Classic cars forum & vehicle restoration.
|
Author |
Message |
mgb Guest
|
Posted: Mon Jun 04, 2007 12:03 pm Post subject: NSP threads - what drill bit size ? |
|
|
Hello
I would like to make a couple of threaded holes to take a 1/8" and 1/4" NSP adapters, could you please tell me what size drill bits I should use.
Many thanks
Mike |
|
Back to top |
|
|
Uncle Joe Guest
|
Posted: Mon Jun 04, 2007 1:36 pm Post subject: |
|
|
First off, they are called NPS, not NSP. Assuming you are not asking for a taper thread, then the ABSOLUTE correct sizes are:
For the 1/8-27 size, use drill size S.
For the 1/4-18 size, use 29/64.
If you dont have these drill sizes, and not many people do! its possible to use an 11/32 for the smaller, and a 7/16 for the larger....
NPS is an American standard, are you sure they arent BSP?
UJ |
|
Back to top |
|
|
Rick Site Admin
Joined: 27 Apr 2005 Posts: 22447 Location: UK
|
|
Back to top |
|
|
Uncle Joe Guest
|
Posted: Mon Jun 04, 2007 2:23 pm Post subject: |
|
|
Yes, welcome to the forum, mgb.
Rick, its nice to know someone appreciates me... |
|
Back to top |
|
|
mgb Guest
|
Posted: Thu Jun 07, 2007 7:02 pm Post subject: |
|
|
Many thanks UJ for the info and to Rick for the welcome.
I got the name of the thread wrong, it should have been npt and I think that it is a tapered thread. I am fitting a fuel pump union to a tank along with a couple of extra unions for a level guage.
Always thought there was a bit if dsylxeia in there somewhere
Cheers
Mike |
|
Back to top |
|
|
Uncle Joe Guest
|
Posted: Thu Jun 07, 2007 8:04 pm Post subject: |
|
|
Do you want the info for NPT? Being the mine of information that I am...
UJ |
|
Back to top |
|
|
mgb Guest
|
Posted: Thu Jun 07, 2007 11:22 pm Post subject: |
|
|
Yes please, that would be a big help |
|
Back to top |
|
|
Uncle Joe Guest
|
Posted: Fri Jun 08, 2007 7:59 am Post subject: |
|
|
Taper threads are a little more difficult to do at home. If I didnt have the tools, I would give the job to a small local engineering company. If any still exist!
For the 1/8" use an R-size drill, follow up with a 1/8NPT Taper Reamer, then tap.
For the 1/4" use a 7/16 drill, follow up with a 1/4" NPT Taper Reamer, then tap.
Do not miss out the reamer step!
Let us all know how you get on.
UJ |
|
Back to top |
|
|
mgb Guest
|
Posted: Fri Jun 08, 2007 12:12 pm Post subject: |
|
|
Many thanks
As I only have 3 holes to do, I think I will take it round to my local engineering firm
Cheers
Mike |
|
Back to top |
|
|
Uncle Joe Guest
|
Posted: Fri Jun 08, 2007 1:07 pm Post subject: |
|
|
If you tell us more about the particular job, then there might be other solutions to suggest.
UJ |
|
Back to top |
|
|
mgb Guest
|
Posted: Fri Jun 08, 2007 2:48 pm Post subject: |
|
|
I am making a petrol tank out of a fire extinguisher case for my autotest car, I have a brass union with an 1/8" npt thread for the outlet and 2 brass 90 degree unions with 1/4" npt thread. One of the 90 degree unions will go at the top of the side of the tank, the other at the bottom, with a length of petrol resistent clear plastic tube between them.
The walls of the tank should be thick enough to drill and tap - hence the question.
Cheers
Mike |
|
Back to top |
|
|
|
|
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
|
php BB powered © php BB Grp.
|