DIY ski pulk
Pulk: Finnish for small cargo sled
I have wanted my own pulk after going on several yurt trips and had to rent or borrow a sled. After witnessing sleds pulled with ropes overturn on descents and/or sleds overtaking the skier and causing amusing wipeouts, I knew I wanted rigid poles. A comfortable harness and a system with a minimal amount of fore and aft movement while ascending or descending was required as well. I blatantly stole ideas from commercial systems and home builders. The goal was to spend around $100, it was close. Costs, photos and links below.
Summary of my (2014) costs and links to parts
Images with descriptions
Click images to enlarge
This is the pulk, with straps/buckles and attachment hardware installed. Most pulk builders agree that two or three bolts through the sled is probably not sufficient for heavy loads pulling against the caster attached to the sled. I fabricated a crude steel plate and installed it underneath the sled rails with bolts and nylock nuts, I also installed an additional bolt/washer/nylock nut through sled plastic and steel plate for increased strength.
Shown is the top of the pulk, casters attached to sled and metal plate below the top rail, the ball joint eye is attached via steel pin with vinyl tubing to pad steel pin for play-free connection. (I didn't feel like drilling the axle hole in the caster for a larger diameter pin.) Vinyl tubing is sold by the foot at Lowes, Home Depot only had pre-cut lengths for sale - lame.
Plate underneath the top rail of the pulk. Plate was simply a sheet of steel, cut with a dremel, holes drilled, then spray-painted to prevent rust. On the left is a webbing slide that blocks the webbing from coming out of the hole. Note to self, don't do this, use longer webbing and the pre-existing holes to thread one piece to form a "U". (Use the 8 holes in the sled, 4 holes on each side, 4 pieces of 4-5' webbing.)
The 6 foot long, 1/2" fiberglass poles are used for electric fences, they come with one end sharpened to a point. I wanted the maximum surface area to join the fiberglass and ball joint fittings so I cut off the pointed ends with the dremel, wear a mask for the fiberglass dust.
This is the jig I used to keep the pole perpendicular to the die when cutting the threads, it is simply a 8" long 2x4 with a 1/2" hole drilled straight through the long side. I used cable routing staples to secure the die holder to the jig but zip ties might work. I centered the holder with the die over the hole (it should self-center.) Make sure the die holder lies flat on the narrow side of the 2x4. Be sure to wear gloves to avoid itchy fiberglass slivers. DAMHIK.
This is the jig with die and holder attached, start the thread cutting by pressing in on the jig/die while turning clockwise. A large vise padded with rubber/old bike tubes is recommended. My smallish, cheap-ass vise was no match for the spinning force on the fiberglass rod, much anti-spin muscle was needed to cut the threads. Remember to back off the jig after each turn and reverse to get neat threads. The 6' poles are long enough that if you botch the threads you could cut them off and try again, make sure both poles are the same length in the end.
Shown is the fiberglass rod end after cutting the threads 1 1/16" long, which is the thread length of the female ball joint fittings. Note that it is faster if you start the thread cutting with the jig, then remove the die and handle to finish the threads.
Important note - because the ball-joints will be epoxied to the fiberglass rods, I needed to decide the plane of the ball joint eyes. Commercial pole eyes are inline. I wanted one end offset 90 degrees from the other due to my harness setup. I cleaned the ball joint ends with rubbing alcohol then dry-fitted them to the fiberglass rods and marked the (offset) positions with a sharpie. My goal was to have all attachment points free of any play for efficiency.
Apply a sufficient amount of (but not too much) epoxy to the ball joint threads and screw on the ball joints noting the proper plane. The female ball joints I used have a small hole between the thread chamber and the ball joint, this means that excess epoxy could ooze into the fitting where the ball rotates, I inserted a toothpick wrapped in paper towel in the hole from the top and didn't have any problems. I used good epoxy with a 8 hour minimum cure time. 5-minute epoxy might not be sufficient, or it might be fine. (Just use the good stuff.)
Attachment of the rods to the harness was not the best solution but it works, I threaded a biner with the spine through the ice-clipper-type webbing loops, the ball joint eyes were too narrow to travel around to the biner spine so they were attached to the gate. The biner gates were "locked" by having the horizontal webbing threaded around the gate top and bottom with the built-in webbing/buckles on the harness.
Biners locked in by webbing built into the harness. There is enough room for the poles to cross behind the harness for pulk tracking and stability. (Cross the poles, it keeps the sled from overturning on side hills!)
The pulk works well, there is zero fore and aft movement, this means it is less tiring to haul. The wide, padded harness is comfortable and the quick release buckle is nice to get in and out of hauling mode quickly. The sled tracks well downhill, but lightening the load by putting some weight on your back makes it easier to ski down steeper hills.
Thoughts, criticisms or questions can be addressed by following the "Contact" link at Utahclimbers.com