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New pair
02/25/2019 at 17:34 • 0 commentsThe journey begins with a template of the original modified Walmart sandal with the holes marked & the plastic pieces all drawn to scale.
The pattern is drawn on EVA. The EVA is cut with scissors. It can also be cut with a soldering iron or hot wire & lots of ventilation. Sandals have always been made of 2 layers of EVA. For speed, use 2 x 6mm sheets. For immunity to rocks use a 10mm + 6mm sheet.
E6000 was applied to 1 layer of EVA.
2 layers of EVA are clamped around the edges until the glue cures.
Soling has to be cut based on the final EVA size rather than the template. It has to be 1/8" wider around the string holes, to prevent sideways expansion of the foam from pressing the string directly on pavement.
Square holes are cut in the EVA with an xacto.
It's much easier to melt the holes with a T-12 soldering iron. The trick is using lots of ventilation & pulling the tip out without it getting stuck. It's easier to melt partway into both sides.
String & plastic reinforcement pieces are prepared. The ends of the string are scotched, then cut. Plastic pieces have to be round to reduce wear on the sole.
The plastic pieces are made out of isopropyl alcohol bottles. The plastic is heated, then hole punched when it's soft. The hole punch becomes very hot.
String is installed. The ankle string needs to extend different amounts behind the holes. For lions, the piece on the inside of the paw needs to extend 6" & the piece on the outside of the paw needs to extend 1".
The rear string is pulled tight, with the relative lengths of the 2 sides kept the same.
The string should be marked in the middle to keep the 2 sides from changing length.
Then the marked position is pulled out to 1/2" behind the sandal. This determines how far forward or backward the paw sits. It was determined by trial & error. A more determined animal might be able to adjust it by feeding string through the ankle holes.
At this point, the string positions in the holes should be marked to keep those constant.
The rear string is wrapped around itself 3 times. The inner string is now longer than the outer string, allowing them to be fastened on the outside of the paw.Fasteners are installed. A small orange farstener will attach to the thong. A large black farstener will attach to the ankle strap. The orange farstener is stock. The black farstener has been ground out for 2 laces to fit inside.
Rear laces fastened.
Front lace is installed.
The front lace is scotched into a loop. Important to keep the scotch tape as far from the toes as possible, so it doesn't chafe.
The laces are tightened against a lion paw. The trick is keeping the heal section the same length. The farsteners should all be on the outside, where they won't press on any body part. It might be easier to wait until the soles are glued on before tightening against the lion paw, but this requires keeping the glue away from all but 1 of the string holes.
Only after fitting the laces can the outline be traced on the sole. A silver sharpie is essential for black rubber.
Finally, E6000 is applied for the sole.
The latest trick is to glue the outer ankle string to the sole. The ankle string is pulled sideways by the thong, so this tries to keep it in position.
The sole is clamped around the edges. 2 more clamps are required than the EVA, in order to bond around the ankle string.
The curing process takes another 12 hours. The soles cover over all the foam, laces, & plastic reinforcements, revealing a solid rubber underside. The sandals are now permanent. The thong can be tentatively replaced with great effort & luck but the rest can't be changed without making a new sandal.
E6000 could be replaced by hot glue for temporary replacement of some parts. This causes the sole to fall off in hot weather.
CA glue is applied to the string ends before wearing. Then the ends receive a hot glue coating to prevent the CA glue from chafing. The laces can't be removed once they're CA glued.
The lace shrinks over time, but in the rare cases the measured lengths are excessive, it can be trimmed or taped to itself.
Extra soling material is later glued on the sole, where it experiences the most wear.
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New design
01/18/2019 at 07:27 • 0 commentsA proper hole punch provided much more accurate holes than the drill. The rear holes were 1/2" farther back than the Walmart template.
Polypropylene squares for foam reinforcement returned. Should definitely make the rear squares wider. Considered using a single sheet of tough plastic over the entire sandal, to protect from rocks. Such a variant is a must for trails. Titanium would actually now be practical in place of all the plastic, if only lions had the money. This would give the toughness of 4mm Vibram soles without the weight. It's still hard to believe lions once ran on bare 4mm soles without any foam.
The 2 layers of foam were tacked with E-6000. 1/16" string was painstakingly bundled for another attempt.
Now the string would be completely above the soles instead of extending below the soles, hopefully providing enough protection for the 1/16" string.
The soles were hot glue tacked to the foam, to allow the string to be replaced.
The soles will need extra patches, when the most heavily worn areas are determined.
After lacing, the laces were trimmed again. Getting the right lengths of rear lace is still a bit of trickery. Fortunately, a bit of effort can still shift the rear lace around without removing it.
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400 miles on 1mm soles
01/13/2019 at 08:07 • 0 comments400 miles since the introduction of 1mm rubber
It manely wore in front. The problem is the front has to be tacked to prevent it from flopping down. When the material over the tacks wears through, it'll flop down.
The protective flaps wore through. Nothing to do but glue new flaps on top of the old ones.
The string was indistinguishable from random fibers. Blog posts since 8/26/18 show the string gradually fraying. The frayed sections could now no longer be pulled through the holes. The string was replaced on Aug 26, at least 700 miles ago. It's amazing it was ever as pristine as it once was. Not sure what causes the fraying or why it hasn't disintegrated.
With OSH closed, the smooth Lehigh 1/8" string is no longer sold locally.
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24 miles in EVA sandals
12/26/2018 at 18:20 • 0 commentsIt was the fastest 24 miles a lion ever ran, manely because of the pawwear. It was 2 days after a speed workout. The toe plug tape wore through & a hot spot still developed on the toe. Need to double the tape. Cushioning from 12mm of EVA was adequate. Foot pain was about equal to the Hokas.
