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PostPosted: Wed Jun 26, 2013 8:28 am 
Lincs, East and South Yorks Deputy AEC
Lincs, East and South Yorks Deputy AEC
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Joined: Sun Apr 08, 2012 11:56 am
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Location: Doncaster
Hi all

I need to clear out the bottle cage and mudguard threads on a frame of mine, what size tap should I buy, I don't know anything about taps and don't know what to ask for.

A link to an online shop or pictures would be good.

Thanks in advance.

Trebz


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PostPosted: Wed Jun 26, 2013 8:43 am 
Retro Guru
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Joined: Thu May 03, 2012 7:13 pm
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Location: The Cock Inn, Tillett, Herts
Use a cotton bud to fill the threads with paint stripper, then turn a normal bolt into it while it's still soft.


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PostPosted: Wed Jun 26, 2013 9:21 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8209
Location: New Forest, UK
M5 for most things, M6 for brake bosses.


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PostPosted: Wed Jun 26, 2013 9:42 am 
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Location: Camden, London
if you're not sure that tap you have is right one, then find bolt that fits the std boss or eye, find a nut that fits that bolt (so same size and thread) and the nut should easily go on tap as if were a bolt. If it starts requiring brute force then something wrong........


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PostPosted: Wed Jun 26, 2013 10:11 am 
Lincs, East and South Yorks Deputy AEC
Lincs, East and South Yorks Deputy AEC
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Chopper1192 wrote:
Use a cotton bud to fill the threads with paint stripper, then turn a normal bolt into it while it's still soft.


I tried just that last night but without the paint stripper, I sheered the thred off the steel bolt I used. The internal thread on the mudguard hangar on top of the dropout is knackered, I need to cut a new thread into the hangar.


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PostPosted: Wed Jun 26, 2013 10:15 am 
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Ah, sorry. Thought you might be cleaning things up after powder coating or summat.


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PostPosted: Wed Jun 26, 2013 10:17 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
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Location: New Forest, UK
You really shouldn't use that much force when clearing a thread. Always also back it off a quarter of a turn every turn or so to clear the thread.
If you still have part of the bolt in the thread then you need to get it out before trying to repair. Re-tapping will not help unless you go to a larger size.


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PostPosted: Wed Jun 26, 2013 2:13 pm 
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Joined: Mon Sep 03, 2012 2:26 am
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Location: Kuala Lumpur
You can make a perfectly effective thread cleaner out of an old bolt. Take a bottle cage bolt with longish thread and make two cuts along the length of the threaded shank using a junior hacksaw or file them using a needle file. Make the cut deeper at the leading end of the bolt shank and shallower toward the bolt head. Remove any burs with a little wire brush if you have one. It's basically a homemade tap, you can't use it to cut new threads but it will repair bruised threads and clean out any muck. You can reuse the same 'tool' for years. Here's a sample pic i found online but i suggest making the cuts deeper and longer than this photo.


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PostPosted: Wed Jun 26, 2013 2:35 pm 
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Location: Camden, London
RadNomad wrote:
You can make a perfectly effective thread cleaner out of an old bolt. Take a bottle cage bolt with longish thread and make two cuts along the length of the threaded shank using a junior hacksaw or file them using a needle file. Make the cut deeper at the leading end of the bolt shank and shallower toward the bolt head. Remove any burs with a little wire brush if you have one. It's basically a homemade tap, you can't use it to cut new threads but it will repair bruised threads and clean out any muck. You can reuse the same 'tool' for years. Here's a sample pic i found online but i suggest making the cuts deeper and longer than this photo.


Interesting tip, not seen this before, do you think it would work with BB threads and old steel cups ?


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PostPosted: Wed Jun 26, 2013 2:36 pm 
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Location: The Cock Inn, Tillett, Herts
Superb tip.


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