Member postings for Michael Gilligan

Try this, Ian

**LINK**

http://www.schaublin.ch/app/webroot/pdf/cat/5.pdf

MichaelG.

I will leave you to it, Jason

... It's really not worth debating

MichaelG.

Jason,

I regret to say that your catalogue clipping further confuses the issue

It illustrates the Modified Bottoming Chamfer, not the Bottoming Chamfer

The 'Chamfer Styles' tab on this page **LINK** does rather better

https://www.mscdirect.com/basicsof/taps

... interestingly; it also distinguishes between 'bottoming' and 'plug' in a way that makes sense, but is, perhaps, uncommon.

[some other sources use those words as US/UK variants]

https://en.wikipedia.org/wiki/Tap_and_die

MichaelG.

Edited By Michael Gilligan on 15/09/2019 14:04:26

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Thanks for trying, Jason ... but (a) the Axminster one has a male centre, and (b) 2-3 threads is about double what 'bottoming' taps normally had.

MichaelG.

Struggling to follow this discussion, and the terminology

I found Axminster's illustration unconvincing as a 'universal' tap: **LINK**

https://www.axminster.co.uk/axminster-hsse-universal-spiral-flute-taps-ax938282

[ is that really suitable for 'bottoming' or 'plug' use ? ]

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Then I discovered this document: **LINK**

http://www.ymwtapsusa.com/download/newsletters/Understanding-the-basics-of-spiral-fluted-taps.pdf

... which is very informative, but lists many variations on the theme

I guess the expedient solution must lie somewhere betwixt these extremes !!

MichaelG.

Indeed, Steve

That's why I've been banging-on about wanting to know how it was made.

It's of no relevance to me personally ... just an interesting puzzle.

MichaelG.

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Yes, Steve : But the Boxford drawing that Pete posted explicitly states 'Plunge Roll'

MichaelG.

"In most of these cases its ignorance or expedience."

... nice summary, Steve.

MichaelG.

Edited By Michael Gilligan on 14/09/2019 22:07:13

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< my emboldening >

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That's what I was wondering, Pete

... hence my hope that someone might know for sure how the metric screws were made.

MichaelG.

Edited By Michael Gilligan on 14/09/2019 21:20:37

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O.K. ... I give up

[ can't find the 'White Flag' smiley ]

Edited By Michael Gilligan on 14/09/2019 19:15:24

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But why would those experts want to roll an ACME thread-form to Metric dimensions.

True ACME is [to the best of my knowledge] exclusively specified in Imperial units.

... If I am wrong; would someone please tell me

MichaelG.

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Perhaps you could explain then, Steve [please]

Why would anyone choose to specify 16mm x some metric pitch in ACME form rather than Metric Trapezoidal ?

[my brain hurts] ... Is it just to make it difficult for customers to second-source spares ?

MichaelG.

To the best of my knowledge, the real 'Picador' is long-gone [although knock-offs of their products seem to be available on ebay]

Best bet is probably to grab these flanges as and when you see them at Car Boot Sales, etc.

MichaelG.

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Edit: ... even Grace's Guide doesn't tell us much

https://www.gracesguide.co.uk/Picador_Engineering_Co

Edited By Michael Gilligan on 14/09/2019 15:25:36

Thanks again, Pete

So we now know [pretty much for sure] that the English version was made for plunge rolling a 10tpi LH ACME form thread ... 'though I can't quite decide whether, or not, the instruction effectively includes the rolling thereof.

[my thinking is that it probably does ... because the ACME form is sufficiently well-prescribed to need no further detailing]

Mystery stll surrounds the [Boxford special] Metric specification though

MichaelG.

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https://www.amesweb.info/Screws/AcmeScrewNutThreadDimensions.aspx

Edited By Michael Gilligan on 14/09/2019 13:23:16

Thanks, Pete

That would be really interesting to see.

MichaelG.

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Quite so, Dave ... and the Pope is usually a Catholic

I am interested in how and where the Boxford screws were made, because that knowledge might help us understand why they chose to use a 'bastard' thread.

MichaelG.

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Thanks for that, Pete

Did they do the thread rolling in-house, or sub-contract, I wonder.

... either way [if I understand the process correctly] that would require a serious machine and long dies.

MichaelG.

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https://m.youtube.com/watch?v=RPcy8-6Hfqg

Edited By Michael Gilligan on 13/09/2019 23:12:25

That's very encouraging, Ron ... thanks for sharing your experience.

MichaelG.

It would be interesting [albeit not particularly useful] to know how Boxford went about making these 'bastard' components.

Presumably; being tooled-up to make make male screws with an ACME thread-form [whether by screw-cutting or by grinding] the easy option would have been to make their own taps to finish the nuts.

If anyone knows how Boxford produced these items, do please tell us.

MichaelG.

Thanks for the clarification, David

... That explains the 'seemingly impossible'

MichaelG.