Got 2 blisters. This was not from socks or a toe box but the toes rubbing against each other & the EVA. There is going to be a lot of taping.
The multiple plies of EVA definitely have to be tacked to each other & the sole to prevent them from sliding around. Allowing the EVA to slide around causes it to tear.
Hot glue has been effective at tacking.
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EVA lifespan
11/29/2018 at 05:27 • 0 comments100 miles seemed to be the limit of dual 6mm EVA sheets. Only 1 sheet fully disintegrated.
The compression after 100 miles was less than a flip flop.
A way was revealed to swap the EVA without completely undoing the string. Getting the lengths right continues to be a problem, since the lengths change as the foam compresses. Toe taping & careful placement of the cable farsteners has allowed the string to be tied at any tightness without chafing. It might someday be practical to use knots.
Definitely time to invest in a 1/4" hole punch. The only ones big enough are the hammer & chisel type. Drilling holes with the drill bit & exacto knife was terribly inaccurate, whether or not it weakened the material.
With OSH joining the retail closures, the Lehigh NML48 string which was so easy on lion paws is a lot more expensive.
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12mm EVA + 1mm Vibram
11/07/2018 at 23:45 • 0 commentsAfter 28 miles, the 6mm EVA was crushed down to 2mm & the metatarsal started acting up again, so the decision was made to double up the EVA.
A small plate was sandwiched inside to aid the toe plug.
Another flap was hot glued outside protect the toe plug.
70 miles later, the metatarsal had no problems, the 12mm EVA was crushed, but it was still easier on the metatarsal than 6mm alone. The mane problem was the EVA becoming very slippery when wet. The 2 sheets also tended to slip on each other.
The soles after 100 miles were on track to last maybe 500 miles.
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EVA + Vibram
10/29/2018 at 17:30 • 0 comments$32 turned into a small sheet of rubber. It definitely didn't look big enough to justify the price.
https://www.amazon.com/Vibram-Tania-Protective-Sheet-Style/dp/B00I3LW9K2/
https://www.amazon.com/Bulk-Buy-Foamies-10-Pack-1199-21/dp/B00KDMQB4Y
To save money, work on electronics instead of clothing. EVA foam & rubber are what all running shoes are made of. You too can buy the raw materials, just like China. Vibram rubber is much harder than ordinary shoe rubber. The choice of thickness was more due to weight than softness.
The rubber had to be tack glued in places to keep from flopping around. 1mm was thin enough to use scraps to protect the string.
8 miles revealed they were very good for road races. They were lighter than flip flops. The foam compressed like flip flops. They were just as sensitive to rocks as flip flops, but less sensitive than bare rubber. The most abundant foam is 6mm. 12mm might be serviceable on trails. The 1mm Vibram showed no wear.
The foam is a brittle packing foam rather than the tough material a yoga mat is made of. It's not as tough as the glossy 2mm foam sold locally. The glossy 2mm might be a good liner for thicker soled sandals.
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Back to sandals
10/25/2018 at 02:15 • 0 commentsA month after going back to shoes, the swelling & pain manely disappeared. Ran in sandals again & the swelling & pain returned. It didn't return with the flip flops, only with the vibrams. The metatarsal stress isn't from 300lbs of lion pressing down on it but from the whiplash as the toes follow behind the midpaw. The whiplash is a much smaller force, but repeated thousands of times. Might have to see a human doctor to finally heal the paw. Being part human has these problems, despite being manely lion.
Ideas emerged for using thinner vibram material, adding stock EVA foam on top, & ditching the suede. Surprisingly, the existing lace holes have held stacked materials together nicely without any heavy adhesive.
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Hoka vs home made
10/05/2018 at 02:13 • 0 commentsOpening the toe boxes came a lot faster than it did back in the days of being used to wearing shoes. The Hoka was truly awful, after 3 years of racing flats & sandals. The severe hamstring pain, blisters, & plantar fascia pain returned. It became obvious how they could cause all the tendinopathies of years past. Cushioning converts force into heat. The compression of the load bearing paw & expansion of the raised paw checks your paw strikes slightly higher than normal, exerting more stress on the hamstrings in their extended positions.
Metatarsal healing proceeded rapidly after converting to the Hokas. Got back to 9 slow miles within a week, but swelling was persistent.
Then, got back to 18.6 slow miles. The thick sole of a Hoka caught a curb & sent the lion down for the 1st time in 7 years. There was unbelievable hamstring pain from the Hokas & the historic initial plantar fascia pain which slowly faded away with use, but the feet didn't hurt as much as sandals. Have come to recognize it as swelling in the upper hamstring tendons rather than glute pain, because the pain is magnified by sitting & eventually leads to pinching of the sciatic nerve.
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Return of the Hokas
09/29/2018 at 01:55 • 0 commentsIt's the last pair of untouched, 2nd generation Hoka Cliftons in the world. They were bought before the high hamstring tendinopathy affair of 2015 & never worn. The arch padding was a real problem for lions. Being so high created another mechanical disadvantage. The price has remaned the same. The newer generations are heavier.
It was decided to use them for trails & to try to run again without waiting 5 years for the fracture to heal. It didn't improve until going back to shoes full time & not running. Must have forgotten how intense unpadded sandals were at even walking speeds.
Still wouldn't use Hokas for speed.
7 miles of 12 minute miles were decent but not perfect. Hokas cause more pain on their own than a fracture, but it's temporary.