Page 29-03 brass elbow fitting (F69-F-04X02) tap size?

[bertschb]

I'm on page 29-03 step 2 where we are asked to install the brass elbow (F69-F-04x02) into the lower gear brace (U-01402). I'd like to run a tap through the threads in the lower gear brace before I install these elbows but I don't know what size tap I need. Can anybody help?

This is the elbow I'm referencing:

 

[BobDz]

The ad appears to show you that it is 1/4 pipe thread on the male end.

 

[stigaro]

Those are tapered NPT threads. You'd have to be careful running a tap in them as they could widen the thread causing the fitting to not seal. NPT fittings seal as you tighten them, so you want a little friction in them. That said, I bought a set of 5 different NPT pipe taps on Amazon, but I don't have the link handy. I've yet to use them.

Just another note, if you are installing the AS Flightlines brake lines or Beringer brakes, you will end up removing these compression fittings and installing AN flare fittings instead.

Edited to change to NPT threads, not SAE.

 

[bertschb]

Just another note, if you are installing the AS Flightlines brake lines or Beringer brakes, you will end up removing these compression fittings and installing AN flare fittings instead.

Oh man, thanks for this. I am installing Beringer brakes w/ AS Flightlines hoses and fittings. The Beringer brakes are backordered from Vans. No clue when they will arrive. Do you know if I will have access to install the AN flare fitting after finishing the fuselage?

I tried very gently threading the elbows into the gear brace but they were tight. In fact, on one of them I couldn't get the elbow started. I didn't want to force it so I decided to clean the threads first. I have a little (very little) Akzo primer overspray in the holes which is probably part of the problem.

I've spent an hour trying to figure out which tap I need. I'm just dizzy. NPT, MPT, FIP, HSS,...As you can tell, I'm no machinist - or is that a pipe fitter?

Will this work:
https://www.amazon.com/dp/B0C7H4JQX...=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM&th=1

 

[stigaro]

Oh man, thanks for this. I am installing Beringer brakes w/ AS Flightlines hoses and fittings. The Beringer brakes are backordered from Vans. No clue when they will arrive. Do you know if I will have access to install the AN flare fitting after finishing the fuselage?

I tried very gently threading the elbows into the gear brace but they were tight. In fact, on one of them I couldn't get the elbow started. I didn't want to force it so I decided to clean the threads first. I have a little (very little) Akzo primer overspray in the holes which is probably part of the problem.

I've spent an hour trying to figure out which tap I need. I'm just dizzy. NPT, MPT, FIP, HSS,...As you can tell, I'm no machinist - or is that a pipe fitter?

Will this work:
https://www.amazon.com/dp/B0C7H4JQX...=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM&th=1

Yes, you can access to these fitting once the fuselage is done. I just removed these to install the AS brake lines a couple weeks ago. No worries there. I would just put a plug in the holes until you get the right fittings and would hold off tapping the threads until then. I know Beringer used banjo fittings a lot, so not sure if they use a banjo or AN fitting at the gear fittings. The AS Flightlines documentation is not the greatest, but it may help out here. I also had to drill out a couple holes in the spar web to allow the AS brake lines to fit through. The AN fittings on the lines are too big to use the existing holes. Again, you might want to check the documentation on this as it might be easier to drill the web while you have better access (I had to use a 90 degree drill with an extension on the finished fuselage).

Those taps look similar to the one I bought. I think that's correct.

 

[jrs14855]

NPT is national pipe thread. Tapered pipe threads on nearly all small airplane brakes are 1/8 NPT NOT 1/4. Cleveland and Grove at the caliper are 1/8. I don't know anything about Berringer.
You are likely to need a bottoming tap to clean up the threads. This is a specialty item from a machine shop supplier.

 

[bertschb]

I also had to drill out a couple holes in the spar web to allow the AS brake lines to fit through. The AN fittings on the lines are too big to use the existing holes. Again, you might want to check the documentation on this as it might be easier to drill the web while you have better access (I had to use a 90 degree drill with an extension on the finished fuselage).

