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Author Topic: Building UHMWPE Toboggan – Part 2:  (Read 16311 times)

Offline HOOP

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Building UHMWPE Toboggan – Part 2:
« on: January 03, 2011, 02:45:09 pm »
Continued from Part 1:  http://wintertrekking.com/index.php?topic=1229.0

Next step is to fasten the lashing lines for the front curl.   I forgot to make a hollow under the pull bar for the line, so I am using the webbing loop system that I use for all the tie down rope sections.   This is a 1/2 inch long (1/8 diameter) steel pop rivet in a countersunk hole, with #8 finishing washer and a steel rivet backing plate washer (close ups to follow).    I use steel rivets on the entire sled because I will be horsing the sled here and there grabbing lines and pulling, placing a lot of force on it.  I think aluminum rivets will pull out.  




The front curl lashing lines installed.   I used a trucker’s hitch and half hitch knots with redundancy, and I have enough line on each to adjust in the bush if need be.   The line is high quality Mammut 4mm accessory cord (bought from MEC, although really more like a 3mm), and it has a water resistant finish so it does not ice up.  




The all important front grab loop, simply drilled and knotted on the other side.  This is 5 or 6mm accessory cord.   This grab loop is important for horsing the sled over logs and around debris.




The end bar.  This receives lower forces, so I used only four #8 machine screw bolts (2 inch bolts, and ends cut off and polished with Dremel tool, and glue gun treated for sharp edges).   Washers and lock washers under the nuts.   The bar is a half inch in from the end, to allow a slot for ski poles or a push stick to jam in there for pushing from behind.    Later, I may also take the torch to it and bend it up slightly, like the back of a ski is curved up.

With only 4 bolts, I can slide the rear grab loop webbing under without grooving the hockey stick.  I reef knotted it.  




Now I will be installing the many riveted tie down webbing loops for the continuous tie down rope system.  I use this round awl heated with a torch to burn the rivet holes through 4 inch pieces of 1 inch webbing.  






I drill, countersink, and pop rivet (steel, 1/2 inch long, 1/8 inch diameter), these webbing loops every 12 inches along the sides.   There is a trade off to consider in the spacing you chose – see later for explanation.  Washers are #8 finishing washers and steel rivet backing plate.

 


Nearly done.  Now I will install the tie down rope system.




I am using this braided polypropylene rope because its totally hydrophobic, and it retains some stiffness so that it sort of sticks out, which is what I want for packing and ease of grabbing and hooking with bungees.




The tie down rope loops installed.  This is a continuous piece, so I can adjust the height of each loop.  




The knot in each webbing loop is simple, and allows for one continuous rope for infinite adjustment of the entire loop system if need be.   I tie onto the first webbing loop at the front curl to anchor it.  Then in each successive webbing loop, I push a rope loop through, then thread the end of the rope through the loop, etc.  In this way I get a cinch on each webbing and I can easily open this to slide and adjust it if need be.  I leave slack rope at the end for this adjustment.




Earlier I mentioned the trade-off for spacing of this W shaped tie down system.   Too narrow, and you have an aggravating number of loops.  Too wide, and pieces of your load will squeeze out into the snow and drag.  Too low and it will be too hard to grab with mitts and gloves in the freezing cold to run lashing lines or bungees under.  Too high and again it makes a hole for the load to squeeze out of.   The advantage of this continuous rope system is that I can adjust the height of these loops if need be.    I am stuck with the 12 inch spacing.
 


I prefer a tied on bungee for lashing so I never lose them.  I buy this 1/4 or 3/8 diameter bungee (I forget which thickness), off the spool in bulk at Canadian Tire.   This is their older bungee stuff and the rubber stays flexible in my experience.  They just changed their brand though, and I have not tested their new stuff which has a black sheath.   I cut 4 foot lengths and tie onto the tie down ropes with a bowline, which can be undone easily in frozen conditions if need be.   I tie one of these on almost every tie down rope loop along one side.  




