Source for 1" x 12 tpi Whit taps and die.

[Eugene]

Forward planning time .... I'd like to make some accessories for my Myford M type lathes which have 1" x 12 tpi Whit spindle nose; dividing head, rotary table, stuff like that.

Given a following wind I can turn a fair to middling thread, but I'd really like to run a final tap or die through to get the kosher thread form and match the existing precision spindle. Browsing the net I haven't found anything.

Any clues?

Thanks in advance,

Eug

[John Rudd]

Looks to me that thread is a special, as the standard Whit thread form is 8 tpi......
You might try one of the specialist makers, Avon engineering.I used them for the t n d set for my Chester 9 x 20, but they aint cheap.....

[Bluechip]

True, not BSW but .... WF Fredding stuff fairly common in sundry TPI's

Like here:

http://www.tracytools.com/taps-and-dies/whitform-taps-dies?product_id=1148

Will erode the Treasury somewhat though .. 

Dave

[Eugene]

Dave,

Thank you, that looks very promising. I didn't see "Whitform" on their website.

Do I take it that this is a true Whitworth thread form not some made up type of thing, and that these are so named because they don't fit the "official Whitworth"  charts? There seems to be no technical description, it's probably so blindingly obvious that everyone understands but me. I can live with the price, didn't think it too bad at all.

Eug

[mattinker]

I suspect that Whitform describes the thread angle, 55° as opposed to the Unified and metric 60° thread.

Regards, Matthew.

[Bluechip]

Eugene, Matthew ..

It is as far as I know.
I can't think of anything else it could mean.
I have B.S.Brass Thread stuff marked eg 1/2" x 26  WF but I prefer W.F. as Whitworth Form ..
As Matthew says  55^o and with the root / crest radii etc. to spec.

Dave

[awemawson]

Whitworth defined not only the 55 degree angle, but also the percentage of rounding of the crests and troughs, so theoretically any diameter and pitch could be Whitworth Form. Then a standard series of preferred diameters was established, each with a corresponding Hex size of head / nut. However the hex sizes were later reduced by 'one size' as a material reduction exercise (WW2 I think).

[Eugene]

Thanks men,

We're somewhere close then; I'll give them a bell tomorrow and get the full SP.

Eug

[Pete W.]

Hi there, Eug,

I suggest that you have a think about using chasers.  They know that they are available for 12 tpi Whit Form, I have a set.

You'd need to 'creep up' on the final diameter but they's handle the thread form part of the exercise.

If you start the thread by single pointing, you could change to the chaser to finish - registering the thread shouldn't be too difficult at 12 tpi. 

[Eugene]

Gents,

Thanks for all your help.

Tracey Tools confirmed today that "Whit Form" is just their designation for parts that are not listed within the normal BSW or BSF range. The threadform is indeed "proper" Whitworth 55 degree, roundy tops and all, and is applied to "specials" which a 1" x 12 tpi is.

When the time comes I'll order some up.

Eug