MOTM

Hi All,

I'm trying to acquire a proper set of machine screw taps here and can't 
figure how to read the US screw dimensions.
According to  Paul's part lists the mounting screws for the modules are

                  #8-32 x 3/8

What is what? Esp. what defines the thread dimensions?

  Thanks a lot, Michael.

Hi,
thanks for the comprehensive answer!

clickmrmike schrieb:

> #8 is the screw size, 32 is the number of threads per inch, and the
> screw is 3/8" long. This is also known as an 8x36UNF screw, or a #8
> Fine screw.

#8 is just a name or tag rather than a measure (like fractions of an
inch)?

> The matching tap is available from Farnell UK as part# 02-2209.
> Part#02-2210 would work too. Farnel wants almost 9GBP for this, 
> which
> would be a massive ripoff in the states, so you may want to shop
> around some of the EU machine shop supply spots.

I found a shop here in Vienna which is reportedly specialised in
"exotic" hardware stuff. I'll have a look how good they are.

> If you are making your own mountings, you could also consider using
> the metric screw M4. It's nearly thae same size (the #8 is about
> 4.17mm) and might be easier for you to find both screws and taps 
> for.
Absolutely!
But I got a couple of second hand rack rails where some threads are
bad by forcing in some wrong screws. I'm trying to fix that with the
proper tap since that bad holes damage the original screws as well
besides just scraping off the paint and looking ugly.

  Thanks a lot, Michael.

#8 is the diameter of the screw (0.160 inches)
32 = 32 threads per inch
3/8 = 3/8th of an inch long

Paul S.

----- Original Message ----- 

From: "Michael Zacherl (aka TonTaub) " <egroups@...>
To: <motm@yahoogroups.com>
Sent: Wednesday, November 15, 2006 2:53 AM
Subject: [motm] Screw Dimensions


> Hi All,
> 
> I'm trying to acquire a proper set of machine screw taps here and can't 
> figure how to read the US screw dimensions.
> According to  Paul's part lists the mounting screws for the modules are
> 
>                  #8-32 x 3/8
> 
> What is what? Esp. what defines the thread dimensions?
> 
>  Thanks a lot, Michael.
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
> 
>

On Wed, 15 Nov 2006, timothy cooper wrote:

> I Believe the "8" is the thickness of the screw(milimeters maybe?

Millimeters?  None of that damned commie nonsense here.  We like
to multiply and divide by numbers other than 10.  How many slugs
does your girlfriend weigh?  What's the speed limit in furlongs
per fortnight.  That's the stuff for us.  :-)  And as particular as
Paul is about parts selection, I was always slightly disappointed
he doesn't use Whitworth fittings....

--
Monty Brandenberg

Tim, Paul, thanks for the responses.
Now that abused threads look like someone forced some M4 (ISO) screws
into the rails. I'm trying to fix that.

Another thing came up:
The M5 cage nuts I got with my rack don't fit into the holes of the
rack rails. What's the correct product I've to use?
Esp. the nut dimensions, since I've to be sure that they slide in.

  Thanks again, Michael.

--- In motm@yahoogroups.com, timothy cooper <shari_en_jin@...> wrote:

> I always seem to forget about the Wikipedia, but here ya go....
> http://en.wikipedia.org/wiki/Screw
> everything anyone would need to know and more...look down to the
> "Unified Thread Standard" section that gives the low-down on all of 
> it!
> Ti_



--- In motm@yahoogroups.com, "Paul Schreiber" <synth1@...> wrote:

>
> #8 is the diameter of the screw (0.160 inches)
> 32 = 32 threads per inch
> 3/8 = 3/8th of an inch long

> The M5 cage nuts I got with my rack don't fit into the holes of the
> rack rails. What's the correct product I've to use?
> Esp. the nut dimensions, since I've to be sure that they slide in.

The MOTM-19A rails use #10-32 screws and #10-32 nuts to mount them to a rack 
frame.

Paul S.

clickmrmike schrieb:
> #8 is the screw size, 32 is the number of threads per inch, and the
> screw is 3/8" long. This is also known as an 8x36UNF screw, or a #8
> Fine screw. 
> The matching tap is available from Farnell UK as part# 	02-2209.
> Part#02-2210 would work too. Farnel wants almost 9GBP for this, which
> would be a massive ripoff in the states, so you may want to shop
> around some of the EU machine shop supply spots.
>   

Today I was at the shop I mentioned before and this people are great!

I took one of this rack rails and some original screws with me and they 
sold me the proper tap

http://shop.spiral.at/detail.asp?itemnr=1073028

for EU 8,07 +VAT (20%).
So Farnell's price is indeed steep.

The sales guy even tried the tap and fixed one of the mauled threads for 
a test.
Very nice!

    :-)   Michael.

On 16.11.2006 16:01 Uhr, Paul Schreiber wrote:
>> The M5 cage nuts I got with my rack don't fit into the holes of the
>> rack rails. What's the correct product I've to use?
>> Esp. the nut dimensions, since I've to be sure that they slide in.
>>     
>
> The MOTM-19A rails use #10-32 screws and #10-32 nuts to mount them to a rack 
> frame.

Thanks Paul! So that means (which is of course obvious) that those parts 
are a tad smaller than the metric stuff I have here.

The difference of the UNC/UTS measure (#10) and the ISO measure (M5) is 
just
about  5 - (0.190 * 25.4) = 0,174mm.

So, for upcoming production runs would it be possible to change the 
diameter of the mounting slots of the rack rail to something slightly 
bigger in order to allow metric hardware to fit?
I personally don't care for the time being since I got a lot of this 
rails from a second hand source.
But since it's definitely necessary to file down the holes it could make 
sense.

Or am I the only european guy who ran into this kind of problem? (or the 
others just widened the slots)

    Just a thought,  :-)  Michael.

The MOTM-19As are *supposed* to ship with mounting screws. If not, email me and 
I will send some.

Paul S.

I'll have to talk to the original buyer why he had to widen the mounting slots and if he got that particular screws.
If I'm unlucky with getting them I'll get back to you.

  Thanks a lot, Michael.


On 17.11.2006 2:55 Uhr, Paul Schreiber wrote:
> The MOTM-19As are *supposed* to ship with mounting screws. If not, email me and I will send some.