The Ski Sled

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About: As long as I can remember I've been building stuff. I think it's high time I shared these projects.

If you were raised sufficiently far north I'm sure you can relate to the joy of waking up to snow covering the ground. My favorite thing about the white stuff is the way it decreases the coefficient of friction between the ground and an object sliding over it. In other words, I love sledding! More than likely this love was inherited from my dad, who one year took an old runner sled and fastened some old skis along the bottoms of the runners. When everyone would get together, this "ski sled" was the fastest sled down the hill, but the addition of the skis kept the runners from flexing - meaning it only went in a very straight line.

Ski Sled 1

Several years later, my dad and I tore apart the ski sled and rebuilt it. This second ski sled had a rudimentary steering system, which worked by flexing the fronts of the skis. Although this system allowed for some steering, it was far from perfect. Then two years ago, I took this sled down an extremely bumpy no winter maintenance road. By the bottom of the mile-long hill, virtually every board on the sled was shattered.

Ski Sled 2

Although, this second ski sled was dead, I knew that one day I would build its successor.

Step 1: Design

Immediately after destroying the second ski sled, I began designing the new sled. I had four main design objectives for this new sled. First, its frame would be made from aluminum to ensure that it would be durable, while keeping its weight as low as possible. Secondly, it should turn better than the previous sled. Third, it would have to be relatively easy to build (In other words, I didn't want to have to weld aluminum tubes together). Finally, riding a sled 1 mile down a bumpy road had me intrigued by the idea of adding suspension. Not only would the suspension make the ride more comfortable, but could also improve control through the rough bits.

I designed the sled in Sketchup around these 4 design criteria. For steering, the skis would pivot along their entire length. Tie rods connected between the handlebar and brackets attached to the skis would tip the skis left or right as the handlebar was turned. Although simply tipping the skis will not cause the sled to turn, it was assumed that with my body weight primarily on the rear of the skis, they would twist along their length, introducing a turning action.Steering

For the suspension, it was decided that two control arms would be used to connect each ski to the central frame of the sled. This frame would consist of a central box tube running the length of the sled, with three smaller box tubes protruding from its sides. The suspension control arms would be attached to the front and rear protruding tubes at points close to the central tube. Small, bicycle shocks would be placed between the ends of the control arms and the ends of the protruding box tubes.

Suspension Design

I decided to use wood for the decking and handlebar. There were two reasons for this. First, using wood made the construction of the deck relatively easy. Secondly, I wanted the finished sled to have a classic look (think an old-time Flexible Flyer sled).

Design

I can't stress how important a full 3D model was to the success of this project. Not only did it eliminated all of the guesswork in knowing if the suspension and steering would freely move through their entire range of motion, but it provided an accurate guide for fabricating each part of the sled.

Step 2: Preparing the Center Box Tube

The core of the frame was constructed from a 3' long 1.25" x 2.5" aluminum box tube of 1/8" in thickness. Several holes were cut in this box for mounting of the handlebar and the perpendicular protruding box tubes.

After drilling a 1/2" hole for the handlebar pivot bolt, a notch for the handlebar to rest in was cut from the end of the box. I cut the sides of this notch using a hacksaw and then drilled closely-spaced holes along the bottom edge, which allowed me to easily break out the notches on both sides of the box tube. Once these aluminum pieces were broken away, the notch was smoothed and squared up using a file.

Cut Handlebar Notch

Smooth Handlebar Knotch

The trickiest holes were the three square holes which needed to be cut through both sides of the box. The perpendicular box tubes would be slid through these holes and bolted into place. I drilled two large (~3/8") holes in adjacent corners of each of the marked squares. By dropping a jigsaw into these holes, I was able to connect the holes and roughly cut out the squares. A file was critical to smoothing out these rough squares so that they would perfectly fit the 1" x 1" box tubes, which would be slid through them.

Cut Square Hole

File Square Hole

Step 3: The Perpendicular Box Tubes

The perpendicular box tubes protruding from the sides of the central box were made from 1" x 1" aluminum box. I recommend using a stronger alloy of aluminum (I used Al 6061, vs. the more commonly available Al 6063), as there is considerable stress where these boxes pass through the central box.

