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Homemade Tensioner


Ash-Kennard

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Yeah, but Bigman, yours is so lanky :P

May as well mount it behind the BB as opposed to the dropout!

A harsh critic methinks :)

Bigmans is simple and effective and suits someone not as likley to smash it to bits.

Mounting behind the BB has got me thinking though... :turned: (lateral head)

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A harsh critic methinks :)

Mounting behind the BB has got me thinking though... :turned: (lateral head)

Nah, I'm just being picky, and an arse ;)

Mounting at the BB works - look at old chain devices which are mounted behind the driveside cup...

A sprung tensioner there would work well, though it would be more vulnerable to knocks etc from landing on your bash/chainring

Could evolve into something though...

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Okay, i'm halfway through making a kennard/bigman style tensioner.... only i've come into some problems trying to drill the holes into the metal. Anyone got any idea what drill bit i need in order to drill it easier, becuase its taking ages just to make a little dimple in the metal :(?

Like a dog returning to its own vomit i've gone and made ANOTHER one. The 4th posted in this thread. This one is to suit pro2. Its a 2 piece with adjustment. The idea is borrowed from the b tension arrangement on rear mechs.

post-8178-1187118976_thumb.jpg

That one is the perfect trials tensioner. Completely out the way, gives fantastic wrap around... now you just need to experiment with different cog sizes and alignment setups and get it marketed. I can see this being a VERY popular style of tensioner.

Edited by Krisboats
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make a dent in it to start off with, just get a nail and twat it with a hammer to start off the hole, stops the bits from moving

I have a dent in the metal.... just no drill bits want to go through it. They just sit there spinning round making f*** all difference to it. I'd imagine i have the wrong drill bits or need a more specialist one, i'm using gold ones (which i thought were designed for metal, maybe not saw blade steel though).

The metal is a cheap wilko's £1 hand saw approxiamtely 1.5mm thick.

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You need to soften the blade really. Get it good and hot (i.e. red) in a blowtorch at the place you want to drill, try to keep the heated area as small as possible cos it doesnt spring as well once softened. Then let it cool slowly, put it down on a brick in some still air (garage shed etc).

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What sort of drill are you using? If it has speed adjustment, slow it right down and apply a good pressure but dont go crazy. Let the bit do the work not you.

Bosch CSB 500 RLE.

0-3000rpm's

I'll give it a go tomorrow, see if b&Q/machine mart have any drill bits designed for cutting hardened steel, should do the job i reckon. I'll give your way a go too before i go have a look though. Cheers dude, Lovin the B-tension based tensioner ;)

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Cutting fluid works wonders to lol.

The drill bits should work fine, the gold ones are the Ti nitride coated ones (think its nitride lol)

I use em at work for drilling through all sorts of steels etc.

Also, make sure the drill is going the right direction ;) made that mistake once or twice haha!

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Okay, its all been drilled now.... after lots of hard work and many snapped drill bits.

Here's some pics of it Built together before i got the metal neatened up.

dsc01369fs5.jpg

dsc01370ei6.jpg

Some tidying

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Attached to the bike

dsc01375li2.jpg

Seems to do the job so far. I can kick it really hard and it just pushes up and returns to place as soon as my foot comes off it. Just need to neaten it up, trim the bolts and sray paint the end sections black.

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Could heat it up with a blowtorch till it's red hot then dip it in used engine oil. Will make it nice and black :)

Sounds like a lot of effort though, and i need to obtain a blowtorch from somewhere :(

I have a can of black spray paint handy on the shelf though, so i'll just spray the end parts i reckon, i can see the spring flexing and the paint cracking and falling off.

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Maybe dip coat it if you have access to a dipcoating thing (blows all the plastic dust up everywhere)

Maybe, a make shift one, heat it up on the stove, and file down a load of plastic? Get the dust from it and throw it over it and hope it works?

Ha ha, that sounds like fun. So i just heat the metal up and hold it above the blender whilst smoe coathangers are in there.... "will it blend" plastic dust stylee?

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