I added one spare on the front in the “glove box” area just in case I need it.   I ran out of the old stock blue and white sheath bungee.  This is CTC’s new black sheath bungee which I have not tested in the cold.  




Done!   The bungees are wrapped for transport.




I did not install other cross bars.   If the sled starts to warp up along the sides, then I will add a couple to keep it flat.  Otherwise it does not need any.

The nice thing about UHMWPE and some types of HDPE toboggans is that they can be rolled up for packing in vehicles.




PS.   I took this toboggan on its first trip last week and it worked great.  TR to come soon showing it packed for hauling in the bush.

Edit:  The webbing loop rivet holes are drilled in 1/2 inch from the edge.  These are 1/8 inch holes, so I think this is reasonably safe from splitting out
« Last Edit: January 04, 2011, 05:43:58 pm by HOOP »
My Youtube Channel: http://www.youtube.com/user/Wintertrekker

"I firmly believe that far from hurting the planet, the growing knowledge of Bushcraft is helping our natural world. When we employ bushcraft skills, it may seem as though we are consuming natural resources.  But of course, the more we learn about the trees, the plants, the animals around us, the more we respect them. The more we respect them, the more we cherish them, the more we nurture and take care of them. That is the underlying principle of Bushcraft.

Offline sethwotten

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #1 on: January 03, 2011, 03:27:03 pm »
Nice work HOOP. I hope to build one myself some day. I may be helping a friend build one this winter, in which case, your documentation will be useful. Thanks!

Offline Kerina

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #2 on: January 03, 2011, 06:57:11 pm »
This is really excellent Hoop, and I love your finished sled.  What a great project.  Could you tell us where you got the UHMWPE plastic from and how much it costs?

Thank you for documenting the process so well and for sharing it.

Kerina

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #3 on: January 03, 2011, 07:04:44 pm »
Hi,

Excellent and informative posting. Could you tell me where you buy the hooks you put on the ends of the bungees? I have never seen those for sale without a bungee...

Thanks,

Kinguq

Offline cousin Pete

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #4 on: January 04, 2011, 10:23:03 am »
Hello HOOP:  Great job doing the write up and pictures to explain your approach to making a toboggan!  Looking good!

Take care,
Cousin Pete
"Tradition means giving votes to the most obscure of all classes, our ancestors. It is the democracy of the dead. Tradition refuses to submit to that arrogant oligarchy who merely happen to be walking around." - G.K. Chesterton, Orthodoxy, 1908

Offline sleddawg

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #5 on: January 04, 2011, 12:15:06 pm »

There have been a number of threads for UHMW sleds but I've never seen a weight mentioned, I'm curious what the weight of 1/4" is per square foot.

Have you tried "Nyloc" nuts, might be better than lock washers and no chance of coming loose.

Cheers
I, haul the sled so therefore I am "the" dawg.....

Offline HOOP

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #6 on: January 04, 2011, 05:59:45 pm »
Could you tell me where you buy the hooks you put on the ends of the bungees? I have never seen those for sale without a bungee...

Hi Kinguq,
I buy the bungee hooks (size 1/4") at Canadian Tire, in the aisle that has the bulk rope and bungee spools (I think all CT stores are the same?), which is usually where the fasteners are too.   Careful with the hook size - they are sized for the diameter of bungee you use.    Its not intuitive at CT:  The pre-made bungees are usually near the automotive section.  You would think they would have them in the same location, but nope. 
My Youtube Channel: http://www.youtube.com/user/Wintertrekker

"I firmly believe that far from hurting the planet, the growing knowledge of Bushcraft is helping our natural world. When we employ bushcraft skills, it may seem as though we are consuming natural resources.  But of course, the more we learn about the trees, the plants, the animals around us, the more we respect them. The more we respect them, the more we cherish them, the more we nurture and take care of them. That is the underlying principle of Bushcraft.

Offline HOOP

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #7 on: January 04, 2011, 06:05:19 pm »
Could you tell us where you got the UHMWPE plastic from and how much it costs?