After cutting these tubes to length, 1/4" holes were drilled vertically through all three boxes for mounting the decking. 5/16" holes were also drilled in the sides of the front and rear box tubes for mounting the control arms and tops of the shocks.

Finish Holes in Box Tubes

To allow the shocks to attach to the ends of these box tubes, a small notch was cut from the bottom ends of each box.

Notch Ends of Box Tubes

After cutting these notches, the bottom edges of the sides of the boxes (adjacent to the notch) were beveled slightly by cutting away the corners with a cutoff disk.

Bevels on Ends of Box Tubes

Step 4: The Control Arms

The control arms were made from a 1" x 1.5" aluminum box tube. Since the top of each control arm needs to be open to allow it to attach to both the frame and shock without interference, 1/4" was cut off the top of each box to form a 3/4" x 1.5" U-channel. Ideally I would have purchased a 3/4" x 1.5" U-channel, but this was not available from my metal suppliers. I drilled the 5/16" holes for mounting the control arms to the frame and shocks before cutting the top off the box tube to ensure the aluminum did not bend during drilling.

Start to Cut Off Top of Control Arm Box

Finish Cutting Off Top of Control Arm Box

With the top of the box removed, the next step was to cut deep notches in the ends of each control arm. These notches allow the control arm to mount to both sides of the perpendicular box tube at one end, while straddling the width of the shock at the other end. After cutting the sides of each notch with the hacksaw, the bottoms were cut using a cutoff disk.

Cut Notches in Control Arms

Four identical control arms were prepared and are presented along with their associated mounting hardware in the image below.

Finish Control Arms

Step 5: The Shoes

Four small shoes were prepared for mounting the frame to the skis. These shoes were made from some 2" x 2" aluminum box tube that my father-in-law had left over from a fencing project. After the shape of the shoes was cut from the box, 5/16" holes were carefully drilled through them from mounting to the lower ends of the shocks and control arms.

Box Tube for Shoes

Large Hole in Shoes

Smaller holes were also drilled in the bottoms of the shoes for mounting to the skis. Note that three screw holes were made in the rear shoes, while only two screw holes were put in the front ones. Since the skis are considerably thinner at the location where the rear shoes attach, the extra screw was added to ensure a secure connection.

Step 6: Assembling the Frame

With all of the frame components prepared, I was ready to assemble them. The frame was assembled according to the sketchup design presented below.

Assembled Frame

Once all of the aluminum bits were sanded to smooth out any surface imperfections, I slid the 1" x 1" box tubes through the square holes prepared for them in the sides of the central box tube.

Slide Tubes into Center Box

When I prepared these 1" x 1" boxes I did not drill holes in them for mounting to the central box. I wanted to first align them in the central box and then use the holes in this box as guides for drilling these holes. By measuring side to side, and using a speed square, I was able to ensure the 1" x 1" boxes were perpendicular and centered relative to the central box. Once I had this position nailed down, I drilled the 1/4" mounting holes through the 1" x 1" boxes.

Drill Box Tubes Through Center Box

After bolting the perpendicular boxes to the central box, I proceeded to bolt the tops of the shocks to the frame. I used shoulder screws for these connections as well as all of the other suspension connections, which are required to pivot freely.

Fasten Tops of Shocks

With the tops of all four shocks mounted, I mounted the control arms to the frame. Once again, shoulder screws were used. Washers were used to fill the gap between the sides of the control arms and the 1" x 1" boxes. I just kept adding washers until there was minimal side to side play.

Attach Control Arms to Frame

With the control arms and shocks bolted to the frame, their bottom ends were jointed to the shoes for mounting to the skis. Once again, shoulder screws and washers were used for these connections. It should be noted that I applied a small layer of grease to the shaft of each shoulder screw to help lubricate each pivot point.

Connect Shoes

Step 7: Prepare the Wood

The handlebar for the sled was made from a piece of 1" thick cherry. After planing the cherry to the correct thickness, I cut out the shape of the handlebar using a jigsaw. The edges of the handlebar were smoothed using a 1/4" round-over router bit.

Cut Wood for Handebar

Two pieces of 1/16" thick aluminum were cut to fit the top and bottom of the handlebar. These aluminum plates add strength to the handlebar where it attaches to the sled and also provide a smooth surface for where the handlebar pivots inside of the central box tube.

