Re: Digest Number 382

> From: RCGipson <rcgipson@...>
>
> hello everyone. i've been reading the discussion about nook ballscrews.
> can someone send me more information as to what screws thay are using
> and price/availability? are they available to the end user?

Look at www.nookindustries.com Prices are comparable to the Thomson
screw McMaster carries, but the Nook nuts have rounded corners that
worked better in my application. They will quote you prices over the
phone, and will sell direct to a business entity that wants to open an
account with them (standard credit reference and all). Otherwise ask
them to refer you to a distributor. The local motion industries
branch took my credit card, and had the parts shipped direclty to me
from Nook. There was a minimum order of a bit over a hundred dollars
which my pair of plain nuts and 2ft screw did not meet, so I spent the
extra for a factory made double-nut preloaded assembly. It makes sense
to figure out what you want and what it will cost on the phone with
Nook, then call up the distributor as they may well have to call up
Nook to get this info then get back to you.

> i want to purchase some screws for a couple of machines i have and get
> the idea that the nook screws can be easily machined.

Easily is a relative term - they are hardened steel just like the
Thomson and presumably all other rolled screws. Take light cuts on a
good lathe with carbide tooling until you get below the minor diameter
of the thread and everything should be fine. Do take a minute to
think about how you are going to hold them (the actual diameter of the
screw may not be anywhere on the datasheet) - either a collet of the
right size or a 3-jaw that you can true up on a test bar of the
same size would probably work.

Chris

--
Christopher C. Stratton, stratton@...
Instrument Maker, Horn Player & Engineer
30 Griswold Street, Cambridge, MA 02138
http://www.mdc.net/~stratton
(617) 492-3358 home/shop