10/32 Thread

[GrahamL]

I need to get hold of a few countersunk examples (allen key ).
Anyone know who sells but a few ?, another thing I bump a lot when searching is 3/16 fine lists as the same but when I try and thread into the saddle plate of my DM4 its not right , is the pitch wrong maybe for what we mostly carry in australia ?

many thanx

[billdan (Bill)]

Have you tried Metric threads, 3/16 is close to 5mm (M5 bolt), and 5/16 is close to 8mm (M8 bolt).

Cheers
Bill

[Wilso]

Hi Graham,

They use the UNC thread which is a courser thread spacing.
I haven't any of that size, if you can't get any you could always tap it out to an m6
They didn't supply the correct screws?

[Wilso]

I just tried mine.
The holes in the underside of the saddle plate use 1/4 UNC

[AndrewJ]

Gday Graham
Small imperial threads here normally use whitworth thread form vs UNC/UNF thread.
Whilst it can have the same pitch, the thread "angles" and shape form are different, ( ie 55deg vs 60 deg and rounded vs flat roots and crests )
I know whitworth thread pitches are the same as UNC from 1/4" to 1/2"
but not sure how close they are when you get below 1/4"
Need to dig out my old machinery handbook
Andrew

[GrahamL]

Thanx , yes the thread for the handle mount is indeed 1/4
these two are on the saddle face plate, i can make a couple of monting brackets for a couple of small scopes if i can find a couple the right thread .

[Wilso]

The screws for the conversion plate are 3/16
M5 might work if your lucky.
Let me know if your interested in buying my conversion plate, I don't use it.

Cheers

[GrahamL]

Thanx ,,I think I'll ask a little more for now 3/16 fine and m5 available to me dont thread into my DM 4 saddle plate .

Does the conversion plate still have to thread into the saddle plate
3" between centres wilso ?

graham

[Baza (Barry)]

Should find 10/32 at any place repairing american light aircraft, it's a common bolt.

[AndrewJ]

Also most custom bolt suppliers will have these and some sell in small quantities.
I used to use a mob called "CostLessbolts" in Moorabbin as you could go in and get advice on whats available and they would sell small quantities.
They also had a very good range in stainless on the shelves.

Andrew

[GrahamL]

Thanks I think i found a guy today that has some, Tom did explain that In the US these are commonly used something to do with step up tap sizes or something .

[ausastronomer (John Bambury)]

Originally Posted by AndrewJ

Gday Graham
I know whitworth thread pitches are the same as UNC from 1/4" to 1/2"
Andrew

Hi Andrew,

I am pretty sure that doesn't work at !/2". 1/2" BSW is 12 TPI and 1/2" UNC is 13 TPI. I know it definitely works up to and excluding 1/2"; where you can interchange UNC and BSW nuts and bolts.

Cheers
John B

[AndrewJ]

Gday John
Agreed, 1/2" is where it differs
( i should remember that as i have a lathe and mill and one uses 13TPI drawbars and the other uses 12TPI :-( )
But then i also noted the originally mentioned 10-32 is actually UNF
so "roughly" matches a BSF thread and these are different
Also found a good site since that shows some of the "form" differences in a concise format
https://anemo.eu/what-difference-bet...bsw-and-unfunc

Andrew