Cut Aluminum Plates for Handlebar

Holes were drilled through these aluminum plates for both mounting to the handlebar (the 1/4" holes) as well as for the 1/2" pivot bolt.

Drill Holes in Aluminum

A vise was used to hold the plates in place over the handlebar and these holes were continued through the wood.

Drill Holes Through Wood

With the holes drilled completely through the handlebar, the plates were bolted to it using two 1/4" screws. Next, two angled holes were drilled for the bolts, which would be used to support the tie rods used to tip the skis. Previously-drilled holes near the ends of the aluminum plates were used as guides for the location of these holes on both sides of the handlebar. I began by drilling the angled holes approximately half-way through the handlebar from the one side. Then, I flipped the handlebar and completed the holes from the other side. This method ensured that the completed holes were at the correct angle through the handlebar.

Drill First Side of Angled Hole

Finished Angled Holes

With all of the holes drilled, the completed handlebar was mounted to the frame using a 1 1/4" long shoulder screw. As with all of the other pivot points, the shaft of this screw was greased. I also applied some grease to the surfaces of the aluminum plates so that they would slide smoothly inside of the notch in the central box tube.

Mount Handlebar to Frame

Step 8: The Deck

The decking was made from a single 1" thick board of cherry, which was cut in half to form two thinner boards. A table saw was used to cut half-way through the board vertically. Then the board was flipped and cut again to create the two thin boards.

Cut Board in Half

Although this method resulted in two remarkably smooth boards, both boards were still planned to around 3/8" to remove any surface imperfections.

Plane Deck Boards

Next, the deck boards were cut to length with the ends being angled slightly. At the rear of the sled the central box is slightly longer than the side rails. This angle on the ends of the deck boards creates a nice transition between the side rails and the end of the central box.

Cut Angles on Deck Boards

With the deck boards cut, they were aligned on the frame and the position of the mounting holes were transferred to them using a hand drill. I then used my friend's drill press to finish up all of these holes in the deck boards. With these holes drilled, both deck boards were bolted to the frame using 1/4" screws.

Drill Holes in Deck Boards

Two 1" x 1" side rails were also ripped from a 1" piece of cherry. After rounding the edges of these rails with a router, I aligned them onto the frame, marked the location of their mounting holes, and drilled these holes through the rails.

Prepare Side Rails

Drill Holes in Side Rails

All of the wood on the sled - including the handlebar - was finished using danish oil. I initially was going to use a finish like polyurethane, but given time restraints I decided to use oil instead. In the end I think this was a better option as the wood will be exposed to a lot of moisture, which could work its way under a hard finish. The oil may not hold up as long, but I can easily re-apply oil at any point in the future.

Step 9: Mount the Skis

My friend found some old 135cm skis in his shed. Not only were these skis the perfect length for my sled, but they had a sidecut to them, which I thought would help with the steering. I positioned the skis under the shoes on the frame and marked the location of the mounting holes onto them.

Position Frame on Skis

Next, I drilled pilot holes in the skis for the mounting screws to thread into. I wanted these holes to be as deep as possible without drilling through the bottom of the skis. To make sure I didn't drill too deep, I wrapped a piece of masking tape around the drill bit at the correct depth. Once the masking tap began brushing the surface of the ski, I knew the hole was the correct depth and I stopped drilling

Drill Holes in Skis

With the skis prepared for mounting, I painted them red. I like red skis as it reminds me of old-time flexible flyer sleds. You'll notice that I also painted a set of straight 135cm skis that I have - although I have yet to try them on the sled.

Paint Skis

After the paint dried, I cut the mounting screws (I used #14 stainless wood screws) to length and attached the skis to the frame.

Attach Skis to Frame

Step 10: The Steering

With the skis attached to the sled, it was time to finish up the steering system. First, I cut the two brackets for mounting to the skis from a sheet of 1/16" aluminum. I drilled a 1/4" hole through each of these pieces close to their one end.

Cut Aluminum for Steering Brackets

Next, I used my bending brake to bend this sheet into the final u-shaped bracket. As you can see, I was barely able to make the second bend with my brake. Notice that I've also drilled two small holes in the bottom of the bracket for mounting to the skis.

