homemade BB chaser?

I will be painting a frame sometime in the next couple months. I will likely want to chase the
threads afterwards, and was wondering if anyone has ever made a homemade thread chaser for the BB?

my idea was to take an old steel BB cup, put a fat bolt through it and nuts tightened down on each
side of it, weld a handle on as a crank, and then carefully mill grooves into it, perpendicular to
the threads (and clean them up as necessary), to allow the chips a place to go. would it work? would
it not be aggressive enough? am i asking for trouble?

anthony

 

Well, it might work. You can do a fair job with a small wire wheel and a dremmel tool to clean most
of the paint crap out actually. You can even carefully clean the face of the shell with a file or
sharp knife to get rid of paint. I've done this when I knew the threads and shell were in good shape
and parallel and it works fine. Not high-tech, but if you're in a pinch, it'll do.

Cheers!

Scott..
--
Scott Anderson

"ant" <[email protected]> wrote in message
news:[email protected]...
> I will be painting a frame sometime in the next couple months. I will likely want to chase the
> threads afterwards, and was wondering if anyone has ever made a homemade thread chaser for the BB?
>
> my idea was to take an old steel BB cup, put a fat bolt through it and nuts tightened down on each
> side of it, weld a handle on as a crank, and then carefully mill grooves into it, perpendicular to
> the threads (and clean them up as necessary), to allow the chips a place to go. would it work?
> would it not be aggressive enough? am i asking for trouble?
>
> anthony

 

ant wrote:
> I will be painting a frame sometime in the next couple months. I will likely want to chase the
> threads afterwards, and was wondering if anyone has ever made a homemade thread chaser for the BB?
>
> my idea was to take an old steel BB cup, put a fat bolt through it and nuts tightened down on each
> side of it, weld a handle on as a crank, and then carefully mill grooves into it, perpendicular to
> the threads (and clean them up as necessary), to allow the chips a place to go. would it work?
> would it not be aggressive enough? am i asking for trouble?

I've done this for damaged threads, but it's not necessary for just paint.

Go to the hardware store and buy a cylindrical wire brush designed to fit into your electric drill.
The typical item for this is about 3 inches long, about an inch in diameter.

At the shop I keep one of these permanently chucked into an old, cheap high-speed 1/4" drill. Stick
it in from the right side of the bb and zzzzzz the paint right out without removing irreplaceable
metal from your BB.

Sheldon "Learned This Trick From Francis Bolag" Brown
+--------------------------------------------------------------+
| The holy passion of Friendship is of so sweet and steady | and loyal and enduring a nature that
| it will last through | a whole lifetime, if not asked to lend money. --Mark Twain |
+--------------------------------------------------------------+ Harris Cyclery, West Newton,
Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts
shipped Worldwide http://captainbike.com http://sheldonbrown.com

 

Yup, many years ago I made a BB thread chaser from an old pitted set of BB cups and I'm still using
them. You need both cups if your BB has British or ISO threads since one side has right hand threads
and the other side has left hand threads (as my bikes do). I believe that Italian threads are right
hand on both sides as are French. I took a hacksaw and made a cut perpendicular to the threads into
both sides of the cups, starting from the inside and going about 2/3 of the way accross. The cup was
so hard that I had to heat the places where the cuts were to go red hot with a propane torch and
then let them sit in the air until they were cool. This softened the steel enough that I could cut
it with my saw. This process puts two slots perpendicular to the threads and when you screw the cup
in the edges of these slots clean and chase the BB threads. The rust, paint, grime, whatever comes
up through the slots. Works very well. I can't say whether it works as well as a real thread chaser
because I've never had one of those My homemade one works well enough that I've never considered
buying a real one. One other tip: You might need to spread the slots slightly by tapping a blade
screwdriver into them. (Put the cup with the outside down on your workbench and put the screwdriver
blade into the slot and tap downward. A blade screwdriver tip is tapered so the further you tap it,
the more youll spread the slot. Don't overdo this. I think I used the homemade chasers without
spreading at first but after some use the slots got narrowed up a bit.) I just turned my chasers
into the BB with regular BB cup tools.

One final thought: Why not put masking tape on the BB threads before you paint? It would still be a
good idea to chase the threads but some tape would minmize the amount of of paint to be removed
(likely there would still be some rust or crud to be removed.

Good luck, Bob Taylor

 

I assume you want to chase the threads because they will be covered with paint. If this is the case,
why not just cover the threads with grease before painting? Wipe it off when done. Ernie

ant wrote:

> I will be painting a frame sometime in the next couple months. I will likely want to chase the
> threads afterwards, and was wondering if anyone has ever made a homemade thread chaser for the BB?
>
> my idea was to take an old steel BB cup, put a fat bolt through it and nuts tightened down on each
> side of it, weld a handle on as a crank, and then carefully mill grooves into it, perpendicular to
> the threads (and clean them up as necessary), to allow the chips a place to go. would it work?
> would it not be aggressive enough? am i asking for trouble?
>
> anthony

 

Why not grease the threads and put stoppers on each end of bb. Use a powerful solvent like methylene
chloride to get any paint that may have gone in off. I screw in an old, steel bb cup to make sure
the threads are smooth. If they are not, go to a local shop and have them chase and face.

On 25 Jan 2003 17:26:08 -0800, [email protected] (ant) wrote:

>I will be painting a frame sometime in the next couple months. I will likely want to chase the
>threads afterwards, and was wondering if anyone has ever made a homemade thread chaser for the BB?

 

You're going to an awful lot of trouble just to keep paint out of the bottom bracket threads! Why
not just install a pair of bottom bracket cups into the frame prior to painting? Afterward just
remove them and all should be well.

--Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

"ant" <[email protected]> wrote in message
news:[email protected]...
> I will be painting a frame sometime in the next couple months. I will likely want to chase the
> threads afterwards, and was wondering if anyone has ever made a homemade thread chaser for the BB?
>
> my idea was to take an old steel BB cup, put a fat bolt through it and nuts tightened down on each
> side of it, weld a handle on as a crank, and then carefully mill grooves into it, perpendicular to
> the threads (and clean them up as necessary), to allow the chips a place to go. would it work?
> would it not be aggressive enough? am i asking for trouble?
>
> anthony

 

"Mike Jacoubowsky" <[email protected]> wrote in message
news:<[email protected]>...
> You're going to an awful lot of trouble just to keep paint out of the bottom bracket threads! Why
> not just install a pair of bottom bracket cups into the frame prior to painting? Afterward just
> remove them and all should be well.

Thanks for the replies, folks. In truth, I never really intended to paint my bb threads. I mentioned
painting because another thread was dealing with chasing after painting. (i was going to mask it
off, but greasing the threads in addition sounds like a good idea)

But i do want a thread chaser, amd it sounds like it could work, so im goign to make myself a lh/rh
pair out of an old bb. the wirebrush method sounds excellent for normal cleaning.

thanks

anthony