Good Morning, Our procurement te 1

[daxmann]

Good Morning,

Our procurement team is having trouble finding a bolt and has asked engineering for some help. The primary drawing callout is NAS428-5-32 with the alternate being NAS1801-5-64. I can't seem to find the alternate anywhere so I'm not sure if it is even a good number. Is there anyone here who knows a good alternate for the NAS428-5-32? Is there maybe a MS... or an NSN... equivalent? Thanks for the help.

 

[WKTaylor]

daxman...

1. Be careful: NAS428 has a much different intended function relative to NAS1801.

The NAS428 has a smooth crowned-head which is intended for precision in-out adjustment and head-contact... such as for a precision adjusted mechanical stop.

The NAS1801 is a true assembly 'screw' with a dished head and shouldn't be used as a stop

2. Per latest Rev NAS428, the -5 [UNF threads, Cd plated steel] was replaced by -5A [UNJF Cd plated steel] threads. Try searching for...

Cad plated steel, thus...
NAS428-5A32 [, NO head pin-hole, NO thread-tip slot]
NAS428H5A32 [Cd plated steel, head pin-hole, NO thread-tip slot]
NAS428K5A32 [Cd plated steel, NO head pin-hole, thread-tip slot]
NAS428HK5A32 [Cd plated steel, head pin-hole, thread-tip slot]

Cad plated A286 CRES, thus...
NAS428P5A32 [Cd plated A286, NO head pin-hole, NO thread-tip slot]
NAS428HP5A32 [Cd plated A286, W/ head pin-hole, NO thread-tip slot]
NAS428KP5A32 [Cd plated A286, NO head pin-hole, W/ thread-tip slot]
NAS428HKP5A32 [Cd plated A286, W/ head pin-hole, W/ thread-tip slot]
NOTE: IF cad plated A286 is NOT required then replace the P code with A, B or M codes

NOTE: a longer-grip length [33 or 34 may also be a possibility].

3. IF, on the off-chance, the NAS428 is used like a 'assembly screw' [NOT a 'stop-head'] then there are other options [than just NAS1801] such as

NAS563--572, thus...

NAS565-32 [Cad plated steel]
NAS565*32 [* = B, C or M code = A286 W Various passive finishes]



Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[daxmann]

Thank you so much WKTaylor. The bolt is used for in and out adjustment so I'll check into the newest rev. Thanks again.

 

[daxmann]

My boss is telling me the change from -5 (UNF threads) to -5A (UNJF)means the threads are different and we can't use them. I can't find anything that shows the threads from a -5 to a -5A makes any difference. Is he correct or is there something I can show him to put his mind at ease?

 

[monkeydog]

The J thread is a "Controlled Root Radius" thread per MIL-S-8879. There has been tolerance studies on the use of UNF to UNJF threads Internal-External and External-Internal. Your Boss was probably burned in his history.

It has been a while since I have looked into it, you can probably find a study on the internet if someone else here does not answer it.

 

[WKTaylor]

daxmann... Huhhhhh?

What does this part thread into... a nut, nutplate, insert, tapped hole?

IF a standard nut, nutplate or insert then threads will likely be [99% probable] UNJF. Some older ANxxx parts might be UNF but they will most likely have -2B quality not UNJF-3B [tight] quality.

A threaded tapped hole might present a problem...but I think that reaming the thread-tips slightly would relieve the problem

IF ANY female threaded part has UNF 2B threads then (a) I'll bet that the UNJF threads will engage 'just fine' or... better-yet... (b) you could upgrade the female threaded part to one that has UNJF threads. I checked several conventional NAS [NASM] nuts and nutplates: all had UNJF -3B threads.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]