Bend Steering Brackets

Once the brackets were bent, I used the hole in the one end of each bracket as a guide to drill the hole in the second side of each bracket. Obviously a drill press would be ideal for this, but I don't currently have one at home so I did it carefully by hand.

Drill Second Holes

These steering brackets were mounted to the front of the skis using the same technique and screws that I used for mounting the skis to the frame.

Attach Steering Bracket to Skis

Moving to the handlebar, I inserted two 3" long 1/4" screws through the angled holes. I used countersunk washers and screws with countersunk oval heads to account for the angle where the screw heads contact the handlebar. Inverted lock nuts and countersunk washers were used to fasten the bolts into the holes on the top side of the handlebar. Additional inverted lock nuts were added close to the ends of the screws. These nuts would be used to fasten the inner tie rod ends.

Install Angled Screws

I fastened tie rod ends to both of the steering brackets using a 1/4" bolt and many washers. These tie rod ends have a 1/4" female fine thread socket for attaching to the tie rods.

Fasten Tie Rod Ends to Brackets

With the tie rod ends attached to the brackets, the tie rods were threaded into them, the inner tie rod ends were attached to the rods, and then these rod ends were slid over and bolted to the tilted bolts.

Install Tie Rod

Step 11: It's Testing Time!

With the sled finally finished, I took it out to some no winter maintenance roads in Pennsylvania and Vermont. On our first day of testing, we learned that the skis had a tendency to flip up-side-down during turning.

Flipped Ski

To fix this, we made some small aluminum stops, which would prevent the skis from tipping beyond approximately 30 degrees.

Stops

This worked well for a few runs, but eventually the stops ended up bending and breaking the very thin control arms they were attached to. I re-built the control arms out of thicker aluminum and with integrated stops to prevent ski flipping.

Broken Control Arms

With the control arms fixed, my wife and I made the 6 hour drive to Lincoln Gap in Vermont. This time everything held together beautifully and I was able to record a maximum speed of 34 mph! However, the sled had a tendency to catch the edge of the outside ski when coming out of a corner. I felt like it was trying to toss me off the side - although it was never successful. I determined if I could always keep the skis in a negative camber configuration this situation would be avoided.

Negative Camber

After receiving a final late winter snow storm, I tested this negative camber configuration on a mountain close to home. It worked as expected; I did not catch an edge and the sled still turned acceptably. The steering is still not quite as sharp and responsive as I would like, but that gives me something to work on for next year. Be sure to follow me here on Instructables or on Youtube if you want to find out how I end up improving this sled in the future.

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Runner Up in the
Woodworking Contest 2017

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    71 Discussions

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    LelandH5

    9 months ago

    First off your videos are entertaining and inspiring. Thank you for sharing them. I saw the videos of the Ski Sled and it looked like so much fun I couldn't think of anything else. I have no cad experience so downloading and figuring out how to use sketchup took me a little bit of playing around. It was pretty simple to use to disassemble and get measurements. Finding aluminum tubing supplier took me the longest. Next time I will pay the dollar per cut fee and give them the measurements. Not that my cuts are that crooked just to save time. Ill post a picture when I'm done.

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    makjosherLelandH5

    Reply 9 months ago

    Thank you! You may be the first to attempt this. I can't wait to see how it comes out! Have fun!

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    JumpinJ1

    11 months ago

    Amazing! I want to make one. Do you have a parts list?

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    Gadget Man 656

    1 year ago

    Could you provide measurements of your sled, and pictures of the build as you go. Where did you get the springs at, and what is the strength of them

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    makjosherGadget Man 656

    Reply 1 year ago

    At this point I haven't put together detailed drawings - although I hope to be able to provide that for future designs. I would recommend downloading the sketchup file and looking at that if you are interested in the dimensions I used (of course you'll have to download sketchup, which is free: https://www.sketchup.com/download) I purchased the springs on eBay for around $8 a piece. They are just cheap rear bicycle "shocks" from China (400 lb/in spring rate). I say "shocks" because there really is no damping, just a spring. I would have liked a slightly lower spring rate, but this was as low as I could find. I'd love to use air shocks in the future - assuming I can afford them :-)

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    makjosherclintg20

    Reply 1 year ago

    Thanks! As many of my projects are - the idea is simple but the execution is much more difficult. That's a bummer that you don't have snow though.

