J3Flyer02m
J3-Cub Member
- Joined
- Oct 18, 2012
- Messages
- 149
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I have a pair of Federal 1500 skis, and considering mounting UHMW plastic on the bottom with a thin strip for the keel. I found this post on another forum, but I'm hesitant to put holes in my 1946 1500 skis. I was considering 1.5" wider around the edges, and fasten with counter sunk flat head bolts with nylon nuts. Thoughts?
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Installed 1/4 UHMW on the bottoms of my 1500As. I dadoed out an area aprox. 1/8 " deep by 1 1/4 inch wide to cover the existing keels. I also built a pair of simple cradles to hold the skis upside down so I could work on them. I don't have the skis in front of me , but I believe I spaced flush head rivits (#4) aprox. 1 inch apart all around the outside. I did not have to do any forming. The UHMW conformed to the bottom of the ski quite nicely with lots of squeeze clamps, c clamps quick clamps, then clecos, until I started driving rivets. I used a pnuematic rivet squeezer (very nice!) but it dented the plastic pretty good too. Next time I will probably hand squeeze them. I attached an 1/8 thick by 1" wide aluminum keel with 10-32 or 10-24 countersunk screws every six inches or so by drilling and tapping holes through the original keel and the bottom of the ski. I believe the keel is also held in place by the front bolt on the ski that holds the tab, and maybe the back bolt also. Next time I would install inserts (heli coils or twinsert) in the ski. Also Next time I would use a strip of UHMW for the keel instead of the alum. Even 1'wide alum causes a lot of drag if you hit gravel or grass etc. I cut the UHMW plastic just a hair bigger than the bottom of the skis. Some of the Super Cub guys are making the UHMW an inch or more wider all the way around thus increasing the surface area for, I would guess, deep, soft snow.
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Dave
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Installed 1/4 UHMW on the bottoms of my 1500As. I dadoed out an area aprox. 1/8 " deep by 1 1/4 inch wide to cover the existing keels. I also built a pair of simple cradles to hold the skis upside down so I could work on them. I don't have the skis in front of me , but I believe I spaced flush head rivits (#4) aprox. 1 inch apart all around the outside. I did not have to do any forming. The UHMW conformed to the bottom of the ski quite nicely with lots of squeeze clamps, c clamps quick clamps, then clecos, until I started driving rivets. I used a pnuematic rivet squeezer (very nice!) but it dented the plastic pretty good too. Next time I will probably hand squeeze them. I attached an 1/8 thick by 1" wide aluminum keel with 10-32 or 10-24 countersunk screws every six inches or so by drilling and tapping holes through the original keel and the bottom of the ski. I believe the keel is also held in place by the front bolt on the ski that holds the tab, and maybe the back bolt also. Next time I would install inserts (heli coils or twinsert) in the ski. Also Next time I would use a strip of UHMW for the keel instead of the alum. Even 1'wide alum causes a lot of drag if you hit gravel or grass etc. I cut the UHMW plastic just a hair bigger than the bottom of the skis. Some of the Super Cub guys are making the UHMW an inch or more wider all the way around thus increasing the surface area for, I would guess, deep, soft snow.
=============================
Dave