Hi Kerina,
I bought the sheet from Nova-Pro Industrial Supply here in Thunder Bay  http://www.nova-pro.com/.   Closer to your home, if you phone around to industrial supply places, you should find some.   Cost?  I can't remember, but for a 4x10 sheet, I think you are talking about $200-$250 ish? 
« Last Edit: January 04, 2011, 06:16:46 pm by HOOP »
My Youtube Channel: http://www.youtube.com/user/Wintertrekker

"I firmly believe that far from hurting the planet, the growing knowledge of Bushcraft is helping our natural world. When we employ bushcraft skills, it may seem as though we are consuming natural resources.  But of course, the more we learn about the trees, the plants, the animals around us, the more we respect them. The more we respect them, the more we cherish them, the more we nurture and take care of them. That is the underlying principle of Bushcraft.

Offline Moondog55

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Re: Building UHMWPE Toboggan � Part 2:
« Reply #8 on: June 03, 2012, 07:55:35 pm »
Hi Hoop.
Do you think a hybrid would work? I have been thinking about making a new sled myself . Would using flat HDPE sheet for the sled and UHMWPE for a pair of runners work?? This stuff is almost three times the cost here in OZ.

Offline HOOP

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Re: Building UHMWPE Toboggan � Part 2:
« Reply #9 on: June 04, 2012, 08:07:10 am »
Hi Hoop.
Do you think a hybrid would work? I have been thinking about making a new sled myself . Would using flat HDPE sheet for the sled and UHMWPE for a pair of runners work?? This stuff is almost three times the cost here in OZ.

Yes I think that would work.  I am surprised that sheets of industrial plastics would be so expensive there?   UHMWPE is a very common plastic for industrial uses, and I would have thought some company might be making it there?  If its all imported, then ya I can see why it would be more expensive.   UHMWPE is about 2x the cost of HDPE here.  But I also think there are several grades of HDPE, some of which are much more flexible than others.  For precise info on HDPE, I recommend contacting Chris at Black River Sleds to ask him what grade he uses.  BR sleds slide really nice, and are easy to roll up too, so you might be happy with a full HDPE sled and skip the UHMWPE if its that expensive?   I have an older home made toboggan made of HDPE and its so stiff I cannot roll it up to store inside a vehicle, so there is some confusion (at least in my head), about whether HDPE has different grades with different flexibility properties.
My Youtube Channel: http://www.youtube.com/user/Wintertrekker

"I firmly believe that far from hurting the planet, the growing knowledge of Bushcraft is helping our natural world. When we employ bushcraft skills, it may seem as though we are consuming natural resources.  But of course, the more we learn about the trees, the plants, the animals around us, the more we respect them. The more we respect them, the more we cherish them, the more we nurture and take care of them. That is the underlying principle of Bushcraft.

Offline Zelandonii

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #10 on: November 07, 2012, 10:04:30 am »
HOOP (and others),

We're looking to make a couple of UHMWPE sleds for this coming season. We plan on replicating your design.

Have you found any disadvantages to not having crossbars?

Also, do you think that 1/4" UHMWPE will be easy enough to cold bend by using tension? I'm hoping we can bypass heat bending it.

We do like your webbing and lashing set-up. Simple and secure.

Thanks.

Offline HOOP

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #11 on: November 07, 2012, 06:33:08 pm »
HOOP (and others),
We're looking to make a couple of UHMWPE sleds for this coming season. We plan on replicating your design.
Have you found any disadvantages to not having crossbars?
Also, do you think that 1/4" UHMWPE will be easy enough to cold bend by using tension? I'm hoping we can bypass heat bending it.
We do like your webbing and lashing set-up. Simple and secure.
Thanks.

Hi Zel,

Re crossbars:  So far I have found that we don't need them.  Since we use countersunk rivets or bolts and webbing loops all around the base to lash the WWWW pattern lashing cord to, then we don't need them to house the lashing cord in the cross bar grooves like some traditional models use.  So far I have not seen any side to side warping that would lead to tipping over.  Should the plastic develop some side to side curvature, then we can easily add cross bars to flatten it.   

