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Author Topic: Building UHMWPE Toboggan – Part 1:  (Read 15784 times)

Offline HOOP

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Building UHMWPE Toboggan – Part 1:
« on: January 03, 2011, 11:31:27 AM »
I made a new 10 footer for this season.   Material is 1/4 inch thick UHMWPE (ultra high molecular weight polyethylene), 16 inches wide.  You can get three 16 inch wide pieces with no waste off a 4x10 sheet.   

I needed a new longer toboggan because this winter I am switching from using rigid pulk sled-boggan hybrids, to a flexible snaky sled, when in deep soft snow conditions.   I have found that my rigid sleds started to develop a twist and would cut out of the sled float while hauling.  Sometimes they would carve out at almost 45 degrees and bog down in deep snow.   It got to the point where it was no longer tolerable time and effort wise, horsing the sled straight again every few minutes.  I noticed my buddies with snaky plastic toboggans never had a tracking problem with their sleds, so flexible is what I am going with in early winter deep soft snow. 

There are many ways to make a plastic toboggan, so this is just my way, and no doubt can be greatly improved upon (since I am semi-useless with tools).  I chose 1/4 inch material because I have always used that in both UHMWPE and HDPE, and it has never cracked in the cold, is super rugged (overkill), and is easy to countersink machine screw bolts by hand drilling with simply eyeballing the depth.   The next option down to save weight is 3/16 inch stock, which I may try next time when I purchase a sheet.  Not sure how it is for countersinking and crack resistance?    I would be interested in other’s assessment of 3/16 inch material, because lighter is better if it does not crack.

This is part 1 because of too many photos and verbiage (yes I have a problem!).  Stay tuned for part 2 after this.

Laying out the sheet to cut the blank with a cheapo rip fence (three 4 foot pieces).  I had to duct tape it to minimize warping, and the circular saw still cut off line.   First mistake - I did not use a table saw (I don’t have one).  I highly recommend a table saw!  If you don’t own one, find a buddy who has one!


 
This is my bending form for the front bend that I made years ago (lots of work, but once its done, you have it for life).  Yes always keep your old hockey sticks – they make great building material!


 

Side view of the bending form.  The curve was made from graph paper with the equation Y=X squared (which makes a parabola shape).   I made the X axis units wider than the Y axis for the gradual parabola.   


 

Note the front bar so that I can jam in the blank and it holds itself in there.



I take a propane torch right to UHMWPE.  Just keep it moving.  This plastic is incredibly strong, but not too hard to bend.  It just takes some elbow grease.   Safety note:  I find that Benzomatic torch fitting with the on/off trigger very safe since I don’t have to leave the torch running.  When I release the trigger it shuts off.   Worth the investment. 
 

I flip it in and out of the form to over-bend it beyond the bend of the form, since it wants to relax back.   That plastic is kept hot with the torch, so I need gloves
 

The front bar also allows the extension of the bending area.



Bending is done, and I leave it in the form with a weight block on it for a few days, when I did not have time to work on it. 



When I return and take it out of the form, it wants to relax back.  That’s OK, its soft enough that my front lashing lines will keep it in the position I want.  The first thing to do is the all-important installation of the front pull bar.   I position it to have some lightness in the front:  Not too far forward, and not too far back. 



I am notorious for not being able to line up drill holes, so I clamp this most important piece of the sled in place so that I drill through the wood and plastic at the same time.   I drill the ends first and insert the bolts upside down just to ensure its lined up.    I know this is stupid basic stuff, but for people without shop skill like myself, this is a major lesson I learned to ensure that holes line up!   This took me years to figure out! 




There was a thread a while back about countersink size and how to gauge the depth.   I use a hand drill and try and pick a bit that is very close to the size of the head of the screw bolt.  I countersink estimating by eye, testing the first few in the holes until I get the image memorized.    For the pull bar I am using six #10 stainless steel machine screws, because there will be major force on these bolts.  My second mistake:  Unfortunately I picked up Phillips head.  I hate, hate, hate Phillips.   I will be replacing these with Robertson head when I have some time.



My pull bar, made of laminated black ash, was made for me by Mapboy, a buddy with great wood working skills, and who owns a big shop, (I should have used his table saw for ripping the sled blank!).   My third mistake:  I bought 1 ½ inch machine screw bolts, and these are too short to fit with the lock washers.  No worries, it will work for the trip I will be using it on, and I have to replace these anyways with Robertson head 2 inch bolts which I will cut off to length after I refit with lock washers.   The wood is also not sealed, so after the trip I will take it off and varnish it and refit. 




A trick I learned is, after drilling the counter sink hole, and before putting the bolt in, is cutting off the burr with a knife.  This burr will catch and drag on the snow and is hard to get off with the screw head in there. 




The pull bar installed with the pull loops installed.  There is a groove cut on the bottom of each pull bar to allow for the webbing.   I used a water knot which is very strong.   This webbing is field replaceable should it break. 




Next is the front bar.   (used the clamps again to ensure drilling lined up).  Those old hockey sticks are great.    I have placed this on the other side before, since the pull is towards the inside of the curl, the bar might work better on the other side, but for this sled I am placing it on the inside for aesthetics.   



For this and the rest of the sled bars I am using  2 inch #8 plated machine screw bolts, with washers and lock washers, since the force on them is less than the pull bar, and I can save weight and cost.   I used 5 bolts on the front bar because it has the constant pull of the front lines which maintain the curl, and this gets some significant force on it when using the front grab handle ( to be installed next). 

The bolts are too long, so with the Dremel tool, (wear your safety goggles!), I cut them to length and polish the sharp ends.


 


Cut to length and polished.  You can see the lock washers with these.   




Those bolt ends are still a potential hazard, so I apply a glop of glue gun stuff on each one. 


