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Old 01-09-12, 06:16 PM   #1
Daveyates
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How to straighten a wooden rim

Hi,

Has anybody got any ingenious ideas of how to unbuckle a wooden rim?
My rear rim has a warp in it and i need to straighten it before lacing the wheel back up.
I read on a Google search that a man put a rim in his shower under hot water and then tied the rim to a straight wheel until it was dry. He said his rim became straighter but not a perfect repair. Any ideas on how to improve on this?

On my rim it pretty much straight but then a 1/4 of it has an s shaped warp to it.
The warp is left and right along the rim and not up and down , so it is still round when viewed from the side.

Also for anybody who has never held wooden rims before they are really flexible when unlaced. If you push down on them they really flex. I'm not 100% sure i would feel safe while riding on them

But i would like to build the wheel up to use at slow speeds and plus i'm building some alloy wheels for everyday use.

Any advice is appreciated.

Thanks
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Old 01-09-12, 06:30 PM   #2
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Steam is the tried and true method of bending wood. Any google search will find a lot on steam bending.

Also, like every other elasic material, there will be an amount of springback. So if you want "flat", you will have to bend the rim beyond "flat". Clamp it down, hit with steam and voila, straight rim.

In addition to flat, you will also need to control the roundness. It would be pretty easy to put a router on a pivot and run a perfectly circular groove in some plywood. the wheel would "snap" in place.

I ride wooden wheels and although I don't have the greatest confidence in them, but they have held up. I have only been unsuccessful in truing a wooden wheel. It's like straightening a rubber band.
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Old 01-09-12, 07:06 PM   #3
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Boatbuiders bend wood by making a steam box. A 2x2 wood box, staple 4mm plastic stick wood in, put a electric a tea kettle and your good to go.So you steam your rim then remove it use gloves then fasten it to a straight rim.It should be pliable enough to get the buckle out.You could probably do it in the shower with a tea kettle.
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Old 01-09-12, 07:21 PM   #4
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I be a little worried moisture would cause any laminations to come unglued. 1/4" side to side seems like it could be corrected in truing...

I put wood rims on my Paramount track, just because!
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Old 01-10-12, 04:20 AM   #5
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I be a little worried moisture would cause any laminations to come unglued. 1/4" side to side seems like it could be corrected in truing...

I put wood rims on my Paramount track, just because!
Sorry i mean't a quarter of the rim is warped not a 1/4 of an inch.

Thanks for the advice guys!

I saw on Youtube a guy steaming wood with a wallpaper stripper so i might try that.

Cheers
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Old 01-10-12, 07:51 PM   #6
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In the boat business we overbend by about 10%. Steam it for an hour per inch of thickness. If it's not too thick you can wrap it in absorbant rags and poor boiling water over it. Rather than a steam box, you can use a piece of large hose. Sometimes the Fire Department will give you a piece of worn fire hose. Don't stop the ends up tight, just stuff some rags in there. The steam should flow through, but not too freely.
I like the idea of tying it to a true rim and tightening the lashings slowly. How far out is it? You can do a lot just by pulling on it with the spokes when you true the wheel.
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Old 01-10-12, 08:06 PM   #7
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You can use a heat gun like a paint stripper, better than a steam rig, because it's hotter and easier to direct the heat where you need it.
But you can burn the wood if not careful.
Your success will depend on the fixture that you'll clamp the rim into, and how much it's over bent. You can clamp it in the fixture, then apply heat.
What kind of wood is the rim made of, and is it glue laminated?
If it is a Euro rim, it is probably Beech, and not laminated.
A picture would be nice.
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Old 01-10-12, 08:11 PM   #8
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Steam is just an easy method to get a lot of heat to a large piece of wood all at once. You don't need the steam; you need the heat. Heat is what softens the lignin in the wood fibers. It's probably worth noting that the Venetian gondola builders use an open fire to get the bends they need in their ribs. So, that being said, I'd say a common home heating pad would be a good place to start, and if that doesn't do the trick then consider a heat gun.
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Old 01-12-12, 05:48 AM   #9
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Thanks for all of the helpful advice!

I'm not sure how i would over bend it by 10% as the warp is S shaped and so the warp is bending on two different sides.
I think i shall try the boiling kettle and rags idea and then strap it to a straight wheel until fully dry.
After i shall see if the 10% spring back can be brought in by spoke tightening.

David i shall post some photos later when i have time.

Cheers
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Old 01-12-12, 06:49 AM   #10
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Maybe lace it up and apply the heat pad after you get it as true as possible, then true it again while heated.
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Old 01-12-12, 08:34 AM   #11
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Maybe lace it up and apply the heat pad after you get it as true as possible, then true it again while heated.
Good idea and thanks.
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Old 01-13-12, 08:24 AM   #12
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Well the rim is bound up so wish me luck!



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Old 01-14-12, 06:48 PM   #13
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I'm quite surprised because this system appears to of worked!

The rim looks straight like the other rim now.

For anybody interested here is what i did
.
As you can see from the photos i bound the rim inbetween two aluminium rims.
I bound them as tight as i could and then placed the whole unit in my shower base.
Inserted the plug and filled up to the top of the rims with hot water.
Left it until the water had cooled and then filled it up with hot water a second time.
Left it again while i went out and then removed the rims when the i got back and the water had cooled.

Then just left to dry.

Unless the rim springs back over the next couple of days the jobs done.
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