my birthday this weekend, a pair of skis would be a nice present to myself :D
rockaukum
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Post by rockaukum »

I had the same problem. I reduced the radius and height of the tip tail blocks and reduced the cavity of the press. Good luck this weekend!
ra
skidesmond
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Post by skidesmond »

Yeah! My epoxy arrived from QCM today! I have all my material now to start pressing. I hope by the weekend to have pics of some new skis. Wish me luck! Woo-Hoo! :D
skidesmond
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Post by skidesmond »

It's almost a year later and still tweaking the press. I added more steel supports to the middle since I was getting too much deflection and losing too much camber.

I tried to avoid messing with it by building a steam box to build in camber ( http://www.skibuilders.com/phpBB2/viewtopic.php?t=2476 ) but the right thing to do was add more steel.

I noticed my top beam had a horizontal bow, about 1.5 inches. That kind of freaked me out! The beam is 8x16x96. I loosened the bolts that hold the beam together and was able straighten back out. I'll have to keep an eye on it.

With the added support in place I pressurized the hoses to 40psi (for the 1st time) and there was no deflection or bending and a lot less creaking noises.

Also building a new cat track. Trying something a little different. I'm using a solid piece of 3/4x20x48 mdf. This part of the cat track is for the running length of the ski. I'll add the typical style cat track for the tip and tail sections and make the that part 1/2inch wide to fit tighter into the tip/tail blocks. It's easier than cutting lots of strips and then wiring them together. Can't think of a down side to this approach. Let me know if I'm off track.

The press has no problem bending the solid mdf and looked ok when I tested it.

I'll post some pics when I get the shop cleaned up.
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