Model Taper Pipe, MTP, tap drill chart needed

[Reed]

I built a fuel pipe for a hit-n-miss engine, it required a 1/8 MTP thread. I have the taps and dies but no specs on the recommended tap drills.

After searching a bit, I just measured the tap and picked out a bit. It is done, however I would _really_ like to find a tap drill chart for MTP threads.

Anyone have this info?

- Reed

PS, here is the required picture content, it has a check valve with a .125 ball.

 

[Metal Butcher]

Hi .I think Bob Shores had MPT drill size chart. I looked but can't seem to find it.
I'll look again, maybe Someone will come along shortly and post the info.

-MB

 

[Jtrain]

PMResearch use to have a drill chart in their catalog, but i don't see it there now. Something will come up.

 

[Metal Butcher]

PMResearch use to have a drill chart in their catalog, but i don't see it there now. Something will come up.

The PM catalog only shows the following;

Model pipe threads MPT. Not MTP model tapered.

3/16-40 =5/32" drill
1/4-40 =7/32" drill
5/16-27 or 1/16 NPT-(National)= 'D' drill

Nothing about 1/8" model pipe fittings or drill size for tapping.

-MB

 

[Metal Butcher]

Okay! I found my chart (not from Bob Shores).

Tap drill sizes for MTP (model taper pipe).

1/8"-56 = #40 drill.

Hope this helps.

-MB

 

[BigBore]

Here's a link:

http://www.livesteamsupplies.com/livesteamsupplies_015.htm

Ed

 

[Reed]

All helpful. This set (5 sizes; 1/8-56 to 5/16-27) was inherited and the origin unknown although "APEX UK" is printed on them.

Nice to use the correct tap drill instead of using the tap to remove excess material. :-0 That chart is printed and included in the set for the time. Added it to this post for a future searcher.

The last "involved" part for this engine is the piston ring set. With a little time, I'll put together a short build article for this 1/2 scale Maytag engine.

Thank you all very much, - Reed