Differential Screws

My idea of differential screws is for them to have different pitches, although they would not need to be the same hand. Turnbuckle screws are opposite hands and normally identical pitches. However, I could imaging a turnbuckle with different pitches and the same hand giving a very slow length to rotation movement. Not something I had thought about much before, interesting. They are all very closely related and no concept is wrong, I believe.

These double-ended screws are not 'differential screws' in the normal, english, meaning. For us, the meaning is wrong. This is not by any means the exception with products offered from elsewhere in the world. Try convincing our US cousins that a bolt is not the same as a screw - and they speak english ... !

I suspect that some of the products we need do not have a specific name in some of the far-flung languages (just as the French have 94 different sauces and we have custard or gravy). But mainly the bloke that cobbles the adverts together has only a modest grasp of our language, and no access to relevant technical dictionaries, or the time to look stuff up. So, he looks for something similar and that will do.

Cheers, Tim

I know, isn't it terrible that Johnnie Foreigner cannot be bothered to learn our language. We won the war and all that jazz. And we had an Empire.

Unfortunately, your thesis falls flat on its face as the 'bloke that cobbles together the adverts' is the proprietor of this company:

https://www.jurassictools.com/contact-us/

Until your enlightenment, I was unaware that people in Dorset did not have English as a first language. I will certainly carry a phrase book next time I travel there.

It's not Dorset, but Darsett

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It’s not quite clear, Tim … but if by “the bloke that cobbles the adverts together” you mean tony4cats

May I suggest that you have a look at his non-ebay website: **LINK**

https://www.jurassictools.com

MichaelG.

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Edit: __ beaten to the post

Edited By Michael Gilligan on 30/10/2022 17:12:27

I have a Sandvik 50mm face/shell mill which takes four plain triangular inserts.
It's similar to this one on eBay, but a size smaller, and mine has the inserts facing the right way; I think they are now obsolete.
https://www.ebay.co.uk/itm/173380439411

Each insert is held by a wedge into a shaped backing pad; the wedges themselves are retained and clamped by these double ended left/right screws; in my case quite small and using an M2.5 Allen key.
The wedge itself is threaded internally.

I struggled to find a suitable description on Sandvik's website, but these are similar to the items, though maybe the wrong sizes.

Screw
https://www.sandvik.coromant.com/en-gb/products/pages/productdetails.aspx?c=267.21-830&tab=MatchingProductsForSP

Wedge
https://www.sandvik.coromant.com/en-gb/products/pages/productdetails.aspx?c=262.2-822M

Sumitomo also seem to call them Differential Screws, at least in the MSC catalog anyway
https://www.mscdirect.com/product/details/53923306 

See also, again over the water
https://www.steinerelectric.com/Product/Sandvik-Coromant-5763335-Differential-Thread-Clamping-Screw-1064928

Bill

Edited By peak4 on 30/10/2022 18:24:24

Thanks, Bill … we’re definitely getting there.

One thing that shouts to me is that the price being asked by Mr English is very modest indeed.

Now … if only I had a design for something useful that needed them

MichaelG.

Self centering 2 jaw chuck.