…..what thread form a 9/16 20tpi thread is? It's not BSF,UNF or CEI
(It's on the crank mainshaft of a Velocette)
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| Anyone know? https://ukbeg.com/forum/viewtopic.php?f=8&t=23905 |
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| Author: | Adam [ 02 Jul 2019 13:41 ] |
| Post subject: | Anyone know? |
…..what thread form a 9/16 20tpi thread is? It's not BSF,UNF or CEI (It's on the crank mainshaft of a Velocette)
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| Author: | pash [ 02 Jul 2019 16:13 ] |
| Post subject: | Re: Anyone know? |
Sounds like British Standard Cycle. Tracey Tools will sell you taps and dies... |
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| Author: | barney [ 02 Jul 2019 18:27 ] |
| Post subject: | Re: Anyone know? |
 
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| Author: | Adam [ 02 Jul 2019 20:47 ] |
| Post subject: | Re: Anyone know? |
Cycle thread was my first choice too, but it turns out to be 26tpi. UNF is the nearest at 18 tpi (I think?) |
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| Author: | pash [ 02 Jul 2019 21:54 ] |
| Post subject: | Re: Anyone know? |
9/16 - 20 is the thread size that’s been used on bicycle pedals since the beginning of time... It’s a BSC as far as I know... |
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| Author: | 03 [ 03 Jul 2019 03:57 ] |
| Post subject: | Re: Anyone know? |
Nick is of course spot on about bicycle pedals. 9/16" 20 tpi is BSCy thread and is also Unified Extra Fine (USA thread). In both cases, they are 60 degree thread form as opposed to other British Standard Thread forms that are typically 55 degrees angle. Since they are used for bicycle pedals, taps and dies are widely available in that size. |
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| Author: | barney [ 03 Jul 2019 06:19 ] |
| Post subject: | Re: Anyone know? |
a very quick and easy google search for 9/16 20 tpi and you get https://www.amazon.com/20-Right-Left-Ha ... B075N48H1S |
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| Author: | barney [ 03 Jul 2019 06:32 ] |
| Post subject: | Re: Anyone know? |
looks like it's a unified USA standard thread https://www.ebay.co.uk/itm/2PCS-9-16-20 ... Sw0RBc66W1 |
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| Author: | x1glider [ 03 Jul 2019 08:00 ] |
| Post subject: | Re: Anyone know? |
barney wrote: looks like it's a unified USA standard thread https://www.ebay.co.uk/itm/2PCS-9-16-20 ... Sw0RBc66W1 Correct. It is a 9/16-20 UN thread per the machinists handbook. And the others are correct about it being a bicycle pedal thread. Apparently, I'm the neighborhood bike repair guy so I have a set for cleaning up botched threads, not that it does you any good from here. Thanks to $2000+ bikes not coming with pedals anymore, it's amazing how many people fuck up their cranks when they try to install their $300 platform pedals. Righty tighty, eh? I hope you're not asking because you need a nut. Difficult to find. None of my fastener sources at work have them and UN threads are common in oil and gas equipment, just not that small. Might have to make one. |
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| Author: | x1glider [ 03 Jul 2019 08:02 ] |
| Post subject: | Re: Anyone know? |
03 wrote: Nick is of course spot on about bicycle pedals. 9/16" 20 tpi is BSCy thread and is also Unified Extra Fine (USA thread). In both cases, they are 60 degree thread form as opposed to other British Standard Thread forms that are typically 55 degrees angle. Since they are used for bicycle pedals, taps and dies are widely available in that size. 9/16"- 24 is actually UNEF. 20 is just UN. |
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| Author: | 03 [ 03 Jul 2019 09:32 ] |
| Post subject: | Re: Anyone know? |
x1glider wrote: 03 wrote: Nick is of course spot on about bicycle pedals. 9/16" 20 tpi is BSCy thread and is also Unified Extra Fine (USA thread). In both cases, they are 60 degree thread form as opposed to other British Standard Thread forms that are typically 55 degrees angle. Since they are used for bicycle pedals, taps and dies are widely available in that size. 9/16"- 24 is actually UNEF. 20 is just UN. I stand corrected, sir 
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| Author: | Adam [ 03 Jul 2019 11:22 ] |
| Post subject: | Re: Anyone know? |
Turns out my confusion has arisen from assuming that British Standard Cycle (BSC) thread is the same as Cycle Engineers Institute (CEI)! The Die I borrowed is etched as 'Cycle' as has 26tpi, this obviously must be CEI. You're advice about 'standard' cycle is spot on, as this is 20tpi. I'm surprised that there's nothing mentioned in my Zeus book. Fire up the Myford!!!
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| Author: | 03 [ 03 Jul 2019 12:59 ] |
| Post subject: | Re: Anyone know? |
Adam wrote: Turns out my confusion has arisen from assuming that British Standard Cycle (BSC) thread is the same as Cycle Engineers Institute (CEI)! The Die I borrowed is etched as 'Cycle' as has 26tpi, this obviously must be CEI. You're advice about 'standard' cycle is spot on, as this is 20tpi. I'm surprised that there's nothing mentioned in my Zeus book. Fire up the Myford!!! NOT IN THE ZEUS BOOK  
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| Author: | Adam [ 03 Jul 2019 13:04 ] |
| Post subject: | Re: Anyone know? |
I was just as surprised. UNEF is in there along with ME threads, which I've never come across, but the commonly used Cycle thread = nil! |
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| Author: | 03 [ 03 Jul 2019 13:13 ] |
| Post subject: | Re: Anyone know? |
Adam wrote: I was just as surprised. UNEF is in there along with ME threads, which I've never come across, but the commonly used Cycle thread = nil! A LOOOOONG time since I looked in a Zeus book! Longer than I care to remember. |
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