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    clintg20

    1 year ago

    I AM FROM AUSTRALIA
    NO SNOW

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    SCHLEPIC

    1 year ago

    Well done! It looks like a wicked good time.

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    makjosherSCHLEPIC

    Reply 1 year ago

    Haha. It is! I just wish I had some steeper hills closer to home.

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    yaşara7

    1 year ago

    it s really nice but i m concerned about the ropes ?

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    MTKapp27

    1 year ago

    Incredible!!! Amazing Instructable. I did not read this whole instructable yet, but i did not see a break.

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    Lardo

    1 year ago

    Why won't the PDF open? I click on the PDF "download" button, and get nothing.

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    makjosherLardo

    Reply 1 year ago

    I'm guessing you mean the skp file? If you don't have sketchup you probably will not be able to open the design file. You can download sketchup for free at: https://www.sketchup.com

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    Lardomakjosher

    Reply 1 year ago

    Nope. The SketchUp file I got. It's the PDF of the instructions that won't download.

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    makjosherLardo

    Reply 1 year ago

    Ok, I see what you mean now. The pdf downloaded fine for me, but hardly any of the pictures came with it. The reason for that has to do with the way I formatted this Instructable. Since I embedded most of the pictures from another site, they aren't showing up in the Instructable pdf download. I would recommend using a pdf printer to print the Instructable to a pdf file.

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    schreib

    1 year ago

    Fantastic Job. other comments ably do justice lauding you for your stature as a designer and presenter. Something new possibly:
    -- keep in mind you gotta stop, especially when going fast towards an oak tree! Suggest a knife type drag keel actuated down into the snow at heels of runners. plus wear a helmet!
    -- It has been years since I downhill skied but as I recall to make a turn . . . it is a process by which one lifts up the entire body a tiny amount to allow pivoting both skiis just above the snow to re-orient them to a new angle. Doing so will be very hard with a platform under your torso where you have no ability to use your body to significantly create a downward force. You can't take the weight off the sled like you can by flexing your legs or hopping a bit with normal skiis. However, What comes to mind is a way to momentarily press some object down into the snow while a mechanism allows a central pivoting action. It would require very quick action and very minor angle adjustment in order to prevent excessive drag and loss of control.
    -- an alternative to this is reconsider the entire flat runner idea. It started out good through your Dad's initial design and your latest work but to advance you may have to AGAIN think out of the box. What comes to mind is going back to flexible runners but with wider bases(ski like) and made of carbon fiber or some composite. Remember, money is no object here! You may even consider going to your local university's mechanical engineering dept and ask them for free consulting assistance. Offering them an opportunity to turn this into an undergrad design class project etc.
    -- It would be nice to know what you think of Sketchup vs traditional CAD. I still use an OLD version of Vectorworks on my OLD MacBook. Been looking for replacement for years that is less than $1000.

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    makjosherschreib

    Reply 1 year ago

    Thank you for the comment and the suggestions. I'm intrigued by your "hopping" sled. :-) Interestingly, there are actually sleds used in the German-speaking parts of the world, where you actually press on the snow with your hand to apply more weight on your outside runner, which forces a sharper turn. I know that's a different configuration than what you are talking about, but you're idea isn't perhaps as out there as you'd think.

    As for Sketchup vs traditional CAD software. I have used Autocad as well as Solidworks and I will say that traditional CAD software is far superior to Sketchup when it comes to easily creating accurate, tool-ready designs. Where Sketchup excels is for more basic geometries (think houses or cabinets instead of machined parts). Sketchup is easier to learn than most CAD programs and you can still create complex geometries, but it will be more difficult to create them. Basically, if you're drawing houses or bookshelves I'd recommend Sketchup. For something mechanical (like this sled) I would recommend a traditional CAD program. Hopefully that helps. As an alternative, I'd recommend checking out Autodesk Fusion 360. It's free for hobbyists and is supposed to be more robust than Sketchup. I have it, but haven't taken the time to learn it yet.