npt - tapered reamers

[prowlerman]

I want to drill-ream-tap an engine case to clean the oil ways then blank with aluminium NPT caps. the thing im not sure of is i need to buy the reamers, do i need a reamer specific to the NPT angle/taper. any help will be very appreciated.

 

[langy]

You don't need a reamer, just drill the hole the size of the start of the tap and then tap out, NPT is a taper thread.
You would be better off using steel pipe plugs.

 

[prowlerman]

Cheers Langy, people ive talked to said it just makes the job easier if you reamer the hole first as it gives you an easier start as the tap is in the hole a couple of mm, the reason behind the aluminium plugs is its a aluminium case sorry i should have said Dave

 

[langy]

I've never used a tapered reamer Dave never was taught to either, In ally it will cut the thread very easy, use lubricant.
I use steel plugs in ally blocks, If you use ally you will struggle to get them out again, If you do get them out the thread will probably be damaged.

Cheers Langy, people ive talked to said it just makes the job easier if you reamer the hole first as it gives you an easier start as the tap is in the hole a couple of mm, the reason behind the aluminium plugs is its a aluminium case sorry i should have said Dave

 

[prowlerman]

I've never used a tapered reamer Dave never was taught to either, In ally it will cut the thread very easy, use lubricant.
I use steel plugs in ally blocks, If you use ally you will struggle to get them out again, If you do get them out the thread will probably be damaged.

Ok thank you Langy, I wont worry about the reamer then , as for the plugs I see what your saying about ali against ali but i was concerned about using steel plugs because of leaks when the two metals expand and contract

 

[brightspark]

Ok thank you Langy, I wont worry about the reamer then , as for the plugs I see what your saying about ali against ali but i was concerned about using steel plugs because of leaks when the two metals expand and contract

it wont be a problem core plugs are made of steel and just a press fit

 

[prowlerman]

it wont be a problem core plugs are made of steel and just a press fit

This is on a high performance vw based engine, its not done on standard engines, but done on engine builds that are costing a few grand to make 100% sure all rubbish is removed from all oilways, thats why i need to pull the orignal press fit blanking plugs out then tap for the npt plugs

 

[langy]

Loctite them in and expansion won't be a problem.

Ok thank you Langy, I wont worry about the reamer then , as for the plugs I see what your saying about ali against ali but i was concerned about using steel plugs because of leaks when the two metals expand and contract

 

[prowlerman]

Loctite them in and expansion won't be a problem.

thanks again Langy, I will order the steel ones then , other people who have done this with the ally ones have said once there in there in for good which only causes problems later on.

 

[langy]

I try to never put ally screw fittings into ally mate, its like asking for problems later.

thanks again Langy, I will order the steel ones then , other people who have done this with the ally ones have said once there in there in for good which only causes problems later on.

 

[paul_f]

Have you got the NPT tap yet?

If not I'd use BSPT and the BSPT plugs as they are far more easily available.