BS4 thread

[ariz]

I apologize for this silly question, but as italian I know well metric threads, only vague ideas about the others

so, I'm going to buy 5 centre drills in England and there are 2 options: BS4 or BS2
what does it mean?
what is the greater of them?

http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=360137180957&ssPageName=STRK:MEWNX:IT

thank you

 

[kvom]

BS2 - 1/16 point, 3/16 body
BS4 - 1/8 point, 5/16 body

 

[CrewCab]

As postage for additional items is only €1 it could be worth getting a set of each, budget permitting that is.

and as you are used to metric

BS2 1.6mm point, 4.8mm body
BS4 3.2mm point, 7.9mm body ............ thanks to Kvom for the original info

CC

 

[ariz]

thank you both mates

 

[Blogwitch]

Here is a chart showing you all you need to know about standard imperial centre drills (slocombe drills).

http://www.i-logic.com/utilities/CenterDrills.htm

You can also buy extended centre drills, up to about 6" long, for those awkward little places. These are very expensive ones, but you can buy them much cheaper if you do a bit of searching.

http://www.drill-service.co.uk/Tools.asp?Tool=040000000000


There are other types of tip, 90 degree, left handed, radiused for between centres taper turning, and protected centre type. There may be others, but I haven't come across them.


Blogs

 

[ariz]

very useful Blogs, thank you

when you speak of 'extended' centre drills, do you mean the 'spotting' drills?

is this one (the lenght) the main difference between the 2 type?

 

[Blogwitch]

Ariz,

Just like an ordinary centre drill, but MUCH longer.

http://www.drill-service.co.uk/Product.asp?Parent=040240000000&Tool=16

Bogs

 

[shred]

Does anybody know why there's no 3/8" body centre(er) drill? That would be a most useful size for me.

I know I can get spotting drills and the like in 3/8", but a plain old center drill would be the thing..

 

[Blogwitch]

Shred,

It might be a little difficult for you in the US, but metric 10mm ones are available, and is as near as damnit, spot on the size you require.

Let me have a root thru my bits 'n bobs and I might be able to find one or two for you, but don't hold your breath.

Bogs

 

[mklotz]

Does anybody know why there's no 3/8" body centre(er) drill? That would be a most useful size for me.

I know I can get spotting drills and the like in 3/8", but a plain old center drill would be the thing..

ENCO has them...

http://www.use-enco.com/CGI/INSRIT?PARTPG=INLMKD&PMPXNO=3904673&PMAKA=891-4747

 

[shred]

Ah, the "Industry Standard" #4-and-one-half I must have thirty of the things, acquired with various used-equipment purchases and never run across the #4-1/2.

Thanks everybody, I'll snag a couple next I'm trying to get to $50 at Enco.

 

[mklotz]

Ah, the "Industry Standard" #4-and-one-half

Yes, the industry standard 4-1/2. Just like the 4-1/2 Morse Taper or the 0000-160 screw.

This is what happens when clueless twits who know nothing about designing a designation system are allowed to run free in the engineering department.

A good designation system should:

1. Be open-ended at both ends so it can logically designate a new addition to the series.
(What happens when you make a drill smaller than an 'A' or larger than a 'Z'?)

2. Have designators that increase with increasing size. (So much for numbered drills)

3. Contain information about the size/function of the object in the designator. (Numbered and letter drills take note. Also sheet and wire gages. Numbered screws, too.)

If you think about those requirements for a bit you'll probably come to the conclusion that the only designation system that makes sense is the size of the object in some rational dimension. It's not by accident that this is exactly what is done in most metric countries.

Allowing measures of convenience (e.g., sheet metal gages) to creep out of the manufactory and into the marketplace should be a capital offense.