If you go with cross bars and a traditional lashing cord rope around the bottom, then I suggest attaching sliding upside down V shaped webbing and rings like Black River Sled uses.  I saw Brian Maruska's sled at the Symposium and to his traditional bottom lashing cord he added independent webbing with mini biners instead of rings, so the idea is that you weave your top lashing line back and forth and clip in as you lash.  Neat idea.  You can keep adding these independent units as your lashing needs vary.  You could also make those units out of heavy duty shock cord.  Lots of options.  I think I could do what Brian did on his sled with my WWWW lashing loops too - I would just add biners.  Chris Evavold of BRS suggested S hooks rather than biners.  There are so many options.

RE bending:  1/4 UHMWPE can develop a curve cold if you shove it some kind of bending position and just leave it for a week.  It will tend to relax if you release it.   But even without trying to pre-bend it, I think it would be worth a try to put that front end bend on cold.  I suggest using a truckers hitch for the cord so that you can crank on it and get the tension you need.  Then just half hitch several times and tie it off.  Its infinitely adjustable this way too.  The most important placement of hardware is your hauling bar.  In my design this is also the anchor for the cord that pulls the front bend.  If that pull bar is set back far enough, (but not too far so its not good as a pull bar), then the angle of pull is low enough to get a nice gradual radius of front end curve.  You want that radius to be gradual.  If its too sharp the sled will plow against the snow.   1/4 inch material is good and strong and that front curve will probably hold its shape pretty well without hot bending.  In my next sled I may try cold bending.

Best of luck with the build, and please post photos of the results!   :)
My Youtube Channel: http://www.youtube.com/user/Wintertrekker

"I firmly believe that far from hurting the planet, the growing knowledge of Bushcraft is helping our natural world. When we employ bushcraft skills, it may seem as though we are consuming natural resources.  But of course, the more we learn about the trees, the plants, the animals around us, the more we respect them. The more we respect them, the more we cherish them, the more we nurture and take care of them. That is the underlying principle of Bushcraft.

Offline Bothwell Voyageur

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #12 on: November 09, 2012, 08:31:22 am »
HOOP's update on the trad toboggan design is a great time saver. We tend to follow old designs often because they look good even though changes to the materials used make some aspects, like crossbars, redundant.

Exactly the same thing happens with canoes so full marks to HOOP for identifying what should stay and what should go!

I've built a couple of toboggans along these lines now but modify the attachments slightly, folding over the webbing to make a tunnel.



I like this better as it hides the ends of the webbing plus it shares the pull from the lines evenly over both sides of the screw. Though I'm confident in the back of my mind that there is no problem with the screw pulling through, it just makes me feel better if the load is vertical rather than off to one side. I'm using big "repair washers" as well to better clamp the webbing.

I leave my side lines to run freely through the loops but I haven't tried tyeing them off. Perhaps it would work better? Something to play with this winter maybe?

BV

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Offline Zelandonii

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #13 on: November 09, 2012, 09:15:46 am »
Thanks for the insightful replies HOOP and BV. I do like your webbing tunnel idea BV. They would provide a more symmetrical support on the lashing, and greater freedom to distribute the load.

Another question, how far would back would you recommend setting back the crossbar tensioning the curve of the lip? HOOP, from your pics, it looks to be about 16"-18" back. And HOOP, how are you running your tow lines? I see your red webbing as tow points, but can't see how they're running the tow lines from there.

I'm thinking of using three crossbars for the front: 1) tip; 2) approx 4" up from bottom profile to use as the tow point; and 3) 16"-18" from the tip for cold bending/holding the curve of the lip.

Offline Slush Walker

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Re: Building UHMWPE Toboggan – Part 2:
« Reply #14 on: November 09, 2012, 09:29:41 am »
I am curious, when you do not use crosssbars on the PE toboggans, are you having any problems with them rounding out on the bottom due to the upward force of the tie down lashing?  If they rounded out, I would think they would be more prone to rolling over.

SW
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