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HOW TO: Sand/Ream a seat tube/fork tube.

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Hey everyone, just wanted to share a simple way I use to sand out imperfections inside tubing, sometimes I find I burn through thin seat tube tubing while welding and end up with a spot inside the tube that will not allow the seat post to fit properly. Or there is rust inside a fork tube that will not let the stem fit properly.

Normally you can just fix it with a half-round or rattail file, but sometimes you need to smooth even further, or deeper than a file can reach, that is where this method works well.

Start with a piece of 3/8 rod and cut a slot in the end:

14849249632_35b14ec618_z.jpg


Slide a piece of doubled over sand paper strip into the slot you created:

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Hammer the slot down closed on the sandpaper so it is held in a bit better:

14869462613_823edeb171_z.jpg


Roll the sandpaper around the rod in the direction your drill travels:

14849247382_ef6aa28ce6_z.jpg


Fit the other end of the rod into your drill and the sandpaper end into the tube and ream away with an up and down motion similar to honing the bores on an engine block.

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Keep checking your sandpaper is remaining firmly held in the slot, as you don't want to lose it inside the tube. Pretty soon you will have a tube that works as intended:

14662954549_a82206e9ed_z.jpg


Luke.

UPDATE April 2019:

The above method is very good for small amounts of reaming, but sometimes the tube shrinks a fair amount when welding and you need something more aggressive...

A 26mm (for a 1" tube) mill broach welded to an old bolt works well, just make sure you use some sort of cutting fluid/lubricant (I use ATF) and hold on!

IMG_20190408_201141527.jpg
 
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Sounds good this will make life easy again.
I used to have a .5"-1" hone that I used but I can't find it & when I went to buy a new one all I can find is .75"-1.5" or bigger.
 
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Sounds good this will make life easy again.
I used to have a .5"-1" hone that I used but I can't find it & when I went to buy a new one all I can find is .75"-1.5" or bigger.
Those little brakes cylinder hones are really great for it too, as you say though, hard to find these days.!

Luke.
 
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Yea I bought one of the .75" ones and its too big for most old forks (at least when they are so rusty) but your deal will hopefully save the day for me because all my vintage bikes need steer tubes cleaned out.
 
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Would this build up enough heat to ruin paint?
 
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Would this build up enough heat to ruin paint?
If you ran it too long I guess that could happen, best bet would be to do a little at a time and keep the paper moving up and down the tube, keep checking the temperature of the tube with your hand, if it starts getting warm, give it a rest for a bit.

Luke.
 
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Excellent idea on the metal rod and the hammer crimp! I've always used wooden dowel rods but no good way to tighten them on the sand paper.
Thanks Luke.
 
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I do the same as steel rod with a fiberglass tent pole, split it with a razor knife and use a long strip of emery cloth. If you dont have a tent pole yiu can buy a fiberglass garage marker pole meant for a reflector. Works well for polishing out corrosion

Weld distortion, bought some drill bits, usually have the right size, or long carbide barrel burr on an air tool kinda pricey for the extended burrs.
 

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