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Re: Lathe user?

Posted: Tue Jun 18, 2019 2:06 pm
by simon.holyfield
Really? thanks for the tip!

Re: Lathe user?

Posted: Wed Jun 19, 2019 10:46 am
by Bob.Murphy
Thanks folks, As I thought - BSCY it will be.

All the dimensions on the CAD drawing are in MMs ( :? ), fortunately I have a couple of Tiger Cub spindles and will use them to get the accurate dimensions.

Ariel spindle (1).pdf
(65.72 KiB) Downloaded 69 times


I'll try to get Bertie's approval before I proceed though ;) .

Bob.

Re: Lathe user?

Posted: Thu Jun 20, 2019 12:30 am
by david.anderson
BSF was also used on Mk2 head bolts/nuts and rocker blocks and VB head bolts. I think Ariel liked to confuse.
David

Re: Lathe user?

Posted: Thu Jun 20, 2019 1:36 am
by john.whiting
1/2"x20 is plain old UNF......and that is what I would use........26tpi is too fine for wheel spindles ,as the threads get bruised ,then strip..............as I well know as Panther used 26 tpi front and rear.....front is Webb forks,and every Webb front spindle is just about knackered with dodgy threads.........and seeing as the spindle is held in a open jaw by the nut tightness.......so for many reasons,I use UNF threads.

Re: Lathe user?

Posted: Thu Jun 20, 2019 9:32 pm
by paul.jameson
On the larger thread sizes, such as those for wheel spindles, Ariel tended to use 20 tpi. I have various sizes of UNF taps and dies which I use to make close replicas of such Ariel originals.

Re: Lathe user?

Posted: Fri Jun 21, 2019 12:23 am
by nevhunter
The UNF is close for 1/2' size. The only difference is 5 degrees on the thread form angle which won't get noticed generally. The trouble with often used fine threads is the wear is a significant factor in loss of strength and they will strip when loose. Also the fine thread is easy to overtighten, as you get more force for less torqueing. Axles generally have to be threaded on a lathe, so you can get a good fit to the nut and have the thread run true to the axis. Nev

Re: Lathe user?

Posted: Fri Jun 21, 2019 11:18 am
by Bob.Murphy
Right, The threads mentioned have the following pitches:

British Standard Whitworth (BSW) = 1/2" x 12
British Standard Fine (BSF) = 1/2" x 16
Unified Fine (UNF) = 1/2" x 20
British Standard Cycle Thread (BSCY) = 1/2" x 26

BertieB is using a Tiger Cub rear hub in his 'LF'. I have a Cub rear wheel spindle in front of me - it has 20 tpi spindle threads.

Ariel use 20 tpi.

So it makes sense to use 20 tpi for the new spindle as well - lets call that a decision 8-)

Now, UNF has a 60 degree thread form - which is what I propose to use. BUT what did Ariel use :?:

I'll be turning the shaft on the lathe and also making the nuts, but I would like it all to be "Standard UNF" thread form - even if I make the nuts a bit larger than standard across the flats.

Bertie (not his real name ;) ) doesn't mind what the spindle thread is so 20 tpi will be OK (I was going to say 'fine', but that might be confusing :D ).

I now need to clear up some questions with BertieB as his CAD drawing doesn't match the standard Cub Imperial bearing sizes :roll: .

Thanks for all the input folks, that was very useful.

Bob.

Re: Lathe user?

Posted: Fri Jun 21, 2019 11:29 am
by simon.holyfield
Ariel would have used BSC, since UNF did not exist in 1929 and BSC/CEI was widely used in the two wheeled manufacturing industry.

Re: Lathe user?

Posted: Fri Jun 21, 2019 12:12 pm
by Mick D
Hi

As stated above, 1/2" CEI / BSC is normally 20 TPI - surely it's easier to use this thread with the matching 'correct' nuts :?

Regards Mick

Re: Lathe user?

Posted: Fri Jun 21, 2019 12:35 pm
by Bob.Murphy
According to my Thread Charts, Cycle Engineers' Institute (CEI) - which metamorphosed into British Standard Cycle (BSCY) used a 60 degree thread angle.

Which makes 1/2" UNF / CEI the same.

Some sizes were dropped when the new standard was compiled. My chart doesn't show 1/2" CEI.

Confused ???

I think it will be easier for all if I stick to UNF, even if I am making the nuts :? .

Bob.