I looked at the "instructions" on the TS Flightlines website and they weren't much help. Just to make sure I drill out the correct holes and to the correct size...

Do I drill the lower of the two holes shown below - and through both the F-01403 and F-01404 spars and on both L&R sides (four holes to be enlarged total)? And is 1/2" adequate?

Wide view here...close up shot on the right ------>

 

[bertschb]

NPT is national pipe thread. Tapered pipe threads on nearly all small airplane brakes are 1/8 NPT NOT 1/4.

This 1/8 and 1/4 stuff is very confusing to this retired IT guy. The threaded hole I'm talking about is larger than both 1/8 and 1/4.

 

[stigaro]

I looked at the "instructions" on the TS Flightlines website and they weren't much help. Just to make sure I drill out the correct holes and to the correct size...

Do I drill the lower of the two holes shown below - and through both the F-01403 and F-01404 spars and on both L&R sides (four holes to be enlarged total)? And is 1/2" adequate?

Wide view here...close up shot on the right ------>
View attachment 58223 View attachment 58224

That's right, only the bottommost holes on each spar web need to be enlarged. I think 1/2" sounds about right, but I'd have to confirm. If you're at the stage where the two fuselage halves are joined, then you don't have much to gain by enlarging the holes now. You're already going to need the extension and 90 degree drill, so you might be better off to wait until you have the brake lines in hand to confirm the size for the Beringer lines. Just be prepared to enlarge these holes in the future. Came as a bit of a surprise to me.

 

[bertschb]

If you're at the stage where the two fuselage halves are joined, then you don't have much to gain by enlarging the holes now.

I haven't joined the halves yet.

 

[stigaro]

This 1/8 and 1/4 stuff is very confusing to this retired IT guy. The threaded hole I'm talking about is larger than both 1/8 and 1/4.

View attachment 58225

Yep. NPT sizes are not the actual dimensions.

 

[bertschb]

Yep. NPT sizes are not the actual dimensions. View attachment 58226

You've got to be kidding me. No wonder this $#@! has confused me for 50 years...sheesh!

 

[stigaro]

I haven't joined the halves yet.

OK, gotcha. Then it might be a good time to drill them out. But maybe confirm with Van's that the Beringer brakes come with AN fittings to the gear brackets. I drilled to 1/2" and used a SB-500-6 snap bushing on each hole.

 

[stigaro]

You've got to be kidding me. No wonder this $#@! has confused me for 50 years...sheesh!

I hear you. I'm Canadian and have been waiting in the wings for 40 years to make the switch to metric.

 

[bertschb]

I drilled to 1/2" and used a SB-500-6 snap bushing on each hole.

Thank you for this. You've been a huge help to me today!

 

[mburch]

This 1/8 and 1/4 stuff is very confusing to this retired IT guy. The threaded hole I'm talking about is larger than both 1/8 and 1/4.

Take a look at the section on pipe thread fittings in section 5 of your plans... there's a table showing the actual diameter of pipe thread fittings from 1/8 to 3/8.

 

[bertschb]

Take a look at the section on pipe thread fittings in section 5 of your plans... there's a table showing the actual diameter of pipe thread fittings from 1/8 to 3/8.

Thank you for this reminder to read section 5. I read it several times last year while preparing for the build but some things (like this pipe thread stuff) didn't click until I read it again today. Lots of relevant information in section 5.27 (pipe thread fittings).

 

[PaulvS]

There can be variation between NPT fittings depending on the manufacturing tolerance when the threads were cut. Sometimes a fitting is "bad" and it is worth checking the hole with another fitting to verify if the problem is the hole or the tapered male fitting.
If you do buy a set of taps, try to get a quality set because the cheap unbranded ones can break off and get stuck in the hole. About the only NPT tap I've needed is 1/8-27, the others have been UNC for #6, #8, #10, 1/4 and UNF for #10, 1/4.