Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 02-16-12, 10:06 AM   #1
ljsense
Senior Member
Thread Starter
 
ljsense's Avatar
 
Join Date: Sep 2009
Location: Madison, Wis.
Bikes:
Posts: 269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
What size drill to use to bore hole for a 9/16" pedal tap

I know that taps recommend a specific drill sizes so that you cut the threads properly.

My googling is turning up lots of tap/drill size combos, but not for the cycling specific 9/16" pedal taps.

Anyone happen to know the recommended drill size?
ljsense is offline   Reply With Quote
Old 02-16-12, 10:53 AM   #2
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 29,660
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 217 Post(s)
Quote:
Originally Posted by ljsense View Post


Anyone happen to know the recommended drill size?
33/64" or .516" inches is correct and will yield a 73% thread which is the close enough to the 75% industrial guideline.

You can also use a 1/2" if that's what you have or if that's the limit of your drill chuck. However using a 1/2" tap will increase the tapping torque and load the tap up faster, so keep that in mind.

Here's a link to a nice site that list tap drills for most threads, and has a calculator for those not listed. Note you need to enter the decimal, not fractional diameter, and use 75% thread as this is as strong as 100% thread, but will reduce strain on the tap.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.

Last edited by FBinNY; 02-16-12 at 11:04 AM.
FBinNY is offline   Reply With Quote
Old 02-16-12, 11:06 AM   #3
HillRider 
Senior Member
 
Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Posts: 28,847
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 66 Post(s)
Pakk Tools makes a set of 9/16x20 pedal taps: http://www.parktool.com/product/peda...x-20-tpi-tap-6 They recommend the 33/64" tap drill FBinNY mentioned.

Remember you need both of these two taps as the nds pedal is left-hand threaded.
HillRider is offline   Reply With Quote
Old 02-16-12, 11:47 AM   #4
Grand Bois
Senior Member
 
Grand Bois's Avatar
 
Join Date: Mar 2005
Location: Pinole, CA, USA
Bikes:
Posts: 16,625
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 54 Post(s)
You don't drill at all if you are retapping 14mm threads to 9/16"!
Grand Bois is offline   Reply With Quote
Old 02-16-12, 11:49 AM   #5
Bianchigirll 
Bianchi Goddess
 
Bianchigirll's Avatar
 
Join Date: Apr 2009
Location: Camp Hill, PA
Bikes: Too many to list here check my signature.
Posts: 22,434
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
I sort of want to know what the OP is doing that he needs to tap something
__________________
Bianchis '87 Sport SX, '90 Proto, '90 Campione del Fausto Giamondi Specialisma Italiano Mundo, '91 Boarala 'cross, '93 Project 3, '86 Volpe, '97 Ti Megatube, , '90 something Vento 603,

Others but still loved,; '80 RIGI, '80 Batavus Professional, '87 Cornelo, '09 Motobecane SOLD, '?? Jane Doe (still on the drawing board), '90ish Haro Escape
Bianchigirll is offline   Reply With Quote
Old 02-16-12, 12:27 PM   #6
fietsbob 
coprolite
 
fietsbob's Avatar
 
Join Date: Jun 2010
Location: NW,Oregon Coast
Bikes: 7
Posts: 19,595
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 429 Post(s)
Taps a re tapered at the end, unless specifically a Bottoming tap.

measure the bottom of the V of the thread in the tap with your caliper.
then look for that drill size.
fietsbob is offline   Reply With Quote
Old 02-16-12, 02:20 PM   #7
JohnDThompson 
Old fart
 
JohnDThompson's Avatar
 
Join Date: Nov 2004
Location: Appleton WI
Bikes: Several, mostly not name brands.
Posts: 16,446
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 89 Post(s)
Quote:
Originally Posted by Bianchigirll View Post
I sort of want to know what the OP is doing that he needs to tap something
Maybe planning on giving Mark Stonich some competition in the crank-shortening business?
JohnDThompson is online now   Reply With Quote
Old 02-16-12, 02:53 PM   #8
Bianchigirll 
Bianchi Goddess
 
Bianchigirll's Avatar
 
Join Date: Apr 2009
Location: Camp Hill, PA
Bikes: Too many to list here check my signature.
Posts: 22,434
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Quote:
Originally Posted by JohnDThompson View Post
Maybe planning on giving Mark Stonich some competition in the crank-shortening business?
That had crossed my mind but that seems a tricky venture without a good drillpress or milling machine
__________________
Bianchis '87 Sport SX, '90 Proto, '90 Campione del Fausto Giamondi Specialisma Italiano Mundo, '91 Boarala 'cross, '93 Project 3, '86 Volpe, '97 Ti Megatube, , '90 something Vento 603,

Others but still loved,; '80 RIGI, '80 Batavus Professional, '87 Cornelo, '09 Motobecane SOLD, '?? Jane Doe (still on the drawing board), '90ish Haro Escape
Bianchigirll is offline   Reply With Quote
Old 02-16-12, 03:09 PM   #9
ThermionicScott 
Gratuitous glib and snark
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers)
Posts: 13,391
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Upgrading the pedals on a one-piece crank?
__________________
Quote:
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
RUSA #7498
ThermionicScott is offline   Reply With Quote
Old 02-16-12, 04:39 PM   #10
ljsense
Senior Member
Thread Starter
 
ljsense's Avatar
 
Join Date: Sep 2009
Location: Madison, Wis.
Bikes:
Posts: 269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
I've got a bare aluminum Sugino triple crankset with 175 mm arms that is sitting around doing nothing.