 

Stay tuned for part 2. 
http://www.wintertrekking.com/community/index.php?topic=1232.0
« Last Edit: August 18, 2012, 11:39:09 AM 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 Bushcra

Offline White Wolf

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Re: Building UHMWPE Toboggan – Part 1:
« Reply #1 on: January 03, 2011, 02:39:30 PM »
Hoop

A great part 1.  just wondering if you can supply the bending form measurement?  would make it easier for us that are getting ready to build.

Offline HOOP

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Re: Building UHMWPE Toboggan – Part 1:
« Reply #2 on: January 03, 2011, 06:07:58 PM »
Hi White Wolf,

I went out to the garage and measured the form.  It is 24 inches long, and 12 1/2 inches high at the highest point.    That’s a 2x2 on the front and back edge which is a good surface area to hold and clamp the blank.    Nothing really special about that dimension, it sort of just happened. 

To make the curve I used the parabolic equation Y=X squared.   I whipped this off on Excel and attached are 3 versions.  You simply stretch the image to get the shape you want, or if manually graphing, vary the X axis unit spacing.  Feel free to copy the JPG graphs and use on your own computer to stretch to the shape you want. 






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 Bushcra

Offline cousin Pete

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Re: Building UHMWPE Toboggan – Part 1:
« Reply #3 on: January 04, 2011, 01:07:50 AM »
Hello HOOP:  You did a great job describing the whole process with the write up and the pictures.  Nice toboggan! 

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 ravinerat

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Re: Building UHMWPE Toboggan � Part 1:
« Reply #4 on: March 21, 2012, 09:51:47 PM »
Hey Hoop. Why not use Nyloc nuts instead of the lock washer and nut? just getting ready to build my toboggan. I use Nyloc nuts on everything.

RR
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Offline HOOP

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Re: Building UHMWPE Toboggan � Part 1:
« Reply #5 on: March 22, 2012, 08:12:11 AM »
Hey Hoop. Why not use Nyloc nuts instead of the lock washer and nut? just getting ready to build my toboggan. I use Nyloc nuts on everything.

Hi RR,

That's a good idea.  But I have never seen those in the stores here.   Crappy Tire's fasteners section gets worse and worse every year.  Home Depot's is also limited.  I try and use the independent hardware stores here (e.g. Maiers), as much as I can, so I guess I will have to search these out.    Its also just one of those things where I have always used lock washers and nuts  and don't know no better  ???    :)   
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 Bushcra

Offline ravinerat

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Re: Building UHMWPE Toboggan � Part 1:
« Reply #6 on: March 24, 2012, 09:17:36 AM »
Hey i remember those days of living in the North. When doing a project you needed everything at the start or it would be there later. It was a 100 km drive to the Home hwd store.  The Nylocs are a great invention and I use them on everything. I'll have lots of more questions as I start my project. Have you tappered your toboggans?

RR
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Offline HOOP

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Re: Building UHMWPE Toboggan � Part 1:
« Reply #7 on: March 24, 2012, 11:39:43 AM »
Have you tappered your toboggans?

No I don't taper mine.
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 Bushcra

Offline Moondog55

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Re: Building UHMWPE Toboggan � Part 1:
« Reply #8 on: June 02, 2012, 07:36:31 PM »
I'm ready for "Part 2"

Offline brianw

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Offline wintair

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Re: Building UHMWPE Toboggan � Part 1:
« Reply #10 on: May 02, 2014, 04:08:39 PM »
Crappy Tire's fasteners section gets worse and worse every year.  Home Depot's is also limited.  I try and use the independent hardware stores here (e.g. Maiers), as much as I can, so I guess I will have to search these out
I know, this thread is old but it still comes up in searches. Hoop did a very good job explaining how he built his toboggan. A big thank you to him.

I'd like to add  a source for the stainless steel fasteners for those having problems finding them. As a general rule, the hardware stores are marking up the price on fasteners by as much as 1000% (because they are sold by the unit and a certain percentage gets stolen).

I buy my fasteners from http://www.nutty.com/. They ship USPS to Canada. There are minimums though.

Here are a few examples, they have whatever your preference might be (qty is minimum order for the product):

  10-24 x 1-1/2 Flat Hd Phillips Machine Screw 18-8 Stainless Steel:  $0.15 x 50

  10-24 Nylon Insert Lock Nut 18-8 Stainless Steel:  $0.0645 x 100
   
  #10 Flat Washer 18-8 Stainless Steel  $0.0270 x 100

A tip I'd like to add, UHMW and HDPE are easy to machine with woodworking tools. To give the edge a nice and smooth finish, I use a hand plane (block plane works well). Like on wood, I get very thin shavings and it leaves a perfect finish on the edge.
   
Cheers,
Wintair
« Last Edit: October 19, 2017, 02:08:17 PM by wintair »
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Offline Teepee

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Re: Building UHMWPE Toboggan – Part 1:
« Reply #11 on: May 10, 2014, 07:46:55 AM »
I'm 6 toboggans in from the first build from this great thread. :)

I decided to swap the Nyloc's and washers on my builds for low profile T-nuts, the knock in type. They come in stainless/galvanised varieties.



As the nut doesn't protrude above the cross member, I find it is kinder to loads, rolls up tighter, weighs a little less  and needs shorter bolts. They've been well tested now over 3 years and I'm happy they won't let go in use. Marking must be dead accurate to avoid chewing the threads when the bolts are screwed home into the T-nuts.
Pete. :)

Offline lonelake

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Re: Building UHMWPE Toboggan – Part 1:
« Reply #12 on: May 11, 2014, 10:36:13 AM »
Interesting, I have every only used stainless screws countersunk from the bottom of the toboggan, or rivets. Never have had a failure......

LL
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