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Good Morning, Our procurement te 1

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daxmann

Aerospace
Jun 16, 2015
39
US
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.
 
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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]
 
Thank you so much WKTaylor. The bolt is used for in and out adjustment so I'll check into the newest rev. Thanks again.
 
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?
 
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.
 
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]
 
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