I'm going to mount a 24t 74 mm BCD chainring to the inner position, then grind and file away the excess spider arm material, put pedals at about 120 mm, and cut and grind off the rest of the arms.

After final filing and a bit of polishing, this crankset is going to replace the Ashtabula crankset on my daughter's bike. I got a bottom bracket adapter from Harris cyclery.
ljsense is offline   Reply With Quote
Old 02-16-12, 04:42 PM   #11
ljsense
Senior Member
Thread Starter
 
ljsense's Avatar
 
Join Date: Sep 2009
Location: Madison, Wis.
Bikes:
Posts: 269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Why, you ask?

Projects like these keep me from drinking.

And I'm intrigued by the concept of a high performing kid's bike. They use them all the time; they might as well have decent bearings and components.
ljsense is offline   Reply With Quote
Old 02-16-12, 04:56 PM   #12
ThermionicScott 
Gratuitous glib and snark
 
ThermionicScott's Avatar
 
Join Date: Aug 2011
Location: CID
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers)
Posts: 13,391
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 131 Post(s)
Cool! Don't take it personally that our attention span is short and we tend to move quickly from the "how" to the "why."
__________________
Quote:
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
RUSA #7498
ThermionicScott is offline   Reply With Quote
Old 02-16-12, 05:54 PM   #13
hueyhoolihan
Senior Member
 
Join Date: Dec 2010
Location: Above ground, Walnut Creek, Ca
Bikes: 7⃥ 9 road bikes
Posts: 6,401
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
just looking at all my cranks and am wondering whether their is enough width at 120mm from the spndle for a pedal eye. but i suppose anybody that has enough ambition and knowhow to attempt it has already addressed this issue...

edit: then again it's not as if Eric Heiden is going to be riding it.
hueyhoolihan is offline   Reply With Quote
Old 02-16-12, 06:47 PM   #14
FBinNY 
Senior Member
 
Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
Posts: 29,660
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 217 Post(s)
Quote:
Originally Posted by hueyhoolihan View Post
just looking at all my cranks and am wondering whether their is enough width at 120mm from the spndle for a pedal eye. ...

edit: then again it's not as if Eric Heiden is going to be riding it.
I think the edit covers it. there's probably adequate strength for a child, though not for an adult. Anyway children heal faster.
__________________
FB
Chain-L site

An ounce of diagnosis is worth a pound of cure.

“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin

“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN

WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FBinNY is offline   Reply With Quote
Old 02-16-12, 07:36 PM   #15
Bianchigirll 
Bianchi Goddess
 
Bianchigirll's Avatar
 
Join Date: Apr 2009
Location: Camp Hill, PA
Bikes: Too many to list here check my signature.
Posts: 22,434
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
You know some guys swoon over some of those older triple cranks.

It does sound like a interesting idea though.
__________________
Bianchis '87 Sport SX, '90 Proto, '90 Campione del Fausto Giamondi Specialisma Italiano Mundo, '91 Boarala 'cross, '93 Project 3, '86 Volpe, '97 Ti Megatube, , '90 something Vento 603,

Others but still loved,; '80 RIGI, '80 Batavus Professional, '87 Cornelo, '09 Motobecane SOLD, '?? Jane Doe (still on the drawing board), '90ish Haro Escape
Bianchigirll is offline   Reply With Quote
Old 02-16-12, 10:33 PM   #16
ljsense
Senior Member
Thread Starter
 
ljsense's Avatar
 
Join Date: Sep 2009
Location: Madison, Wis.
Bikes:
Posts: 269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Quote:
Originally Posted by Bianchigirll View Post
You know some guys swoon over some of those older triple cranks.

It does sound like a interesting idea though.
When she outgrows the bike, I'll take off the crank and put it on eBay and someone will be the only one in the Rivendell Reader circulation with a 120 mm Sugino triple, and they can regale their friends with the advantages of short crankarms, ("I barely even have to bend my knees!") as is suddenly popular.
ljsense is offline   Reply With Quote
Old 02-16-12, 10:35 PM   #17
ljsense
Senior Member
Thread Starter
 
ljsense's Avatar
 
Join Date: Sep 2009
Location: Madison, Wis.
Bikes:
Posts: 269
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 5 Post(s)
Quote:
Originally Posted by FBinNY View Post
33/64" or .516" inches is correct and will yield a 73% thread which is the close enough to the 75% industrial guideline.

You can also use a 1/2" if that's what you have or if that's the limit of your drill chuck. However using a 1/2" tap will increase the tapping torque and load the tap up faster, so keep that in mind.

Here's a link to a nice site that list tap drills for most threads, and has a calculator for those not listed. Note you need to enter the decimal, not fractional diameter, and use 75% thread as this is as strong as 100% thread, but will reduce strain on the tap.
Thanks! and thanks to HillRider, too.
ljsense is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 07:29 AM.